Nanowire Transistor‐Based Ultrasensitive Virus Detection with Reversible Surface Functionalization

We have applied a reusable silicon nanowire field-effect transistor (SiNW-FET) as a biosensor to conduct ultrasensitive detection of H5N2 avian influenza virus (AIV) in very dilute so- lution. The reversible surface function- alization of SiNW-FET was made possi- ble using a disulfide linker. In the sur- face functionalization, 3-mercaptopro- pyltrimethoxysilane (MPTMS) was first modified on the SiNW-FET (referred to as MPTMS/SiNW-FET), with subse- quent dithiothreitol washing to reduce any possible disulfide bonding between the thiol groups of MPTMS. Subse- quently, receptor molecules could be immobilized on the MPTMS/SiNW- FET by the formation of a disulfide bond. The success of the reversible sur- face functionalization was verified with fluorescence examination and electrical measurements. A surface topograph of the SiNW-FET biosensor modified with a monoclonal antibody against H5N2 virus (referred to as mAbH5/ SiNW-FET) after detecting approxi- mately 10 17 m H5N2 AIVs was scanned by atomic force microscopy to demonstrate that the SiNW-FET is ca- pable of detecting very few H5N2 AIV particles.