Therefore, there is a strong need to develop label-free methods of DNA detection that are simple, low-cost, and highly sensitive. Optical methods are typically used for DNA sensing applications, but these approaches require labeling the relevant DNA sequence with fluorescent molecules, as well as sophisticated photodetectors 4, 5. Nucleic acid sequences can also be developed into artificial DNA aptamers, designed to bind to biomolecules of interest for early disease detection 3. This novel method of biosensor functionalization can be applied to many semiconductor materials for highly sensitive and label-free detection of a wide range of biomolecules.ĭNA detection has many applications in clinical diagnostics and biomedical research, prompting development in a large variety of methods to detect small quantities of specific DNA sequences 1, 2. Au NP decoration also enables sub-nanomolar DNA detection in passivated ZnO NWs that are resilient to dissolution in aqueous solutions. By attaching a DNA aptamer for streptavidin to the biosensor, we detect both streptavidin and the complementary DNA strand at sub-nanomolar concentrations. Without additional functionalization, we electrically detect DNA binding on the nanowire at sub-nanomolar concentrations and visualize individual DNA strands using atomic force microscopy (AFM). Magnetron-sputtering of a Au target combined with a quadrupole mass filter for cluster size selection was used to deposit Au NPs on the ZnO NWs. Uniform ZnO NW devices were fabricated using a vapor-solid-liquid method in a chemical vapor deposition (CVD) furnace. We instead demonstrate the use of gas-phase synthesis of gold nanoparticles (Au NPs) to decorate zinc oxide nanowire (ZnO NW) devices for biosensing applications. Typically, chemical functionalization of the oxide surface is necessary for specific biological analyte detection. Metal oxide semiconductor nanowires have important applications in label-free biosensing due to their ease of fabrication and ultralow detection limits.

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