Investigation of an improved electricidal coating for inhibiting biofilm formation on urinary catheters

Abstract

A catheter coating consisting of polydimethylsiloxane (PDMS) mixed with powdered metals silver and zinc has been investigated. The coating is easily applicable to existing silicone devices and effective in inhibiting the formation of biofilm. Following manufacturing of the coating, its surface materials characteristics were analyzed through scanning electron microscopy (SEM) and energy dispersive X-ray (EDX). The antibacterial properties of the coating were investigated by applying a thin film to the surface of a standard silicone catheter. A unique coating formulation of zinc and silver was found to inhibit biofilm and planktonic growth of E. coli over a six-day period, seemingly related to the release of heavy metal ions, generation of electric fields, hydrogen peroxide formation or combinations of these effects. Open-circuit cell potential for a zinc and silver foil was measured to be 1.2 V and 0.97 V within a deionized (DI) water and urine solution, respectively. Zone of inhibition experimental results suggest the possibility of silver ion diffusion when using mixed metals since bacteria formation is inhibited beyond the sample edge. Hydrogen peroxide measurements were taken over a period of 13 days for all samples. Samples containing zinc were found to produce hydrogen peroxide, a known antimicrobial agent. Wettability measurements of samples showed that the introduction of active materials lead to an increase of hydrophilicity, potentially affecting bacterial adhesion.