Nanowire biosensor p-type with immobilized antibodies for highly sensitive registration of the molecules of HCVcoreAg, a protein marker of viral hepatitis C

Abstract

Aim. To detect HCVcoreAg using a nanowire detector based on silicon-on-insulator structures (SOI-NW) with p-type conductivity with immobilized antibodies. Methods. Silicon-on-insulator (SOI) structures with p-type conductivity were used. The cut-off layer thickness was 32 nm; the buried oxide (BOX) layer thickness was 300 nm. In the experiments, the sensor width was w = 3µm, the thickness was t = 32 nm, the length was l = 10 µm, and the number of nanowires (NWs) on the crystal was 12. The surface of NWs was modified in aminopropyltriethoxysilane (APTES) vapor. Antibodies against HCVcoreAg were covalently immobilized onto the modified NW surface using a dithiobis (sulfosuccinimidyl propionate) (DTSSP) crosslinker. Throughout the measurements, a measuring cell (500 µL volume), whose bottom was a crystal with NW structures, was used. The diameter of sensor area was ~2 mm. The solution in the cell was stirred at 3000 rpm. Electrical measurements were conducted using a Keithley picoampermeter. Results. The study demonstrated that the NW biosensor with p-type SOI-NWs with immobilized antibodies was capable for detecting HCVcoreAg in buffer solutions with neutral and acidic pH. The lowest HCVcoreAg concentration, at which the protein was detectable, was 10^-15 M. Conclusion. The viral hepatitis C biomarker can be detected in solutions in real time using a biosensor based on p-type NWs with immobilized antibodies, without using labels. The concentration sensitivity of the analysis was of the order of 10^-15 M.