CN111660558A

CN111660558A - Method for preparing nano microneedle template by laser direct writing

Info

Publication number: CN111660558A
Application number: CN202010529609.3A
Authority: CN
Inventors: 史强; 胡海龙
Original assignee: Yantai Magic Technology Nano Technology Co ltd
Current assignee: Yantai Magic Technology Nano Technology Co ltd
Priority date: 2020-06-11
Filing date: 2020-06-11
Publication date: 2020-09-15

Abstract

The invention provides a method for preparing a nano microneedle template by laser direct writing, which comprises the following steps: (1) establishing a three-dimensional model of a nano microneedle template, and introducing the three-dimensional model into a three-dimensional photoetching machine; (2) dripping the photoresist required by microneedle template printing on the molding substrate; (3) curing the photoresist on the substrate by two-photon focused laser according to the three-dimensional model established in the step (1) by adopting a laser direct writing technology to obtain a molded sample; (4) and developing and drying the molded sample, and then carrying out secondary exposure to obtain the nano-scale microneedle template. By the method, any shape of microneedle can be printed, the diameter of the obtained microneedle can be smaller than 20 micrometers, the height of the obtained microneedle can be smaller than 50 micrometers, the printing limit of the traditional method and the existing 3D printing method is broken through, and in addition, the method has the advantages of high controllability, high printing precision and high printing efficiency.

Description

Method for preparing nano microneedle template by laser direct writing

Technical Field

The invention relates to the technical field of preparation of nano microneedle templates, in particular to a method for preparing a nano microneedle template by laser direct writing.

Background

Transdermal drug delivery is a drug delivery route, and can avoid some defects caused by oral drugs and injection drugs; however, transdermal delivery is affected by the stratum corneum of the skin, resulting in only a small fraction of small molecule drugs being suitable for use in the formulation, and the presence of the stratum corneum also has a different effect on the absorption and release of the drug, thereby preventing the formulation from being prepared.

In order to improve the application of transdermal drug delivery, microneedles are gradually generated, are miniature needles with the length of 10-2000 mu m and are arranged in a regular array, and can penetrate through the stratum corneum of the skin to form a large number of mu m-level reversible channels, so that the transdermal efficiency of hydrophilic drugs and biomacromolecule drugs is improved; the mode of the array micro-needle has the advantages of painlessness, micro-wound, high efficiency and the like, so the array micro-needle becomes a research hotspot in the field of transdermal drug delivery systems.

The array micro-needle is divided into an inorganic micro-needle, a metal micro-needle and a polymer micro-needle according to different material compositions; among them, the polymer array micro-needle has the advantages of good biocompatibility, safe administration, good toughness, accurate and controllable drug-loading rate, low cost and easy processing into various forms, and is considered to be the array micro-needle with the most application prospect.

At present, the preparation method of the polymer array micro needle comprises a micro template method, a stretching method and a 3D printing method, wherein the micro template method is one of the most widely applied methods. The method for preparing the microneedle mould by the micro-mould method mainly utilizes direct or indirect methods such as laser etching, ion etching, mould overturning and the like to prepare the array microneedle mould with the conical microstructure, and the methods have the defects of complex preparation process and high cost, and the obtained finished microneedle mould has poor precision, density and shape freedom.

The preparation of the nano microneedle template by the laser direct writing technology is a technology for controlling laser to carry out three-dimensional solidification on liquid photoresist by a three-dimensional photoetching machine according to the forming track of a microneedle three-dimensional model, and can be applied to the printing of the nano microneedle template due to the advantage of high precision, but the application in the field of microneedle preparation is limited due to the defect of low printing speed.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a method for preparing a nano microneedle template by laser direct writing, and microneedle models in any shapes can be printed by the method provided by the application, so that different microneedle templates can be obtained; in the microneedle template obtained by the invention, the diameter of the microneedle model can be smaller than 20 μm, and the height of the microneedle model is smaller than 50 μm, so that the printing limit of the traditional method and the existing 3D printing method is broken, and in addition, the method has the advantages of high controllability, high printing precision and high printing efficiency.

The technical scheme of the invention is as follows:

a method for preparing a nano microneedle template by laser direct writing comprises the following steps:

(1) establishing a three-dimensional model of a nano microneedle template, and introducing the three-dimensional model into a three-dimensional photoetching machine;

(2) dripping the photoresist required by microneedle template printing on the molding substrate;

(3) curing the photoresist on the substrate by two-photon focused laser according to the three-dimensional model established in the step (1) by adopting a laser direct writing technology to obtain the outline of the microneedle template;

(4) and developing and drying the outline of the microneedle template, and performing secondary exposure to obtain the nanoscale microneedle template.

Preferably, the height of the microneedle model on the microneedle template is between 20 and 2000 mu m, the diameter of the cone bottom is between 50 and 200 mu m, and the density of the microneedle model is 500-10000 roots/cm²。

Preferably, the shape of the microneedle model is a cone, a triangular pyramid, a polygonal pyramid, or the like.

Preferably, in the step (2), the photoresist consists of a resin and an initiator, and the weight ratio of the resin to the initiator is 90-99.5: 0.5-10; the preparation method comprises the following steps: adding the resin and the initiator into a lightproof container at room temperature, stirring for 8-16h by a magnetic stirrer or a mechanical stirring paddle, and uniformly mixing to obtain the resin.

Preferably, the resin is acrylate, modified acrylic resin, epoxy resin or phenolic resin; the initiator is one or more of IRGACURE369, IRGACURE819, IRGACURE184 or TPO.

Preferably, the acrylate is one or more of ethoxylated pentaerythritol tetraacrylate, di-pentaerythritol hexaacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate or dipentaerythritol hexaacrylate.

Preferably, the modified acrylic resin may be epoxy-modified, urethane-modified, or silicon-modified.

Preferably, in the step (2), the substrate is subjected to ultrasonic treatment for 5-10 minutes respectively with acetone, isopropanol and ultrapure water, is dried by nitrogen, is placed into a plasma cleaning machine, and is subjected to plasma treatment for 5 minutes respectively on the front side and the back side in an air atmosphere.

Preferably, the specific process of step (3) is: and (2) immersing a focusing lens into the photoresist, starting printing according to the three-dimensional model established in the step (1), and curing the photoresist on the substrate to obtain the outline of the microneedle template.

Preferably, the printing can be single-layer printing or multi-layer printing; single layer printing uses a galvanometer in an optical system to achieve laser beam deflection and scanning printing at a focal plane. The change of the focusing plane is realized by the lifting device of the sample, the lifting device of the focusing lens or the change of the beam angle of the laser beam entering the focusing lens in the optical system, thereby realizing the multilayer printing.

Preferably, in the step (4), the developing process includes immersing the glass substrate carrying the outline of the microneedle template in propylene glycol methyl ether acetate or acetone for 5-10 minutes, then transferring the glass substrate into isopropanol to be immersed for 1-5 minutes, taking out and drying the glass substrate, and then irradiating the glass substrate for 5-10 minutes by using an ultraviolet lamp to perform secondary exposure or heating the glass substrate at the temperature of 60-120 ℃ for 5-30 minutes to realize internal curing, so as to obtain the nanoscale microneedle template.

In the application, the microneedle models are positioned on the microneedle templates, and different microneedle templates can be obtained by printing microneedle models with different shapes; the microneedle model outline is a portion of the outline of the microneedle template.

Compared with the prior art, the invention has the beneficial effects that:

1. by the method provided by the application, microneedle models in any shapes can be printed, so that different microneedle templates can be obtained; in the microneedle template obtained by the invention, the diameter of the microneedle model can be smaller than 20 μm, and the height of the microneedle model is smaller than 50 μm, so that the printing limit of the traditional method and the existing 3D printing method is broken.

2. The method has the advantage of high controllability when the microneedle template is printed, and particularly can effectively control the height of the microneedle model on the microneedle template, the diameter of the microneedle model and the gap between the microneedle models, so that the microneedle manufacturing by using the microneedle template obtained by the method has controllability.

3. The printing method provided by the invention only prints the outline of the microneedle template, the printed outline of the microneedle template is only solidified on the outer surface, and the interior is still liquid photoresist, after development, secondary exposure or heating is carried out by using ultraviolet light to realize internal solidification, and the microneedle template is obtained. By adopting the process, the volume needing two-photon laser curing is reduced by 50-500 times, and the printing efficiency of the microneedle template is improved by 50-500 times.

4. The photoresist provided by the invention has the characteristics of good flexibility, low viscosity, high reactivity and low skin irritation, is suitable for manufacturing a microneedle template, is easy to obtain monomer raw materials, low in price, mild in preparation conditions and easy to realize large-scale production.

Drawings

In order to more clearly illustrate the embodiments or technical solutions in the prior art of the present invention, the drawings used in the description of the embodiments or prior art will be briefly described below, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without creative efforts.

Fig. 1 is a schematic diagram of a microneedle template prepared by a laser direct writing technique.

FIG. 2 is a scanning electron micrograph (50) of a microneedle template prepared by the laser direct writing technique.

Fig. 3 is a scanning electron microscope (x 200) photograph of a microneedle template prepared by using the laser direct writing technique.

Fig. 4 is a scanning electron microscope (x 500) photograph of a microneedle template prepared by the laser direct writing technique.

Fig. 5 is a scanning electron microscope (x 1000) photograph of a microneedle template prepared by the laser direct writing technique.

In the figure, 1-substrate, 2-photoresist, 3-microneedle model, 4-focusing laser, 5-focusing lens, 6-galvanometer and 7-printing platform.

Detailed Description

In order to make those skilled in the art better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The present application is described in detail with reference to fig. 1-5, as follows:

example 1

1. Construction of three-dimensional nano microneedle 3 template

Constructing a conical microneedle three-dimensional model to be printed, wherein the diameter of the bottom surface of the conical microneedle three-dimensional model is 50 mu m, the height of the conical surface of the conical body is 150 mu m, and the wall thickness of the conical surface is 0.5 mu m; and exporting the three-dimensional model into a format recognized by three-dimensional photoetching machine control software and importing the three-dimensional model into a photoetching machine.

2. Photoresist preparation

The photoresist is added into a brown glass container according to the proportion of 44% of ethoxylated pentaerythritol tetraacrylate, 55% of dipentaerythritol pentaacrylate, 3690.5% of IRGACURE and 8190.5% of IRGACURE under the condition of room temperature and light shielding, stirred for 10 hours by a magnetic stirrer and uniformly mixed for later use.

3. Substrate processing

Taking a clean glass sheet with the thickness of 76mm x 26mm x 1mm as a substrate 1 of a printing substrate, blowing the substrate 1 by using compressed nitrogen, immersing the substrate 1 in an acetone solution, carrying out ultrasonic treatment for 10 minutes, and then transferring the substrate to an isopropanol solution, and immersing and carrying out ultrasonic treatment for 5 minutes; then the mixture is quickly transferred to pure water to be immersed and ultrasonically treated for 5 minutes and then taken out, the surface liquid drops are dried by compressed nitrogen and then put into a vacuum plasma cleaning machine, and the front side and the back side of the mixture are respectively subjected to plasma treatment for 5 minutes in the air atmosphere for later use.

4. Microneedle template printing

Described with reference to fig. 1: coating a proper amount of photoresist 2 prepared in the step 2 on the surface of a substrate 1 cleaned by vacuum plasma, wherein the thickness of the photoresist is more than 300 mu m, the area of the photoresist is about 2-4 square centimeters, putting the substrate 1 coated with the photoresist into a photoetching machine, setting the distance between every two microneedle models 3 to be 150 mu m, and setting the density of the microneedle models 3 to be 4489 per square centimeter, and performing array printing on the microneedle models 3; immersing a focusing lens 5 into the photoresist 2, focusing laser light 0.1 mu m above the substrate 1, adjusting the position of the focusing laser light 4 through a galvanometer 6 to solidify and form a first layer of a microneedle model 3 (shown in figure 5), and then lifting the first layer by 0.1 mu m through a printing platform 7 to print a second layer; the above operations are repeatedly performed until printing of a single or several microneedle models 3 is completed; then, continuously printing the next or a plurality of microneedle models 3 by adjusting the position of the printing platform 7 until the whole microneedle template is printed; the printing process is a process of directly solidifying and molding the photoresist 2 on the substrate 1 in the shape of the microneedle model 3 by using the focused laser 4; wherein the height of a single microneedle model 3 is 150 μm, the diameter is 50 μm, the distance between adjacent microneedle models 3 is 150 μm, the density of the microneedle models 3 is 4489 per square centimeter, the photoresist 2 is liquid before use and becomes solid after being printed by a photoetching machine; and after printing is finished, obtaining the outline of the microneedle template, taking out the microneedle template from the photoetching machine, and developing.

5. Development of nano microneedle templates

After printing is finished, the glass substrate with the printed outline of the microneedle template is placed into propylene glycol methyl ether acetate for soaking for 5 minutes, then is transferred into isopropanol for soaking for 3 minutes, and is taken out and dried; then irradiating for 5-10min by using an ultraviolet lamp, carrying out secondary exposure, and enhancing the curing effect to obtain the nano microneedle template, which is shown in figures 2-5.

The nano microneedle template obtained in this example has the following appearance: the surface is smooth and complete, is consistent with the designed model, and has no fracture and collapse; the glass substrate is well jointed with the glass substrate without collapse and loss phenomena; the printing time was 3.5 hours.

Example 2

This example 2 provides a method for preparing a nano microneedle template:

the present embodiment 2 differs from embodiment 1 in that:

preparing a photoresist: according to the method, 45% of ethoxylated pentaerythritol tetraacrylate, 45% of dipentaerythritol pentaacrylate, 3695% of IRGACURE and 8195% of IRGACURE are added into a brown glass container under the condition of room temperature and yellow light, stirred for 8 hours by a magnetic stirrer or a mechanical stirring paddle and uniformly mixed to obtain the product.

Substrate treatment: taking a clean glass sheet with the thickness of 76mm x 26mm x 1mm as a substrate 1 of a printing substrate, blowing the substrate 1 by using compressed nitrogen, immersing the substrate 1 in an acetone solution for ultrasonic treatment for 5 minutes, and then transferring the substrate to an isopropanol solution for immersion ultrasonic treatment for 10 minutes; then the mixture is quickly transferred to pure water to be immersed and ultrasonically treated for 7 minutes, then the mixture is taken out, the surface liquid drops are dried by compressed nitrogen and then put into a vacuum plasma cleaning machine, and the front side and the back side of the mixture are respectively subjected to plasma treatment for 5 minutes in the air atmosphere for later use.

Developing the nano microneedle template: the process comprises the steps of putting the glass substrate 1 with the printed microneedle template into propylene glycol methyl ether acetate for soaking for 7 minutes, then transferring the glass substrate into isopropanol for soaking for 1 minute, taking out and airing to obtain the three-dimensional nanometer microneedle template.

The nano microneedle template obtained in this example has the following appearance: the surface is smooth and complete, the designed models are consistent, and the conditions of fracture and collapse are avoided; the glass substrate has good bonding performance and no collapse or loss phenomenon. The same effects as in example 1 were obtained; the printing time was 3.2 hours.

Example 3

This example 3 provides a method for preparing a nano microneedle template:

the present embodiment 3 differs from embodiment 1 in that: in the step 5 nanometer microneedle template development process, the following method is adopted:

after printing, placing the glass substrate carrying the printed outline of the microneedle template into acetone for soaking for 5 minutes, then transferring the glass substrate into isopropanol for soaking for 3 minutes, taking out and airing; and heating for 20 minutes at the temperature of 100 ℃ to realize internal curing, thereby obtaining the nano microneedle template.

The nano microneedle template obtained in this example has the following appearance: the surface is smooth and complete, is consistent with the designed model, and has no fracture and collapse; the glass substrate is well jointed with the glass substrate without collapse and loss phenomena; the printing time period was 3.6 hours.

Comparative example 1

This comparative example is different from example 1 in that an ormocom photoresist was used as the photoresist.

The nano microneedle template obtained in this comparative example 1 had an appearance: since the Ormocomp photoresist has long curing time and low strength compared with the photoresist of the invention, the phenomena of microneedle breakage, microneedle bending and microneedle dulling can be caused because local microneedles are not cured in time when microneedle outline printing is carried out.

Comparative example 2

The comparative example differs from example 1 in that the substrate treatment process was: taking a clean glass sheet with the thickness of 76mm x 26mm x 1mm as a substrate 1 of a printing base, blowing the substrate 1 by using compressed nitrogen, immersing the substrate 1 in an acetone solution, carrying out ultrasonic treatment for 10 minutes, and then transferring the substrate to an isopropanol solution to immerse and rinse for 1 minute; then the substrate is quickly transferred to pure water to be immersed and rinsed for 1 minute, then the substrate is taken out, the surface liquid drops are dried by compressed nitrogen and then put into a vacuum plasma cleaning machine, and the single surface is subjected to plasma cleaning treatment for 5 minutes in the air atmosphere for standby use (the treatment method of the substrate in the prior art).

The nano microneedle template obtained in this comparative example 2 had an appearance: because the substrate treatment process is not appropriate, the printed micro-needle is not well attached to the substrate, and some micro-needles cannot be printed; some collapse and flow away in the photoresist during printing; and some were dumped during development.

Comparative example 3

The comparative example 3 is different from the example 1 in that the printing speed is reduced by using the ormocom photoresist, the printing effect is recorded as 8 hours in the same way as the example 1, and the printing time is prolonged by 129% compared with the example 1, and the printing efficiency is obviously reduced.

As can be seen from comparison of the appearances of the products obtained by the methods of example 1, example 2, comparative example 1 and comparative example 2, the appearance effect of the product obtained by the method provided by the application is the best, and as can be seen from example 1 and comparative example 2, the treatment of the substrate is closely related to the printing process, which is mainly because the bonding area of the product and the glass substrate is reduced when the method provided by the application is used for nano microneedle printing, and obviously, the substrate treated by the prior art is not suitable for bonding with a small-sized product; in addition, it can be seen from observation that the conventional glass substrate processing and developing method can cause the breakage and collapse of part of the microneedles, which affects the quality of microneedle template preparation. The method for printing the outer surface of the microneedle is adopted, and the glass substrate processing method and the developing method provided by the invention are matched, so that the good forming, the collapse prevention, the fracture prevention and the good effect of the microneedle printing template can be ensured on the basis of improving the printing speed by 50-500 times.

Although the present invention has been described in detail by referring to the preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made on the embodiments of the present invention by those skilled in the art without departing from the spirit and scope of the present invention, and these modifications or substitutions are within the scope of the present invention/any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A method for preparing a nano microneedle template by laser direct writing is characterized by comprising the following steps:

(4) and developing and drying the outline of the microneedle template, and then carrying out secondary exposure to obtain the nanoscale microneedle template.

2. The method for preparing a nano microneedle template by laser direct writing according to claim 1, wherein the height of the microneedle model on the microneedle template is between 20-2000 μm, the diameter of the conical bottom is between 20-200 μm, and the density of the microneedle model is 500-10000 roots/cm²。

3. The method for preparing a nano microneedle template by laser direct writing according to claim 2, wherein the shape of the microneedle model is a cone, a triangular pyramid, a multi-faceted pyramid, or the like.

4. The method for preparing a nano microneedle template by laser direct writing according to any one of claims 1 to 3, wherein in the step (2), the photoresist is composed of a resin and an initiator at a weight ratio of 90-99.5: 0.5-10; the preparation method comprises the following steps: adding the resin and the initiator into a lightproof container at room temperature, stirring for 8-16h by a magnetic stirrer or a mechanical stirring paddle, and uniformly mixing to obtain the resin.

5. The method for preparing a nano microneedle template by laser direct writing according to claim 4, wherein the resin is acrylate, modified acrylic resin, epoxy resin or phenolic resin; the initiator is one or more of IRGACURE369, IRGACURE819, IRGACURE184 or TPO.

6. The method for preparing a nano microneedle template by laser direct writing according to claim 5, wherein the acrylate is one or more of ethoxylated pentaerythritol tetraacrylate, bis-pentaerythritol hexaacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate or dipentaerythritol hexaacrylate.

7. The method for preparing a nano microneedle template by laser direct writing according to claim 5, wherein the modified acrylic resin may be epoxy modified, polyurethane modified or silicon modified.

8. The method for preparing a nano microneedle template by laser direct writing according to claim 4, wherein in the step (2), the substrate is subjected to ultrasonic treatment with acetone, isopropanol and ultrapure water for 5-10 minutes respectively, is dried by nitrogen, is placed into a plasma cleaning machine, and is subjected to plasma treatment on the front and back surfaces of the substrate for 5 minutes respectively in an air atmosphere.

9. The method for preparing nano microneedle templates by laser direct writing according to claim 4, wherein the specific process of the step (3) is as follows: and (2) immersing a focusing lens into the photoresist, starting printing according to the three-dimensional model established in the step (1), and curing the photoresist on the substrate to obtain the outline of the microneedle template.

10. The method for preparing a nano microneedle template by laser direct writing according to claim 4, wherein in the step (4), the developing process is to put the glass substrate carrying the outline of the microneedle template into propylene glycol methyl ether acetate or acetone for soaking for 5-10 minutes, then transfer the glass substrate into isopropanol for soaking for 1-5 minutes, take out and dry the glass substrate, and then irradiate the glass substrate with an ultraviolet lamp for 5-10 minutes to perform secondary exposure or heat the glass substrate at 60-120 ℃ for 5-30 minutes to realize internal curing, thereby obtaining the nano microneedle template.