Preparation method and application of drug-loaded porous hollow microneedles with photothermal response

Abstract

The present invention provides a method for preparing a drug-loaded porous hollow microneedle with photothermal response, the method uses electrospray technology to prepare gelatin microspheres, after mixing with an oil phase material, a pair of matching yin and yang microneedle templates are used to replicate the hollow microneedles, and after curing and demolding, the gelatin microspheres in the microneedles are melted with hot water to obtain porous hollow microneedles, the hollow part of the microneedles is loaded with drug-loaded hydrogel, and a photothermal substrate is added to make the drug-loaded porous hollow microneedles have photothermal response performance. The microneedles prepared by the present invention have a special three-layer structure, which blocks the direct contact between excessive drugs and the wound surface, provides sufficient space for the loading of drugs, and improves the utilization efficiency of drugs. In addition, the photothermal substrate allows the controlled release of drugs on demand. This microneedle preparation method based on electrospray technology and multi-step template replication technology has excellent biocompatibility and mechanical properties of the prepared microneedles, high drug delivery efficiency, and low cost.

Description

Technical Field

[0001] The present invention belongs to the field of biomaterial technology, and specifically relates to a preparation method and application of a drug-loaded porous hollow microneedle with photothermal response. The prepared microneedle array can be applied to technical fields such as wound repair, safe and efficient painless drug delivery, etc. Background Art

[0002] Microneedle arrays are an effective transdermal drug delivery vehicle. The three-dimensional structure of microneedles can pierce the skin's stratum corneum to form microporous channels, promoting drug penetration through physical means with virtually no damage or pain. However, traditional microneedle structures are overly simple, mostly solid, and lack multifunctional and personalized designs. On the one hand, hollow microneedles are more suitable for loading biomacromolecules and high-dose drugs than conventional solid microneedles, and have increasingly broad application prospects in vaccination, insulin administration, nucleic acid delivery, ocular drug delivery, and micro-blood sampling. Currently, research on hollow microneedles is limited, and they are prone to problems such as weak preparation materials and demanding manufacturing processes, resulting in needle breakage and irritation in the skin, making them unsuitable for various practical applications. On the other hand, interconnected porous network structures can provide more channels for drug release, greatly improving the efficiency of transdermal drug delivery. However, their preparation often involves chemical changes and has poor biocompatibility. Furthermore, while microneedles can deliver drugs minimally invasively and painlessly, once inserted into the skin, they can only release drugs at a pre-set rate. Any change often requires re-applying the microneedle, resulting in unnecessary waste of resources. While responsive smart drug-releasing microneedles can be developed to achieve precise drug release under certain conditions, the manufacturing process for these microneedles is demanding, making large-scale production difficult.

[0003] Therefore, the present invention combines a porous structure with a hollow microneedle and integrates a photothermal substrate to design and invent a new type of porous hollow microneedle array, which provides suitable drug loading conditions and release-promoting methods for drug delivery, thereby achieving transdermal administration. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method and application of drug-loaded porous hollow microneedles with photothermal response to address the shortcomings of traditional microneedles with low drug delivery efficiency and inability to control drug delivery rate.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] (1) The present invention provides a method for preparing drug-loaded porous hollow microneedles with photothermal response. The prepared microneedle array has a three-layer structure, namely a porous hollow shell, a GelMA drug-loaded layer and a photothermal base layer. It is prepared by the following steps:

[0007] S1. Mix gelatin microspheres with oil-phase material and pour them into the microneedle template. Vacuum the mixture to allow the gelatin microspheres to accumulate in the needle tip. Then, a positive mold template that matches the microneedle template (negative mold template) is embedded in the liquid surface. After solidification and demolding, the gelatin microspheres in the microneedle are melted with hot water to obtain porous hollow microneedles.

[0008] S2. Add drug-loaded hydrogel to the hollow part of the microneedle and solidify it, add hydrogel mixed with photothermal material to the base and solidify it to obtain drug-loaded porous hollow microneedles with photothermal response.

[0009] In a preferred embodiment, the method for preparing a drug-loaded porous hollow microneedle with photothermal response is characterized in that, in step S1, the gelatin microspheres are 5-20% w / v porcine gelatin, and the diameter of the gelatin microspheres is 50-100 μm.

[0010] In a preferred embodiment, the method for preparing a drug-loaded porous hollow microneedle with photothermal response is characterized in that in step S1, gelatin microspheres are prepared by electrospraying, and the diameter of the gelatin microspheres is changed by adjusting the flow rate of the electrospray injection pump and the DC high voltage voltage. By increasing the flow rate of the injection pump or reducing the DC high voltage voltage, the diameter of the ejected gelatin microspheres becomes larger.

[0011] In a preferred embodiment, the method for preparing a drug-loaded porous hollow microneedle with photothermal response is characterized in that, in step S1, the oil phase material is ethoxylated trimethylolpropane triacrylate (ETPTA), and 1% w / w HMPP photoinitiator is added to the oil phase material.

[0012] In a preferred embodiment, the method for preparing a drug-loaded porous hollow microneedle with photothermal response is characterized in that, in step S2, the drug-loaded hydrogel is 15% w / v gelatin methacrylate (GelMA), and 1% w / w HMPP photoinitiator is added to the drug-loaded hydrogel.

[0013] In a preferred embodiment, the method for preparing a drug-loaded porous hollow microneedle with photothermal response is characterized in that in step S2, the photothermal material is graphene oxide in the hydrogel mixed with the photothermal material, the hydrogel is polyethylene glycol diacrylate (PEGDA), and 1% w / w HMPP photoinitiator is added to the hydrogel mixed with the photothermal material.

[0014] In a preferred embodiment, the method for preparing a drug-loaded porous hollow microneedle with photothermal response is characterized in that the concentration of graphene oxide in the hydrogel mixed with the photothermal material is 4 mg / mL and the concentration of polyethylene glycol diacrylate is 30% w / v.

[0015] (2) The present invention also provides a drug-loaded porous hollow microneedle with photothermal response, which is prepared by the preparation method described above.

[0016] (3) The present invention also provides the use of the above-mentioned drug-loaded porous hollow microneedles with photothermal response in wound repair and painless drug delivery.

[0017] Beneficial effects of the present invention:

[0018] (1) The present invention forms pores by melting electrosprayed gelatin microspheres with hot water. The method is simple and easy to operate, does not require high technical requirements, and the pore-forming process only involves physical changes. It has good biocompatibility and the pore size is controllable.

[0019] (2) The present invention designs a drug-loaded porous hollow microneedle array with photothermal response, which can load a variety of large amounts of drugs, achieve long-term drug administration and sustained drug release, and can control the drug release rate under different near-infrared light powers.

[0020] (3) The porous hollow microneedles prepared by the present invention can be used for transdermal drug delivery to treat wounds, achieving painless, safe, and autonomous drug delivery. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the preparation of drug-loaded porous hollow microneedles with photothermal response;

[0022] Figure 2 Structural characterization of the drug-loaded porous hollow microneedle array prepared in Example 1 under light microscopy and electron microscopy; (a) cross-sectional image of the microneedle under light microscopy, (b) electron microscopic image of the microneedle array, (c) electron microscopic image of a representative microneedle tip, (de) side and cross-sectional images of the porous hollow shell under electron microscopy, (f) cross-sectional image of the drug-loaded porous microneedle under electron microscopy; the scale bars in Figures (ad) are 200 μm, and the scale bars in Figures (ef) are 100 μm;

[0023] Figure 3 This is a graph showing the mechanical strength data of the drug-loaded porous hollow microneedle array prepared in Example 1;

[0024] Figure 4 This is a graph showing the photothermal response performance of the drug-loaded porous hollow microneedles prepared in Example 1 under different infrared excitation photocurrents;

[0025] Figure 5The drug sustained-release performance test data of drug-loaded porous hollow microneedles; (a) Drug release kinetic curves of drug-loaded porous hollow microneedles at different GelMA concentrations at 37°C; (b) Drug release kinetic curves of drug-loaded porous hollow microneedles at different temperatures when the GelMA concentration is 15% (w / v); (c) Fluorescence images of the GelMA needle tip at 0 (i), 4 (ii), 8 (iii), and 12 (iv) hours of drug release. The scale in Figure (c) is 100 μm.

[0026] Figure 6 Biocompatibility test of the drug-loaded porous hollow microneedles prepared in Example 1; (ab) Fluorescence images (a) and cell viability test data (b) of the control group and the drug-loaded porous hollow microneedles prepared in Example 1 co-incubated with 3T3 cells for 1 day (i), 2 days (ii), and 3 days (iii). The scale in Figure (a) is 100 μm. DETAILED DESCRIPTION

[0027] To make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the relevant drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. The implementation conditions not specified in the embodiments are generally the conditions in routine experiments.

[0028] Example 1:

[0029] The embodiment of the present invention provides a method for preparing drug-loaded porous hollow microneedles with photothermal response. The prepared microneedle array has a three-layer structure, namely a porous hollow shell, a GelMA drug-loaded layer and a photothermal base layer. Figure 1 As shown, it is prepared by the following steps:

[0030] (1) Preparation of electrosprayed gelatin microspheres:

[0031] First, a microfluidic electrospray device was fabricated using glass capillaries. The capillaries were drawn using a tube puller, and the tip diameter was ground to 80 μm. The capillaries were then immersed in alcohol for ultrasonic cleaning. After drying, the capillaries were fixed to a glass slide using AB glue for later use. During electrospraying, a 7.5 kV high voltage was applied to the syringe needle, and a 5% (w / v) porcine gelatin solution was injected using a microinjection pump. The ejected porcine gelatin microspheres were collected in a small dish containing ETPTA solution. The size of the ejected gelatin microspheres could be controlled by adjusting the voltage, the flow rate of the refractive pump, and the diameter of the glass capillary.

[0032] (2) Preparation of porous hollow microneedles:

[0033] A template with a 10×10 MN array was used. The MNs were conical, with a base diameter of 430 μm and a height of 950 μm. First, a positive mold was created using PDMS. A 10:1 mixture of PDMS and curing agent was poured into the negative microneedle mold. Vacuum was applied to remove all bubbles, and the mold was then placed in an oven to cure overnight. Demolding yielded a positive mold that matched the negative mold.

[0034] A mixed solution of ethoxylated trimethylolpropane triacrylate (ETPTA), gelatin microspheres, and 1% w / w HMPP photoinitiator was added to a negative mold template. The mixture was vacuumed and centrifuged to densely pack the gelatin microspheres within the microneedle tips of the negative mold. The positive mold was then inserted into the negative mold, and the excess solution was removed. Subsequently, the mixture was cured using a UV lamp for 1 minute, and the positive and negative molds were removed to produce a hollow MN array containing gelatin microspheres. The porous, hollow microneedle array was prepared by soaking the melted gelatin in hot water and ultrasonically cleaning it.

[0035] (3) Preparation of drug-loaded microneedles with photothermal response:

[0036] First, rhein was dissolved in PBS buffer to a concentration of 0.05%. Gelatin methacrylate (GelMA) was added to create a 15% (w / v) GelMA-Rhein solution. A 1% (w / w) photoinitiator was then added. The GelMA-Rhein solution was then added to the hollow microneedles and vacuum-cured to fill the hollow portion. The solution was then UV-cured for 20 seconds to form drug-loaded porous hollow microneedles.

[0037] A 4 mg / mL graphene oxide (GO) dispersion was prepared, and polyethylene glycol diacrylate (PEGDA) was added to prepare a 30% (w / v) polyethylene glycol diacrylate (PEGDA) solution. A 1% w / w photoinitiator was added and added to the drug-loaded microneedles. After UV light curing, drug-loaded porous hollow microneedles with a photothermal response substrate were formed.

[0038] Depend on Figure 2 As shown, the drug-loaded microneedles with photothermal response prepared in this embodiment have a three-layer structure as a whole, which consists of a porous hollow shell, a drug-loaded layer and a photothermal base layer from top to bottom. The microneedle height is 830 μm, the bottom diameter of each needle is 360 μm, and the center distance between two adjacent microneedles is 1000 μm.

[0039] Example 2

[0040] The mechanical properties, photothermal response properties, drug sustained-release properties and biocompatibility of the drug-loaded porous hollow microneedle with photothermal response prepared in Example 1 were measured.

[0041] (1) Mechanical properties determination:

[0042] like Figure 3 As shown in the figure, for the three groups of microneedles with internal porous structures, the maximum pressure at which the needle body breaks is about 0.4 N. This value is much greater than the pressure required for microneedles to penetrate skin tissue (0.08 N), ensuring that the photothermal responsive drug-loaded porous hollow microneedles will not break when piercing the skin.

[0043] (2) Photothermal response performance measurement:

[0044] like Figure 4 As shown, the drug-loaded porous hollow microneedles prepared in this embodiment have a fast and stable photothermal response under different infrared excitation photocurrents (powers), and the light power is almost linearly related to the temperature after stabilization. Therefore, the temperature change of the microneedle array can be precisely controlled by changing the light power.

[0045] (3) Determination of drug sustained-release performance:

[0046] like Figure 5 As shown, the drug-loaded porous hollow microneedles with photothermal response prepared in this embodiment can release drugs continuously, slowly and relatively evenly, and appropriately increasing the temperature can accelerate the drug release rate, that is, the designed microneedles can achieve intelligent and precise drug controlled release and long-term drug delivery through photothermal response.

[0047] (4) Biocompatibility determination:

[0048] like Figure 6 As shown, the photothermal-responsive drug-loaded porous hollow microneedles prepared in this embodiment were co-incubated with 3T3 cells, and the cell growth and reproduction trend was consistent with that of the control group, proving that the microneedles had no cytotoxicity and good biocompatibility, and could be widely used as a drug delivery system in wound repair, cancer treatment and other fields.

[0049] The present invention creates pores by melting electrosprayed gelatin microspheres with hot water. This method is simple, easy to operate, and requires no high technical requirements. The pore-forming process involves only physical changes, resulting in good biocompatibility and controllable pore diameters. The resulting photothermally responsive, drug-loaded, porous hollow microneedle array can load a wide variety of drugs, enabling long-term drug delivery and sustained release. The drug release rate can be controlled at varying near-infrared light powers, making it suitable for transdermal wound therapy, achieving painless, safe, and autonomous drug delivery.

[0050] The above are only preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the scope of protection of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications without departing from the principle of the present invention should be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a drug-loaded porous hollow microneedle with photothermal response, characterized in that: The following steps are involved: S1, mixing gelatin microspheres with oil phase material and pouring them into the microneedle template, evacuating the gelatin microspheres to make them accumulate in the needle tip, then embedding a positive mold template that matches the microneedle template on the liquid surface, and after curing and demolding, using hot water to melt the gelatin microspheres in the microneedle to obtain a porous hollow microneedle; the oil phase material is ethoxylated trimethylolpropane triacrylate; S2. Add drug-loaded hydrogel to the hollow part of the microneedle and solidify it, add hydrogel mixed with photothermal material to the base and solidify it, so as to obtain drug-loaded porous hollow microneedles with photothermal response.

2. The method for preparing the drug-loaded porous hollow microneedles with photothermal response according to claim 1, characterized in that: In the step S1, the gelatin microspheres are 5-20% w / v porcine gelatin, and the diameter of the gelatin microspheres is 50-100 μm.

3. The method for preparing the drug-loaded porous hollow microneedles with photothermal response according to claim 1, characterized in that: In step S1, gelatin microspheres are prepared by electrospraying, and the diameter of the gelatin microspheres is changed by adjusting the flow rate of the injection pump and the DC high voltage voltage of the electrospray. Increasing the flow rate of the injection pump or decreasing the DC high voltage voltage increases the diameter of the sprayed gelatin microspheres.

4. The method for preparing the drug-loaded porous hollow microneedles with photothermal response according to claim 1, characterized in that: In the step S1, 1% w / w HMPP photoinitiator is added to the oil phase material.

5. The method for preparing the drug-loaded porous hollow microneedles with photothermal response according to claim 1, characterized in that: In the step S2, the drug-loaded hydrogel contains 15% w / v methacrylate gelatin; and 1% w / w HMPP photoinitiator is added to the drug-loaded hydrogel.

6. The method for preparing the drug-loaded porous hollow microneedles with photothermal response according to claim 1, characterized in that: In the step S2, in the hydrogel mixed with the photothermal material, the photothermal material is a graphene oxide dispersion, and the hydrogel is polyethylene glycol diacrylate; and 1% w / w HMPP photoinitiator is added to the hydrogel mixed with the photothermal material.

7. The method for preparing the drug-loaded porous hollow microneedles with photothermal response according to claim 6, characterized in that: In the hydrogel mixed with the photothermal material, the concentration of graphene oxide is 4 mg / mL, and the concentration of polyethylene glycol diacrylate is 30% w / v.

8. The drug-loaded porous hollow microneedles with photothermal response prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the drug-loaded porous hollow microneedles with photothermal response prepared by the preparation method according to any one of claims 1 to 7 in the preparation of wound repair materials.

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