Electrochemical Detection of Lead in Real Samples Using Carbon Nanostructure and Inactivated E. coli as Low-Cost Sensitive Biosensor with High Electrocatalytic Performance

A new electrochemical sensor based on inactivated Escherichia coli (E. coli) was prepared for the determination of lead ions (Pb2+) in real samples. The biorecognition element was obtained by inactivation of the E. coli bacteria. The biosensing platform was constructed by mixing bovine serum albumin (BSA) with inactivated Escherichia coli (E. coli*) deposited on the surface of platinum (Pt) electrode modified with conductive poly(vinylidene fluoride) (PVDF)/multiwall carbon nanotubes (MWCNT)-gold nanoparticles MWCNTs-PVDF-AuNPs/E. coli*-BSA. The impedance characterization of the nanocomposite reveals performance improvements in the charge transfer process (Ret = 20 Omega) compared to the use of Pt bare electrode (Ret =115 Omega). Moreover, the bioelectrochemical reaction between the released-enzymes from inactivated E. coli* and the inhibitor (Pb2+) was confirmed and successfully demonstrates the inhibition system. The electrochemical detection of Pb2+ was performed by square wave voltammetry (SWV) with a detection limit of 0.13 mu g/l and a quantification limit of 0.43 mu g/l. The sensor was applied to detect lead ions in real samples like waste-water and lipstick with an excellent selectivity against copper ions. The biosensor is highly sensitive (30.1 mu A/ppb.cm(2)) with good stability and reliable reproducibility with a relative standard deviation (RSD= 0.23%) for monitoring lead ions and seems operational for monitoring other hazardous materials.