A novel Staphylococcus aureus-modified electrochemical biosensor for determination of heavy metals

Official URL: https://risc01.sabanciuniv.edu/record=b2708490_(Table of contents)

Heavy metals, even in low concentrations, can harm living organisms. Therefore, in this research, the dried Staphylococcus aureus-modified carbon paste electrode's ability to detect different heavy metals ions in three different buffers, including Tris-HCl, sodium acetate, and phosphate-buffered saline (PBS), at pH 6 and 7 were investigated. Using cyclic voltammetry (CV), the capability of the modified biosensor for detecting Cd(II) ions was clearly shown. The effects of buffer pH and preconcentration time on the performance of the developed biosensor for detecting Cd(II) were also studied. CV results showed that the PBS at pH 6 resulted in the peak with the highest peak current (3 µA). Therefore, this buffer was selected as the primary buffer for carrying out the rest of the experiments to detect Cd(II). Among four different preconcentration times, 15 minutes was the optimum one according to both CV and differential pulse anodic stripping voltammetry (DPASV) results. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Fourier-transform infrared (FTIR) spectroscopy results of modified carbon paste also confirmed the adsorption of Cd(II) ions. According to the FTIR spectrum, phosphate groups played an important role in accumulating Cd(II) ions. The control experiment performed using unmodified carbon paste showed no response to Cd(II) ions. Finally, using the calibration curve, the biosensor's limit of detection and sensitivity were calculated as 45 nM (5.4 µg/L) and 7.61814 µA/µM, respectively, and its linearity was within the range of 100 nM (0.011 mg/L) to 2 µM (0.22 mg/L).