Search

In this article we present a relevant strategy for a non-trivial time-programmed release of water-soluble macromolecules from biocompatible μ-containers. The system is based on self-scrolled chitosan acetate (CA) fibers, encapsulated in a poly(dimethylsiloxane) matrix. Mass transfer between a fiber and the external environment takes place via the only opened extremity of the fiber. Fluoroscein isocyanate dextran (FID) is initially deposited at the inner surface of the CA fiber according to a programmed pattern. The FID molecules became mobile after the arriving of the swelling front, which propagates along the fiber's axis upon the immersion of the system in aqueous solution. Diffusion of the macromolecules into the environment is enabled by the open-tube geometry of the swollen part of the fiber, while a programmed kinetics of the drug release is due to patterning of the polymer film prior to rolling. The release of the macromolecules can be retarded by a few hours according to the placement of the FID spot with respect to the fibers orifice. A pulsatile release kinetics is demonstrated for a discrete pattern. A few millimeter spacing of the FID spots results in a few hours time interval between the release impulses. Random walk model is plugged in the effective diffusion coefficient for Fick's law and the release kinetics are simulated., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Transepidermal drug delivery achieves high drug concentrations at the action site and ensures continuous drug delivery and better patient compliance with fewer adverse effects. However, drug delivery through topical application is still limited in terms of drug penetration. Chitosan is a promising enhancer to overcome this constraint, as it can enhance drug diffusion by opening the tight junctions of the stratum corneum. Therefore, here, we developed a novel chitosan nanosponge (CNS) with an optimal ratio and molecular weight of chitosan to improve drug penetration through skin. To prepare the CNS, two types of chitosan (3 and 10 kDa) were each conjugated with poloxamer 407 using para-nitrophenyl chloroformate, and the products were mixed with poloxamer 407 at ratios of 5:5, 8:2, and 10:0. The resulting mixtures were molded to produce flexible soft nanosponges by simple nanoprecipitation. The CNSs were highly stable in biological buffer for four weeks and showed no toxicity in human dermal fibroblasts. The CNSs increased drug permeability through human cadaver skin in a Franz-type diffusion cell, with substantially higher permeability with 3 kDa chitosan at a ratio of 8:2. This suggests the applicability of the novel CNS as a promising carrier for efficient transepidermal drug delivery.

Transepidermal drug delivery achieves high drug concentrations at the action site and ensures continuous drug delivery and better patient compliance with fewer adverse effects. However, drug delivery through topical application is still limited in terms of drug penetration. Chitosan is a promising enhancer to overcome this constraint, as it can enhance drug diffusion by opening the tight junctions of the stratum corneum. Therefore, here, we developed a novel chitosan nanosponge (CNS) with an optimal ratio and molecular weight of chitosan to improve drug penetration through skin. To prepare the CNS, two types of chitosan (3 and 10 kDa) were each conjugated with poloxamer 407 using para-nitrophenyl chloroformate, and the products were mixed with poloxamer 407 at ratios of 5:5, 8:2, and 10:0. The resulting mixtures were molded to produce flexible soft nanosponges by simple nanoprecipitation. The CNSs were highly stable in biological buffer for four weeks and showed no toxicity in human dermal fibroblasts. The CNSs increased drug permeability through human cadaver skin in a Franz-type diffusion cell, with substantially higher permeability with 3 kDa chitosan at a ratio of 8:2. This suggests the applicability of the novel CNS as a promising carrier for efficient transepidermal drug delivery. [ABSTRACT FROM AUTHOR]