Low friction core-shell nanofibrous membranes for delivery of active ingredients to the wet skin

1. A membrane comprising a plurality of randomly oriented core-shell nanofibers, each of said core-shell nanofibers comprising:

a non-polymeric nanofiber shell which is composed of one or more active ingredients and remains intact under a dry condition but is instantly dissolvable under a wet condition; and

a polymeric nanofiber core comprising a polymer incorporated with one or more active ingredients which remains intact under either a dry or wet condition but is able to release the one or more active ingredients in a controlled release manner when said nanofiber shell is dissolved;

wherein the one or more active ingredients in any of the non-polymeric nanofiber shell and the polymeric nanofiber core are small molecules having a molecular weight of 400 Da or below; and

wherein said membrane is shifted with a shearing force of 500 mN or below when the non-polymeric nanofiber shell of the membrane is substantially dissolved during contact with a wet skin.

2. The membrane of claim 1 , wherein said core-shell nanofiber has a diameter of 100-1000 nm.

3. The membrane of claim 1 , wherein the nanofiber core has a diameter of 50-900 nm.

4. The membrane of claim 1 , wherein the nanofiber shell has a thickness of 25-250 nm.

5. The membrane of claim 1 , wherein the core-shell nanofiber has a surface potential of 10-100 V.

6. The membrane of claim 1 , wherein the small molecules have skincare properties comprising one or more of hydration, moisturizing, acne treatment, anti-irritation, whitening, anti-aging, and/or anti-oxidant.

7. The membrane of claim 6 , wherein the small molecules having hydration and/or moisturizing properties comprise urea, pyrrolidone carboxylic acid (PCA), panthenol, trehalose, cyclomethicone, caprylyl glycol, lecithin, tocopheryl acetate, squalane, hydrolysed collagen, polyquaternium-51 and methyl gluceth-20.

8. The membrane of claim 6 , wherein the small molecules having acne treatment property comprise alpha hydroxyl acid (AHA), salicylic acid, menthol and niacinamide.

9. The membrane of claim 6 , wherein the small molecules having anti-irritation property comprise allantoin, bisabolol and dimethicone.

10. The membrane of claim 6 , wherein the small molecules having whitening property comprise ascorbic acid, kojic acid, hydroquinone, azelaic acid and niacinamide.

11. The membrane of claim 6 , wherein the small molecules having anti-aging property comprise vitamin E and retinoic acid.

12. The membrane of claim 6 , wherein the small molecules having anti-oxidant property comprise resveratrol, epigallocatechin-3 gallate (EGCG), lycopene, genistein, and trehalose.

13. The membrane of claim 6 , wherein the small molecules are incorporated into the polymeric core and interact with each other via hydrogen bonding or electrostatic attraction.

14. The membrane of claim 1 , wherein the polymer of the polymeric core comprises nylon, cellulose acetate (CA), polystyrene (PS), polyacrylonitrile (PAN), poly(lactic acid) (PLA), poly(lactic-co-glycolic acid) (PLGA), polybutylene terephthalate (PBT), polyurethane (PU), gelatin, chitosan and polyhydroxybutyrate-co-hydroxyvalerate (PHBV).

15. The membrane of claim 1 , wherein said membrane delivers small molecules of the active ingredients instantly when the non-polymeric nanofiber shell of the membrane is in contact with a wet skin and sequentially delivers said small molecules from the polymeric nanofiber core in a controlled release manner when the non-polymeric nanofiber shell is substantially dissolved to form a high concentration solution at the interface between the wet skin and the polymeric nanofiber core.

16. The membrane of claim 15 , wherein the small molecules from both the non-polymeric nanofiber shell and polymeric nanofiber core are delivered transdermally into the wet skin.

17. A superabsorbent polymer of a diaper comprising the membrane of claim 1 as acquisition layers to reduce rewet amount by at least 25% as compared to the same type of superabsorbent polymer without said membrane.

18. The membrane of claim 1 , wherein said core-shell nanofiber is prepared by:

mixing one or more active ingredients with a polymer solution to form a mixture and loading the mixture into a reservoir capable of moving back and forth through an electrode at high voltage;

loading an active ingredient solution containing at least one active ingredient into the same reservoir simultaneously with said mixture such that the electrode is coated with both the mixture and the solution;

placing a grounded moving substrate at a certain distance above the electrode such that an electric potential difference is created between the electrode and the substrate;

applying an electric force to the mixture and solution to form multiple cone-like structures along the electrode;

when the electric force is sufficient to overcome the surface tension of the mixture and the solution, a polymer jet is initiated from each cone-like structure, wherein the polymer jet is a coaxial structure comprising an active ingredient-loaded polymer solution core and an active ingredient solution shell surrounding the core;

evaporating the solvent of the mixture and the solution such that a plurality of the polymer jets solidifies and forms core-shell nanofibers; and

collecting said core-shell nanofibers on the moving substrate.