Amperometric nitric oxide microsensor based on nanopore-platinized platinum: the application for imaging NO concentrations.

This paper reports an amperometric nitric oxide (NO) microsensor based on a cone-shaped nanopore-platinized Pt working electrode. The senor was fabricated using the following procedure: (1) a parent nanodisk electrode was prepared by polishing an etched Pt wire (radius = 12.5 microm; dimension of etched tip end point <10 nm) embedded in a glass capillary, (2) the nanodisk Pt was further etched to produce a nanopore (pore opening radius <1 microm; pore depth approximately 30 microm), (3) the Pt base surface in the nanopore electrode was platinized electrochemically to improve the sensor sensitivity, and (4) silanization and further modification with the electropolymerized polymeric film [poly(5-amino-1-naphthol)] on the nanopore-platinized Pt electrode were carried out to obtain the sensor selectivity to NO. The analytical performance of the sensor was characterized. For example, a sensor with a pore opening radius of 797 nm exhibited a decent linear dynamic range (at least for 0.2-1.8 microM), detection limit of < approximately 32 nM, response time (t(90%)) of < approximately 5 s, and sensitivity of 6.5 +/- 0.02 pA/nM. This sensor was used successfully as a NO-selective probe tip in scanning electrochemical microscopy (SECM) to obtain a two-dimensional image of the local NO concentrations for an inlaid NO-emitting microdisk film (radius = 12.5 microm) on a glass substrate.