Physical study of film-forming acrylate emulsion polymers for biosensor applications

A variety of alkyl acrylate emulsion polymers were investigated using rotating disc voltammetry and atomic force microscopy to assess their suitability as immobilisation matrices for biosensors. Continuous films with reproducible transport properties were the target. The rotating disc experiments showed that films formed from the emulsions Poly 14, Poly X1 and Poly X6 were continuous up to a thickness of 4.39 mg cm−2. These three different emulsions were assessed to determine the influence of entrapped glucose oxidase on the film characteristics. Poly X1 films were still observed to be continuous, and the filmʹs permeability increased only slightly when enzyme was mixed with the polymer, which made these the best performing films. The enzyme was shown to disrupt Poly 14 most significantly, causing pin-holes in the enzyme/polymer films. All three emulsions gave similar glucose response curves when the concentration of the analyte, glucose, was monitored by the production of hydrogen peroxide. However, when the extent of the biochemical reaction was monitored by measuring the consumption of oxygen, the least permeable enzyme matrix (formed by Poly X1) was observed to have the shortest dynamic range.