Electrospun Antibacterial Chitosan-Based Fibers Milena Ignatova, Nevena Manolova, Iliya Rashkov* Chitosan is non-toxic, biocompatible, and biodegradable polysaccharide from renewable resources, known to have inherent antibacterial activity, which is mainly due to its polycationic nature. The combining of all assets of chitosan and its derivatives with the unique properties of electrospun nanofibrous materials is a powerful strategy to prepare new materials that can find variety of biomedical applications. In this article the most recent studies on different approaches for preparation of antibacterial fibrous materials from chitosan and its derivatives such as electrospinning, coating, and electrospinning-electrospraying, loading of drugs or bioactive nanoparticles are summarized. 1. Introduction In recent years there has been an increasing interest in the preparation of nanofibrous materials. At present electro- spinning is recognized as the most efficient technique for producing significant in length continuous polymer fibers having diameters in the nanoscale. [1–9] In electrospinning nanofibers are produced using an external electric field imposed on a polymer solution or melt. Under the action of an external high voltage electric field a thin jet is drawn out of polymer solution or of melt and is directed to a collector. During the time of flight the solvent evaporates and dry fibers are collected. The composition and the properties of the spinning solution such as polymer nature, chain conformation, viscosity (concentration), conductivity, and surface tension, and also the processing conditions such as applied field strength, gap between the nozzle and collector, and feeding rate affect the diameter and the morphology of the nanofibers. [1,2,10] Because of their unique properties, such as high specific surface area, high porosity, small pore size, and 3D structure, the electrospun nanofibrous materials may find a variety of applications, e.g., in pharmacy, in medicine, and in cosmetics, for design of military protective clothing, for filters, in nanosensors, or in electronics. [1–4,11,12] It is noteworthy that technology transfer from laboratory to industrial scale can be easily achieved. To date, more than hundred different polymers, most of them in the form of solutions, but yet some heated into melts, have already been electrospun. Among the synthetic polymers, aliphatic polyesters, such as polylac- tide (PLA), polyglycolide, poly(e-caprolactone) (PCL) and their copolymers have been successfully electrospun and have been studied as materials for biomedical applications due to their biodegradability and good physicomechanical properties. There is an increasing interest in the preparation of electrospun nanofibrous materials from natural poly- mers. Although biopolymers such as chitosan and its derivatives, collagen, gelatin, hyaluronic acid, silk fibroin (SF), alginate, and cellulose derivatives have been electro- spun in a number of studies, [1,2,4,11,13–19] the preparation of fibrous materials from natural polymers alone by electro- spinning is still a challenge. Prof. M. Ignatova, Prof. N. Manolova, Prof. I. Rashkov Institute of Polymers, Laboratory of Bioactive Polymers, Bulgarian Academy of Sciences, Acad. G. Bonchev St, Bl. 103A BG-1113, Sofia, Bulgaria E-mail: rashkov@polymer.bas.bg Feature Article ß 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Macromol. Biosci. 2013, DOI: 10.1002/mabi.201300058 1 wileyonlinelibrary.com Early View Publication; these are NOT the final page numbers, use DOI for citation !! R