Bactericidal Properties of the Sol-gel Layer on Polymer Substrates in Medical Applications

Abstract

Polymeric biomaterials are a group of plastics used in medical devices, implants, and artificial organ components. In order to maintain the higher asepticity of the products, solutions based on the modification of the volume or surface of a plastic with biocidal agents, e.g. antibiotics, nanoparticles, are used. One of the methods used to impart biocidal properties to the material can be the use of layers applied by the sol-gel method. The aim of this study was to produce homogeneous and durable coatings on inert and hydrophobic silicone surfaces based on polysiloxane sols with biocidal activity against model bacteria: Gram negative (Escherichia coli, Klebsiella pneumoniae) and Gram positive (Staphylococcus aureus, Enterococcus faecalis). This paper presents results of investigations on a commercial biomedical silicone material (DEMED Sp. zoo) modified with eight sols, siloxane (TD), phenol-siloxane (FD), siloxanealuminum (TD-Al), siloxane-titanium (TD-Ti), titanium (Ti), zinc (Zn), and TD and TD-Al sols modified with green tea extract (TD-GT, TD-Al-GT). The reference for the tested materials was unmodified silicone. In order to be prepared for coating, the siloxane samples were etched with hydrofluoric acid. Residual acid was removed from the silicone by washing and the substrates were then coated with sols by means of dip coating. The modified materials were then polymerized at 100°C for one week. The produced layered composites were subjected to microstructural, physicochemical, structural and microbiological analysis by contacting them with Gramm negative and Gramm positive bacteria. It was shown that the strongest biocidal properties were exhibited by samples modified with the sols based on - Zn, TD-Ti, Ti, TD-Al-GT and TD-GT.