A bovine serum albumin-coated magnetoelastic biosensor for the wireless detection of heavy metal ions

Abstract A magnetoelastic (ME) biosensor functionalized by bovine serum albumin (BSA) was firstly developed for the wireless detection of heavy metal ions in solution. The biosensor was fabricated by coating a gold-modified ME ribbon with BSA. Its resonance oscillation and resonance frequency can be actuated and wirelessly monitored through magnetic fields. The combination of heavy metal ions and BSA produces the precipitation adhered to the biosensor surface, resulting in the increase of mass loading, and consequently leads to a decrease in the resonance frequency, corresponding to the concentrations of heavy metal ions. The biosensor was used to separately detect Pb2+, Cd2+ and Cu2+. Its response is linearly proportional to the low concentrations, becoming sub-linear at higher concentrations. Moreover, the SEM, fluorescence microscopy and EDS spectrum analysis proved that the modification and detection process were successful. The biosensor is more sensitive to the heavy metal with larger molecular weight, and has the sensitivity for Pb2+, Cd2+ and Cu2+ of about 9.4 × 107 Hz per mol/L, 7.1 × 107 Hz per mol/L and 4.7 × 107 Hz per mol/L, respectively. The detection limits for Pb2+ and Cd2+ of 3.3 × 10−7 mol/L and 2.4 × 10−7 mol/L, respectively, are lower than the standard limit (GB 8978-1996).