Self-folding polymer microparticles
View Patent ↗A method for forming three-dimensional polymeric particulate microstructures through self-folding of thin-film microparticles. Self-folding of two-dimensional polymeric precursors produces various three-dimensional particulate microstructures. Dumpling-like microstructures with oil cores and polymer coats are prepared by an interfacial-tension driven self-folding method. Roll-like and bowl-shaped hydrogel microstructures are fabricated by self-folding induced by differential volume shrinkage. Curled microstructures are produced by self-folding that is the result of a two-polymer or bilayer method wherein one of the polymers is a volume changeable polymer.
1. A method for fabricating polymer microparticles, comprising the steps of:
(a) coating a polymer stamp with a polymeric solution to create a continuous layer of polymer on said stamp, wherein said stamp further comprises a plurality of microstructures on at least one side of said stamp for receiving said polymeric solution, and wherein said microstructures further comprise a plurality of micro-pillars and a plurality of micro-wells;
(b) removing said layer of polymer from said micro-pillars;
(c) creating polymer microparticles by transferring said layer of polymer from said micro-wells onto a substrate, wherein said substrate further comprises a layer of dissolvable material covering said substrate;
(d) applying a thin layer of oil to said substrate to selectively cover said microparticles; and
(e) placing said substrate in a solvent to dissolve said dissolvable material and release said microparticles into solution.
2. The method of claim 1 , wherein said stamp is a polydimethyl siloxane stamp.
3. The method of claim 1 , wherein said polymeric solution further comprises poly (propyl methacrylate).
4. The method of claim 1 , wherein said substrate is a glass slide.
5. The method of claim 1 , wherein said layer of dissolvable material further comprises chitosan.
6. The method of claim 1 , wherein said oil further comprises food-grade soybean oil.
7. The method of claim 1 , wherein said solvent further comprises acetic acid.
8. A method for fabricating polymer microparticles, comprising the steps of:
(a) coating a polymer stamp with a partially cured liquid hydrogel precursor, wherein said stamp further comprises a plurality of microstructures on at least one side of said stamp for receiving said hydrogel precursor, and wherein said microstructures further comprise a plurality of micro-pillars and a plurality of micro-wells;
(b) completely curing said partially cured liquid hydrogel precursor to create a substantially solid hydrogel in said micro-wells;
(c) creating hydrogel microparticles by transferring said cured hydrogel from said micro-wells onto a substrate, wherein said substrate further comprises a layer of dissolvable material covering said substrate; and
(d) placing said substrate in a solvent to dissolve said dissolvable material and release said microparticles into solution.
9. The method of claim 8 , wherein said stamp is a polydimethyl siloxane stamp.
10. The method of claim 8 , wherein said hydrogel solution further comprises polyhydroxyethyl methacrylate or polymethacrylic acid.
11. The method of claim 8 , wherein said substrate is a glass slide.
12. The method of claim 8 , wherein said layer of dissolvable material further comprises polyvinyl alcohol.
13. The method of claim 8 , wherein said solvent further comprises water and a buffer solution.
14. The method of claim 8 , wherein the cured hydrogel from the micro-wells is transferred onto the substrate in a maimer such that the cured hydrogel directly contacts the layer of dissolvable material on the substrate.
15. The method of claim 8 , wherein the microparticles consist essentially of substantially solid hydrogel.
16. A method for fabricating polymer microparticles, comprising the steps of:
(a) coating a polymer stamp with a partially cured liquid hydrogel precursor, wherein said stamp further comprises a plurality of microstructures on at least one side of said stamp for receiving said hydrogel precursor, and wherein said microstructures further comprise a plurality of micro-pillars and a plurality of micro-wells;
(b) completely curing said partially cured liquid hydrogel precursor to create a substantially solid hydrogel in said micro-wells;
(c) coating said stamp with a second polymeric solution to create a continuous layer of polymer on said stamp;
(d) removing said layer of polymer from said micro-pillars;
(e) creating bi-layer polymer microparticles by transferring said polymers from said micro-wells onto a substrate, wherein said substrate further comprises a layer of dissolvable material covering said substrate; and
(f) placing said substrate in a solvent to dissolve said dissolvable material and release said bilayer microparticles into solution.
17. The method of claim 16 , wherein said stamp is a polydimethyl siloxane stamp.
18. The method of claim 16 , wherein said hydrogel and second polymer solution further comprise polymethacrylic acid and polylactic-co-glycolic acid, respectively.
19. The method of claim 16 , wherein said substrate is a glass slide.
20. The method of claim 16 , wherein said layer of dissolvable material further comprises polyvinyl alcohol.
21. The method of claim 16 , wherein said solvent further comprises water.
22. The method of claim 16 , wherein the hi-layer polymer microparticles are created by transferring said polymers from said micro-wells directly onto the dissolvable material on the substrate.
23. The method of claim 16 , wherein the microparticles consist essentially of substantially solid hydrogel and the polymer of said second polymer solution.