Investigation of the effects of plasma-treated chitosan electrospun fibers onto biofilm formation.

Surface modification of polymers is an important technique in developing physicochemical polymer properties. The various surface modification techniques including the mechanical, physical, chemical and biological methods were used to modify the surface properties of polymers. Thanks to these different methods, the polymers may have different properties such as biocompatibility, wettability and functionality. However, the applications of the chemical and mechanical methods currently used to modify polymer surfaces are limited (e.g., hazards associated with chemical wastes and problems related to changes below micrometers).

As physicalmethods,RF-rotating plasma,ionbeam, electronbeamand UV and gamma-ray offer some advantages over chemical methods such as oxidation, sulfonation, chlorination and acetylation. These methods are safe and clean processes without any chemical wasting. Low-pressure RF-rotating plasma process is one of the physical methods used without alerting polymer bulk properties. This process is used to modify surface properties of polymers such as hydrophilicity, adhesion and biocompatibility.

Biofilms are defined as microbial communities thatlive attached to non-biological and biological surfaces and often embedded within a matrix of extracellular polymeric substances (EPS) produced by the microbial cells. Biofilm formation protects the microbial cells from death by providing a diffusional barrier against antibiotics, clearance and the host defenses. Furthermore, the inhibition of biofilm formation by various methods such as detergents, sonication, and vortexing is very difficult[20]. Therefore, many researchers have reached consensus on the view that there still is need for long-term research. Organic compounds containing aromatic heterocyclic rings such as thiophene, furan and their derivatives are widely distributed in nature and play an important role during various biochemical operations because of its biological and pharmacological properties.

This study reported for the first time the effects of thiophene, furan and EDOT plasma-treated chitosan fibers on biofilm formation. P. aeruginosa PA01 was selected as the model bacterium for the biofilm due to its prevalence in the hospital setting and reputation as one of the most challenging species to treat among nosocomial infections. Chitosan was modified with monomers by using RF rotating plasma technique. Hydrazine plasma modified chitosan [10] has been particularly used in study due to its more functional NH2 side groups. The plasma-treated chitosan powders were characterized by FTIR, PL and XPS. Later, electrospinning process was used to produce electrospun fibers of plasma-treated chitosan derivatives on the quartz crystal electrode surface. The surfacemorphologies of electrospun fibers were investigated by using SEM. Furthermore, a quartz crystal microbalance (QCM) technique was used to detectthe inhibition of P. aeruginosa PA01 biofilmformation on the electrode surfaces by measuring the changes in frequency of a quartz crystal electrode.