ELECTROCHEMICAL CHIRAL BIOSENSORS

Abstract

Recognition of chiral molecules in biological assemblies has been a subject of extensive research. The aim of this work was to fabricate and characterise biocompatible composite materials suitable for chiral recognition. Collagen, the most abundant chiral, extracellular protein, was chosen as a possible matrix. The chiral recognition properties were evaluated by a comparative study in collagen, collagen incorporated in tetramethyl orthosilicate (TMOS) and TMOS. In electrochemical studies, ferrocene was incorporated to facilitate electron transfer. The recognition characteristics of two chiral enzymes, L-lactate oxidase and D-glucose oxidase were tested using circular dichroism (CD), Fourier Transform Infra-Red (FTIR) spectroscopy and electrochemical methods. A surprising result revealed an inversion of chiral selectivity. The effect of various parameters such as immobilisation, temperature, chemical modification, solvent systems, on enantioselectivity is well known. Stereoinversions caused by the ‘sergeants and soldiers’ effect in gel-forming p-conjugated molecules caused by co-assembly has been reported by several groups. The inversion of stereoselectivity observed in this study is probably due to a combination of the microenvironment and electrostatic interactions of the enzyme, mediator and substrate with the chiral collagen matrix. The results may have important implications for biosensing, asymmetric syntheses and understanding the nature of chiral interactions in biological systems.