Single-Use Electrochemical Platform for Monitoring of Antimicrobial Activity in Comparison to Minimum Inhibitory Concentration Assay

Abstract

Determination of antimicrobial properties of (bio)molecules has been conventionally performed using minimum inhibitory concentration (MIC) assay based on visual monitoring of turbidity which may cause incorrect interpretations. Surfactants are widely used as disinfectants because of their antimicrobial properties, especially in todays’ world struggling with infections. In this study, surfactants are chosen as the model molecules for the fabrication of a voltammetric biosensor for monitoring antimicrobial activity for the first time in the literature. The antimicrobial effect of anionic and cationic surfactants on E. coli and S. aureus and the effect of alkyl chain length of cationic surfactants were investigated. Anodic peak current (Ia) value was measured by cyclic voltammetry (CV) in a redox probe containing K3[Fe(CN)6] and K4[Fe(CN)6] ions to understand the biointeraction mechanisms. The effect of the surfactants on the microorganisms was characterized by optical microscopy, SEM, and FTIR. The electrochemical biosensor could detect the antimicrobial properties of the surfactants by obtaining consistent results with MIC assay and spectroscopy. While cationic surfactants were more effective on the microorganisms, hexadecyltrimethylammonium bromide (CTAB) is the most effective surfactant by reaching a low MIC level. This article has novelty using disposable PGEs in combination with the CV technique for antimicrobial activity evaluation.