Microstructure for transdermal absorption and method for manufacturing same
The present invention relates to a microstructure including a biocompatible polymer or an adhesive and to a method for manufacturing the same. The present inventors optimized the aspect ratio according to the type of each microstructure, thereby ensuring the optimal tip angle and the diameter range for skin penetration. Especially, the B-type to D-type microstructures of the present invention minimize the penetration resistance due to skin elasticity at the time of skin attachment, thereby increasing the penetration rate of the structures (60% or higher) and the absorption rate of useful ingredients into the skin. In addition, the D-type microstructure of the present invention maximizes the mechanical strength of the structure by applying a triple structure, and thus can easily penetrate the skin. When the plurality of microstructures are arranged in a hexagonal arrangement type, a uniform pressure can be transmitted to the whole microstructures on the skin.
1. A method for manufacturing a microstructure, the method comprising:
(a) supplying a biodegradable and biocompatible polymer or an adhesive into a micro-mold, wherein the biodegradable and biocompatible polymer or the adhesive comprise hyaluronic acid;
(b) injecting the biodegradable and biocompatible polymer or adhesive into a hole of the micro-mold;
(c) drying the biodegradable and biocompatible polymer or adhesive; and
(d) separating the dried biocompatible polymer and biocompatible or adhesive from the micro-mold to form a microstructure,
wherein the aspect ratio (w:h), configured of the diameter (w) of the bottom surface of the microstructure and the height (h) of the microstructure, is 1:5 to 1:1.5, and the angle of a distal tip (α) is 10°-40°,
wherein injecting is carried out by (i) applying a centrifugal force of 800-1000 g to the micro-mold or (ii) applying a pressure of not less than 500 and less than 760 mmHg inside the micro-mold.
2. The method of claim 1 , wherein step (c) is carried out (i) at room temperature for 36 to 60 hours, (ii) at 40 to 60° C. for 5 to 16 hours, or (iii) at 60 to 80° C. for 2 to 4 hours.
3. The method of claim 1 , wherein the biodegradable and biocompatible polymer further comprises at least one polymer selected from the group consisting of carboxymethyl cellulose (CMC), alginic acid, pectin, carrageenan, chondroitin sulfate, dextran sulfate, chitosan, polylysine, collagen, gelatin, carboxymethyl chitin, fibrin, agarose, pullulan polylactide, polyglycolide (PGA), polylactide-glycolide copolymer (PLGA), pullulan polyanhydride, polyorthoester, polyetherester, polycaprolactones, polyesteramide, poly(butyric acid), poly(valeric acid), polyurethane, polyacrylate, ethylene-vinyl acetate polymer, acrylic substituted cellulose acetate, non-degradable polyurethane, polystyrene, polyvinyl chloride, polyvinyl fluoride, poly(vinyl imidazole), chlorosulphonate polyolefin, polyethylene oxide, polyvinylpyrrolidone (PVP), polyethylene glycol (PEG), polymethacrylate, hydroxypropyl methylcellulose (HPMC), ethylcellulose (EC), hydroxypropyl cellulose (HPC), cyclodextrin, copolymers of monomers forming these polymers, and cellulose.
4. The method of claim 1 , wherein the hyaluronic acid has a molecular weight of 240 to 490 kDa.
5. The method of claim 1 , wherein, in step (a), the solid content of the biodegradable and biocompatible polymer is 1 to 30% (w/v) on the basis of the entire composition of the microstructure.
6. The method of claim 1 , wherein the adhesive further comprises at least one material selected from the group consisting of silicone, polyurethane, a physical adhesive, a polyacrylic material, ethylcellulose, hydroxymethyl cellulose, ethylene vinyl acetate, and polyisobutylene.
7. The method of claim 1 , wherein a plurality of microstructures are arranged in a square or hexagonal shape.
8. The method of claim 7 , wherein the plurality of microstructures are arranged at intervals (p) of 250 to 1500 μm.
9. The method of claim 1 , wherein the microstructure has i) a cone shape; ii) a double structure of a cylinder and a cone; iii) a double structure of a truncated cone and a cone; or iv) a triple structure of two truncated cones and a cone.