Chemical and electrochemical conversion of magnetic nanoparticles to Prussian blue for label-free and refreshment-enhanced electrochemical biosensing of enrofloxacin

Magnetic biosensor takes advantage of rapid and facile magnetic separation/collection of targets, however, generally relies on additional signal labels to generate signal in a tedious and high-cost way. Here, we proposed a chemical and electrochemical conversion (C-ECC) method to develop a label-free electrochemical magnetic biosensor to detect antibiotics enrofloxacin (ENR). The C-ECC method integrates the chemical decomposition of magnetic beads (MBs) to release ironic ions and the simultaneous electrochemical deposition of Prussian blue (PB) analogs through the reaction of ironic ions and co-existing K4Fe(CN)6. Unlike conventional method that relies on the physical magnetic property of MBs, the C-ECC method fully exploited the chemical/electrochemical properties of MBs to produce electrochemically active PB to generate signal, thus endowing MBs with dual roles in both sample treatment and signal generation. The incorporation of chemical and electrochemical conversion produced more PB with higher electroactivity when compared with sole chemical or electrochemical conversion. Moreover, an interesting electrochemical refreshment (ER) was designed to remove insulative species on the electrode surface to improve electroactivity of electrode and benefit amperometric detection significantly. Under

Automated summary

A label-free electrochemical magnetic biosensor was developed using a chemical and electrochemical conversion method. The method utilized the chemical and electrochemical properties of magnetic beads to generate electrochemically active Prussian blue for signal generation. The incorporation of chemical and electrochemical conversion improved the electroactivity of Prussian blue and an electrochemical refreshment method further enhanced the detection efficiency.