Highly Stable and Selective Sensing of Hydrogen Sulfide in Living Mouse Brain with NiN₄ Single-Atom Catalyst-Based Galvanic Redox Potentiometry

Abstract

Hydrogen sulfide (H 2 S) is recognized as a gasotransmitter and multifunctional signaling molecule in the central nervous system. Despite its essential neurofunctions, the chemical dynamics of H 2 S during physiological and pathological processes remains poorly understood, emphasizing the significance of H 2 S sensor development. However, the broadly utilized electrochemical H 2 S sensors suffer from low stability and sensitivity loss in vivo due to sulfur poisoning-caused electrode passivation. Herein, we report a high-performance H 2 S sensor that combines single-atom catalyst strategy and galvanic redox potentiometry to overcome the issue. Atomically dispersed NiN 4 active sites on the sensing interface promote electrochemical H 2 S oxidation at an extremely low potential to drive spontaneous bipolarization of a single carbon fiber. Bias-free potentiometric sensing at open-circuit condition minimizes sulfur accumulation on the electrode surface, thus significantly enhancing the stability and sensitivity. The resulting sensor displays high selectivity to H 2 S against physiological interferents and enables real-time accurate quantification of H 2 S-releasing behavior in the living mouse brain.

Biocompatible Microelectrode for In Vivo Sensing with Improved Performance

“…According to the equation, the sensitivity of the open-circuit potential (i.e., 2.3 RT /(1 – a ) nF ) is constant and independent of the electroactive surface area of the microsensor, which is totally different with the amperometric sensor and voltammetric sensor affected by the active area of the microelectrode. Ag 2 S/AgNPs/CFE and other electrodes based on the OCP or GRP method can achieve a consistent slope of precalibration and postcalibration curves in vivo. ,,, Moreover, GRP has an extremely low degree of electrode reaction to reduce the accumulation of electrochemical reaction products on the electrode surface and passivation at the reaction site (Figure f) . It is worth mentioning that the near-zero circuit current minimizes the potential drop and electric field generation induced by brain tissue to avoid electrical effects on adjacent neurons, which enables the microsensor to also be compatible with electrophysiological recording, enabling the synchronous recording of both chemical and electrical signals. , …”

“…This Cu–N 2 catalyst-modified microsensor shows excellent in vivo sensing performance with high selectivity, enabling its application in the real-time quantitative investigation of the dynamics of H 2 O 2 production induced by mercaptosuccinate and glutathione monoethyl ester in a living animal brain. Until now, many other single-atom catalysts have been developed and showed good electrochemical properties for neurochemicals including DA, nitric oxide, and hydrogen sulfide . However, there is still an urgent need for more single-atom catalysts with better catalytic performance and wider application for in vivo analysis.…”

Engineering of Bi–S3 and sulfur-vacancy dual sites for efficient photocatalytic N-alkylation of amines

“…[13][14][15][16][17][18][19][20][21][22][23][24][25] Recently, single-atom catalysts (SACs) have been widely studied for enhancing the catalytic activities in various reactions, due to their nearly 100% atom utilization efficiency and abundant active sites. [26][27][28][29][30] Li et al comprehensively summarized the relationship between the atomic scale active site and catalytic performance, providing important guidelines for designing single-atom catalysts (SACs). 31 Notably, single-atom photocatalysts (SAPCs) are regarded as one of the promising strategies for achieving economical and efficient photocatalysts.…”

Nickel Single-Atom Catalyst-Mediated Efficient Redox Cycle Enables Self-Checking Photoelectrochemical Biosensing with Dual Photocurrent Readouts

“…Therefore, to circumvent the plague of the related hole- or electron-trapping agents, the introduction of recyclable redox couples and corresponding efficient cocatalysts is a potential and practical approach for an efficient interfacial reaction. Atomically dispersed metal–nitrogen–carbon materials as one of the most promising single-atom catalysts (SACs) have aroused considerable concern as effective cocatalysts, which display excellent catalytic performance due to their unique electronic structures and fully exposed active sites. − Hence, it is greatly expected to slightly adjust the voltage for achieving photocurrent polarity switching in the presence of redox couples and advanced SACs.…”