CN108619080B

CN108619080B - Microneedle drug delivery system loaded with nano-material wrapped ovulation-promoting drug and preparation method thereof

Info

Publication number: CN108619080B
Application number: CN201810367005.6A
Authority: CN
Inventors: 陈惠琄; 李春炜; 刘繁茂; 杭天; 何根; 林迪安; 唐瑞; 曹毅人; 杨成端; 张爱华; 王自鑫; 谢曦
Original assignee: Sun Yat Sen University
Current assignee: Sun Yat Sen University
Priority date: 2018-04-23
Filing date: 2018-04-23
Publication date: 2021-04-06
Anticipated expiration: 2038-04-23
Also published as: CN108619080A

Abstract

The invention provides a microneedle drug delivery system loaded with a nanomaterial-encapsulated ovulation-promoting drug, which comprises a microneedle patch bottom and a microneedle tip positioned on the microneedle patch bottom, wherein the microneedle tip is internally embedded with the ovulation-promoting drug, and the ovulation-promoting drug is encapsulated by the nanomaterial. The microneedle drug delivery system can relieve pain of patients in the treatment medication stage, prolong the drug release time, improve the drug absorption rate and reduce adverse side effects.

Description

Microneedle drug delivery system loaded with nano-material wrapped ovulation-promoting drug and preparation method thereof

Technical Field

The invention belongs to the field of medicines, and particularly relates to a microneedle drug delivery system loaded with a nano-material-coated ovulation-promoting drug and a preparation method thereof.

Background

At present, the population proportion of infertility is on the rising trend year by year, the incidence rate of the infertility in the world is 10-15%, the incidence rate of the infertility in certain developing countries can even reach 30%, and the infertility becomes a global medical problem affecting the development and health of human beings. Therefore, the WHO has taken infertility, cardiovascular diseases and tumor diseases as three major diseases affecting human life and health nowadays.

The first condition for female pregnancy is to discharge the ovum smoothly, otherwise ovulation failure type infertility may be caused. Therefore, infertility treatment is primarily to solve the problem of ovulation failure in women. The female is unable to discharge ovum smoothly, i.e. ovulation disorder, is mainly caused by abnormal secretion of ovulation-related hormones such as FSH (follicle-stimulating hormone) and LH (luteinizing hormone) in the female. In women, modulation of the intact hypothalamic-pituitary-ovarian axis (HPOA) is essential for ovulation. During a period, the significant change in the preovulatory body of a female is that the blood estrogen level is continuously increased, the secretion of a key hormone LH is promoted, the key feature of ovulation, namely the LH surge, is caused, and then the follicle is finally matured under the stimulation of a large amount of LH to finish the ovulation. The functional cause of female anovulation, mainly the HPOA regulation, is a problem and is divided into three categories: hypothalamic-pituitary hypofunction type; hypothalamic-pituitary dysfunctional type; ovarian failure type. The current main means for treating ovulation failure is drug induced ovulation, for example, glycoprotein hormone secreted by placenta villus tissue, hCG (human chorionic Gonadotropin, hCG) is an approved prescription drug, is an endogenous drug, is safe and nontoxic, and is widely used for treating infertility, at present, the main administration means of hCG is injection administration by injection, but injection is used for percutaneous administration, and due to frequent injection, adverse side reactions such as keratinization, redness and swelling, induration and the like of skin at frequently applied parts can be caused, and strong pain and discomfort can be brought to patients, therefore, the minimally invasive painless soluble microneedle patch is widely researched as a novel administration means, and related research results can be applied to the fields of vaccination, diabetes treatment, cancer treatment and the like, in the aspect of drug controlled release, the microneedle drug delivery system can also use biodegradable nanoparticles to wrap the drug to achieve the effect of controlling slow release. The biodegradable nano-particles are utilized to wrap polypeptide or protein macromolecules such as hCG and the like, after the medicine enters a human body, the nano-particles can degrade and release the medicine after a certain time, and the medicine can be fully combined with a receptor at a focus part to exert the effect, so that better biological absorption rate is obtained. Therefore, the nano particles and the microneedle patch are combined to carry out controlled drug release, and the drug release patch has wide application prospect due to the advantages of no pain, minimal invasion, convenience, easy use and high drug utilization rate.

Because ovulation-promoting drugs such as hCG are mainly protein macromolecular drugs, and oral administration can be decomposed by in-vivo enzymes and gastric acid to cause failure, the ovulation-promoting drugs cannot be taken in an oral administration mode, and the current main application method is to supplement the ovulation-promoting drugs by injection. However, ovulation induction by injection administration has a plurality of defects: because the treatment needs to be carried out by multiple injections with strictly controlled dosage so as to avoid the ovarian hyperstimulation by the ovulation-promoting drugs, the patients feel pain and discomfort due to repeated injections, and local red swelling, induration and other adverse reactions can be caused by allergy, so that great pain and pressure are brought to the physiology and the psychology of the patients.

Disclosure of Invention

The invention aims to overcome the defects of the traditional injection administration and provide a microneedle sustained-release administration system carrying a nanomaterial and externally wrapping an ovulation-promoting drug.

Therefore, the invention adopts the following technical scheme:

a microneedle drug delivery system loaded with a nanomaterial-coated ovulation-promoting drug comprises a microneedle patch bottom and a microneedle tip located on the microneedle patch bottom, wherein the ovulation-promoting drug is embedded in the microneedle tip and is coated by the nanomaterial.

Preferably, the ovulation-promoting drug includes, but is not limited to, hCG. More preferably, the ovulation promoting drug is hCG encapsulated by chitosan nanoparticles.

Preferably, the nanomaterial is a chitosan nanoparticle.

Preferably, the microneedle tip is water-soluble.

Preferably, the material of the microneedle tip is a soluble biocompatible material, and more preferably sodium carboxymethyl cellulose.

Preferably, the length of the dissolvable microneedle tip is 500 μm to 1 mm.

Preferably, other ovulation-promoting drugs except the drug can be embedded in the microneedle tip, so that a better combined treatment effect is achieved, and the ovulation-promoting success rate is higher.

The invention also provides a preparation method of the microneedle drug delivery system, which comprises the following steps:

(1) preparing a nano material;

(2) coating the ovulation-promoting medicine into the nano material;

(3) embedding the ovulation-promoting drug wrapped with the nano material in the microneedle tip.

Preferably, the nanomaterial is a chitosan nanoparticle.

More preferably, the step (1) is: purified chitosan is treated by ultrasonic in acetic acid solution, and tripolyphosphate is added to form chitosan-tripolyphosphate nanoparticles. More preferably, the concentration of the acetic acid solution is 1% w/v.

Preferably, the ovulation-promoting drug is encapsulated in the nanomaterial in an incorporated form.

Preferably, the ovulation-promoting drug is encapsulated in the nanomaterial in the form of an incubation.

Preferably, the step (3) is: the ovulation-promoting drug wrapped with the nano material is dissolved in sodium carboxymethyl cellulose aqueous solution and molded. More preferably, the weight concentration of the ovulation-promoting drug and the sodium carboxymethyl cellulose aqueous solution ranges from 0.5% to 20% (W/W), and the proportion can be adjusted according to the required condition.

More preferably, the mass concentration of the sodium carboxymethyl cellulose aqueous solution is 5% to 10%, more preferably 8%.

As a preferred embodiment, the polypeptide medicament hCG for ovulation promotion is wrapped by the chitosan nanoparticle, then the chitosan nanoparticle is filled into a microneedle patch made of a soluble material SCMC, and then the microneedle patch is released into a human body to promote ovulation. In the case of hCG, after confirming that the patient is ovulatory disorder due to hypohormone secretion, 2000-10000 units (depending on the patient) of hCG per day are required to be supplemented until the patient ovulates.

The microneedle patch is superior to the traditional injection administration method in the aspects of drug utilization rate, patient comfort and the like. Because the micro-needle is tiny (the length is about 500 mu m-1mm), the micro-needle only penetrates the stratum corneum of the skin without touching nerves and blood vessels, and the patient can not generate the pain which is difficult to endure; after the microneedle is inserted, since the used material is a soluble material with biocompatibility, such as but not limited to SCMC (Sodium salt of carbon Methyl Cellulose, Sodium carboxymethyl Cellulose) has good water solubility, and can be rapidly degraded after entering the stratum corneum and contacting with body fluid, the wound is micron level, and the skin is easy to self-heal. Meanwhile, by designing and preparing outer wrapping layers of various medicines, the time for releasing the medicines by the nano particles can be controlled, the low absorption rate caused by too fast failure of the medicines or the generation of adverse side effects caused by too fast release of the medicines are avoided, for example, the outer wrapping layers can prevent polypeptide macromolecular medicines such as hCG from being decomposed too fast by in-vivo enzymes to fail, and meanwhile, the adverse consequences of multiple pregnancies and the like caused by over-use and over-stimulation of ovaries are avoided.

The ovulation-promoting drug used in the invention is a polypeptide macromolecular drug hCG which is composed of two subunits of alpha and beta, the number and the sequence of amino acids of the alpha subunit are almost completely the same as that of a key hormone LH (luteinizing hormone) required by ovulation, so that the hCG has high homology with the LH, and the biological effect and the immune characteristic are basically similar, so that the LH is simulated by a method of supplementing the hCG at present, and the hCG is combined with a receptor on a follicle to promote mature ovulation of the follicle.

The wrapping material used in the invention includes but is not limited to chitosan (chitosan, also called deacetylated chitin), which is obtained by deacetylating chitin (chitin) widely existing in the nature, and the degradation product is glucose and the like, so that the wrapping material has good biocompatibility, blood compatibility, biological safety and other properties, and can be applied to the outer wrapping layer of the medicine.

When the drug-coated nanoparticles are prepared, one drug can be coated, and multiple drugs can be coated, so that a better combined treatment effect is achieved, and the ovulation promoting success rate is higher.

When the nano particles for coating the medicine are prepared, the parameters such as the type of the used materials, the molecular weight, the concentration of the solvent, the feeding mass ratio and the like can have important influence on the properties such as the particle size, the zeta potential, the stability and the like of the finally formed particles, and the parameters of the particles can influence the release rate and the degradation rate of the particles in organisms. These parameters can be adjusted, for example, using more suitable materials to achieve better encapsulation efficiency, stability, safety, low toxicity, and more conveniently controlled release times.

In the preparation process of the microneedle, the mass concentration range of the nano-particles containing the ovulation-promoting drug and the high molecular solution used for preparing the microneedle for forming is 0.5-20% (W/W), and the proportion can be adjusted according to the required condition. However, the amount of the nanoparticles should be controlled to be within 20%, and when the amount of the nanoparticles is too large, the microneedles cannot be formed or become brittle and cannot pierce the stratum corneum. The loading rate of the nano particles and the integrity and the shape of the micro needles can be influenced by key parameters such as the types of the selected raw materials, and the optimal loading effect can be achieved by selecting different materials and optimizing proportion parameters.

The invention combines the nano-particles and the microneedle array to release an endogenous safe and nontoxic polypeptide drug hCG to promote ovulation and treat infertility, and has the advantages of both the nano-particles and the microneedle array. The method is used for treating ovulation disorder infertility, on one hand, the pain of a patient in a treatment medication stage can be relieved by using the characteristics of tiny micro-needle patch needle heads, minimally invasive painlessness, convenient use, friendly patient use experience and the like in a medication mode, on the other hand, the time for releasing the medicine is prolonged by using the nano-particle coating, so that the medicine can be fully combined with a receptor, the absorption rate of the medicine is improved, and adverse side effects caused by the fact that a large amount of external hormone enters a human body in a short time are avoided by slow release.

Drawings

Fig. 1 is a schematic structural view of a microneedle delivery system according to the present invention.

Fig. 2 is a schematic view of sustained release administration of a microneedle delivery system according to the present invention.

Fig. 3 is a schematic view of the drug action of the microneedle delivery system according to the present invention.

Detailed Description

The present invention will be described in more detail with reference to the following embodiments and drawings, but the present invention is not limited to the following embodiments.

Fig. 1 is a schematic structural diagram of a microneedle drug delivery system according to the present invention, which includes a microneedle patch base 1, a soluble microneedle tip 2, a nanomaterial (e.g., chitosan nanoparticle) 3 encapsulating an ovulation-promoting drug (e.g., hCG)4, the ovulation-promoting drug 4, and the ovulation-promoting drug 4 embedded in the microneedle tip 2. The microneedle tip is prepared from 5-10% SCMC (sodium carboxymethyl Cellulose), and the ovulation promoting drug hCG 4 is wrapped by chitosan nano-material 3 which is a degradable biocompatible material. The final parameters of the obtained microneedle patch are as follows: the base area of the patch is 1cm × 1cm, and the density of the needle points is 72-81 needles/cm²And the length is 500 mu m-1 mm.

Fig. 2 is a schematic view of sustained release administration of a microneedle delivery system according to the present invention. When the drug is administered, as shown in fig. 2, the microneedle punctures the cuticle 5 and the epidermis 6 to reach the dermis 7, then the microneedle is gradually dissolved after 10 to 15 minutes, and the dissolved microneedle tip 8 releases the ovulation-promoting drug 4 wrapped with the chitosan nanoparticle into the human circulation. After contacting with body fluid environment, the chitosan nano-particles of the coating layer are gradually hydrolyzed by enzyme in vivo to release the ovulation-promoting drug 4 contained in the coating layer.

Fig. 3 is a schematic view of the drug action of the microneedle delivery system according to the present invention. As shown in fig. 3, after the ovulation-promoting drug 4 is released, if it is not decomposed, it will finally bind to the hCG receptor 10 on the immature follicular cell membrane 9 after in vivo circulation, promoting its development into mature follicle, and finally releasing ovum, thereby achieving smooth ovulation.

Example 1: preparation of hCG-chitosan nanoparticles

S1, purifying chitosan:

the solid chitosan flakes were mixed in 1mol/L aqueous NaOH solution (1g chitosan/10 ml NaOH solution). The solid-liquid mixture was then heated to 70 ℃ with continuous stirring for 2 hours, followed by filtration on a buchner funnel. The flakes recovered by filtration were thoroughly washed and dried at 40 ℃ for 12 hours. The NaOH-treated chitosan flakes were dissolved in a 0.1mol/L acetic acid solution, and the residue of insoluble particles was removed by filtration. The pH of the filtrate was adjusted to pH8.0 using 1mol/L aqueous NaOH solution to yield purified chitosan as a white precipitate. The precipitated chitosan was thoroughly washed with deionized water, and the product was vacuum-dried at room temperature for 24 hours and then used for preparing nanoparticles.

S2, preparing chitosan nano particles:

sonicating the purified low, medium, high molecular weight chitosan in 1% (w/v) acetic acid solution to produce chitosan concentrations of 0.05, 0.10, 0.15, 0.20, 0.25, and 0.30% (w/v). When TPP (tripolyphosphate, here Sodium tripolyphosphate) is added to the chitosan solution and mixed, the chitosan-TPP nanoparticles will spontaneously begin to form due to the ionic cross-linking and aggregation mechanism induced by TPP. While nanoparticles were formed with a concentration of 0.30% (w/v) chitosan at chitosan to TPP weight ratios of 3:1, 4:1, 5:1, 6:1 and 7:1, respectively. The prepared nanoparticle suspension was gently stirred at 20 ± 2 ℃ for 60min for further analysis and application. Different concentrations and ratios can ultimately achieve technical effects. When the concentration of the chitosan is 0.1(w/v), the weight ratio of the chitosan to the TPP is 3: the effect is best at 1 time.

S3, wrapping hCG into chitosan nano-particles

Protein loading in the chitosan nanoparticle system can be accomplished by one of two methods, incorporation (incorporation) or incubation (incubation), to obtain hCG-chitosan nanoparticles.

The doping method comprises the following steps: hCG was premixed with chitosan solution, the pH was adjusted to 5.5 and maintained at a temperature of 20 + -2 deg.C. When TPP was flushed into hCG-chitosan solution and mixed, hCG-chitosan nanoparticles spontaneously began to form. The nanoparticle suspension was gently stirred at 20 ± 2 ℃ for 60min for further analysis and application. During the incorporation process, protein molecules are embedded/embedded in the chitosan-protein nano-network, while some protein molecules are also absorbed into the interior of the particle by the surface of the particle.

The cultivation method comprises the following steps: TPP was added first to coagulate to form chitosan nanoparticles, and then the solution containing nanoparticles was mixed with a solution containing hCG at a predetermined concentration. The mixed solution was gently stirred for 60min to allow the protein adsorption process on the nanoparticles to reach isothermal equilibrium. In this method, the coating of the protein is accomplished only by the adsorption of the chitosan nanoparticle surface.

Example 2: evaluation of hCG-chitosan nanoparticle encapsulation rate, Release Rate and stability

S1, measuring the wrapping rate:

the hCG-chitosan nanoparticles obtained in example 1 were transferred into a 5ml centrifuge tube and then ultracentrifuged at 30,000rpm at a temperature of 10 ℃ for 30min, and then the nanoparticles were separated from the solution. The centrifuged supernatant was transferred and the protein content of the supernatant was analyzed at regular intervals using Bradford protein assay with UV spectrophotometer at λ 595 nm. The measurement result shows that the coating rate can reach more than 90% by selecting chitosan with proper molecular weight and concentration, and almost all the medicine can be coated into the chitosan nano-particles. The larger the molecular weight is, the better the coating effect is, the chitosan with the molecular weight of more than 10 ten thousand and the concentration of 0.1(w/v) is selected, and the coating rate is the best.

S2, release rate measurement (in simulated fluid):

the nanoparticles in the form of the sediment obtained in example 1 were transferred to a clean 5ml centrifuge tube with 3ml PBS (phosphate buffer saline). The tube was sealed and placed in a water bath with the temperature maintained at 37 + -1 deg.C. At specified collection times (e.g., 2h), 100 μ l samples were taken from the tubes and the protein concentration was measured using the Bradford reagent. The tubes were filled with 100. mu.l of fresh PBS solution each time a sample was removed. The measurement result shows that the chitosan materials with different molecular weights are selected, the time for the drug release rate to reach 50% is different from 3 to 60 hours (the lower the molecular weight of the chitosan is, the faster the release speed is), and the time for the drug release can be controlled by designing and selecting the parameters of the coating material so as to achieve better drug utilization effect.

S3, evaluation of stability

An amount of the hCG-chitosan nanoparticle obtained in example 1 was taken, and divided into 7 parts in equal amounts, and added to water, PBS, and a cell culture medium (Eagle medium to which Earle balanced salt solution was added, 2mM L-glutamine, 1mM Na-pyruvic acid, 10% fetal bovine serum, and 1% penicillin/streptomycin in equal amounts, respectively) and then left at a constant temperature of 37 ℃ for 24 hours. The particle size of the particles is measured at intervals, for example 3 h. The measurement results show that after 24h, the particle size of the nanoparticles in the PBS solution is obviously increased, and the nanoparticles in water and cell culture medium are almost unchanged, which indicates that the stability of the nanoparticles is good.

Example 3: preparation of hCG-chitosan nanoparticle loaded microneedle patch

The nano particles loaded with drug molecules are dissolved in 8 percent (W/W) SCMC (Sodium salt of Caboxy Methyl Cellulose, Sodium carboxymethyl Cellulose) aqueous solution (the mass concentration range of the nano particles containing the ovulation-promoting drug and the macromolecular solution is between 0.5 percent and 20 percent (W/W), the proportion can be adjusted according to the required condition), and 50 mul of the solution is added to a microneedle patch mould. The mold was then placed in a centrifuge and centrifuged at 4000rpm for 5min to force the solution into the pinhole cavity in the mold. After centrifugation, the solution was removed from the cavity and air dried overnight to allow the solution to solidify. 200 μ l of 8% (w/w) SCMC solution was added to the mould and centrifuged at 4000rpm for 1 min. And after the centrifugation is finished, standing the mold, and drying to form the microneedle patch.

After the patch is formed, the patch is peeled from the mold. Finally, the parameters of the obtained microneedle are as follows: the base area of the patch is 1cm × 1cm, and the density of the needle points is 72-81 needles/cm²And the length is 500 mu m-1 mm.

Example 4: testing of microneedle patches

Microneedle patches for testing were prepared in the same manner as in example 3.

S1, intra-microneedle drug distribution:

in order to visualize the distribution of drug molecules within the microneedle patch, rhodamine b (red fluorescence) having red fluorescence property was used as the hCG instead of the label to load the microneedle patch. The fluorescent molecular distribution was observed using a confocal fluorescence microscope. The results show that most of the fluorescent molecules are distributed at the tip of the microneedle.

S2, stability of drug retained in microneedles:

in order to evaluate the stability of hCG nanoparticles remaining in the microneedle patch, the amount of hCG in the obtained solution was quantitatively analyzed by ELISA (progesterone microneedles were quantitatively analyzed using an HPLC system), and the effective amount of intact hCG after the microneedle patch was manufactured and placed was evaluated. In this experiment, the effective amount of intact hCG was measured once after the hCG was loaded on the microneedle patch; after placing the microneedle patch at 4 ℃ for 1 week, the effective amount of intact hCG was measured again. The microneedle patch was placed at high temperature for a short time (30 minutes at 90 ℃) and then measured as a negative control group. The results show that: about 90% (± 10%) of the drug remains stable after microneedle patch manufacture, while about 80% (± 20%) of the drug may remain stable after microneedle patch placement for 1 week at 4 ℃; in contrast, in the negative control group, only about 4% of the drug remained stable after a short period of high temperature exposure. Therefore, the stability of the drug in the microneedle patch can be ensured when the microneedle patch is stored under normal conditions.

S3, distribution of the drug released by the microneedle after skin penetration:

in order to observe the molecular distribution of the drug released from the microneedle patch after skin permeation, the microneedle patch loaded with rhodamine b was applied to the dorsal skin of the rat for 20 minutes and then removed. After 2 or 6 hours of microneedle patch insertion, the skin near the penetration site was dissected and prepared for imaging. Frozen sections were imaged by confocal microscopy (Olympus FV-1000) to determine the distribution of released rhodamine b. The results show that: after 2h exposure of the microneedles, fluorescent molecules were deposited in the dermal layer (depth of about 100 μm or greater). After 6 hours of action, the fluorescent molecules were observed to continue to diffuse over a larger area within the dermal layer near the needle puncture site. These results indicate that microneedle patches can stably carry drugs and deliver drug molecules into the skin.

S4, skin irritation test:

safety of topically applied microneedle patches was assessed by testing skin irritation after treatment. Microneedle patches were applied to the back surface of mice once a day for 3 consecutive days, and removed after 20 minutes. The skin treated with the microneedle patch was observed for visible irritation. The results show that: no visible irritation was observed on the skin treated with the microneedle patch compared to untreated skin. On the fourth day, the skin around the microneedle puncture site was dissected and examined histologically to see if there was infiltration of inflammatory cells in the skin. Untreated skin served as a control group. Compared with untreated skin, no obvious skin inflammatory cell infiltration is observed on the skin after the microneedle patch is repeatedly inserted, which shows that the application of the microneedle patch can not induce the skin to generate obvious inflammatory reaction, and the microneedle patch is safe and reliable.

Example 5: drug efficacy test of microneedle patch

Experiments were performed using the microneedle patch prepared in example 3.

Selecting a cow of an appropriate age that has undergone at least one birth, is not pregnant, and has a normal oestrus cycle. Ovaries were visualized by Ultrasonography (USG) and examined for follicular and luteal (CL) morphology and recorded, followed by intramuscular injection of prostaglandin (PGF2 α) (5ml) and repeated one injection after 10 days. Then, they were divided into two groups:

group A: intramuscular injection of 1.000IU hCG hormone on day 2 after the last prostaglandin (PGF2 α) injection;

group B: 1.000IU of hCG-chitosan nanoparticles were provided by microneedle patch on day 2 after the last PGF2 α injection.

USG (ultrasound apparatus model SIUI Veterinary model CST 7700V, 10.4 inch monitor LCD and 7.5MHz Linier rectal probe) observations were made daily starting with the second PGF2 α injection until ovulation. The diameter and development of the follicles and corpus luteum were observed. The bovine rectum was emptied of feces prior to transrectal USG observation. During observation, both the left and right ovaries were scanned and the diameters of all observable follicles and corpus luteum were measured one by one. The measurement result shows that the drug effect of the microneedle drug delivery is not obviously different from that of the injection drug delivery, the follicle maturation and ovulation can be effectively promoted, and the microneedle drug delivery can be used as a new drug delivery means for promoting the ovulation of the infertility patients, so that the microneedle drug delivery has application value.

Claims

1. A microneedle drug delivery system loaded with a nanomaterial-encapsulated ovulation-promoting drug is characterized in that: the anti-ovulation drug delivery system comprises a microneedle patch bottom and a microneedle needle point positioned on the microneedle patch bottom, wherein an ovulation-promoting drug is embedded in the microneedle needle point and is wrapped by a nano material; the nano material is chitosan nano particles; the ovulation-promoting drug is hCG; the needle tip of the microneedle is sodium carboxymethyl cellulose;

the microneedle delivery system is prepared by the following steps:

(1) preparing the nano material: mixing solid chitosan sheets in 1mol/L NaOH aqueous solution, dissolving 1g of chitosan in 10ml of NaOH solution, heating the solid-liquid mixture to 70 ℃, continuously stirring for 2 hours, then filtering by using a Buchner funnel, thoroughly washing the sheets obtained by filtering and recovering, drying at 40 ℃ for 12 hours, dissolving the NaOH-treated chitosan sheets in 0.1mol/L acetic acid solution, filtering to remove residues of insoluble particles, adjusting the pH value of the filtrate to pH8.0 by using 1mol/L NaOH aqueous solution, generating purified chitosan in the form of white precipitate, thoroughly washing the precipitated chitosan by using deionized water, and vacuum-drying the product at room temperature for 24 hours; sonicating the purified chitosan in a 1% w/v acetic acid solution to produce 0.1% w/v chitosan; adding tripolyphosphate into the chitosan solution, and mixing, wherein the weight ratio of chitosan to TPP is 3: 1; the prepared nano-particle suspension is stirred for 60min at the temperature of 20 +/-2 ℃;

(2) encapsulating the ovulation-promoting drug into the nanomaterial: firstly, tripolyphosphate is added to be coagulated to form chitosan nanoparticles, then the solution containing the nanoparticles is mixed with the solution containing hCG with the preset concentration, and the mixed solution is stirred gently for 60min to ensure that the protein adsorption process on the nanoparticles reaches isothermal balance;

(3) embedding the nano material coated with the ovulation-promoting drug in the sodium carboxymethyl cellulose: dissolving nanoparticles carrying drug molecules in 8% W/W sodium carboxymethyl cellulose aqueous solution, wherein the mass concentration range of the nanoparticles containing ovulation-promoting drugs and high molecular solution is 0.5% -20% W/W, adding 50 mul of the solution to a microneedle patch mold, then placing the mold in a centrifuge, centrifuging for 5min at the rotating speed of 4000rpm to enable the solution to enter a pinhole cavity on the mold, completing centrifugation, removing the solution outside the cavity, air-drying overnight to enable the solution to solidify, then adding 200 mul of 8% W/W sodium carboxymethyl cellulose solution into the mold, centrifuging for 1min at the rotating speed of 4000rpm, standing the mold after centrifugation is completed, and drying to form the microneedle patch.

2. A microneedle delivery system according to claim 1, wherein a drug other than the ovulation-promoting drug is further embedded in the tip of the microneedle.