Porous-Pt-CuO-driven electrochemical biosensor for tracking of endogenous H2S biomessenger molecules

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Hydrogen sulfide (H2S) is considered to be the third endogenous gas messenger after nitric oxide and carbon monoxide, and is closely related to physiological and pathological functions of human being. Rapid and real-time monitoring of endogenous H2S production in living cells is of great significance for clinical diagnoses of related disease and in-depth investigation of pathological processes. The application of electrochemical sensors has become a promising method to achieve real-time H2S monitoring comparing to other methods. Up to now, low-cost, and highly sensitive electrocatalysts for H2S detection are conspicuously scarce. Herein, we developed a high-efficient method to construct a H2S electrochemical sensor, which configure dissolved–H2S–sensitive electrochemical sensor using porous Pt-modified copper oxide (Pt–CuO) as electrocatalyst. The obtained sensor possessed remarkable H2S detection performance, achieving the detection limit of 0.5 ppm and apparent selectivity toward various gases (e.g., ammonia, nitrogen dioxide, and carbon dioxide). The electrochemical sensor was also applied for monitoring H2S released from mesenchymal stem cells. The enhanced sensing performance was attributed to: (1) electrocatalytic reaction between CuO and [H2S] (H2S and HS−) was observed in the cyclic voltammetry curves with oxidation current peaks; (2) Pt catalytic activity promoted electron transfer during the detection process and further decreasing Pt–CuO resistance; and (3) enhanced diffusion of detection molecules/ions, which increased the reactivity sites through forming cross porous structures using sodium carbonate as sacrifice template. The proposed Pt–CuO-based electrochemical sensor shows great potential for applications in clinical diagnoses, and provides effective means to understand the role of H2S in biological processes.