Facile Fabrication of Gold Functionalized Nanopipette for Nanoscale Electrochemistry and Surface Enhanced Raman Spectroscopy

Nanopipette has emerged as a versatile nanosensor. It is desirable to expand the sensing capabilities of nanopipette by integrating multiple sensing methods into one nanopipette. In this work, we presented a seeded growth approach to facilely, cheaply and quickly deposit a gold layer with controllable length at the inner surface of the nanopipette tip. The deposited gold formed a wireless ring-shape gold nanoelectrode at the nanopipette tip and enabled multimode single entity detection. With the presence of gold at the nanopipette apex, the nanopore based resistive-pulse sensing capability was obviously improved. The integrated ring-shape gold nanoelectrode could be used as a wireless bipolar electrode for electrochemical measurement. We further demonstrated that the gold coated nanopipette could be used as a substrate for surface enhanced Raman spectroscopy.