Reagentless sensing of vancomycin using an indium tin oxide electrode grafted with molecularly imprinted polymer including ferrocenyl group

Vancomycin (VCM) is a first-line antimicrobial agent against methicillin-resistant Staph-ylococcus aureus, a cause of nosocomial infections. Therapeutic drug monitoring is strongly recom-mended for VCM-based chemotherapy. The authors attempted to develop a simple VCM sensor based on molecularly imprinted polymer (MIP), which can be used with simple operations. Meth-acrylic acid (MAA), acrylamide, methylenebisacrylamide, and allylamine carboxypropionate-3-fer-rocene (ACPF) were copolymerized in the presence of VCM and grafted from the surface of indium-tin oxide (ITO) to obtain MIP-coated electrodes. The MIP-grafted ITO electrode was used for differential pulse voltammetry (DPV) measurements in a buffer solution containing VCM or whole bo-vine blood. The obtained current depends on the VCM concentration with high linearity. The dy-namic range covered the therapeutic range (20–40 μg/mL) of the VCM but was almost insensitive to teicoplanin, which has a similar structure to VCM. The ITO electrodes grafted by the same pro-cedure except for omitting either VCM or APCF were not sensitive to VCM. The sensitivity of the MIP electrodes to VCM in whole blood and buffered saline, but the background current in blood was higher than that in saline. This high background current was also seen in the deproteinized plasma. Thus, the current is probably originated from the oxidation of low molecular weight reduc-ing agents in the blood. The MIP-grafted ITO electrode using ACPF as a functional monomer would be a promising highly selective sensor for real-time monitoring of VCM with proper correction of the background current.