AgS/Ag Nanoparticle Microelectrodes for In Vivo Potentiometric Measurement of Hydrogen Sulfide Dynamics in the Rat Brain.

Hydrogen sulfide (HS) plays a pivotal role in gas signal transduction, neuroprotection, and regulation of physiological and pathological processes. However, in vivo tracking the dynamic of hydrogen sulfide in the complex brain environment still faces huge challenges. This study demonstrates a new potentiometric method to monitor in vivo the dynamics of hydrogen sulfide in the rat brain using silver nanoparticles (AgNPs)-modified carbon fiber microelectrodes (AgNPs/CFE) pretreated with NaS (i.e., AgS/AgNPs/CFE), which acts as a solid-contact and ion-selective microelectrode. The AgS/AgNPs/CFE exhibits good potential response toward hydrogen sulfide in the range of 2.5-160 μM, with a detection limit of 0.8 μM. Because of the presence of AgS, the AgS/AgNPs/CFE shows good selectivity to hydrogen sulfide, avoiding the interference from coexistent electroactive neurochemicals and the analogies, such as ascorbic acid and cysteine in the central nervous system. This good selectivity combined with the reversibility, protein antifouling, and biocompatibility of the microelectrode enables the AgS/AgNPs/CFE to detect hydrogen sulfide in the rat brain during local microinfusion of NaS and the change in pH. Our study provides a reliable method to track hydrogen sulfide selectively in vivo, which will help to explore the function of hydrogen sulfide in neurophysiology and pathology.