Ultrasensitive DNA biosensor for hepatitis B virus detection based on tin-doped WO₃/In₂O₃ heterojunction nanowire...

The fabrication of a highly sensitive DNA biosensor based on tin-doped WO₃/In₂O₃ nanowires as heterojunction photoelectrode for detection of hepatitis B virus is reported. The tin-doped WO₃/In₂O₃ nanowires were fabricated via a physical vapor deposition mechanism and were nearly 50 nm in width. The single-strand DNA probe was covalently immobilized on the nanowire surface. The biosensor could detect the hybridization of complementary DNA in a label-free approach at very low concentrations. The biodetection processes were conducted through reduction-oxidation reactions in the electrochemical impedance spectral measurements. The electrochemical impedance responses were biased under laser amplification to achieve the detection limit of 1 fM. The fabricated biosensor could detect DNA concentrations from 0.1 pM to 10 μM linearly in the calibration plot. Due to laser amplification, more charged carriers were released and they interacted with DNA on the electrode surface. The efficiency of the charge transfer parameter was enhanced by a photogeneration process, and the electron-hole recombination rate could intensively increase biosensor sensitivity, selectivity, and distinguishability. The stability of the nanowire biosensor under laser amplification demonstrated 96% of its initial responses after 6 weeks of maintenance. Graphical abstract.