CN111991370A - Intestinal-targeting double-cavity calcium alginate-based composite microcapsule with pumping and constant-speed drug release characteristics and preparation method thereof - Google Patents

Intestinal-targeting double-cavity calcium alginate-based composite microcapsule with pumping and constant-speed drug release characteristics and preparation method thereof Download PDF

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CN111991370A
CN111991370A CN202010843135.XA CN202010843135A CN111991370A CN 111991370 A CN111991370 A CN 111991370A CN 202010843135 A CN202010843135 A CN 202010843135A CN 111991370 A CN111991370 A CN 111991370A
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chamber
boosting
microcapsule
phase fluid
calcium alginate
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CN111991370B (en
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巨晓洁
温霜
褚良银
谢锐
汪伟
刘壮
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Sichuan University
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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K9/00—Medicinal preparations characterised by special physical form
    • A61K9/48—Preparations in capsules, e.g. of gelatin, of chocolate
    • A61K9/50—Microcapsules having a gas, liquid or semi-solid filling; Solid microparticles or pellets surrounded by a distinct coating layer, e.g. coated microspheres, coated drug crystals
    • A61K9/5089—Processes
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K31/00—Medicinal preparations containing organic active ingredients
    • A61K31/33—Heterocyclic compounds
    • A61K31/395—Heterocyclic compounds having nitrogen as a ring hetero atom, e.g. guanethidine or rifamycins
    • A61K31/40—Heterocyclic compounds having nitrogen as a ring hetero atom, e.g. guanethidine or rifamycins having five-membered rings with one nitrogen as the only ring hetero atom, e.g. sulpiride, succinimide, tolmetin, buflomedil
    • A61K31/403—Heterocyclic compounds having nitrogen as a ring hetero atom, e.g. guanethidine or rifamycins having five-membered rings with one nitrogen as the only ring hetero atom, e.g. sulpiride, succinimide, tolmetin, buflomedil condensed with carbocyclic rings, e.g. carbazole
    • A61K31/404—Indoles, e.g. pindolol
    • A61K31/405—Indole-alkanecarboxylic acids; Derivatives thereof, e.g. tryptophan, indomethacin
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K31/00—Medicinal preparations containing organic active ingredients
    • A61K31/33—Heterocyclic compounds
    • A61K31/395—Heterocyclic compounds having nitrogen as a ring hetero atom, e.g. guanethidine or rifamycins
    • A61K31/435—Heterocyclic compounds having nitrogen as a ring hetero atom, e.g. guanethidine or rifamycins having six-membered rings with one nitrogen as the only ring hetero atom
    • A61K31/44—Non condensed pyridines; Hydrogenated derivatives thereof
    • A61K31/4422—1,4-Dihydropyridines, e.g. nifedipine, nicardipine
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K31/00—Medicinal preparations containing organic active ingredients
    • A61K31/60—Salicylic acid; Derivatives thereof
    • A61K31/612—Salicylic acid; Derivatives thereof having the hydroxy group in position 2 esterified, e.g. salicylsulfuric acid
    • A61K31/616—Salicylic acid; Derivatives thereof having the hydroxy group in position 2 esterified, e.g. salicylsulfuric acid by carboxylic acids, e.g. acetylsalicylic acid
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K47/00—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient
    • A61K47/30—Macromolecular organic or inorganic compounds, e.g. inorganic polyphosphates
    • A61K47/32—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds, e.g. carbomers, poly(meth)acrylates, or polyvinyl pyrrolidone
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K47/00—Medicinal preparations characterised by the non-active ingredients used, e.g. carriers or inert additives; Targeting or modifying agents chemically bound to the active ingredient
    • A61K47/30—Macromolecular organic or inorganic compounds, e.g. inorganic polyphosphates
    • A61K47/36—Polysaccharides; Derivatives thereof, e.g. gums, starch, alginate, dextrin, hyaluronic acid, chitosan, inulin, agar or pectin
    • A61K47/38—Cellulose; Derivatives thereof
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K9/00—Medicinal preparations characterised by special physical form
    • A61K9/48—Preparations in capsules, e.g. of gelatin, of chocolate
    • A61K9/50—Microcapsules having a gas, liquid or semi-solid filling; Solid microparticles or pellets surrounded by a distinct coating layer, e.g. coated microspheres, coated drug crystals
    • A61K9/5005—Wall or coating material
    • A61K9/501—Inorganic compounds
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    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K9/00—Medicinal preparations characterised by special physical form
    • A61K9/48—Preparations in capsules, e.g. of gelatin, of chocolate
    • A61K9/50—Microcapsules having a gas, liquid or semi-solid filling; Solid microparticles or pellets surrounded by a distinct coating layer, e.g. coated microspheres, coated drug crystals
    • A61K9/5005—Wall or coating material
    • A61K9/5021—Organic macromolecular compounds
    • A61K9/5026—Organic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds, e.g. polyvinyl pyrrolidone, poly(meth)acrylates
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K9/00—Medicinal preparations characterised by special physical form
    • A61K9/48—Preparations in capsules, e.g. of gelatin, of chocolate
    • A61K9/50—Microcapsules having a gas, liquid or semi-solid filling; Solid microparticles or pellets surrounded by a distinct coating layer, e.g. coated microspheres, coated drug crystals
    • A61K9/5005—Wall or coating material
    • A61K9/5021—Organic macromolecular compounds
    • A61K9/5036—Polysaccharides, e.g. gums, alginate; Cyclodextrin
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K9/00—Medicinal preparations characterised by special physical form
    • A61K9/48—Preparations in capsules, e.g. of gelatin, of chocolate
    • A61K9/50—Microcapsules having a gas, liquid or semi-solid filling; Solid microparticles or pellets surrounded by a distinct coating layer, e.g. coated microspheres, coated drug crystals
    • A61K9/5005—Wall or coating material
    • A61K9/5021—Organic macromolecular compounds
    • A61K9/5036—Polysaccharides, e.g. gums, alginate; Cyclodextrin
    • A61K9/5042—Cellulose; Cellulose derivatives, e.g. phthalate or acetate succinate esters of hydroxypropyl methylcellulose
    • A61K9/5047—Cellulose ethers containing no ester groups, e.g. hydroxypropyl methylcellulose
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K9/00—Medicinal preparations characterised by special physical form
    • A61K9/48—Preparations in capsules, e.g. of gelatin, of chocolate
    • A61K9/50—Microcapsules having a gas, liquid or semi-solid filling; Solid microparticles or pellets surrounded by a distinct coating layer, e.g. coated microspheres, coated drug crystals
    • A61K9/5005—Wall or coating material
    • A61K9/5021—Organic macromolecular compounds
    • A61K9/5052—Proteins, e.g. albumin
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K9/00—Medicinal preparations characterised by special physical form
    • A61K9/48—Preparations in capsules, e.g. of gelatin, of chocolate
    • A61K9/50—Microcapsules having a gas, liquid or semi-solid filling; Solid microparticles or pellets surrounded by a distinct coating layer, e.g. coated microspheres, coated drug crystals
    • A61K9/5073—Microcapsules having a gas, liquid or semi-solid filling; Solid microparticles or pellets surrounded by a distinct coating layer, e.g. coated microspheres, coated drug crystals having two or more different coatings optionally including drug-containing subcoatings

Abstract

The invention provides an intestine-targeted double-cavity calcium alginate-based composite microcapsule with pumping and constant-speed drug release characteristics and a preparation method thereof. The composite microcapsule is provided with two independent cavities, namely a boosting chamber and a medicine carrying chamber, wherein the boosting chamber and the medicine carrying chamber are separated by a diaphragm, the capsule walls of the boosting chamber and the medicine carrying chamber consist of a calcium alginate-chitosan inner layer, a protamine intermediate layer and a silicon dioxide shell layer, and enteric-coated microspheres are embedded in the inner layer of the capsule wall of the medicine carrying chamber; the boosting chamber is internally sealed with a mixed solution of sodium carboxymethylcellulose and a boosting agent, and the medicine carrying chamber is internally sealed with a mixed solution of sodium carboxymethylcellulose and a hydrophobic medicine; under the condition of intestinal pH, the boosting chamber provides pumping boosting effect for the release of the medicine in the medicine carrying chamber, so that the medicine in the medicine carrying chamber is released at a zero-order constant speed. The invention can solve the problem that the existing microcapsule can not realize the intestinal targeted constant-speed release of the hydrophobic medicament.

Description

Intestinal-targeting double-cavity calcium alginate-based composite microcapsule with pumping and constant-speed drug release characteristics and preparation method thereof
Technical Field
The invention belongs to the field of oral intestinal targeted drug delivery systems, and relates to an intestinal targeted double-cavity calcium alginate-based composite microcapsule with the characteristic of constant-speed delivery by pumping and a preparation method thereof.
Background
The oral intestinal targeted drug delivery system can be positioned in the intestine to release drugs, can avoid the denaturation and inactivation of the drugs such as protein, polypeptide and the like in the low pH value environment of the stomach, and has unique advantages in the aspect of treating intestinal diseases. The microcapsule technology is used for encapsulating the medicine to prepare the microcapsule for oral administration, so that a plurality of problems of traditional preparations such as tablets, pills, capsules and the like can be solved, for example, the bad smell of the medicine can be shielded, the stability of the medicine can be improved, the bioavailability of the medicine can be improved, and the release process of the medicine is more controllable. The existing drug release mechanism of most microcapsules still takes the concentration difference of the drug as a driving force, and the constant-speed release of the drug cannot be realized. Therefore, the research and development of novel intestinal targeting microcapsules capable of realizing the constant-speed release of the drug have important significance.
The osmotic pump type drug delivery system prepared by the osmotic pressure difference principle can realize the constant-speed release of the drug, and the drug release behavior is less influenced by physiological factors, so the osmotic pump type drug delivery system is widely applied to the field of drug controlled release. The osmotic pump controlled release preparation is mostly an osmotic pump tablet which is prepared by the comprehensive effects of a tablet core prepared from a medicament and an osmotic accelerator, a coating film with semi-permeability and better mechanical strength and a drug release hole. For example, Chaudhary and the like prepare a micro colon-targeted double-layer osmotic pump tablet simultaneously encapsulating dicyclomine hydrochloride and diclofenac potassium, and the micro colon-targeted double-layer osmotic pump tablet utilizes specific enzymes in colon to decompose pectin on a coating film to generate small holes for releasing drugs, thereby realizing the intestinal-targeted drug release. Enteric material is used as film coating to obtain intestine-targeted osmotic pump preparation for preventing drug release in stomach. However, most osmotic pump tablets use large amounts of organic solvents in the coating process, which is environmentally limited and costly. He and the like are used for preparing double-chamber calcium alginate microcapsules, different substances can be encapsulated in two chambers of the microcapsules, and temperature-responsive nanogel is added into the shell on one side of the double-chamber capsule, so that the permeability of the chamber on the one side has temperature-sensitive permeability, the chamber on the other side has constant diffusion permeability, and the synergistic release of the different substances is realized. However, calcium alginate is easily dissolved and swollen in the intestinal pH environment, has poor stability and mechanical properties, is difficult to control the release rate and release time of hydrophobic drugs in the intestinal part, and is difficult to apply in the field of intestinal targeted drug release.
Disclosure of Invention
The invention aims to overcome the defects of the existing osmotic pump preparation, and provides an intestine-targeted double-cavity calcium alginate-based composite microcapsule with the characteristic of pumping and constant-speed drug release and a preparation method thereof, so as to realize the intestine-targeted constant-speed release of a hydrophobic drug.
In order to achieve the purpose, the invention adopts the following technical scheme:
the intestinal targeting double-chamber calcium alginate-based composite microcapsule with the pumping constant-speed drug release characteristic provided by the invention is provided with a boosting chamber and a drug carrying chamber which are independent, the boosting chamber and the drug carrying chamber are separated by a diaphragm, the main component of the diaphragm is calcium alginate, the capsule walls of the boosting chamber and the drug carrying chamber are composed of a calcium alginate-chitosan inner layer, a protamine intermediate layer and a silicon dioxide shell layer, and enteric-coated microspheres are embedded in the inner layer of the capsule wall of the drug carrying chamber; the boosting chamber is internally enveloped with a mixed solution of sodium carboxymethylcellulose and a boosting agent, the boosting agent is a high polymer material with pH responsiveness, and the medicine carrying chamber is enveloped with a mixed solution of sodium carboxymethylcellulose and a hydrophobic medicine; under the intestinal pH condition, the boosting chamber provides pumping boosting effect for the release of the medicine in the medicine carrying chamber, so that the medicine in the medicine carrying chamber is released at a zero-order constant speed.
In the technical scheme of the composite microcapsule, the enteric-coated microspheres are dissolved under the intestinal pH condition, so that more drug release microchannels can be provided for a drug carrying chamber, the diameter of the enteric-coated microspheres is preferably 40-60 μm, the enteric-coated microspheres are made of materials which can be rapidly dissolved under the intestinal pH condition (pH 1.5-3.0) and can not be dissolved under the stomach pH condition (pH 6.5-7.5), and the enteric-coated microspheres can be made of cellulose or acrylic resin enteric-coated high polymer materials, for example, the enteric-coated microspheres can be made of hydroxypropyl methyl cellulose phthalate (HPMCP).
In the technical scheme of the composite microcapsule, the boosting agent is a polymer material with pH responsiveness, more specifically, the pKa value of the boosting agent should be greater than the pH value of the stomach environment (pH 1.5-3.0) but less than the pH value of the intestinal environment (pH 6.5-7.5), generally, the pKa range of the boosting agent is 4-6, which can ensure that the boosting agent is in a contracted conformation in the stomach environment and in an extended conformation in the intestinal environment, and swells after absorbing water, thereby generating osmotic pressure and solvent pressure, and feasible boosting agents include polyacrylic acid (PAA) and polymethacrylic acid (PMAA).
In the technical scheme of the composite microcapsule, the main component of the diaphragm is calcium alginate, the diaphragm also contains chitosan, and enteric-coated microspheres are embedded in the diaphragm at one side of the drug loading chamber; the chitosan in the diaphragm and the calcium alginate network form a calcium alginate-chitosan polyelectrolyte compound through electrostatic interaction.
In the technical scheme of the composite microcapsule, the calcium alginate-chitosan is a calcium alginate-chitosan polyelectrolyte compound formed by a calcium alginate network and chitosan through electrostatic interaction.
In the technical scheme of the composite microcapsule, the size of the composite microcapsule can be adjusted according to different requirements of practical application, and the composite microcapsule provided by the application is mainly administered orally, so that the size of the composite microcapsule is preferably millimeter, and more preferably, the length of the composite microcapsule in an acidic environment is not more than 5 mm. Generally, the shape of the composite microcapsule is similar to an ellipsoid, the short diameter of the ellipsoid is about 3 to 4mm, and the long diameter is about 4 to 5 mm.
According to the technical scheme of the composite microcapsule, after freeze drying, the thickness of the capsule wall of the boosting chamber and the capsule wall of the medicine carrying chamber are usually 70-120 microns.
In the technical scheme of the composite microcapsule, the volume of the boosting chamber is equivalent to that of the medicine carrying chamber, namely the volume of the boosting chamber is substantially equal to that of the medicine carrying chamber, more specifically, the composite microcapsule is in an acidic solution environment (for example, in a stomach environment with the pH value of 1.5-3.0), and the volume of the boosting chamber is equivalent to that of the medicine carrying chamber.
In the technical scheme of the composite microcapsule, in a mixed solution of sodium carboxymethylcellulose encapsulated in a boosting chamber and a boosting agent, the concentration of the sodium carboxymethylcellulose is 1-1.5 wt%, and the concentration of the boosting agent is 0.5-1 wt%; in the mixed solution of the sodium carboxymethylcellulose and the hydrophobic drug encapsulated in the drug carrying chamber, the concentration of the sodium carboxymethylcellulose is 1 wt% -1.5 wt%, and the concentration of the hydrophobic drug can be determined and adjusted according to the actual application requirements, for example, the concentration of the hydrophobic drug can be 20-65 mg/mL. The hydrophobic drug can be determined and adjusted according to the actual application requirements, for example, the hydrophobic drug can be aspirin, nifedipine, indomethacin and the like.
The invention also provides a preparation method of the composite microcapsule, which comprises the following steps:
(1) preparing the inner phase fluid, the outer phase fluid and the collecting fluid of the boosting chamber and the medicine carrying chamber
Boosting indoor phase fluid: adding sodium carboxymethylcellulose and a boosting agent into water, and uniformly mixing to obtain a boosting indoor phase fluid, wherein the concentration of the sodium carboxymethylcellulose is 1-1.5 wt% and the concentration of the boosting agent is 0.5-1 wt% in the boosting indoor phase fluid;
boosting of the outdoor phase fluid: adding sodium alginate and sodium dodecyl sulfate into water, and uniformly mixing to obtain a boosting outdoor phase fluid, wherein the concentration of the sodium alginate in the boosting outdoor phase fluid is 1.5-2.5 wt%, and the concentration of the sodium dodecyl sulfate in the boosting outdoor phase fluid is 0.2-0.5 wt%;
the inner phase fluid of the medicine carrying chamber: adding sodium carboxymethylcellulose and a hydrophobic drug into water, and uniformly mixing to obtain a medicament-carrying chamber internal phase fluid, wherein the concentration of the sodium carboxymethylcellulose in the medicament-carrying chamber internal phase fluid is 1-1.5 wt%;
carrying out phase fluid outside the medicine carrying chamber: adding sodium alginate and sodium dodecyl sulfate into water, uniformly mixing, adjusting the pH value to 3-5 by using a glacial acetic acid solution, and adding enteric microspheres to obtain an exterior phase fluid of the drug-carrying chamber, wherein in the exterior phase fluid of the drug-carrying chamber, the concentration of the sodium alginate is 1.5-2.5 wt%, the concentration of the sodium dodecyl sulfate is 0.2-0.5 wt%, and the concentration of the enteric microspheres is 0.05-1 mg/mL;
receiving liquid: adding chitosan and glacial acetic acid into water, uniformly mixing, adding calcium nitrate, and uniformly mixing to obtain a receiving solution, wherein the concentration of the chitosan is 0.2-0.5 wt%, the concentration of the glacial acetic acid is 1-1.5 v/v%, and the concentration of the calcium nitrate is 10-15 wt%;
(2) preparation of composite microcapsules
Firstly, preparing a double-chamber calcium alginate-chitosan microcapsule by adopting a pair of capillary co-extrusion micro-fluidic devices, respectively injecting a boosting chamber internal phase fluid and an external phase fluid into an inner tube and an outer tube of one of the capillary co-extrusion micro-fluidic devices to form a boosting chamber liquid drop, simultaneously respectively injecting a medicine carrying chamber internal phase fluid and an external phase fluid into an inner tube and an outer tube of the other capillary co-extrusion micro-fluidic device to form a medicine carrying chamber liquid drop, fusing the boosting chamber liquid drop and the medicine carrying chamber liquid drop before reaching the liquid level of a receiving liquid positioned below the capillary co-extrusion micro-fluidic devices, and then dropping the boosting chamber liquid drop and the medicine carrying chamber liquid drop into the receiving liquid to react with the receiving liquid for 1-5;
controlling the flow rate of the boosting indoor phase fluid and the flow rate of the medicine carrying indoor phase fluid to be 20-30 mL/h, and controlling the flow rate of the boosting outdoor phase fluid and the flow rate of the medicine carrying outdoor phase fluid to be 10-20 mL/h;
placing the double-cavity calcium alginate-chitosan microcapsule into 1.5-2.5 mg/mL protamine sulfate aqueous solution, and stirring to enable protamine sulfate to be adsorbed to the surface of the double-cavity calcium alginate-chitosan microcapsule to form a protamine intermediate layer, so as to obtain the double-cavity calcium alginate-chitosan/protamine microcapsule;
thirdly, adding the double-chamber calcium alginate-chitosan/protamine microcapsules into a sodium silicate solution with the concentration of 50-70 mmol/L of sodium silicate prepared from a glacial acetic acid solution, stirring to react to form a silicon dioxide shell layer on the surfaces of the double-chamber calcium alginate-chitosan/protamine microcapsules, and washing to obtain the composite microcapsules.
In the technical scheme of the preparation method of the composite microcapsule, the distance between the lower end of the outer tube of the capillary co-extrusion microfluidic device and the liquid level of the receiving liquid is controlled to be 3-7 cm in the step (2).
In the technical scheme of the preparation method of the composite microcapsule, the type and concentration of the hydrophobic drug adopted in the drug-loaded indoor phase fluid are determined according to the actual application requirements, for example, the concentration of the hydrophobic drug can be 20-65 mg/mL, and the hydrophobic drug can be aspirin, nifedipine, indomethacin and the like.
According to the technical scheme of the preparation method of the composite microcapsule, the receiving solution is prepared from chitosan, glacial acetic acid and calcium nitrate, in an acidic receiving solution environment, chitosan is positively charged, alginic acid is negatively charged, and the two polysaccharide macromolecules with opposite charges form a calcium alginate-chitosan polyelectrolyte compound (namely an inner capsule wall material of the double-cavity calcium alginate-chitosan microcapsule) through electrostatic interaction, so that the stability of the composite microcapsule in a high-pH environment can be improved.
In the step (2) of the technical scheme of the preparation method of the composite microcapsule, the double-chamber calcium alginate-chitosan microcapsule is placed in a protamine sulfate aqueous solution, stirring is carried out for 20-40 min so that protamine sulfate is adsorbed to the surface of the double-chamber calcium alginate-chitosan microcapsule to form a protamine intermediate layer, and the stirring is usually carried out at the rotating speed of 150-300 r/min.
In the third step (2) of the technical scheme of the preparation method of the composite microcapsule, the double-chamber calcium alginate-chitosan/protamine microcapsule is added into a sodium silicate solution prepared from a glacial acetic acid solution, and a silica shell layer is formed on the surface of the double-chamber calcium alginate-chitosan/protamine microcapsule after stirring reaction for 0.5-1 h, and is usually stirred at the rotating speed of 150-300 r/min. The sodium silicate solution can be prepared from 0.2-0.3 mol/L glacial acetic acid solution and sodium silicate. Preferably, the washing is carried out by using 0.2 to 0.3mol/L glacial acetic acid solution.
In the technical scheme of the preparation method of the composite microcapsule, the step (2) can adopt a capillary co-extrusion micro-fluidic device shown in the figure (a) of figure 1 to prepare the double-chamber calcium alginate-chitosan microcapsule, the capillary co-extrusion micro-fluidic device is formed by assembling a round glass tube and a square glass tube, and the square glass tube is fixed in the round glass tube. More specifically, the bottom end of a square glass tube is slightly burned on an alcohol lamp, the bottom end of the square glass tube is made to be square into a circle, then the square glass tube is placed in a circular glass tube, the bottom end of the square glass tube is about 1-2 mm away from the circular glass tube, glue is used for fixing the square glass tube on a glass slide, a plastic seat of a needle head is cut into a notch with a proper size, the glass tube is conveniently embedded, glue is coated on the end face of the plastic seat to enable the plastic seat to be fixed at a channel opening of the glass tube, finally, the gap at the joint of the notch of the needle head base and the channel of the glass tube is sealed by the glue, and the contact part of the needle head base and the glass.
The intestinal targeting constant-speed drug release mechanism of the composite microcapsule provided by the invention is shown in fig. 2 (fig. 2 shows the situation that HPMCP microspheres are taken as enteric microspheres and PAA is taken as a boosting agent): typically, the pH of the stomach environment is below 3, the pH of the stomach may rise to 5 after eating, and the pH of the intestine is typically 6.5-7.5. The HPMCP enteric-coated microspheres are stable in an acidic solution with the pH value of less than 5.5, and can be quickly dissolved under the pH condition of intestinal fluid to provide a micro-valve of a drug release channel. The pKa value of the booster PAA is 4.25, the booster PAA is chelated with calcium ions through charge adsorption to form gel characteristics, and the PAA is in a charge neutral and contracted conformation in a gastric juice environment, particularly a gastric juice environment under an empty stomach condition (pH < pKa); while in an intestinal fluid environment (pH > pKa), PAA is negatively charged due to deprotonation, is in an extended conformation under the action of electrostatic repulsion, and swells upon absorption of water, thereby generating osmotic and swelling pressures. In the composite microcapsule provided by the invention, the electrostatic interaction between the calcium alginate gel network and protamine molecules enables the permeation of the capsule wall to have pH response characteristics. Under the condition of lower pH value of the stomach, the diffusion permeability of the whole capsule is lower, the micro valve of the drug release channel of the drug loading chamber is closed, the boosting chamber does not provide pushing force, and the drug loaded in the drug loading chamber is protected and cannot be released in the stomach; under the condition of intestinal pH, the diffusion permeability of the composite microcapsule is high, the enteric-coated microspheres are rapidly dissolved, a micro valve of a drug release channel of the drug loading chamber is opened, and meanwhile, PAA in the boosting chamber absorbs water and swells to provide a driving force to push the drug in the drug loading chamber to be stably released at a constant speed, so that the pumping controlled release characteristic and the drug intestinal targeted delivery of the composite microcapsule are realized.
Compared with the prior art, the technical scheme provided by the invention has the following beneficial technical effects:
1. the invention provides an intestine-targeted double-cavity calcium alginate-based composite microcapsule with pumping and constant-speed drug release characteristics, which is provided with a boosting chamber and a drug-loading chamber, wherein the capsule walls of the boosting chamber and the drug-loading chamber consist of a calcium alginate-chitosan inner layer, a protamine intermediate layer and a silicon dioxide shell layer, and enteric-coated microspheres are embedded in the inner layer of the capsule wall of the drug-loading chamber; the boosting chamber is encapsulated with a boosting agent, and the medicine carrying chamber is encapsulated with a hydrophobic medicine. The invention designs the structure of the composite microcapsule and the composition of the capsule wall, so that the composite microcapsule can not release the medicine in the stomach, under the condition of intestinal pH, protamine molecules with positive electricity are adsorbed to calcium alginate networks with negative electricity due to electrostatic adsorption, so that gel network diffusion channels are opened, meanwhile, the microspheres are quickly dissolved, and the micro valve of the drug release channel of the drug loading chamber is in an open state, so that more channels are provided for the drug release process, the drug in the drug loading chamber is more easily released to the intestinal environment through the capsule wall, meanwhile, the boosting agent swells under the intestinal pH condition, provides a pumping promoting effect for the release of the drug, realizes the targeted zero-order constant release of the drug in the intestinal tract, solves the defect that the conventional microcapsule can not realize the intestinal targeted constant-speed release of the hydrophobic drug, and has good application value in the field of intestinal targeted drug controlled release.
2. The composite microcapsule provided by the invention contains chitosan in the capsule wall, chitosan is positively charged and alginic acid is negatively charged in an acidic receiving solution environment, and the two polysaccharide macromolecules with opposite charges form a calcium alginate-chitosan polyelectrolyte compound through electrostatic interaction, so that the stability of the composite microcapsule in a high pH environment can be improved.
3. The composite microcapsule provided by the invention has two independent cavities, can avoid cross contamination of substances encapsulated in the two cavities, can be used for independent encapsulation of various different substances, provides a new encapsulation environment for independent encapsulation of drugs and other reagents, and has important application value in the biomedical fields of active substance encapsulation, drug controlled release and the like.
4. The composite microcapsule provided by the invention has good biocompatibility, has the potential of being used as a safe carrier for drug delivery, has good intestinal targeting property and slow release property in New Zealand white rabbits, and has good clinical application prospect.
5. The invention also provides a preparation method of the composite microcapsule, which is simple to operate, does not need to use an organic solvent, and has the characteristics of safety, environmental protection and low cost.
Drawings
Fig. 1 is a schematic diagram of the preparation process of the composite microcapsule of the present invention, wherein (a) is a schematic diagram of the structure of a capillary co-extrusion microfluidic device, (b) is a schematic diagram of the formation of a double-chamber calcium alginate-chitosan microcapsule in a receiving solution, (c) is a schematic diagram of the adsorption of protamine, (d) is a schematic diagram of the biosilication, and (e) to (g) are schematic diagrams of partial enlargements of the products generated in (b) to (d), respectively.
Fig. 2 is a schematic diagram of the mechanism of the enteric-targeted constant-speed drug release characteristic of the composite microcapsule of the present invention, wherein (a) is a schematic diagram of oral composite microcapsule, (b) is a schematic diagram of drug protection in stomach, and (c) is a schematic diagram of drug release in small intestine.
Fig. 3 is an optical micrograph of HPMCP microspheres of example 2 in buffer at pH 2.5(a) and pH 6.8(b) at different times.
Fig. 4 is a plot of particle size of HPMCP microspheres of example 2 over time at pH 2.5 and pH 6.8 in buffer.
FIG. 5 is the volume change rate of the single-chamber calcium alginate-chitosan microcapsules before and after silicification and the single-chamber calcium alginate-chitosan microcapsules encapsulating PAA in example 3 under different pH conditions.
FIG. 6 is an optical photograph of the double-chamber microcapsules before and after silicidation in example 1, wherein (a) shows the double-chamber calcium alginate-chitosan microcapsules, and (b) shows the composite microcapsules with a scale of 5 mm.
Fig. 7 is a confocal laser microscope photograph of fluorescent dye encapsulated in one side chamber of the composite microcapsule in example 1.
FIG. 8 is a confocal laser microscope photograph of the wall of the composite microcapsule of example 1, wherein (a), (b), and (c) show the wall of the booster chamber, the membrane, and the wall of the drug-carrying chamber, respectively.
FIG. 9 is a SEM photograph of the composite microcapsule of example 1, in which the graphs (a) to (d) are respectively the whole, cross-section, wall cross-section and diaphragm between two chambers.
Fig. 10 is a size and optical photograph of the composite microcapsule of example 4 under different pH conditions.
Fig. 11 is a scanning electron micrograph of the composite microcapsule of example 4 after it is left to stand in a buffer solution with pH 6.8 for 8 hours, in which the graphs (a) to (d) are respectively the whole, cross-section, wall cross-section and diaphragm between the two chambers.
FIG. 12 is the variation of the drug content of the composite microcapsule in example 5 stored in 0.2mol/L acetic acid solution with time.
Fig. 13 is an in vitro release profile of the composite microcapsules of example 6, wherein (a) is a release profile of the composite microcapsules containing different concentrations of HPMCP microspheres under different pH conditions, and (b) to (d) are release profiles of the composite microcapsules under pH 2.5 and pH 6.8 conditions at drug loading concentrations of 22.5, 45 and 65mg/mL, respectively.
FIG. 14 shows the results of 12h, 24h and 48h cytotoxicity experiments in vitro on composite microcapsules of example 7, wherein (a) represents 3T3 cells, and (b) represents L929 cells.
Fig. 15 is a graph of the measured blood concentration in animals of example 8, wherein (a) is a graph of a composite microcapsule administration experiment using a new zealand white rabbit as an animal model, (a1) is a graph of rabbit restraint, (a2) is a graph of rabbit administration, and (b) is a graph of the blood concentration.
Detailed Description
The intestinal targeting double-chamber calcium alginate-based composite microcapsule with pumping and constant-speed drug release characteristics and the preparation method thereof provided by the invention are further explained by the following examples. It should be noted that the following examples are only for illustrating the present invention and should not be construed as limiting the scope of the present invention, and those skilled in the art can make some insubstantial modifications and adjustments to the present invention based on the above disclosure and still fall within the scope of the present invention.
In the following examples:
polyacrylic acid (PAA) was obtained from the hubei ferry chemical company, ltd, and hydroxypropylmethylcellulose phthalate (HPMCP) was obtained from the mclin agents company.
As shown in fig. 1(a), the capillary coextrusion microfluidic device (a pair) used includes inner phase fluid and outer phase fluid conduits (inner tube and outer tube), the inner phase fluid conduit is a rectangular glass capillary, the size of the through hole is 1.0 × 1.0mm, the port thereof is processed into a circle, the outer phase fluid conduit is a circular glass capillary, the inner diameter is 2mm, and the outer diameter is 2.4 mm; the internal phase fluid and the external phase fluid are fed into the internal phase fluid and external phase fluid conduits by syringe pumps.
Describing the formation process of the composite microcapsule with reference to fig. 1, in the first step, a pair of capillary co-extrusion microfluidic devices as shown in fig. 1(a) is used in combination with a complex coacervation method to prepare a double-chamber calcium alginate-chitosan microcapsule, as shown in fig. 1(b) (e), one side chamber of the microcapsule is a drug loading chamber, in which hydrophobic drugs are encapsulated, and meanwhile, enteric-coated microspheres are embedded in the wall of the microcapsule to provide a drug release channel microvalve, and the other side chamber is a boosting chamber, in which boosting agents are encapsulated; secondly, utilizing electrostatic adsorption to adsorb protamine molecules on the surface of the double-chamber calcium alginate-chitosan microcapsule to prepare the double-chamber calcium alginate-chitosan/protamine microcapsule, as shown in (c) and (f) of figure 1; and thirdly, coating a silicon dioxide layer on the outer layer of the double-cavity calcium alginate-chitosan/protamine microcapsule by using a bionic silicification method to prepare the composite microcapsule, as shown in the figure 1(d) (g).
Example 1
In this example, the preparation of the non-drug-loaded composite microcapsule comprises the following steps:
(1) preparing the inner phase fluid, the outer phase fluid and the collecting fluid of the boosting chamber and the medicine carrying chamber
Boost indoor phase fluid (IF 1): adding sodium carboxymethylcellulose and a promoter PAA into water, and uniformly mixing to obtain IF1, wherein in IF1, the concentration of the sodium carboxymethylcellulose is 1 wt% and the concentration of the promoter PAA is 0.5 wt%;
boost outdoor phase fluid (OF 1): adding sodium alginate and sodium dodecyl sulfate into water, and uniformly mixing to obtain OF1, wherein the concentration OF sodium alginate is 2 wt% and the concentration OF sodium dodecyl sulfate is 0.2 wt% in OF 1;
infusor internal phase fluid (IF 2): adding sodium carboxymethylcellulose into water, and mixing to obtain IF2, wherein the concentration of sodium carboxymethylcellulose in IF2 is 1 wt%;
drug-loaded outdoor fluid (OF 2): adding sodium alginate and sodium dodecyl sulfate into water, uniformly mixing, adjusting the pH value to 3-5 by using a 0.2mol/L glacial acetic acid solution, and adding enteric microspheres (namely HPMCP microspheres) to obtain OF2, OF2, wherein the concentration OF the sodium alginate is 2 wt%, the concentration OF the sodium dodecyl sulfate is 0.2 wt%, and the concentration OF the enteric microspheres is 0.5 mg/mL;
receiving liquid: adding chitosan and glacial acetic acid into water, uniformly mixing, adding calcium nitrate, and uniformly mixing to obtain a receiving solution, wherein the concentration of the chitosan is 0.2 wt%, the concentration of the glacial acetic acid is 1 v/v%, and the concentration of the calcium nitrate is 10 wt%.
(2) Preparation of composite microcapsules
Firstly, a pair OF capillary co-extrusion micro-fluidic devices are adopted to prepare double-chamber calcium alginate-chitosan microcapsules, IF1 and OF1 are respectively injected into an inner tube and an outer tube OF one OF the capillary co-extrusion micro-fluidic devices to form a boosting chamber liquid drop, IF2 and OF2 are respectively injected into an inner tube and an outer tube OF the other capillary co-extrusion micro-fluidic device to form a medicine carrying chamber liquid drop, the boosting chamber liquid drop and the medicine carrying chamber liquid drop are fused before reaching the liquid level OF a receiving liquid below the capillary co-extrusion micro-fluidic devices, and then the boosting chamber liquid drop and the medicine carrying chamber liquid drop are dropped into the receiving liquid to react with the receiving liquid for 1min to form the double-chamber calcium alginate-chitosan microcapsules, and an optical.
In the step, the distance between the lower end OF an outer tube OF the capillary co-extrusion microfluidic device and the liquid level OF a receiving liquid is controlled to be 5cm, the flow rate OF IF1 is controlled to be 25mL/h, the flow rate OF OF1 is controlled to be 10mL/h, the flow rate OF IF2 is controlled to be 20mL/h, and the flow rate OF OF2 is controlled to be 15 mL/h.
Secondly, placing the double-cavity calcium alginate-chitosan microcapsule into a protamine sulfate aqueous solution of 2mg/mL, mechanically stirring for 30min at a rotating speed of 200r/min, and adsorbing protamine sulfate to the surface of the double-cavity calcium alginate-chitosan microcapsule to form a protamine intermediate layer to obtain the double-cavity calcium alginate-chitosan/protamine microcapsule.
Thirdly, adding the double-chamber calcium alginate-chitosan/protamine microcapsule into a sodium silicate solution with the concentration of 60mmol/L prepared from a glacial acetic acid solution with the concentration of 0.2mol/L, mechanically stirring and reacting for 1h at the rotating speed of 200r/min to form a silicon dioxide shell layer on the surface of the double-chamber calcium alginate-chitosan/protamine microcapsule, washing the shell layer for three times by using the glacial acetic acid solution with the concentration of 0.2mol/L to obtain the composite microcapsule, wherein an optical photo of the composite microcapsule is shown in (b) of figure 6, and the obtained composite microcapsule is stored for later use at the temperature of 4 ℃.
And (3) characterizing the appearance of the composite microcapsule:
in order to examine the separation effect of the membranes between the composite microcapsules, 1,6,7, 12-tetrachloro-3, 4,9, 10-perylenetetracarboxylic dianhydride dye (LR 300) with red fluorescence is added when the IF1 is prepared in the step (1), the other operations are the same as the steps (1) and (2), the composite microcapsules with the fluorescent dye LR 300 encapsulated in one cavity are prepared, so as to distinguish the composite microcapsules from two different cavities which exist independently, and the laser confocal microscope photograph of the prepared composite microcapsules is shown in fig. 7. As can be seen from FIG. 7, no diffusion of fluorescence to other chambers was observed after silicidation, indicating that the membrane between the two chambers of the composite microcapsule has a separation effect, which can avoid cross-contamination between the two chambers, and can be used for substance encapsulation, providing a new encapsulation environment for independent encapsulation of drugs and other reagents.
In order to observe the conditions of the capsule wall and the diaphragm of the composite microcapsule under a laser confocal microscope, a part of the composite microcapsule prepared in the step (2) is soaked in 10 mu mol/L rhodamine B solution for 72 hours, and is freeze-dried for 48 hours, rhodamine B molecules move from the inside to the outside of the composite capsule due to the vacuum pumping effect in the freeze-drying process, most of the rhodamine B molecules are adsorbed on the capsule wall of the microcapsule to enable the capsule wall to have red fluorescence, and the capsule wall thickness of the composite microcapsule is basically consistent in a laser confocal photograph shown in figure 8.
And (5) utilizing SEM to characterize the microstructure of the freeze-dried composite microcapsule. The preparation method of the complete composite microcapsule freeze-dried sample comprises the following steps: and spreading the composite microcapsule on the bottom of a plastic beaker, and freeze-drying for 48 h. The preparation process of the freeze-dried sample of the composite microcapsule section comprises the following steps: and (3) putting the composite microcapsule into liquid nitrogen for freezing for several seconds, quickly taking out the composite microcapsule when the composite microcapsule is in an incomplete icing state, cutting the composite microcapsule along the long diameter of the composite microcapsule by using a scalpel, immediately putting the composite microcapsule into the liquid nitrogen for completely freezing, and freeze-drying for 48 hours. The scanning electron micrograph of the double-chamber composite microcapsule prepared in this example is shown in fig. 9, wherein the (a) to (d) are SEM micrographs of the composite microcapsule as a whole, a cross section, a wall cross section and a diaphragm, respectively. As can be seen from fig. 9, the freeze-dried composite microcapsule has a good capsule shape, a compact and smooth surface; the cross section of the composite microcapsule presents an irregular loose microstructure due to freeze drying, and the composite microcapsule is clearly observed to have two independent chambers from the cross section, and a remarkable convex structure is arranged in the middle of a diaphragm between the two chambers, which is probably caused by the speed of calcium ions diffusing from outside to inside and the shrinkage of alginate chains; from the figure (c), the outermost layer of the capsule wall of the composite microcapsule has a compact silicon dioxide shell layer; from (d) it can be seen that there is a distinct septum between the two chambers.
Example 2
In this example, a first-stage microfluidic device is combined with an emulsion solvent diffusion method, and oil-in-water (O/W) emulsion droplets are used as a template to prepare HPMCP microspheres (enteric microspheres) and study the enteric properties thereof, and the steps are as follows:
(1) preparation of enteric coated microspheres
Preparing an inner oil phase fluid: 0.14g of HPMCP was dissolved in 20mL of a mixture of dichloromethane and ethanol (dichloromethane to removed volume ratio of 9: 1).
Preparing external water phase fluid: sodium lauryl sulfate was dissolved in water to prepare a 0.6 wt% solution.
Injecting the inner oil phase fluid and the outer water phase fluid into an inner tube and an outer tube of the microfluidic device according to the flow rate of the inner oil phase fluid of 500 mu L/h and the flow rate of the outer water phase fluid of 1400 mu L/h to prepare oil-in-water emulsion droplets, dripping the emulsion droplets into deionized water of a receiving solution, washing the emulsion droplets with the deionized water for three times after the reaction is finished, and drying the emulsion droplets for 6 hours at 60 ℃ to obtain the HPMCP microspheres.
(2) Study of enteric Properties of HPMCP microspheres
Phosphate buffer at pH 2.5 was used as simulated gastric fluid and phosphate buffer at pH 6.8 was used as simulated intestinal fluid. preparation of pH 2.5 phosphate buffer: firstly preparing K with the concentration of 1mg/mL2HPO4Aqueous solution, then the pH of the solution was adjusted to 2.5 with dilute hydrochloric acid. preparation of pH 6.8 phosphate buffer: firstly, KH with the concentration of 0.68mg/mL is prepared2PO4The pH value of the aqueous solution is then adjusted to 6.8 with 0.1mol/L NaOH solution.
The HPMCP microspheres are dispersed in phosphate buffer solutions with pH 2.5 and pH 6.8, respectively, and photomicrographs of the HPMCP microspheres under different pH conditions are shown in fig. 3, since HPMCP is a typical enteric polymer, it is insoluble in an acidic solution with pH <5.5, and can be rapidly dissolved in intestinal juice with pH 6.8. The particle size change of the HPMCP microspheres under different pH conditions is shown in fig. 4, the particle size of the HPMCP microspheres is basically kept unchanged after the HPMCP microspheres are stored in a phosphate buffer solution with pH 2.5 for 180min, but the HPMCP microspheres are quickly and completely dissolved in a phosphate buffer solution with pH 6.8 within 5min, which indicates that the HPMCP microspheres have good enteric properties.
Example 3
In this example, the pumping performance of the composite microcapsule boosting chamber was studied.
(1) Preparation of Single Chamber microcapsules
Taking 1 wt% sodium carboxymethylcellulose aqueous solution as an internal phase fluid, taking 2 wt% sodium alginate aqueous solution as an external phase fluid, controlling the flow rate of the internal phase fluid to be 20mL/h and the flow rate of the external phase fluid to be 15mL/h, and preparing the single-cavity calcium alginate-chitosan microcapsule (o-AC) by adopting a co-extrusion micro-fluidic device.
And secondly, taking a mixed aqueous solution of sodium carboxymethylcellulose and PAA as an internal phase fluid, wherein the concentration of the sodium carboxymethylcellulose is 1 wt%, the concentration of the PAA is 0.5 wt%, taking a2 wt% sodium alginate aqueous solution as an external phase fluid, controlling the flow rate of the internal phase fluid to be 20mL/h and the flow rate of the external phase fluid to be 15mL/h, and preparing the PAA-encapsulated single-cavity calcium alginate-chitosan microcapsule (PAA @ o-AC) by adopting a co-extrusion micro-fluidic device.
③ adsorbing protamine on o-AC and PAA @ o-AC respectively according to the operation of the step (2) in the example 1 and forming a silica shell layer by biomimetic programming, thus obtaining the single-cavity calcium alginate-chitosan/protamine/silica composite microcapsule (o-ACPSi) and the o-ACPSi composite microcapsule (PAA @ o-ACPSi) encapsulated with PAA.
(2) The pumping performance of the boosting chamber of the double-chamber microcapsule is researched by researching the swelling ratio of the four microcapsules prepared in the step (1) under the condition that the pH value is 6.8
Placing the four microcapsules prepared in the step (1) in phosphate buffer solution with pH of 2.5, standing for 3h, then transferring the microcapsules into phosphate buffer solution with pH of 6.8, standing for 19h, photographing and recording the microcapsules by a digital camera periodically, calculating the diameters of the four single-cavity microcapsules at different times by using statistical analysis software, converting the diameters into volumes, and calculating the Swelling Rate (SR) of the microcapsules at each time point (i) according to the formula (1)i) As shown in FIG. 5, the swelling ratio of PAA @ o-AC is large as shown in FIG. 5In o-AC, the addition of PAA increases the volume swelling ratio of the capsule by about 90%, which shows that PAA can provide driving force under the condition that pH is 6.8, and the swelling ratio of the siliconized capsules o-ACPSi and PAA @ o-ACPSi is very small, which shows that the swelling behavior of the microcapsule can be effectively inhibited by the silica shell layer.
Figure BDA0002642154170000111
In the formula (1), V0Is the initial volume of the microcapsules, ViIs the volume of the microcapsules at different time points.
Example 4
In this example, the stability of the composite microcapsules in different buffers was investigated by investigating the morphology and structure changes of the composite microcapsules under the conditions of pH 2.5 and pH 6.8.
The composite microcapsule prepared in example 1 was allowed to stand in a phosphate buffer solution having a pH of 2.5 for 3 hours, and then transferred to a phosphate buffer solution having a pH of 6.8, during which time images were taken periodically with a digital camera, and changes in major and minor diameters of the composite microcapsule at different times were calculated with statistical analysis software, and the results are shown in fig. 10. As can be seen from fig. 10, under the simulated gastric pH condition (pH 2.5), since the calcium alginate network accepts protons in a contracted state, and has a dense and stable gel network, the size and the capsule shape of the composite microcapsule hardly change. After the composite microcapsule is transferred to a simulated intestinal juice pH condition (pH is 6.8), the swelling rate of the composite microcapsule is controlled to be about 10% at 12h, because the stability of the composite microcapsule is improved by adding chitosan, the composite microcapsule can be ensured to be kept complete at a higher pH value, meanwhile, the hard silicon dioxide outer layer can further inhibit the swelling of the calcium alginate capsule, and the composite microcapsule has a stable structure at the higher pH value.
After the composite microcapsule prepared in example 1 was left to stand in phosphate buffer solution with pH of 6.8 for 8 hours, the microstructure was characterized by scanning electron microscopy, and the results are shown in fig. 11, in which (a) to (d) are scanning electron micrographs of the whole composite microcapsule, the cross section, the wall cross section, and the membrane between the two chambers, respectively. As can be seen from fig. 11, the freeze-dried composite microcapsule maintains a good capsule shape, ravines are formed on the surface of the composite microcapsule during the freeze-drying process, the cross section of the composite microcapsule has an irregular loose microstructure due to freeze-drying, and the membrane is deformed and bent, which indicates that when the boosting force is provided by the swelling of the boosting chamber, the medicine can be extruded to be released from the medicine-carrying chamber, and as can be seen from fig. 11 (d), the outermost layer of the composite microcapsule still maintains a dense silica shell layer, thereby improving the mechanical stability of the microcapsule.
Example 5
In this example, the preparation of the drug-loaded composite microcapsule comprises the following steps:
(1) preparing the inner phase fluid, the outer phase fluid and the collecting fluid of the boosting chamber and the medicine carrying chamber
The booster indoor phase fluid (IF1), the drug loading chamber external phase fluid (OF2) and the receiving fluid are the same as in example 1;
infusor internal phase fluid (IF 2): adding sodium carboxymethylcellulose and indometacin into water, and mixing to obtain IF2, wherein in IF2, the concentration of sodium carboxymethylcellulose is 1 wt% and the concentration of indometacin is 25 mg/mL.
(2) Preparation of composite microcapsules
Firstly, the fluid of each phase prepared in the step (1) of the embodiment is adopted to prepare the double-chamber calcium alginate-chitosan microcapsule according to the operation and conditions of the step (2) of the embodiment 1.
Secondly, placing the double-cavity calcium alginate-chitosan microcapsule into a protamine sulfate aqueous solution of 2mg/mL, and mechanically stirring at a rotating speed of 200r/min for 30min to enable protamine sulfate to be adsorbed to the surface of the double-cavity calcium alginate-chitosan microcapsule to form a protamine intermediate layer, thus obtaining the double-cavity calcium alginate-chitosan/protamine microcapsule.
Thirdly, adding the double-chamber calcium alginate-chitosan/protamine microcapsule into a sodium silicate solution with the concentration of 60mmol/L prepared from a glacial acetic acid solution of 0.2mol/L, mechanically stirring and reacting for 1h at the rotating speed of 200r/min to form a silicon dioxide shell layer on the surface of the double-chamber calcium alginate-chitosan/protamine microcapsule, washing for three times by using the glacial acetic acid solution of 0.2mol/L to obtain the composite microcapsule, and storing the obtained composite microcapsule for later use at the temperature of 4 ℃.
Randomly dividing the composite microcapsules prepared in the step (2) of the embodiment into 4 groups, wherein each group comprises 10 composite microcapsules, taking one group of test tubes to measure the average value of the initial drug content of each composite microcapsule, respectively storing the remaining 3 groups of test tubes in which 0.2mol/L acetic acid solution is contained, measuring the drug release amount of the composite microcapsules in each group of test tubes on days 0, 7, 14, 21 and 28, calculating the average drug release amount of each single microcapsule, and calculating the initial drug content (m) of each single composite microcapsule according to the average drug release amount of each group of test tubes0) And the amount of drug released at time point i (w)i) Calculating the rate of change (R) of the drug content of the composite microcapsule at the time point i from the formula (2)2i) As shown in fig. 12, it can be seen from fig. 12 that the drug content in the composite microcapsules remained almost constant during storage, indicating that the medium can be used for the composite microcapsules for storing the drug, and the leakage of the drug in the microcapsules can be effectively prevented.
Figure BDA0002642154170000121
Example 6
In the embodiment, indomethacin is used as a model drug to study the in-vitro intestinal targeted drug controlled release performance of the composite microcapsule.
(1) Composite microcapsule embedded with HPMCP microspheres with different concentrations
In order to explore the influence of the concentration of the HPMCP microspheres on the release rate of the medicine, composite microcapsules embedded with HPMCP microspheres with different concentrations are prepared.
Preparing an out-phase fluid (OF2) OF a drug-loaded chamber containing HPMCP microspheres with different concentrations: adding sodium alginate and sodium dodecyl sulfate into water, uniformly mixing, adjusting the pH value to 3-5 by using a 0.2mol/L glacial acetic acid solution, and adding different amounts OF HPMCP microspheres to obtain OF2, wherein in the OF2, the concentration OF the sodium alginate is 2 wt%, the concentration OF the sodium dodecyl sulfate is 0.2 wt%, and the concentrations OF the HPMCP microspheres are 0.5, 0.25, 0.125 and 0.0625mg/mL respectively.
Formulation of the drug-loaded indoor phase fluid (IF 2): adding sodium carboxymethylcellulose and indometacin into water, and mixing to obtain IF2, wherein in IF2, the concentration of sodium carboxymethylcellulose is 1 wt%, and the concentration of indometacin is 25 mg/mL;
the other phase fluids were prepared in the same manner as in step (1) of example 1.
Secondly, by adopting the fluids of all phases prepared in the step I, the HPMCP microsphere composite microcapsules embedded with different concentrations prepared in the step 2 in the embodiment 1 are prepared according to the operation of the step 2 in the embodiment 1.
Standing the composite microcapsules embedded with the HPMCP microspheres with different concentrations in a phosphate buffer solution with the pH value of 2.5 for 3 hours, transferring the composite microcapsules to a phosphate buffer solution with the pH value of 6.8 for drug release, and measuring the cumulative drug release rate under different pH conditions, wherein the drug release operation is as follows:
at 37 ℃, randomly dividing the composite microcapsules into 3 groups, respectively placing the groups into phosphate buffer solution with pH of 2.5 for releasing drugs for 3h, then respectively transferring the groups into phosphate buffer solution with pH of 6.8 for releasing drugs for 19h, taking 1mL of supernatant at different time points, measuring the drug concentration by using an ultraviolet-visible spectrophotometer, and pouring the supernatant into a drug release container after the measurement. And (3) after drug release is finished, mechanically destroying the composite microcapsule, carrying out ultrasonic treatment for 30min in a mixed solution of phosphate buffer solution with the pH value of 6.8 and ethanol at a ratio of 1:1(v/v) to ensure that the drug is completely released, centrifuging for 10min at a rotating speed of 8000r/min, measuring the concentration of the drug in the supernatant, and calculating the cumulative release rate of the drug.
(2) Preparing composite microcapsules with different drug-loading concentrations
Preparing a drug-loaded indoor phase fluid (IF2) containing indomethacin with different concentrations: adding sodium carboxymethylcellulose and different amounts of indomethacin into water, and mixing to obtain IF2, wherein the concentration of sodium carboxymethylcellulose is 1 wt% and the concentration of indomethacin is 22.5, 45, and 65mg/mL respectively in IF 2.
The other phase fluids were prepared in the same manner as in step (1) of example 1.
③ in order to explore the functions OF the propellant and the enteric microspheres in the composite microcapsule in the drug release process, IF1 and OF2 are changed, the preparation method OF the fluid OF each phase is the same as the step (1) OF the example 1, and the following four kinds OF composite microcapsules carrying drugs are prepared according to the operation OF the step (2) OF the example 1:
composite microcapsules (θ -ACPSi): IF1 is 1 wt% sodium carboxymethylcellulose aqueous solution; OF2 the concentration OF sodium alginate was 2 wt% and the concentration OF sodium lauryl sulfate was 0.2 wt%.
The boosting chamber encapsulates a theta-ACPSi composite microcapsule (PAA @ theta-ACPSi) of PAA: the concentration of PAA in IF1 was 0.5 wt%, and the concentration of sodium carboxymethylcellulose was 1 wt%; OF2 the concentration OF sodium alginate was 2 wt% and the concentration OF sodium lauryl sulfate was 0.2 wt%.
The theta-ACPSi composite microcapsule (HPMCP @ theta-ACPSi) with HPMCP enteric-coated microspheres embedded in the capsule wall of the drug-loading chamber: IF1 is 1 wt% sodium carboxymethylcellulose aqueous solution; in OF2, the concentration OF sodium alginate was 2 wt%, the concentration OF sodium dodecyl sulfate was 0.2 wt%, and the concentration OF HPMCP microspheres was 0.5 mg/mL.
(PAA + HPMCP) @ theta-ACPSi composite microcapsule: the concentration of PAA in IF1 was 0.5 wt%, and the concentration of sodium carboxymethylcellulose was 1 wt%; in OF2, the concentration OF sodium alginate was 2 wt%, the concentration OF sodium lauryl sulfate was 0.2 wt%, and the concentration OF HPMCP microspheres was 0.5 mg/mL.
Phosphate buffer at pH 2.5 was used as simulated gastric fluid and phosphate buffer at pH 6.8 was used as simulated intestinal fluid. The four composite microcapsules with different drug-loading concentrations are respectively placed in simulated gastric fluid and simulated intestinal fluid, a drug-release experiment is performed according to the drug-release operation in the step (1) of the embodiment, and the measured drug-release curve is shown in fig. 13. As shown in the graph (a) of fig. 13, in simulated gastric fluid with pH of 2.5, due to electrostatic repulsion among a large number of positively charged protamine molecules, the gaps of the electrically neutral calcium alginate gel network are blocked by the protamine molecules, the HPMCP microspheres are kept stable, the microvalve of the drug release channel in the drug loading chamber is in a closed state, and the indomethacin in the composite microcapsule is hardly released under the protection of the microcapsule shell; and in the simulated intestinal fluid with the pH value of 6.8, indomethacin is continuously released from the composite microcapsule, when the pH value is 6.8, the positively charged protamine molecules are adsorbed on the calcium alginate network with negative charge due to electrostatic adsorption, so that a gel network diffusion channel is opened, part of the drugs in the composite microcapsule are diffused out, and meanwhile, the HPMCP microspheres are quickly dissolved, the microvalve of the drug carrying chamber channel is in an open state, so that more microchannels are opened in the drug release process, the indomethacin is more easily released through the capsule wall, and the release rate of the indomethacin is improved along with the increase of the concentration of the HPMCP microspheres.
Fig. 13 (a) is a drug release curve of the composite microcapsules embedded with different concentrations of HPMCP microspheres under different pH conditions, and (b) to (d) are drug release curves of the composite microcapsules under pH 2.5 and pH 6.8 conditions with drug loading concentrations of 22.5, 45, and 65mg/mL, respectively. As can be seen from fig. 13, in simulated gastric juice, indomethacin in the four composite microcapsules is hardly released under the protection of the capsule shell; under simulated intestinal fluid conditions, the drug is gradually released. Under the dual action of the PAA and the HPMCP enteric-coated microspheres, the release rate of the (HPMCP + PAA) @ theta-ACPSi composite microcapsule in simulated intestinal fluid with the pH value of 6.8 is the fastest among the four microcapsules, the constant-speed release is kept, and the zero-order constant-speed and constant-release of the medicine is realized.
Example 7
In this example, the composite microcapsules prepared in example 1 were tested for cytotoxicity.
Mouse embryonic fibroblast L-929 and fibroblast 3T3 were selected as normal cell models, and the CCK-8 method was used to examine the cytotoxicity of the composite microcapsules prepared in example 1. The cell activity was calculated according to formula (3):
Figure BDA0002642154170000141
in the formula (3), Cell Viability is Cell activity, AsThe absorbance value of the experimental well (suspension containing cell culture medium, CCK-8 and composite microcapsules), AcAs absorbance values for control wells (medium containing cells, CCK-8, and composite microcapsule suspension), AbAbsorbance values for blank wells (suspension of medium containing composite microcapsules and free of cells and toxic substances).
This step in the boosting process, the composite microcapsule suspensions were tested for several different composite microcapsule concentrations of 50, 125, 250, 500, 750, 1000, 2000 μ g/mL.
The cytotoxicity of the composite microcapsules at a composite microcapsule concentration ranging from 50 to 2000 μ g/mL was measured by 3T3 cells and L929 cells, and the results are shown in fig. 14, where the bar graphs at each test time point in fig. 14 represent the cases of composite microcapsule concentrations of 50, 125, 250, 500, 750, 1000, and 2000 μ g/mL in order from left to right. As can be seen from fig. 14, the composite microcapsule hardly inhibited the growth of cells, indicating that the composite microcapsule had good biocompatibility.
Example 8
This example tests the change of blood concentration of the drug-loaded composite microcapsule prepared in example 6 in New Zealand white rabbits.
6 new zealand white rabbits (the weight is about 2.8-3 kg, the center for laboratory animals of southwestern medical university) are randomly divided into 2 groups (A/B) after one week of observation, and the rabbits are fasted and can freely drink water. After 12h, the rabbits are fixed, and the administration dose of the experimental animal is about 2.5mg/kg according to the conversion of the administration dose of the human and the animal, wherein 10 granules of composite microcapsules (IMC Capsules) are respectively orally taken by the group A, and 2.5mL of suspensions (IMC Suspension) of sodium carboxymethylcellulose and indometacin are respectively infused into the stomach and the like. 2mL of blood was collected at the ear vein (or heart) of rabbit at 0, 0.5, 1, 1.5, 2, 2.5, 3,4, 6, 8, 12h after administration in heparinized tube, stored at-20 deg.C, and allowed to drink after 8 h. The obtained blood sample was centrifuged at 4000rpm at 4 ℃ for 10min, and the plasma sample of the supernatant was sampled and subjected to indomethacin concentration measurement by high performance liquid chromatography.
The calculation results in a drug-time curve as shown in fig. 15, and the peak time T of the oral indomethacin composite microcapsule is compared with that of indomethacin in suspension after the oral administration of the indomethacin composite microcapsule to New Zealand white rabbitsmaxDelayed for 4h, and composite microcapsule TmaxWider range, CmaxHigher values, the drug concentration was maintained after 12h administration. The AUC ratio of the drug-loaded composite microcapsule to the indometacin suspension is about 1.76 as calculated by a trapezoidal method. The AUC value of the indometacin suspension is lower than that of the indometacin-loaded composite microcapsule, because the indometacin is almost insoluble in water and has extremely low absorption in the gastrointestinal tract, and the indometacin suspension can be quickly absorbed after being orally takenThe gastrointestinal tract is emptied, resulting in a very low amount of indomethacin absorbed in the blood and therefore a low bioavailability and corresponding small AUC values; the indometacin-loaded composite microcapsule can delay the emptying of the drug by the gastrointestinal tract, and the drug can be slowly released, so that the indometacin-loaded composite microcapsule is more absorbed in the blood, has higher bioavailability and has a larger AUC value in comparison. In a word, the composite microcapsule provided by the application presents relatively high local drug concentration in the intestine of a New Zealand white rabbit, and has good clinical application prospect.
Example 9
In this example, the preparation of the drug-loaded composite microcapsule comprises the following steps:
(1) preparing the inner phase fluid, the outer phase fluid and the collecting fluid of the boosting chamber and the medicine carrying chamber
Boost indoor phase fluid (IF 1): the preparation method is the same as that of example 1, wherein in IF1, the concentration of sodium carboxymethylcellulose is 1.5 wt%, and the concentration of the promoter PAA is 1 wt%;
boost outdoor phase fluid (OF 1): the preparation method is the same as that OF example 1, wherein in OF1, the concentration OF sodium alginate is 2.5 wt%, and the concentration OF sodium dodecyl sulfate is 0.5 wt%;
infusor internal phase fluid (IF 2): adding sodium carboxymethylcellulose and nifedipine into water, and mixing uniformly to obtain IF2, wherein in IF2, the concentration of the sodium carboxymethylcellulose is 1.5 wt%, and the concentration of the nifedipine is 35 mg/mL;
drug-loaded outdoor fluid (OF 2): the preparation method is the same as that OF example 1, wherein in OF2, the concentration OF sodium alginate is 2.5 wt%, the concentration OF sodium dodecyl sulfate is 0.5 wt%, and the concentration OF enteric-coated microspheres is 1 mg/mL;
receiving liquid: the preparation method was the same as in example 1, and the concentration of chitosan in the receiving solution was 0.5 wt%, the concentration of glacial acetic acid was 1.5 v/v%, and the concentration of calcium nitrate was 15 wt%.
(2) Preparation of composite microcapsules
Two-chamber calcium alginate-chitosan microcapsules were prepared by following the procedure OF step (2) OF example 1 using the fluids OF each phase prepared in step (1) OF this example, with the flow rate OF IF1 being controlled at 30mL/h, the flow rate OF OF1 being controlled at 10mL/h, the flow rate OF IF2 being controlled at 25mL/h, and the flow rate OF OF2 being controlled at 15 mL/h.
Secondly, placing the double-cavity calcium alginate-chitosan microcapsule into a protamine sulfate aqueous solution of 2.5mg/mL, mechanically stirring at the rotating speed of 300r/min for 20min, and adsorbing protamine sulfate to the surface of the double-cavity calcium alginate-chitosan microcapsule to form a protamine intermediate layer to obtain the double-cavity calcium alginate-chitosan/protamine microcapsule.
Thirdly, adding the double-chamber calcium alginate-chitosan/protamine microcapsules into a sodium silicate solution with the concentration of 70mmol/L prepared from a glacial acetic acid solution with the concentration of 0.2mol/L, mechanically stirring and reacting for 0.5h at the rotating speed of 300r/min to form a silicon dioxide shell layer on the surfaces of the double-chamber calcium alginate-chitosan/protamine microcapsules, washing for three times by using the glacial acetic acid solution with the concentration of 0.2mol/L to obtain the composite microcapsules, and storing the obtained composite microcapsules for later use at the temperature of 4 ℃.
Example 10
(1) Preparing the inner phase fluid, the outer phase fluid and the collecting fluid of the boosting chamber and the medicine carrying chamber
Boosting the indoor phase fluid (IF1), the infusion chamber phase fluid (IF2) and the receiving fluid are the same as in example 1;
boost outdoor phase fluid (OF 1): the preparation method is the same as that OF example 1, wherein in OF1, the concentration OF sodium alginate is 1.5 wt%, and the concentration OF sodium dodecyl sulfate is 0.3 wt%;
drug-loaded outdoor fluid (OF 2): the preparation method is the same as that OF example 1, wherein in OF2, the concentration OF sodium alginate is 1.5 wt%, the concentration OF sodium dodecyl sulfate is 0.3 wt%, and the concentration OF enteric microspheres is 0.1 mg/mL;
(2) preparation of composite microcapsules
Firstly, the fluid of each phase prepared in the step (1) of the embodiment is adopted, and the double-chamber calcium alginate-chitosan microcapsule is prepared according to the operation and process conditions of the step (2) of the embodiment 1.
Secondly, placing the double-cavity calcium alginate-chitosan microcapsule into 1.5mg/mL protamine sulfate aqueous solution, mechanically stirring for 40min at the rotating speed of 150r/min, and adsorbing protamine sulfate to the surface of the double-cavity calcium alginate-chitosan microcapsule to form a protamine intermediate layer to obtain the double-cavity calcium alginate-chitosan/protamine microcapsule.
Thirdly, adding the double-chamber calcium alginate-chitosan/protamine microcapsule into a sodium silicate solution with the concentration of 50mmol/L prepared from a glacial acetic acid solution with the concentration of 0.2mol/L, mechanically stirring and reacting for 1h at the rotating speed of 150r/min to form a silicon dioxide shell layer on the surface of the double-chamber calcium alginate-chitosan/protamine microcapsule, washing for three times by using the glacial acetic acid solution with the concentration of 0.2mol/L to obtain the composite microcapsule, and storing the obtained composite microcapsule for later use at the temperature of 4 ℃.

Claims (10)

1. The intestinal targeting double-cavity calcium alginate-based composite microcapsule with the pumping constant-speed drug release characteristic is characterized in that the composite microcapsule is provided with two independent cavities, namely a boosting chamber and a drug carrying chamber, the boosting chamber and the drug carrying chamber are separated by a diaphragm, the main component of the diaphragm is calcium alginate, the capsule walls of the boosting chamber and the drug carrying chamber are composed of a calcium alginate-chitosan inner layer, a protamine intermediate layer and a silicon dioxide shell layer, and enteric-coated microspheres are embedded in the inner layer of the capsule wall of the drug carrying chamber; the boosting chamber is internally enveloped with a mixed solution of sodium carboxymethylcellulose and a boosting agent, the boosting agent is a high polymer material with pH responsiveness, and the medicine carrying chamber is enveloped with a mixed solution of sodium carboxymethylcellulose and a hydrophobic medicine; under the condition of intestinal pH, the boosting chamber provides pumping boosting effect for the release of the medicine in the medicine carrying chamber, so that the medicine in the medicine carrying chamber is released at a zero-order constant speed.
2. The intestine-targeted dual-chamber calcium alginate-based composite microcapsule with the pumping constant-speed drug release characteristic of claim 1, wherein the diameter of the enteric-coated microspheres is 40-60 μm, and the enteric-coated microspheres are made of cellulose or acrylic resin enteric-coated polymer materials.
3. The intestine-targeted double-chamber calcium alginate-based composite microcapsule with the pumping constant-speed drug release characteristic according to claim 1, wherein the boosting agent is polyacrylic acid or polymethacrylic acid.
4. The intestinal-targeting double-chamber calcium alginate-based composite microcapsule with the pumping constant-speed drug release characteristic according to any one of claims 1 to 3, wherein the size of the composite microcapsule is millimeter, and after freeze-drying, the thickness of the capsule wall of the boosting chamber and the drug loading chamber is 70-120 μm.
5. The intestine-targeted double-chamber calcium alginate-based composite microcapsule with the pumping constant-speed drug release characteristic according to claim 4, wherein the length of the composite microcapsule in an acidic environment is not more than 5 mm.
6. The intestinal-targeted double-chamber calcium alginate-based composite microcapsule with the pumping constant-speed drug release characteristic according to any one of claims 1 to 3, wherein the volume of the boosting chamber of the composite microcapsule is equivalent to that of the drug-loaded chamber.
7. The intestinal-targeted double-chamber calcium alginate-based composite microcapsule with the pumping constant-speed drug release characteristic according to any one of claims 1 to 3, wherein the concentration of the sodium carboxymethyl cellulose in the mixed solution of the sodium carboxymethyl cellulose encapsulated in the boosting chamber and the boosting agent is 1-1.5 wt%, and the concentration of the boosting agent is 0.5-1 wt%.
8. The intestinal targeting double-chamber calcium alginate-based composite microcapsule with pumping constant-speed drug release characteristic according to any one of claims 1 to 3, wherein the concentration of the sodium carboxymethyl cellulose in the mixed solution of the sodium carboxymethyl cellulose encapsulated in the drug carrying chamber and the hydrophobic drug is 1-1.5 wt%.
9. The preparation method of the intestine-targeted double-chamber calcium alginate-based composite microcapsule with pumping constant-speed drug release characteristics, which is disclosed by any one of claims 1 to 8, is characterized by comprising the following steps:
(1) preparing the inner phase fluid, the outer phase fluid and the collecting fluid of the boosting chamber and the medicine carrying chamber
Boosting indoor phase fluid: adding sodium carboxymethylcellulose and a boosting agent into water, and uniformly mixing to obtain a boosting indoor phase fluid, wherein the concentration of the sodium carboxymethylcellulose is 1-1.5 wt% and the concentration of the boosting agent is 0.5-1 wt% in the boosting indoor phase fluid;
boosting of the outdoor phase fluid: adding sodium alginate and sodium dodecyl sulfate into water, and uniformly mixing to obtain a boosting outdoor phase fluid, wherein the concentration of the sodium alginate in the boosting outdoor phase fluid is 1.5-2.5 wt%, and the concentration of the sodium dodecyl sulfate in the boosting outdoor phase fluid is 0.2-0.5 wt%;
the inner phase fluid of the medicine carrying chamber: adding sodium carboxymethylcellulose and a hydrophobic drug into water, and uniformly mixing to obtain a medicament-carrying chamber internal phase fluid, wherein the concentration of the sodium carboxymethylcellulose in the medicament-carrying chamber internal phase fluid is 1-1.5 wt%;
carrying out phase fluid outside the medicine carrying chamber: adding sodium alginate and sodium dodecyl sulfate into water, uniformly mixing, adjusting the pH value to 3-5 by using a glacial acetic acid solution, and adding enteric microspheres to obtain a drug-loaded indoor phase fluid, wherein in the drug-loaded outdoor phase fluid, the concentration of the sodium alginate is 1.5-2.5 wt%, the concentration of the sodium dodecyl sulfate is 0.2-0.5 wt%, and the concentration of the enteric microspheres is 0.05-1 mg/mL;
receiving liquid: adding chitosan and glacial acetic acid into water, uniformly mixing, adding calcium nitrate, and uniformly mixing to obtain a receiving solution, wherein the concentration of the chitosan is 0.2-0.5 wt%, the concentration of the glacial acetic acid is 1-1.5 v/v%, and the concentration of the calcium nitrate is 10-15 wt%;
(2) preparation of composite microcapsules
Firstly, preparing a double-chamber calcium alginate-chitosan microcapsule by adopting a pair of capillary co-extrusion micro-fluidic devices, respectively injecting a boosting chamber internal phase fluid and an external phase fluid into an inner tube and an outer tube of one of the capillary co-extrusion micro-fluidic devices to form a boosting chamber liquid drop, simultaneously respectively injecting a medicine carrying chamber internal phase fluid and an external phase fluid into an inner tube and an outer tube of the other capillary co-extrusion micro-fluidic device to form a medicine carrying chamber liquid drop, fusing the boosting chamber liquid drop and the medicine carrying chamber liquid drop before reaching the liquid level of a receiving liquid positioned below the capillary co-extrusion micro-fluidic devices, and then dropping the boosting chamber liquid drop and the medicine carrying chamber liquid drop into the receiving liquid to react with the receiving liquid for 1-5;
controlling the flow rate of the boosting indoor phase fluid and the flow rate of the medicine carrying indoor phase fluid to be 20-30 mL/h, and controlling the flow rate of the boosting outdoor phase fluid and the flow rate of the medicine carrying outdoor phase fluid to be 10-20 mL/h;
placing the double-cavity calcium alginate-chitosan microcapsule into 1.5-2.5 mg/mL protamine sulfate aqueous solution, and stirring to enable protamine sulfate to be adsorbed to the surface of the double-cavity calcium alginate-chitosan microcapsule to form a protamine intermediate layer, so as to obtain the double-cavity calcium alginate-chitosan/protamine microcapsule;
thirdly, adding the double-chamber calcium alginate-chitosan/protamine microcapsules into a sodium silicate solution with the concentration of 50-70 mmol/L of sodium silicate prepared from a glacial acetic acid solution, stirring to react to form a silicon dioxide shell layer on the surfaces of the double-chamber calcium alginate-chitosan/protamine microcapsules, and washing to obtain the composite microcapsules.
10. The preparation method of the intestine-targeted double-chamber calcium alginate-based composite microcapsule with the pumping constant-speed drug release characteristic according to claim 9, wherein in the step (2), the distance between the lower end of the outer tube of the capillary co-extrusion microfluidic device and the liquid level of the receiving liquid is controlled to be 3-7 cm.
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