Electrochemical properties and topology of gold electrodes with adsorbed penicillin G for biosensor applications

Staphylococcus aureus is the leading cause of nosocomial infections. Almost as soon as penicillin was introduced, penicillin-resistant strains of S. aureus began to appear. This resistance was due to the production of inducible, narrow spectrum β-lactamase, efficient at hydrolysing penicillins. In our days, conventional methods are time consuming and still remain the predominant approaches for detection and identification of bacteria and resistance patterns. Thus, there is an important clinical need for rapid detection of bacteria directly from patient samples. Rapid methods based on physical or electrochemical technologies can contribute significantly. In this paper, we use cyclic voltammetry and impedance spectroscopy technique to study the electric properties of the immobilized penicillin G for biosensor application. The penicillin G can be immobilized by simple adsorption on gold electrode via sulfur group. Fourier transform infra-red spectroscopy and atomic force microscopy has been used to study the molecular structure and the distribution of the penicillin G on the electrode. The selective detection of the two strains S. aureus bacteria (one resistance and the other sensitive) can be observed by quartz crystal microbalance technique.