Capacitive nanobiosensing of ?-1,4-galactosyltransferase-V colorectal cancer biomarker

beta-1,4-GalT-V is an enzyme with glycosyltransferase activity that glycosylates proteins and synthesizes the lac-tosylceramide sphingolipid in the Golgi apparatus. Colorectal cancer (CRC) tumor cells produce these bio-molecules in high concentrations concerning normal cells, releasing them into the blood serum. Hence, beta-1,4-GalT-V glycoprotein has emerged as a promising CRC biomarker, and its detection opens opportunities for the diagnosis/prognosis of CRC. We report the first capacitive nanobiosensor for the detection of beta-1,4-GalT-V based on disposable screen-printed carbon electrodes (SPCEs) nanostructured with gold nanorods (AuNRs) and the Prussian blue (PrB) redox-active compound. AuNRs increased the SPCE surface area for antibody immobilization by physical adsorption and promoted the deposition of PrB onto the SPCE surface. Antibody-glycoprotein mo-lecular biorecognition event onto the SPCE/AuNRs/PrB surface perturbed the PrB redox density-of-states and hence redox capacitance (C mu). We found that changes in the inverse of C mu correlated well with the increasing concentrations of beta-1,4-GalT-V in the linear range from 50 to 400 fM with a sensitivity of 1.5 mu F fM-1 cm-2 and a limit of detection of 20 fM. The nanobiosensor detected the beta-1,4-GalT-V glycoprotein from raw human serum samples with high specificity, ultrasensitivity, and reagentless label-free electrochemical transduction. The nanobiosensor could be applied as a CRC diagnosis/prognosis tool in a decentralized setting, with minimal patient sample manipulation and rapid response.