Nanometer size electrode for nitric oxide and S-nitrosothiols measurement

Abstract

Nitric oxide (NO) is a ubiquitous, gaseous messenger involved in various physiological phenomena. Investigation of the local cellular response of NO production in vivo or in vitro requires a measurement method with high spatial resolution. For the selective detection of NO, a series of NO electrodes has been developed with tip diameters as small as 7 μm . However, there is a continuing demand for even smaller NO sensors. Here we describe the performance characteristics of a new NO nanosensor with a tip diameter of just 100 nm. The new NO sensor is an integrated ultramicrosensor that consists of a single carbon fiber working electrode combined with a reference electrode. The surface of the working electrode is modified with unique, multi-layered, NO selective membranes. Experimental data presented demonstrates that this nanosensor exhibits a linear response ( R 2=0.997) to NO over a concentration range 10 nM to 1 μM . The lower detection limit for NO is 2 nM ( S/ N=2). Preliminary selectivity studies reveal that the nanosensor is immune to the majority of potentially reactive species found in biological samples (e.g., nitrite, ascorbic acid, dopamine and serotonin, etc.) that may otherwise elicit a false response at physiological concentrations. It is envisaged that this new NO nanosensor will be important in many applications where accurate, real-time, selective detection of NO is required at the single cell and micro-capillary levels.