Electrospun nanofibers for localized delivery of dexamethasone: preliminary investigation on formulation parameters

Electrospinning is an electrostatic fiber fabrication technique producing homogeneous fibers in nanometer range. The process involves dropping a polymer solution in an electric field in such a way that the electric forces overcome polymer solution surface tension and the drop is stretched forming a stable Taylor cone and eventually depositing polymer fibers on a metal collector (Figure 1b). The process can take place starting from a polymer solution or melted polymer. Using polymer solution enables working at room temperature conditions, but introduces a solvent whose evaporation should be completed as long as the fiber is deposited on the collector, while using a melted polymer high temperatures can be detrimental for the polymer and/or other nanofibers constituents. A lot of literature on the topic can be found, explaining the technique, the parameters and process conditions affecting fibers formation, its applications, and reporting polymers used in electrospinning1. Summarizing, it can be said that electrospinning is a simple one step technique to produce nanofibrous matrices useful in different areas, however its potentialities have not been completely developed yet, and the process should be studied according to the single polymer or combination of polymers to be processed. In the biomedical field electrospun matrices made of biodegradable biocompatible polymers show interest as temporary scaffolds for tissue regeneration2- 5. Recent studies have shown that nanoscale fibers presenting high area/volume ratio, high interconnectivity and superior biomechanical properties could have advantages also as drug delivery systems, including high drug loading efficiency, drug controlled release, excellent stability, and/or improvement of bioactive molecules apparent solubility Moreover, the encapsulation of active molecules into electrospun nanofibers can be exploited to perform local delivery to a target site5,6. The preliminary study is focused on manufacturing, characterization and in vitro evaluation of electrospun nanofibers matrices (ElNanoMats) made of the biodegradable copolymer Polylactide-co-poly--caprolactone and loaded with dexamethasone (DXM) whose application could be local delivery of DXM through patches for treating skin diseases (i.e. keloid and psoriasis).