A chromogenic particle and an absorbable microneedle patch and their application in skin marking

Abstract

The present invention belongs to the field of transdermal microneedle technology, and more specifically, relates to a color-developing particle and an absorbable microneedle patch, and their application for skin marking. The present invention discloses a microneedle color-developing particle, produced by reacting an amine compound (cyclohexylmethylamine or 2,4,6-trimethylaniline) with genipin under specific conditions. When used for skin marking, the transdermal microneedle patch prepared using this color-developing particle significantly prolongs the color development time, avoiding the problem of frequent re-application of markings during radiotherapy, improving the accuracy and consistency of treatment, and reducing the impact on patients' daily lives. The transdermal microneedle patch of the present invention enables patterned marking on the skin with minimal or no pain. The marked pattern is temporary and highly acceptable to patients. Furthermore, the transdermal microneedle patch of the present invention has a simple preparation process, simple and mild reaction conditions, low raw material costs, and is suitable for large-scale production, possessing excellent application value and prospects.

Description

Technical Field

[0001] The present invention belongs to the field of transdermal microneedle technology, and more specifically, relates to a color-developing particle and an absorbable microneedle patch and their application in skin marking. Background Art

[0002] During radiotherapy, it is necessary to mark the surface of the patient's body in order to achieve multiple, repeatable, and precise positioning of the treatment area. Currently, the commonly used surface marking methods mainly include marking with a marker pen and tattoo marking. Marking with a marker pen is easy to operate, low-cost, and will not cause harm to the patient, but the visibility of the mark will be reduced due to factors such as daily bathing and friction from clothing. It has a short maintenance time and requires frequent re-application, which increases the complexity of the operation and the risk of error. Tattoo marking is a permanent mark. Although it has the advantages of long-lasting stability, its production process is complicated and requires professional skills and equipment. It will cause pain to the patient during marking, and the marked pattern will permanently exist on the body surface, which can easily cause aesthetic, religious or psychological resistance in patients. Therefore, there is an urgent need to develop a surface marking technology that can maintain a long time but is not permanent.

[0003] Transdermal microneedle technology, a painless or minimally painful drug delivery method, has recently been applied to the cosmetic field for tattoo creation. However, existing transdermal microneedle marking systems typically use permanent tattoo pigments (e.g., Chinese patent CN108325065A), while non-permanent pigments have a relatively short development time (typically less than 16 weeks). This lack of stability meets the requirements for radiotherapy, requiring a non-permanent marking duration of at least six months, limiting the effectiveness and convenience of transdermal microneedle skin marking in clinical practice. While existing absorbable transdermal microneedle marking systems can achieve painless or minimally painful patterned marking, they use permanent marking inks, leaving the marking pattern permanently on the body surface. Most patients prefer this approach, while other marking pigments are easily metabolized or excreted by the skin, resulting in insufficient stability within the skin. This results in a short development time, making it difficult to meet the needs of long-term treatment.

[0004] Therefore, developing skin marking technology with a color development time of 6-12 months has become a technical problem that needs to be solved urgently. Summary of the Invention

[0005] The present invention aims to overcome the obvious shortcomings of existing color-developing transdermal microneedles in color development time, and provides a microneedle color-developing particle. After the transdermal microneedle patch prepared using the color-developing particle is marked on the skin surface, it can stably develop color on the skin for a long time, and the color development time can be up to 45 weeks.

[0006] The first object of the present invention is to provide a microneedle patch color-developing particle and a preparation method thereof.

[0007] A second object of the present invention is to provide an absorbable transdermal microneedle patch.

[0008] The third object of the present invention is to provide applications of the above-mentioned color-developing particles and the above-mentioned absorbable transdermal microneedle patch.

[0009] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0010] The present invention introduces a novel color-developing particle into the microneedle. When a transdermal microneedle patch prepared with the color-developing particle is used for skin marking, the color development time can be significantly prolonged. Therefore, the present invention claims protection for the following solutions:

[0011] The present invention provides a method for preparing microneedle patch color-developing particles, comprising the following steps:

[0012] S1. Genipin was added to the amine compound solution, and the reaction was stirred at 50-70 ° C under anaerobic conditions for 2.5-3.5 hours, and the solid reaction product was recovered;

[0013] S2. The solid reaction product obtained in step S1 is dissolved in a solvent, stirred and reacted at 70-90 ° C for 5-7 hours, and the solid reaction product is recovered to obtain color-developing particles;

[0014] Wherein, the amine compound is cyclohexylamine or 2,4,6-trimethylaniline.

[0015] As an optional embodiment, in the amine compound solution in step S1, the final concentration of the amine compound is 15-35 mg / mL, and the final concentration of genipin is 15-25 mg / mL.

[0016] As an optional embodiment, in the amine compound solution in step S1, the final concentration of the amine compound is 16-34 mg / mL, and the final concentration of genipin is 16-20 mg / mL.

[0017] As an optional embodiment, the solvent in step S2 needs to be able to dissolve the solid reaction product of step S1 and not react with it. The solvent can be methanol or ethanol.

[0018] As an optional embodiment, the concentration of the methanol solution is 30-70% (preferably 50%).

[0019] As an optional embodiment, the solvent of the amine compound solution in step S1 is a solvent mixed with water, anhydrous ethanol and phosphate buffered saline in a volume ratio of 1:1:1.

[0020] As an optional embodiment, the anaerobic condition in step S1 can be provided in the following manner: the reaction solution is subjected to a deoxygenation treatment, such as nitrogen bubbling treatment.

[0021] Preferably, the amine compound solution in step S1 further contains polyamino acid.

[0022] More preferably, in the amine compound solution in step S1, the final concentration of the polyamino acid is 8-20 mg / mL.

[0023] Further more preferably, in the amine compound solution in step S1, the final concentration of polyamino acid is 10-17 mg / mL.

[0024] Preferably, in the amine compound solution in step S1, the concentration ratio of the polyamino acid to the amine compound is (1-3): (1-7).

[0025] More preferably, in the amine compound solution in step S1, the concentration ratio of the polyamino acid to the amine compound is 1:1 or 3:7.

[0026] As an alternative embodiment, the polyamino acid includes polyleucine, polyaspartic acid, polylysine, polythreonine, polycysteine and polyglutamic acid.

[0027] As an alternative embodiment, the polyamino acid is polyglutamic acid or polylysine.

[0028] As an optional embodiment, the solid reaction product is recovered in step S1 by extraction and drying, and the specific extractant used is dichloromethane.

[0029] As an optional embodiment, the solid reaction product is recovered in step S2 by washing and drying, and the washing liquid used is dichloromethane.

[0030] As an optional embodiment, the drying in steps S1 and S2 is vacuum drying.

[0031] As an optional specific embodiment, a method for preparing microneedle patch color-developing particles comprises the following steps:

[0032] S1. Genipin and polyamino acid were added to the amine compound solution, the solution was bubbling with nitrogen, and then stirred at 50-70 ° C for 2.5-3.5 hours, and the reaction product was extracted and dried to obtain a solid;

[0033] S2. The solid obtained in step S1 is dissolved in methanol solution, stirred at 70-90 ° C for 5-7 hours, and the reaction product is washed and dried to obtain color particles;

[0034] The amine compound is cyclohexylmethylamine or 2,4,6-trimethylaniline, the polyamino acid is polyglutamic acid or polylysine, and the concentration ratio of the polyamino acid to the amine compound in the amine compound solution is (1-3): (1-7).

[0035] The microneedle patch color-developing particles prepared by the above preparation method are also within the protection scope of the present invention, and the particle size of the color-developing particles is 30 μm-120 μm.

[0036] Preferably, the particle size of the color-developing particles is 60 μm to 90 μm.

[0037] The present invention also provides an absorbable transdermal microneedle patch, comprising a substrate and a needle tip, wherein the needle tip is filled with a needle body suspension, and the needle body suspension comprises an absorbable polymer material and the above-mentioned color-developing particles.

[0038] Preferably, in the absorbable transdermal microneedle patch, the mass ratio of the absorbable polymer material to the color-developing particles is 200:(45-60).

[0039] Specifically, the substrate includes an absorbable polymer material and a stabilizer, and the absorbable polymer material is at least one of polyvinyl pyrrolidone, hyaluronic acid, and polyvinyl alcohol.

[0040] As an optional embodiment, the stabilizer includes sucrose, propylene glycol, lactose, trehalose and inorganic salts (preferably sucrose or propylene glycol).

[0041] As an optional embodiment, the preparation method of the above-mentioned absorbable transdermal microneedle patch comprises the following steps:

[0042] (1) Dissolving the absorbable polymer material and the stabilizer in phosphate buffer to obtain a basal layer solution;

[0043] (2) mixing the absorbable polymer material and the color-developing particles in a phosphate buffer solution to obtain a needle suspension;

[0044] (3) Fill the needle body suspension into the needle tip area of the mold and centrifuge to remove bubbles;

[0045] (4) Filling the base layer solution into the base area of the mold, drying and molding, and then demolding to obtain the absorbable transdermal microneedle patch.

[0046] As an optional embodiment, the mass ratio of the absorbable polymer material to the stabilizer in step (1) is 200:(15-20).

[0047] As an optional embodiment, the concentration of the absorbable polymer material in the base layer solution in step (1) is 80-120 mg / mL, and the concentration of the stabilizer is 5-10 mg / mL.

[0048] As an optional embodiment, the concentration of the absorbable polymer material in the base layer solution in step (1) is 100 mg / mL, and the concentration of the stabilizer is 7.5-10 mg / mL.

[0049] As an optional embodiment, in step (2), the mass ratio of the absorbable polymer material to the color-developing particles is 200:(45-60).

[0050] As an optional embodiment, the concentration of the absorbable polymer material in the needle suspension in step (2) is 100-150 mg / mL, and the concentration of the color-developing particles is 25-35 mg / mL.

[0051] As an optional embodiment, the concentration of the absorbable polymer material in the needle suspension in step (2) is 100-133 mg / mL, and the concentration of the color-developing particles is 30 mg / mL.

[0052] As an optional embodiment, the centrifugation in step (3) is performed at 5000-6000 rpm.

[0053] As an optional embodiment, the drying in step (4) is vacuum drying at 37°C for 15 hours.

[0054] The use of the above-mentioned color-developing particles or the above-mentioned absorbable transdermal microneedle patch in the preparation of skin marking products should also be within the scope of protection of the present invention.

[0055] The present invention has the following beneficial effects:

[0056] The present invention introduces novel chromogenic particles into transdermal microneedles. When used for skin marking, the transdermal microneedle patch prepared using these particles significantly prolongs the color development time. The chromogenic particles provided by the present invention are compatible with the absorbable transdermal microneedle system of the present invention. They exhibit good biocompatibility and absorbability, and can remain stable in the skin. The marking period can reach 29 to 45 weeks, avoiding the frequent re-applying required for radiotherapy, improving treatment accuracy and consistency, and minimizing the impact on patients' daily lives. Furthermore, the marking period is limited to 12 months, making it suitable for radiotherapy of skin marks.

[0057] The transdermal microneedle patch of the present invention enables painless or minimally painful patterned marking on the skin. The resulting marking is temporary, highly acceptable to patients, and the marking duration is extended. Furthermore, the transdermal microneedle patch of the present invention features a simple preparation process, simple and mild reaction conditions, and low raw material costs, making it suitable for large-scale production. It has great application value and prospects in the field of skin marking. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 Flow chart for the preparation of transdermal microneedle patches.

[0059] Figure 2 This is an appearance diagram of the transdermal microneedle patch of Example 1.

[0060] Figure 3 These are the skin marking effects of the transdermal microneedle patch in Example 1, (a) shows the effect of mouse skin marking on day 0, and (b) shows the effect of mouse skin marking on week 25. DETAILED DESCRIPTION

[0061] The present invention will be further described below with reference to the accompanying drawings and specific examples, but the examples do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0062] The preparation process of transdermal microneedle patch is as follows Figure 1 shown.

[0063] Unless otherwise specified, the reagents and materials used in the following examples were commercially available.

[0064] Genipin, CAS No.: 6902-77-8, structural formula: .

[0065] Cyclohexylmethylamine, CAS number: 3218-02-8, structural formula: .

[0066] 2,4,6-Trimethylaniline, CAS number: 88-05-1, structural formula: .

[0067] Polylysine, CAS number: 25104-18-1.

[0068] Polyglutamic acid, CAS number: 25513-46-6.

[0069] In the following examples, the mold used to prepare the microneedle patch is a PDMS mold, manufactured by Microchip Pharmaceutical Technology Co., Ltd., model number Y254 (the microneedles prepared by this mold have a length of 800 μm, a diameter of 320 μm, and a conical shape).

[0070] The mice used in the following examples were purchased from Guangdong Provincial Animal Center and were SD female rats.

[0071] Example 1 Preparation of transdermal microneedle patch

[0072] 1. Preparation of color-developing components

[0073] 1. Prepare mixed solvent

[0074] Deionized water, anhydrous ethanol, and PBS (pH = 7.4) were mixed in a volume ratio of 1:1:1 to obtain a mixed solvent.

[0075] 2. Preparation of color-developing particles

[0076] Dissolve 0.5 g of cyclohexylmethylamine in 15 mL of a mixed solvent and sparge with nitrogen. Subsequently, slowly add 0.25 g of genipin powder and stir at 60°C for 3 hours. After completion of the reaction, extract with dichloromethane and vacuum dry the resulting solid. This solid is then dissolved in 30 mL of 50% methanol (water:methanol volume ratio = 1:1) and stirred at 80°C for 6 hours. The resulting product is washed with dichloromethane and vacuum dried to obtain color-developing particles.

[0077] The color-developing particles were screened using a 170-mesh sieve to select particles with a particle size of 60 to 90 μm.

[0078] 2. Preparation of Microneedle Patches

[0079] (1) Prepare the basal layer solution by dissolving 200 mg of hyaluronic acid and 15 mg of propylene glycol in 2 mL of PBS solution (0.01 M, pH = 7.4).

[0080] (2) Preparation of a color-developing needle suspension: 200 mg of hyaluronic acid and 45 mg of the color-developing particles (60-90 μm) prepared in this example were mixed in 1.5 mL of PBS solution (0.01 M, pH = 7.4) to obtain a needle suspension;

[0081] (3) Filling the needle tip: Take 0.5 mL of the color-developing needle suspension and fill it into the mold;

[0082] (4) Centrifugation: Place in a centrifuge at 5500 rpm;

[0083] (5) Filling the base: Take 1 mL of the base layer solution and fill it into the mold until the mold is completely covered;

[0084] (6) Molding: The mold was placed in a vacuum oven at 37°C and dried for 15 hours. The transdermal microneedle patch was finally obtained after demoulding. The appearance of the transdermal microneedle patch is as follows: Figure 2shown.

[0085] Example 2 Preparation of transdermal microneedle patch

[0086] 1. Preparation of color-developing particles

[0087] A mixed solvent (water: anhydrous ethanol: PBS = 1:1:1) was prepared according to the method in Example 1. 0.5 g of 2,4,6-trimethylaniline was dissolved in 15 mL of the mixed solvent and sparged with nitrogen. Subsequently, 0.3 g of genipin powder was slowly added and stirred at 60°C for 3 hours. After the reaction was complete, the solid was extracted with dichloromethane and dried under vacuum. The solid was then dissolved in 30 mL of 50% methanol (water:methanol volume ratio = 1:1) and stirred at 80°C for 6 hours. The resulting product was washed with dichloromethane and dried under vacuum to obtain color-developing particles.

[0088] The color-developing particles were screened using a 170-mesh sieve to select particles with a particle size of 60 to 90 μm.

[0089] 2. Preparation of Microneedle Patches

[0090] (1) Prepare the basal layer solution by dissolving 200 mg of hyaluronic acid and 20 mg of sucrose in 2 mL of PBS solution (0.01 M, pH = 7.4).

[0091] (2) Preparation of a color-developing needle suspension: 200 mg of hyaluronic acid and 45 mg of the color-developing particles (60-90 μm) prepared in this example were mixed in 1.5 mL of PBS solution (0.01 M, pH = 7.4) to obtain a needle suspension;

[0092] (3) Filling the needle tip: Take 0.5 mL of the color-developing needle suspension and fill it into the mold;

[0093] (4) Centrifugation: Place in a centrifuge at 5500 rpm;

[0094] (5) Filling the base: Take 1 mL of the base layer solution and fill it into the mold until the mold is completely covered;

[0095] (6) Molding: The mold was placed in a vacuum oven at 37°C and dried for 15 hours. The transdermal microneedle patch was finally obtained after demolding.

[0096] Example 3 Preparation of transdermal microneedle patch

[0097] 1. Preparation of color-developing particles

[0098] A mixed solvent (water:anhydrous ethanol:PBS = 1:1:1) was prepared according to the method in Example 1. 0.15 g of polyglutamic acid and 0.35 g of 2,4,6-trimethylaniline were dissolved in 15 mL of the mixed solvent and sparged with nitrogen. Subsequently, 0.3 g of genipin powder was slowly added and stirred at 60°C for 3 hours. After the reaction was complete, the solid was extracted with dichloromethane and vacuum dried to obtain a solid. The solid was then dissolved in 30 mL of 50% methanol (water:methanol volume ratio = 1:1) and stirred at 80°C for 6 hours. The resulting product was washed with dichloromethane and vacuum dried to obtain color-developing particles.

[0099] The color-developing particles were screened using a 170-mesh sieve to select particles with a particle size of 60 to 90 μm.

[0100] 2. Preparation of Microneedle Patches

[0101] (1) Prepare the basal layer solution by dissolving 200 mg of hyaluronic acid and 20 mg of sucrose in 2 mL of PBS solution (0.01 M, pH = 7.4).

[0102] (2) Preparation of a color-developing needle suspension: 200 mg of hyaluronic acid and 60 mg of the color-developing particles (60-90 μm) prepared in this example were mixed in 2 mL of PBS solution (0.01 M, pH = 7.4) to obtain a needle suspension;

[0103] (3) Filling the needle tip: Take 0.5 mL of the color-developing needle suspension and fill it into the mold;

[0104] (4) Centrifugation: Place in a centrifuge at 5500 rpm;

[0105] (5) Filling the base: Take 1 mL of the base layer solution and fill it into the mold until the mold is completely covered;

[0106] (6) Molding: The mold was placed in a vacuum oven at 37°C and dried for 15 hours. The transdermal microneedle patch was finally obtained after demolding.

[0107] Example 4 Preparation of transdermal microneedle patch

[0108] 1. Preparation of color-developing particles

[0109] A mixed solvent (water: anhydrous ethanol: PBS = 1:1:1) was prepared according to the method in Example 1. 0.25 g of polylysine and 0.25 g of cyclohexylmethylamine were dissolved in 15 mL of the mixed solvent and sparged with nitrogen. Subsequently, 0.3 g of genipin powder was slowly added and stirred at 60°C for 3 hours. After completion of the reaction, the solid was extracted with dichloromethane and dried under vacuum. The solid was then dissolved in 30 mL of 50% methanol (water:methanol volume ratio = 1:1) and stirred at 80°C for 6 hours. The resulting product was washed with dichloromethane and dried under vacuum to obtain color-developing particles.

[0110] The color-developing particles were screened using a 170-mesh sieve to select particles with a particle size of 60 to 90 μm.

[0111] 2. Preparation of Transdermal Microneedle Patches

[0112] (1) Prepare the basal layer solution by dissolving 200 mg of polyvinyl alcohol and 15 mg of propylene glycol in 2 mL of PBS solution (0.01 M, pH = 7.4).

[0113] (2) Preparation of a color-developing needle suspension: 200 mg of polyvinyl alcohol and 45 mg of the color-developing particles (60-90 μm) prepared in this example were mixed in 1.5 mL of PBS solution (0.01 M, pH = 7.4) to obtain a needle suspension;

[0114] (3) Filling the needle tip: Take 0.5 mL of the color-developing needle suspension and fill it into the mold;

[0115] (4) Centrifugation: Place in a centrifuge at 5500 rpm;

[0116] (5) Filling the base: Take 1 mL of the base layer solution and fill it into the mold until the mold is completely covered;

[0117] (6) Molding: The mold was placed in a vacuum oven at 37°C and dried for 15 hours. The transdermal microneedle patch was finally obtained after demolding.

[0118] Comparative Example 1 Preparation of transdermal microneedle patch

[0119] 1. Preparation of color-developing particles

[0120] A mixed solvent (water: anhydrous ethanol: PBS = 1:1:1) was prepared according to the method in Example 1. 0.5 g of chitosan was dissolved in 15 mL of the mixed solvent and sparged with nitrogen. Subsequently, 0.25 g of genipin powder was slowly added and stirred at 60°C for 3 hours. After the reaction was complete, the solid was extracted with dichloromethane and dried under vacuum. The solid was then dissolved in 30 mL of 50% methanol (water:methanol volume ratio = 1:1) and stirred at 80°C for 6 hours. The resulting product was washed with dichloromethane and dried under vacuum to obtain color-developing particles.

[0121] The color-developing particles were screened using a 170-mesh sieve to select particles with a particle size of 60 to 90 μm.

[0122] 2. Preparation of Microneedle Patches

[0123] (1) Prepare the basal layer solution by dissolving 200 mg of sodium hyaluronate and 15 mg of propylene glycol in 2 mL of PBS solution (0.01 M, pH = 7.4).

[0124] (2) Prepare a color-developing needle suspension: dissolve 200 mg of sodium hyaluronate and 45 mg of the color-developing particles (60-90 μm) prepared in this comparative example in 1.5 mL of PBS solution (0.01 M, pH = 7.4) to obtain a needle suspension;

[0125] (4) Filling the needle tip: Take 0.5 mL of the color-developing needle suspension and fill it into the mold;

[0126] (5) Centrifugation: Place in a centrifuge at 5500 rpm;

[0127] (6) Filling the base: Take 1 mL of base layer solution and fill it into the mold until the mold is completely covered;

[0128] (7) Molding: The mold was placed in a vacuum oven at 37°C and dried for 15 hours. The transdermal microneedle patch was finally obtained after demolding.

[0129] Comparative Example 2 Preparation of Transdermal Microneedle Patch

[0130] 1. Preparation of color-developing particles

[0131] A mixed solvent (water: anhydrous ethanol: PBS = 1:1:1) was prepared according to the method in Example 1. 0.5 g of polylysine was dissolved in 15 mL of the mixed solvent and sparged with nitrogen. Subsequently, 0.25 g of genipin powder was slowly added and stirred at 60°C for 3 hours. After completion of the reaction, the solid was extracted with dichloromethane and vacuum dried to obtain a solid. The solid was then dissolved in 30 mL of 50% methanol (water:methanol volume ratio = 1:1) and stirred at 80°C for 6 hours. The resulting product was washed with dichloromethane and vacuum dried to obtain color-developing particles.

[0132] The color-developing particles were screened using a 170-mesh sieve to select particles with a particle size of 60 to 90 μm.

[0133] 2. Preparation of Microneedle Patches

[0134] (1) Prepare the basal layer solution by dissolving 200 mg of sodium hyaluronate and 15 mg of propylene glycol in 2 mL of PBS solution (0.01 M, pH = 7.4).

[0135] (2) Prepare a color-developing needle suspension: dissolve 200 mg of sodium hyaluronate and 45 mg of the color-developing particles (60-90 μm) prepared in this comparative example in 1.5 mL of PBS solution (0.01 M, pH = 7.4) to obtain a needle suspension;

[0136] (3) Filling the needle tip: Take 0.5 mL of the color-developing needle suspension and fill it into the mold;

[0137] (4) Centrifugation: Place in a centrifuge at 5500 rpm;

[0138] (5) Filling the base: Take 1 mL of the base layer solution and fill it into the mold until the mold is completely covered;

[0139] (6) Molding: Place the mold in a vacuum oven at 37 °C and dry for 15 hours. Finally, demold the mold to obtain a transdermal microneedle patch.

[0140] Comparative Example 3 Preparation of transdermal microneedle patch

[0141] 1. Preparation of color-developing particles

[0142] A mixed solvent (water: anhydrous ethanol: PBS = 1:1:1) was prepared according to the method in Example 1. 0.5 g of dimethylethylamine was dissolved in 15 mL of the mixed solvent and sparged with nitrogen. Subsequently, 0.25 g of genipin powder was slowly added and stirred at 60°C for 3 hours. After the reaction was complete, the solid was extracted with dichloromethane and vacuum dried to obtain a solid. The solid was then dissolved in 30 mL of 50% methanol (water:methanol volume ratio = 1:1) and stirred at 80°C for 6 hours. The resulting product was washed with dichloromethane and vacuum dried to obtain color-developing particles.

[0143] The color-developing particles were screened using a 170-mesh sieve to select particles with a particle size of 60 to 90 μm.

[0144] 2. Preparation of Microneedle Patches

[0145] (1) Prepare the basal layer solution by dissolving 200 mg of sodium hyaluronate and 20 mg of sucrose in 2 mL of PBS solution (0.01 M, pH = 7.4).

[0146] (2) Prepare a color-developing needle suspension: dissolve 200 mg of sodium hyaluronate and 45 mg of the color-developing particles (60-90 μm) prepared in this comparative example in 1.5 mL of PBS solution (0.01 M, pH = 7.4) to obtain a needle suspension;

[0147] (3) Filling the needle tip: Take 0.5 mL of the color-developing needle suspension and fill it into the mold;

[0148] (4) Centrifugation: Place in a centrifuge at 5500 rpm;

[0149] (5) Filling the base: Take 1 mL of the base layer solution and fill it into the mold until the mold is completely covered;

[0150] (6) Molding: The mold was placed in a vacuum oven at 37°C and dried for 15 hours. The transdermal microneedle patch was finally obtained after demolding.

[0151] Comparative Example 4 Preparation of Transdermal Microneedle Patch

[0152] 1. Preparation of color-developing particles

[0153] Prepare a mixed solvent (water: anhydrous ethanol: PBS = 1:1:1) according to the method in Example 1. Dissolve 0.5 g of isopropylethylamine in 15 mL of the mixed solvent and sparge with nitrogen. Subsequently, slowly add 0.25 g of genipin powder and stir at 60°C for 3 hours. After the reaction is complete, extract with dichloromethane and vacuum dry to obtain a solid. This solid is then dissolved in 30 mL of 50% methanol (water:methanol volume ratio = 1:1) and stirred at 80°C for 6 hours. The resulting product is washed with dichloromethane and vacuum dried to obtain color-developing particles.

[0154] The color-developing particles were screened using a 170-mesh sieve to select particles with a particle size of 60 to 90 μm.

[0155] 2. Preparation of Microneedle Patches

[0156] (1) Prepare the basal layer solution by dissolving 200 mg of sodium hyaluronate and 15 mg of propylene glycol in 2 mL of PBS solution (0.01 M, pH = 7.4).

[0157] (2) Prepare a color-developing needle suspension: dissolve 200 mg of sodium hyaluronate and 45 mg of the color-developing particles (60-90 μm) prepared in this comparative example in 1.5 mL of PBS solution (0.01 M, pH = 7.4) to obtain a needle suspension;

[0158] (3) Filling the needle tip: Take 0.5 mL of the color-developing needle suspension and fill it into the mold;

[0159] (4) Centrifugation: Place in a centrifuge at 5500 rpm;

[0160] (5) Filling the base: Take 1 mL of the base layer solution and fill it into the mold until the mold is completely covered;

[0161] (6) Molding: Place the mold in a vacuum oven at 37°C and dry for 15 hours. Finally, demold the mold to obtain a transdermal microneedle patch.

[0162] Experimental Example 1

[0163] 1. Marking time test method

[0164] After cleaning and disinfecting the mouse skin, the transdermal microneedle patches of Examples 1-4 and Comparative Examples 1-4 were applied to the mouse skin and gently pressed for 3 minutes until the needle tip was completely dissolved and separated from the substrate. The marking color was observed every 7 days (weekly) and the marking time was recorded (if the marking disappeared after 7 days, the marking time was recorded as 1 week). The experiment was repeated 3 times, and only integers were retained for data analysis.

[0165] 2. Experimental Results

[0166] The results of the experimental determination of the marking time of different transdermal microneedle patches are shown in Table 1. The skin marking effect of the transdermal microneedle patch of Example 1 is as follows: Figure 3 As shown, the results show that the labeling time of the transdermal microneedle patch of the embodiment is significantly longer than that of the comparative example. The labeling time of the embodiment is 29-45 weeks, while the labeling time of the comparative example is 4-18 weeks. Among them, the transdermal microneedle patch of Example 3 has the longest labeling time, reaching an average of 45 weeks, which is 2.5 times the labeling time of the transdermal microneedle patch of Comparative Example 2 and 11 times the labeling time of the transdermal microneedle patch of Comparative Example 1.

[0167] Table 1 Labeling time of different transdermal microneedle patches

[0168]

[0169] Experimental Example 2

[0170] 1. Preparation of color-developing particles

[0171] Color-developing particles were prepared according to the method of Example 3. Color-developing particles with particle sizes of 0-30 μm, 30 μm-60 μm, 60 μm-90 μm, 90 μm-120 μm, 120 μm-180 μm, and 180 μm-210 μm were screened using 400 mesh, 240 mesh, 170 mesh, 120 mesh, 80 mesh, and 70 mesh sieves, respectively.

[0172] 2. Preparation of Microneedle Patches

[0173] Set up different treatment groups:

[0174] Treatment group a: chromogenic particles with a particle size of 0-30 μm;

[0175] Treatment group b: color-developing particles with a particle size of 30 μm to 60 μm;

[0176] Treatment group c: chromogenic particles with a particle size of 60 μm to 90 μm;

[0177] Treatment group d: chromogenic particles with a particle size of 90 μm to 120 μm;

[0178] Treatment group e: chromogenic particles with a particle size of 120 μm to 180 μm;

[0179] Treatment group f: chromogenic particles with a particle size of 180 μm to 210 μm;

[0180] (1) Prepare the basal layer solution by dissolving 200 mg of polyvinyl alcohol and 15 mg of propylene glycol in 2 mL of PBS solution (0.01 M, pH = 7.4).

[0181] (2) Preparation of color-developing needle suspension: Dissolve 200 mg of polyvinyl alcohol and 45 mg of color-developing particles of different treatment groups in 1.5 mL of PBS solution (0.01 M, pH = 7.4) to obtain color-developing needle suspensions of different treatment groups;

[0182] (3) Filling the needle tip: Take 0.5 mL of the color-developed needle suspension of different treatment groups and fill it into the mold;

[0183] (4) Centrifugation: Place in a centrifuge at 5500 rpm;

[0184] (5) Filling the base: Take 1 mL of the base layer solution and fill it into the mold until the mold is completely covered;

[0185] (6) Molding: The mold was placed in a vacuum oven at 37°C and dried for 15 hours. The transdermal microneedle patch was finally obtained after demolding.

[0186] 3. Marking Time Test Method

[0187] Referring to the labeling time test method in Experimental Example 1, transdermal microneedles from different treatment groups (treatment groups af) were applied to the skin of mice and gently pressed for 3 minutes until the needle tip completely dissolved and separated from the substrate. The labeling time was subsequently recorded. The experiment was repeated 3 times, and only integers were retained for data analysis.

[0188] 4. Experimental Results

[0189] Table 2 shows the results of transdermal microneedle patch labeling time measurements for different treatment groups. The results show that labeling times for treatment groups b, c, and d were significantly longer than those for treatment groups a and e, while treatment group f failed to achieve color development. These experimental results suggest that particle size is related to the color development time of the microneedle patch. Color-enhancing particles with too large a size cannot be effectively used in this transdermal microneedle system, while particles with too small a size significantly shorten the labeling time. Therefore, selecting the appropriate particle size for color development is crucial.

[0190] Table 2 Transdermal microneedle patch labeling time in different treatment groups

[0191]

[0192] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. An absorbable transdermal microneedle patch, characterized in that: It comprises a base and a needle tip, wherein the needle tip is filled with a needle suspension, and the needle suspension comprises an absorbable polymer material and color-developing particles; The method for preparing the color-developing particles comprises the following steps: S1. Genipin was added to the amine compound solution, and the reaction was stirred at 50-70 ° C under anaerobic conditions for 2.5-3.5 hours, and the solid reaction product was recovered; S2. The solid reaction product obtained in step S1 is dissolved in a solvent, stirred and reacted at 70-90 ° C for 5-7 hours, and the solid reaction product is recovered to obtain color-developing particles; Wherein, the amine compound is cyclohexylmethylamine; In the amine compound solution of step S1, the final concentration of the amine compound is 15-35 mg / mL, and the final concentration of genipin is 15-25 mg / mL; The particle size of the color-developing particles is 30 μm-120 μm.

2. The absorbable transdermal microneedle patch according to claim 1, characterized in that: The solvent in step S2 is methanol or ethanol.

3. The absorbable transdermal microneedle patch according to claim 1, characterized in that: The amine compound solution in step S1 also contains polyamino acid.

4. The absorbable transdermal microneedle patch according to claim 3, characterized in that: In the amine compound solution in step S1, the final concentration of polyamino acid is 8-20 mg / mL.

5. The absorbable transdermal microneedle patch according to claim 1, characterized in that: The solid reaction product is recovered in step S1 by extraction and drying.

6. The absorbable transdermal microneedle patch according to claim 1, characterized in that: The mass ratio of the absorbable polymer material to the color-developing particles is 200:(45-60).

7. Use of the absorbable transdermal microneedle patch according to any one of claims 1 to 6 in the preparation of skin marking products.

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