Chapter 8 - Electrochemical sensors for the determination of hydrogen sulfide production in biological samples

Abstract

This chapter presents a novel polarographic H2S sensor (PHSS) for real-time physiological measurement of H2S in vivo and in vitro and discusses its usefulness to better understand the role of H2S in cell signaling. The PHSS amperometric signal for H2S is highly dependent on solution pH and under physiological conditions near neutral pH, small changes in pH can alter the PHSS signal. The PHSS method of real-time H2S measurement allows for investigation of the potentially complex H2S kinetic responses of organs, tissues, cells, and mitochondria, as levels of O2 and NO as well as metabolic state are adjusted within physiological limits. Kinetic changes in H2S concentration continuously reported by the PHSS, which are not seen with other H2S measurement techniques, suggest potentially complex interactions of H2S production and consumption mechanisms. H2S may likely exist as a cellular pool of free and labile persulfides that are able to rapidly respond to redox challenges with production and consumption pathways that operate to maintain the pool. This possible scenario reinforces the need for the PHSS as a valuable tool to provide a continual report of H2S throughout the course of an experimental treatment or to accurately determine H2S levels in situ. Miniaturization of PHSS can allow it to function as an indwelling catheter for continuous in-situ measurement of H2S in blood and tissues. PHSS can also be used for continuous measurement of H2S at hydrothermal vent communities during ocean floor investigations, provided the required modifications to withstand pressure are made. With the ever-expanding understanding of H2S biology and physiology, the demand for different geometries and applications of the PHSS is expected to increase.