Photo-thermal responsive bionic core-shell microneedle patch as well as preparation method and application thereof

Abstract

The invention discloses a photo-thermal responsive bionic core-shell microneedle patch as well as a preparation method and application thereof. The microneedle patch comprises a backing layer and a plurality of core-shell microneedles arranged on the backing layer, the core-shell microneedle comprises an external microneedle shell and an internal phase change core; the microneedle shell is made of a polylactic acid-glycolic acid copolymer; the phase-change core is formed by mixing phase-change materials with photo-thermal characteristics, namely black phosphorus, gelatin and carrageenan, and a loaded drug, and has proper phase-change temperature and temperature rising performance, so that the high efficiency and safety of a drug delivery mode are ensured. The prepared microneedle patch has the advantages of being almost painless, minimally invasive, harmless to the body, not prone to infection, convenient to use, easy to operate and the like, the compliance of a patient is good, the administration speed can be regulated and controlled through external stimulation, and the microneedle patch is slowly administered without stimulation and is stable in effect.

Description

Technical Field

[0001] The present invention belongs to the field of biomedicine, and in particular relates to a photothermal responsive bionic core-shell microneedle patch and a preparation method and application thereof. Background Art

[0002] Many hormones in the body have the characteristics of rhythmic secretion. The shortest ones are secreted in pulses with a period of minutes or hours, such as some pituitary hormones. Most of them show circadian rhythmic secretion, such as growth hormone and cortisol, which have obvious circadian rhythmicity. The longer ones are secreted in cycles of months, seasons, etc., such as the monthly periodic secretion of female sex hormones; thyroid hormones even have seasonal periodic fluctuations. The continuous administration of certain hormones and their synthetic analogs may show effects that are completely different from expectations. Therefore, for patients with hormone deficiency, designing a drug delivery system that mimics the level and rhythm of hormone release under the normal physiological state of the body can maximize the therapeutic effect and reduce toxic side effects.

[0003] Pulsatile drug delivery system (PDDS) generally refers to a drug delivery system that releases drugs in a timely and quantitative manner according to the characteristics of the human body's biological rhythm changes and the needs of physiology and treatment. Pulsatile preparations can release drugs quickly at a specific time after a time lag by means of preparations to achieve the best therapeutic effect. There are two main drug release mechanisms of pulse drug delivery systems that are currently being studied: one is to trigger drug release by external stimuli, which can be divided into biochemical stimuli (gastrointestinal pH, blood sugar levels in the body, secretions from lesions, etc.) and physicochemical stimuli (sound waves, magnetic fields, electric fields, temperature, etc.), but its biosafety is not high; the other is to use the program designed by the preparation itself to release drugs in a pulsed manner, such as coating the tablet core or the pellet core, dissolving or swelling the preparation, and regulating the time lag time by adjusting the thickness of the controlled release coating film, the amount of pore-forming agent and hydrophilic polymer. After a certain time lag, the drug is released rapidly, such as explosive pulse release tablets, pulse micropellets, etc., but the drug cannot be continuously released after rapid drug release.

[0004] For patients with hormone deficiency, it is necessary to maintain hormone concentration levels for a long time, and also to simulate the frequency and secretion rhythm of hormone pulse release in the body, but the existing drug dosage forms have obvious deficiencies. Ultimately, they cannot well simulate the level and rhythm of hormone release under physiological conditions in the body, and thus cannot fully exert their efficacy. Or they are expensive and highly irritating, making them difficult to promote and use. Summary of the invention

[0005] Purpose of the invention: The technical problem to be solved by the present invention is to provide a bionic core-shell drug-loaded microneedle patch with good timed pulse release effect, small safety and toxic side effects, high patient compliance and low price in view of the shortcomings of the prior art.

[0006] In order to achieve the above purpose, the technical means adopted by the present invention are as follows: A photothermal responsive bionic core-shell microneedle patch comprises a backing layer and a plurality of core-shell microneedles arranged on the backing layer; the core-shell microneedles comprise an external microneedle shell and an internal phase change core; the microneedle shell is made of polylactic acid-glycolic acid copolymer; the phase change core is a mixture of a phase change material with photothermal properties and a loaded drug.

[0007] Specifically, the phase change material with photothermal properties includes black phosphorus (BP), gelatin and carrageenan, preferably a mixture of black phosphorus, gelatin and carrageenan.

[0008] Specifically, the loaded drug includes but is not limited to at least one of prolactin, growth hormone, adrenocorticotropic hormone, and melatonin.

[0009] Preferably, the microneedle shell is conical, with a base diameter of 310-450 μm, a tip diameter of no more than 20 μm, and a height of 700-1040 μm; the distribution density of the core-shell microneedles on the backing layer is 50-100 / cm 2 The distance between the tips of two adjacent core-shell microneedles is 500-800 μm.

[0010] Furthermore, the present invention also provides a method for preparing the above-mentioned photothermal responsive bionic core-shell microneedle patch, comprising the following steps: (1) Preparation of microneedle shells: adding a polylactic acid-glycolic acid copolymer acetone mixed solution to a microneedle mold, centrifuging the mixed solution to fill the cavity of the microneedle mold, and vacuum drying to obtain a microneedle shell; (2) Preparing a phase change core: uniformly mixing the required loaded drug with the phase change material having photothermal properties, and then filling it into the microneedle shell prepared in step (1), centrifuging it to fully fill it into the microneedle shell, and cooling and solidifying it to obtain a phase change core; (3) Preparing a microneedle cap layer: continuing to add the mixed solution prepared in step (1) to the microneedle mold, and evaporating the solvent by centrifugation, thereby forming a cap layer on the top of the microneedle; (4) Preparation of backing layer and demolding: Continue to add polyvinyl alcohol solution to the microneedle mold, dry it and then demold it.

[0011] Preferably, in step (1), the mass percentage of polylactic acid-glycolic acid copolymer in the mixed solution is 5-15%; the centrifugal speed is controlled at 3000-5000 rpm, the centrifugal time is 2-3 min, and after centrifugation, the excess mixed solution outside the microneedle cavity in the microneedle mold is removed; and the vacuum drying time is more than 30 min.

[0012] Preferably, in step (2), the phase change material with photothermal properties is prepared by mixing black phosphorus, gelatin and carrageenan, specifically, a gelatin aqueous solution and a carrageenan aqueous solution are mixed, and then black phosphorus and the required loaded drug are added to obtain a drug-loaded composite hydrogel solution, and the phase change core is obtained after solidification; in the drug-loaded composite hydrogel solution, the mass percentage of gelatin is 15-25%, the mass percentage of carrageenan is 0.6-1.5%, the concentration of black phosphorus is 0.05-0.4 mg / mL, and the amount of the loaded drug is 1-2 μg / μL.

[0013] Preferably, in step (2), the filling temperature is controlled at 39-45°C, the centrifugal speed is controlled at 3000-5000 rpm, and the centrifugal time is 2-3 min.

[0014] Preferably, in step (4), the mass concentration of the polyvinyl alcohol solution is 15-25%, and the polyvinyl alcohol solution is prepared from a phosphate buffer solution; and the drying temperature is controlled at 30-40°C.

[0015] Furthermore, the present invention also claims to protect the use of the above-mentioned photothermal responsive bionic core-shell microneedle patch in loading and releasing hormone drugs. Beneficial Effects

[0016] (1) The microneedle patch of the present invention has a core-shell structure, wherein the outer shell is made of polylactic acid-glycolic acid copolymer, and the inner core is a mixture of phase change materials (black phosphorus, gelatin and carrageenan) with photothermal properties and loaded drugs; wherein gelatin and carrageenan have fast and reversible phase change properties, and black phosphorus has good near-infrared (NIR) absorption performance, photothermal conversion efficiency and low toxicity. The composite hydrogel made of the three has a suitable phase change temperature and heating performance, thereby ensuring the high efficiency and safety of the drug delivery method.

[0017] (2) The microneedle patch of the present invention has the advantages of being almost painless, minimally invasive, harmless to the body, not prone to infection, convenient to use, and easy to operate. It has good patient compliance, can regulate the drug delivery rate through external stimulation, and can deliver the drug slowly in the absence of stimulation, with a stable effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become more clear.

[0019] Figure 1 Ratio screening of microneedle core phase change materials: a is the phase change temperature change of different concentrations of gelatin, n = 3 in each group; b is the effect of different concentrations of carrageenan on the phase change temperature of the mixed system, n = 3 in each group; c is the phase change temperature of the mixed system of 20% gelatin + 0.65% carrageenan; d is the phase change that occurred after 20% gelatin and different concentrations of carrageenan (0.65% and 0.7%) were mixed and heated to 39.3℃ and 40.5℃ respectively, from solid to fluid state.

[0020] Figure 2 NIR responsiveness of microneedle core phase change materials: a is the thermal image of the microneedle core material with 20% gelatin + 0.65% carrageenan + 0.2 mg / mL BP before and after NIR irradiation at different powers; b is the relationship between the temperature of the microneedle core material and the irradiation at different NIR powers, with n=3 for each group; c is the thermal image of the microneedle core material containing black phosphorus (BP) and the microneedle core material without black phosphorus at 1.5 W / cm 2 Thermal images before and after near-infrared irradiation, d is the thermal images of black phosphorus microneedle core material and non-black phosphorus microneedle core material at 1.5 W / cm 2 Temperature variation with time before and after near-infrared irradiation.

[0021] Figure 3 The present invention is a flow chart for preparing the microneedle patch.

[0022] Figure 4 Observation and evaluation of the morphology of microneedles: a Optical microscope image of photothermal responsive core-shell microneedles (scale bar = 450 μm), b Fluorescence characterization of the core-shell structure of photothermal responsive core-shell microneedles (scale bar = 200 μm), c Scanning electron microscope image of photothermal responsive core-shell microneedles (scale bar = 50 μm), d Statistics of uniformity of the length of photothermal responsive core-shell microneedles, e Compression force of photothermal responsive core-shell microneedles (n = 3 for each group), e HE staining image of photothermal responsive core-shell microneedles after piercing the skin (scale bar = 100 μm).

[0023] Figure 5 The in vitro phase change heating characteristics of the microneedle patch are investigated: a is the in vitro photothermal response heat map of microneedles without black phosphorus and with black phosphorus, b is the in vitro photothermal response heating curve of microneedles without black phosphorus and with black phosphorus, and c is the heating characteristics of the microneedle patch under 7 NIR irradiation cycles.

[0024] Figure 6In vitro qualitative detection of the release characteristics of the microneedle patch: a is a fluorescent photograph of FITC-BSA loaded microneedles in agar blocks under 0, 1, 4 and 7 NIR irradiation cycles (with an interval of 1 hour between each irradiation); b is a fluorescent photograph of FITC-BSA loaded microneedles in agar blocks under 0, 1, 4 and 7 hours without NIR irradiation (scale bar = 300 μm).

[0025] Figure 7 In vitro quantitative detection of microneedle drug release characteristics. Result figure: Drug release characteristics of microneedle patches with and without NIR irradiation in PBS solution.

[0026] Figure 8 The biocompatibility and safety evaluation of the present invention: a is the Calcein / PI method to evaluate the effect of the microneedle material on the viability of 3T3 cells, b is the CCK-8 method to evaluate the effect of the microneedle material on the activity of 3T3 cells, and c is the recovery of the skin at the puncture site after the microneedle punctures the mouse skin.

[0027] Fig. 9 This is an investigation of the in vivo phase change heating characteristics of the microneedle patch: a is the photothermal response heat map of the photothermal responsive microneedle patch after application to mouse skin.

[0028] Fig.10 Table 1 and Table 1 are the statistical results of in vivo quantitative detection of microneedle drug release characteristics: a intervention scheme of prolactin-loaded microneedles in high-fat model mice, b normal diet group mice (Control), high-fat diet model group for 10 weeks (Model), high-fat diet model combined with subcutaneous direct administration of prolactin group mice (PRL), high-fat diet model combined with prolactin-loaded microneedle group (PRL-MN), high-fat diet model combined with prolactin-loaded microneedle and near-infrared stimulation group (PRL-MN-NIR), after 10 weeks of high-fat diet modeling, the level of prolactin in the serum of high-fat diet mice every 4 hours within a day (ZT0 represents 8 am, ZT4 represents 12 am, ZT8 represents 4 pm, ZT12 represents 8 pm, ZT16 represents 12 pm, and ZT20 represents 4 am the next day). DETAILED DESCRIPTION

[0029] The present invention can be better understood with reference to the following examples. Example 1

[0030] This embodiment provides a combined screening process of gelatin / carrageenan as a microneedle phase change core material.

[0031] The present invention prepares gelatin solutions with concentrations of 15%, 20%, and 25% (weight percentage), respectively, converts them into solid state, heats to melt the solid gelatin gel, and records the critical temperature as the phase transition temperature. Carrageenan solutions with concentrations of 0.6%, 0.65%, 0.7%, 0.8%, 0.9%, 1.2%, and 1.5% (weight percentage) are respectively prepared, converted into solid state, heated to melt the solid gelatin gel, and the critical temperature is recorded as the phase transition temperature. The results are as follows Figure 1 As shown. Among them, Figure 1 a shows that as the gelatin concentration increases, its phase transition temperature increases slightly (29.2-32°C). Figure 1 b shows that when carrageenan is doped into gelatin hydrogel, the phase transition temperature of the mixed hydrogel gradually increases (38-50°C) as the concentration of carrageenan increases. Figure 1 c is the phase transition temperature of the mixed system of 20% gelatin + 0.65% carrageenan, 39.3°C; Figure 1 d is 20% gelatin and different concentrations of carrageenan (0.65% and 0.7%) mixed and heated to 39.3℃ and 40.5℃ respectively, and phase transitions were observed from solid to fluid state. When 20% gelatin is doped with 0.65% carrageenan, the phase transition temperature of the mixed hydrogel is 39.3℃, which avoids uncontrolled melting at body temperature and skin burns caused by excessive temperature. Example 2

[0032] This example provides an evaluation of the photothermal responsiveness of the microneedle phase change core material BP / gelatin / carrageenan.

[0033] In order to study the NIR response and phase change ability of the microneedle core material, the present invention tests the photothermal conversion and phase change process in its near-infrared response. Gelatin and carrageenan were added to a 0.2 mg / mL BP (black phosphorus) solution to obtain a BP / gelatin / carrageenan composite hydrogel, wherein the weight percentage of gelatin in the composite hydrogel is 20%, and the weight percentage of carrageenan in the composite hydrogel is 0.65%.

[0034] Focused NIR light with a wavelength of 808 nm was used at 1.0 W / cm 2 , 1.25 W / cm 2 , 1.5 W / cm 2 The composite hydrogel was irradiated vertically with a power of 1000 nm, and the temperature change of the composite hydrogel was recorded by a handheld infrared camera. The heating process of the composite hydrogel was filmed under a microscope. The results are shown in Figure 2 As shown, Figure 2 a and Figure 2 b shows that when NIR irradiates the composite hydrogel, the local temperature increases with time. In the same time, the local temperature of the composite hydrogel is proportional to the power. We found that at 1.5 W / cm2 Under NIR light, when the loaded BP concentration was 0.2 mg / mL, the temperature could rise to 39.3 °C within 2 min. Figure 2 c and Figure 2 d Comparison of the composite hydrogel with and without BP at 1.5 W / cm 2 The results of the temperature rise under continuous NIR irradiation show that the phase change core material will have a significant temperature rise only when the composite hydrogel contains BP, which indicates that the BP in the composite hydrogel can efficiently absorb light energy and convert it into heat energy. Example 3

[0035] This embodiment provides a method for preparing a photothermal responsive bionic core-shell microneedle patch loaded with prolactin.

[0036] Take 200 μL of 10% PLGA acetone solution into the PDMS microneedle mold and centrifuge (4000 rpm, 3 min), fill the microneedle cavity of the microneedle mold with PLGA solution, remove the excess PLGA solution and move to a vacuum drying oven to dry for 30 minutes to form a PLGA shell on the surface of the microneedle cavity. The number of times the above operation is repeated and the concentration of PLGA can determine the thickness of the microneedle shell. Fill 100 μL of drug-loaded composite hydrogel (containing 1μg / μL prolactin, 20% gelatin, 0.65% carrageenan and 0.2 mg / mL BP) into the microneedle shell at 40°C to form a phase change core material (4000 rpm, 3 min), and centrifuge to remove excess hydrogel from the backing layer. After the drug-loaded composite hydrogel is cooled and solidified, add 50 μL of 10% PLGA solution to the mold, centrifuge to evaporate the solvent, and form a cap layer on the top of the microneedle (4000 rpm, 2 min). Finally, 20% PVA solution was added to the mold as a soluble backing layer, dried at 35°C, and demolded to prepare a photothermal responsive bionic core-shell microneedle patch. The preparation flow chart is shown in Figure 3 When using microneedles, a near-infrared NIR laser emitter (808 nm) is required. Example 4

[0037] This example provides the morphological observation and evaluation of the photothermal responsive bionic core-shell microneedle patch.

[0038] The morphology of the microneedles was observed by naked eyes and scanning electron microscope (SEM). Figure 4 As shown. Figure 4a It can be seen that the size of the microneedle patch is uniform, the needle body is conical, the surface is smooth, the tip is sharp, and the array is complete. In order to further examine the core-shell structure of the microneedle, FITC-BSA, which represents the macromolecular protein drug, is encapsulated into the core material of the core-shell microneedle. Under a fluorescence microscope, it is observed that the core material of the microneedle loaded with FITC-BSA emits green fluorescence, and the microneedle shell labeled with Oil Red O shows red fluorescence, as shown in Figure 2. Figure 4 b. The microneedle patch was observed by scanning electron microscopy. Figure 4 As shown in Figure c, each needle body is in the shape of a cone, and the core-shell structure is obvious. The needle length of the microneedle is measured to be 965 ± 30 μm, the base diameter is 420 ± 15 μm, and the needle tip distance is 700 ± 12 μm. The base diameter and needle tip distance are basically consistent with the mold. The present invention conducts statistics on the uniformity of the length of the microneedle, and the results are as follows Figure 4 As shown in Figure d, the prepared photothermal responsive bionic core-shell microneedles have high uniformity. In order to evaluate the skin penetration ability of the photothermal responsive bionic core-shell microneedles, the mechanical strength of the microneedles was evaluated by a force measurement system. The results are shown in Figure d. Figure 4 As shown in e, each microneedle can withstand a force of 0.58 ± 0.04 N before bending or breaking, which significantly exceeds the 0.3 N force per needle required to pierce the skin, ensuring that the microneedle patch can deliver drugs into the body. The microneedle patch was applied to the mouse ex vivo skin in vitro, and the HE staining results were shown in Figure 4 As shown in f, the results show that the microneedles can penetrate the ex vivo skin of mice. Example 5

[0039] This example investigates the photothermal response characteristics of a prolactin-loaded photothermal responsive bionic core-shell microneedle patch through in vitro experiments.

[0040] Drug release mechanism of photothermal responsive bionic core-shell microneedles Figure 5 As shown. Figure 5 a It can be seen that when there is no NIR irradiation, the microneedles release the drug slowly. Under NIR irradiation, the microneedles release the drug faster. In the photothermal response test, the microneedles were inserted into the gel and exposed to 1.5 W / cm 2 Under 808 nm near-infrared radiation, the temperature change curve and thermal image were recorded by a thermal imager. 2 Under NIR light irradiation, when the BP concentration was 0.2 mg / mL, the temperature of the microneedle could rise to 39.3°C within 2 min. Subsequently, the temperature of the microneedle containing phase change material was increased to 39.3°C within 2 min when the BP concentration was 0.2 mg / mL. 2 The temperature rise of the phase change core material under continuous NIR irradiation shows that only in the presence of BP will there be an obvious temperature rise process ( Figure 5b and 5c). In order to further observe the photothermal response performance of the photothermal responsive core-shell microneedle, NIR irradiation was turned on to irradiate the microneedle until its temperature reached a specific temperature (42-43°C), then NIR irradiation was turned off. After the microneedle naturally cooled to room temperature, NIR irradiation was turned on again to irradiate the microneedle. Once the temperature dropped to room temperature, the next cycle began. It was observed that the microneedle still had good photothermal response performance when given 7 NIR light cycles ( Figure 5 d). Example 6

[0041] This example demonstrates through in vitro qualitative detection that NIR irradiation can increase the cumulative drug release rate of the microneedle patch loaded with prolactin.

[0042] In order to demonstrate the drug loading and release capabilities of peptide and protein drugs in the core-shell microneedle system, FITC-BSA, which represents macromolecular protein drugs, was encapsulated into the core of the core-shell microneedle, and the green fluorescence intensity of FITC-BSA represented the release of the drug. The microneedles were embedded in agar blocks and divided into a group without NIR irradiation (a) and a group with NIR irradiation for 2 min every hour (b). The green fluorescence intensity of the microneedle core was observed by microscopic photography. The results are shown in Figure 2. Figure 6 As shown in the figure, the green fluorescence intensity of the microneedles in the non-NIR irradiation group weakened over time, indicating that the microneedles can release FITC-BSA; compared with the non-NIR irradiation group, the green fluorescence intensity of the microcores in the NIR irradiation group was significantly weakened, indicating that NIR irradiation can promote the release of FITC-BSA from the microneedles. The above results prove that the microneedles can release drugs and have good photothermal response characteristics. Example 7

[0043] This example demonstrates through in vitro quantitative detection that NIR irradiation can increase the cumulative drug release rate of the microneedle patch loaded with prolactin.

[0044] In order to quantitatively study the drug release process, the photothermal responsive microneedles loaded with 1 μg BSA-FITC were divided into a NIR irradiation group (Microneedles with NIR) and a non-NIR irradiation group (Microneedles without NIR). The NIR irradiation group irradiated the microneedles for 2 min every hour, and the irradiation cycle was 1 hour. The non-NIR irradiation group did not irradiate the microneedles under other equal conditions. The above microneedles were placed in PBS solution, and oscillated at 300 rpm / min at 37°C using an oscillator. Samples were taken every hour, and quantitative measurements were performed using a fluorescence quantitative analyzer. The results are shown in Figure 2. Figure 7 As shown, the microneedle release rate and total release amount in the NIR irradiation group were significantly higher than those in the non-NIR irradiation group, indicating that after NIR irradiation, the drug was released faster and more completely. Example 8

[0045] This example investigates the biocompatibility of the microneedle patch.

[0046] Before applying the microneedle patch, the biocompatibility and cytotoxicity of the microneedle were evaluated by observing the effect of the microneedle material on the viability of 3T3 cells. NIH 3T3 cells were divided into 5 groups and cultured in a 96-well plate. Each group had 5 replicates. The initial number of cells in each well was about 4 × 10 3 The first group was a blank control group (Control), the second group was a PLGA microneedle shell treatment group (Shell-cap), the third group was a BP / carrageenan / gelatin microneedle core phase change material (Core matrix), the fourth group was a microneedle backing material PVA treatment group (Backing), and the fifth group was a microneedle combined with NIR treatment group (NIR). After 1 day of treatment, CCK-8 (purchased from Biyuntian, item number: C0042) was used to measure cell viability to evaluate the biocompatibility and cytotoxicity of the microneedles. The results are shown in Figure 8 As shown. Figure 8 a-8b It can be seen that the microneedle material and NIR stimulation have almost no negative impact on the growth of 3T3 cells. After the microneedle was inserted into the back skin of the mouse, the microneedle was removed 90 minutes later. Figure 8 c The results showed that there was no sign of inflammation, redness or swelling at the insertion site, and the mouse skin basically returned to normal. The above results show that the microneedles have good cell compatibility and low cytotoxicity. Example 9

[0047] This example investigates the in vivo phase change temperature rise characteristics of the microneedle patch.

[0048] In the NIR-triggered heating experiment of microneedles on the skin, microneedles were pressed into the skin on the back of mice and heated at 1.5 W / cm 2 808 nm NIR irradiation, using a thermal imager to count the temperature changes and thermal images of the microneedles. The microneedles loaded with prolactin were inserted into the back of mice. Fig. 9 As shown, under NIR light stimulation, the microneedle heated up to 40°C within 62 seconds, and the photothermal response heat map showed that the microneedle could quickly heat up in the mouse body, thereby accelerating the release of prolactin. Example 10

[0049] This example demonstrates that the microneedle patch loaded with prolactin releases prolactin in a pulsed manner in mice through in vivo testing. Fig.10 and Table 1.

[0050] The mice were randomly divided into 5 groups. Fig.10As shown in a, group 1 is the normal diet control group (Control), group 2 is the high-fat diet model group (Model), group 3 is the prolactin subcutaneous administration group (PRL), group 4 is the prolactin microneedle administration group (PRL-MN), and group 5 is the prolactin microneedle combined with NIR administration group (PRL-MN-NIR). After the modeling was completed in week 10, the mice were killed, and blood was collected from the tail vein of the mice at 8 o'clock (ZT0), 12 o'clock (ZT4), 16 o'clock (ZT8), 20 o'clock (ZT12), 24 o'clock (ZT16) on the day before the killing of the mice, and 4 o'clock in the morning of the next day (ZT20) to measure the prolactin level in the mouse blood. The results are shown in Fig.10 As shown in Table 1, the prolactin subcutaneous injection group and the prolactin microneedle combined with NIR administration group can significantly increase the prolactin level of mice at 20 points, and the prolactin microneedle combined with NIR administration group can increase the prolactin level in the blood at other time points. This shows that the microneedle patch loaded with prolactin can mimic the release of prolactin under physiological conditions in mice.

[0051] Table 1. Statistical results of in vivo quantitative detection of microneedle drug release characteristics

[0052] The present invention provides a photothermal responsive bionic core-shell microneedle patch and its preparation method and application ideas. There are many methods and ways to implement the technical solution. The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention. All components not specified in this embodiment can be implemented by existing technologies.

Claims

1. A photothermal responsive bionic core-shell microneedle patch, characterized in that: It comprises a backing layer and a plurality of core-shell microneedles arranged on the backing layer; the core-shell microneedles comprise an external microneedle shell and an internal phase change core; the microneedle shell is made of polylactic acid-glycolic acid copolymer; the phase change core is a mixture of a phase change material with photothermal properties and a loaded drug.

2. The photothermal responsive bionic core-shell microneedle patch according to claim 1, characterized in that: The phase change material with photothermal properties includes black phosphorus, gelatin and carrageenan.

3. The photothermal responsive bionic core-shell microneedle patch according to claim 1, characterized in that: The loaded drug includes at least one of prolactin, growth hormone, adrenocorticotropic hormone and melatonin.

4. The photothermal responsive bionic core-shell microneedle patch according to claim 1, characterized in that: The microneedle shell is conical, with a base diameter of 310-450 μm, a tip diameter of no more than 20 μm, and a height of 700-1040 μm; the distribution density of the core-shell microneedles on the backing layer is 50-100 / cm 2 The distance between the tips of two adjacent core-shell microneedles is 500-800 μm.

5. The method for preparing the photothermal responsive bionic core-shell microneedle patch according to claim 1, characterized in that: The steps include: (1) Preparation of microneedle shells: adding a polylactic acid-glycolic acid copolymer acetone mixed solution to a microneedle mold, centrifuging the mixed solution to fill the cavity of the microneedle mold, and vacuum drying to obtain a microneedle shell; (2) Preparing a phase change core: uniformly mixing the required loaded drug with the phase change material having photothermal properties, and then filling it into the microneedle shell prepared in step (1), centrifuging it to fully fill it into the microneedle shell, and cooling and solidifying it to obtain a phase change core; (3) Preparing a microneedle cap layer: continuing to add the mixed solution prepared in step (1) to the microneedle mold, and evaporating the solvent by centrifugation, thereby forming a cap layer on the top of the microneedle; (4) Preparation of backing layer and demolding: Continue to add polyvinyl alcohol solution to the microneedle mold, dry it and then demold it.

6. The method for preparing the photothermal responsive bionic core-shell microneedle patch according to claim 5, characterized in that: In step (1), the mass percentage of polylactic acid-glycolic acid copolymer in the mixed solution is 5-15%; the centrifugal speed is controlled at 3000-5000 rpm, the centrifugal time is 2-3 min, and after centrifugation, the excess mixed solution outside the microneedle cavity in the microneedle mold is removed; and the vacuum drying time is more than 30 min.

7. The method for preparing the photothermal responsive bionic core-shell microneedle patch according to claim 5, characterized in that: In step (2), the phase change material with photothermal properties is prepared by mixing black phosphorus, gelatin and carrageenan. Specifically, a gelatin aqueous solution and a carrageenan aqueous solution are mixed, and then black phosphorus and the required loaded drug are added to obtain a drug-loaded composite hydrogel solution, and a phase change core is obtained after solidification; in the drug-loaded composite hydrogel solution, the mass percentage of gelatin is 15-25%, the mass percentage of carrageenan is 0.6-1.5%, the concentration of black phosphorus is 0.05-0.4 mg / mL, and the amount of loaded drug is 1-2 μg / μL.

8. The method for preparing the photothermal responsive bionic core-shell microneedle patch according to claim 5, characterized in that: In step (2), the filling temperature is controlled at 39-45°C, the centrifugal speed is controlled at 3000-5000 rpm, and the centrifugal time is 2-3 min.

9. The method for preparing the photothermal responsive bionic core-shell microneedle patch according to claim 5, characterized in that: In step (4), the mass concentration of the polyvinyl alcohol solution is 15-25%, and the drying temperature is controlled at 30-40°C.

10. Use of the photothermal responsive bionic core-shell microneedle patch according to claim 1 for loading and releasing hormone drugs.

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