Optimization of Osmium Metal Loading in Redox Polymer for Biosensing Applications

Abstract

Historically, polymers have been utilized to provide a three-dimensional interface for proteins and enzymes in devices such as biosensors and biohybrid solar cells. While these polymers can provide a scaffold onto which biomolecules can be immobilized, their true utility comes from the ability of some polymers to enhance electrochemical processes. Osmium-containing redox polymers are crucial in biosensor applications because they can exclude signals from interferent molecules by shifting the operating voltage of the working electrode. While osmium redox polymers have been used for many years, there is little literature available discussing the incorporation of the osmium onto the polymer backbone. Specifically, how the polymer properties are affected by varying metal loadings is particularly lacking. In this work, the metal loading, or the percentage of polymer side chains containing an osmium unit, is varied from 2 – 32% (as determined by 1H NMR). The electrochemical properties of the osmium-containing polymers are then determined by cyclic voltammetry. It is hypothesized that higher osmium loading will correlate with easier electron transfer and overall improved sensor performance when interfaced with biosensors. Preliminary data has supported this hypothesis and further reinforces the need for such a comprehensive, yet fundamental study of osmium redox polymers to inform the biosensor community.