Proteus Mirabilis Bacteria Biosensor Development Based on Modified Gold Electrode with 4-Carboxyphenyl Diazonium Salts for Heavy Metals Toxicity Detection

Abstract

In this work we describe a new biosensor for heavy metals detection, based on the immobilization of bacteria, Proteus mirabilis on gold electrode modified with aryl electrografting film. To enhance the stability of the biosystem, additional materials were used such as functionalized Fe3O4 nanoparticles (NPs), cationic (PAH), anionic (PSS) polyelectrolytes, Bovine Serum Albumin (BSA) and glutaraldehyde as a cross-linking agent. Before the immobilization step, the activity of Proteus mirabilis bacteria in the presence of heavy metals ions was attempted using the ion ammonium selective electrodes (ISEs). The modication of the gold electrodes with the electrochemical reduction of 4- carboxyphenyl diazonium salts to form stable layers for sensing applications was characterized by cyclic voltammetry and chronoamperometry measurements. The adhesion of the bacteria cell on gold electrode was evaluated using contact angle measurements. The immobilized bacteria-metal interaction was evaluated using the electrochemical impedance spectroscopy (EIS) measurements. A notable effect of metal on the bacteria activity is observed in the concentration range from 10-3 to 1 µM and from 1µM to 1nM for Co2+, Cd2+, Cu2+ and Hg2+, respectively.

Keywords

• Proteus mirabilis bacteria
• Fe3O4 nanoparticles
• Diazonium salts
• Impedance spectroscopy
• Gold electrodes
• Heavy metals.