An Ultramicroelectrode Electrochemistry and Surface Plasmon Resonance Coupling Method for Cell Exocytosis Study.

Exocytosis of a single cell has been extensively researched in recent years due to its close association with numerous diseases. However, current methods only investigate exocytosis at either the single-cell or multiple-cell level, and a method for simultaneously studying exocytosis at both levels has yet to be established. In this study, a combined device incorporating ultramicroelectrode (UME) electrochemistry and surface plasmon resonance (SPR) was developed, enabling the simultaneous monitoring of single-cell and multiple-cell exocytosis. PC12 cells were cultured directly on the SPR sensing Au film, with a carboxylated carbon nanopipette (c-CNP) electrode employed for electrochemical detection in the SPR reaction cell. Upon exocytosis, the released dopamine diffuses onto the inner wall of c-CNP, undergoing an electrochemical reaction to generate a current peak. Concurrently, exocytosis can also induce changes in the refractive index of the Au film surface, leading to the SPR signal. Consequently, the device enables real-time monitoring of exocytosis from both single and multiple cells with a high spatiotemporal resolution. The c-CNP electrode exhibited excellent resistance to protein contamination, high sensitivity for dopamine detection, and the capability to continuously monitor dopamine exocytosis over an extended period. Analysis of both SPR and electrochemical signals revealed a positive correlation between changes in the SPR signal and the frequency of exocytosis. This study introduces a novel method and platform for the simultaneous investigation of single-cell and multiple-cell exocytosis.

Atomically dispersed Au anchored on CeO2to enhancing the antioxidant activity.

The modification of Au nanoparticles can improve the antioxidant activity of CeO2, however, nano Au/CeO2has also met some problems such as low atomic utilization, the limit of reaction conditions, and high cost. Au single atom catalysts can well solve the above-mentioned problems, but there are some contradictory results about the activity of single atom Au1/CeO2and nano Au/CeO2. Here, we synthesized rod-like Au single atom Au/CeO2(0.4% Au1/CeO2) and nano Au/CeO2(1% Au/CeO2, 2% Au/CeO2and 4% Au/CeO2), and their antioxidant activity from strong to weak is 0.4% Au1/CeO2, 1% Au/CeO2, 2% Au/CeO2and 4% Au/CeO2, respectively. The higher antioxidant activity of 0.4% Au1/CeO2is mainly due to the high Au atomic utilization ratio and the stronger charge transfer between Au single atoms and CeO2, resulting in the higher content of Ce3+. Due to the coexistence of Au single atoms and Au NPs in 2% Au/CeO2, the antioxidant activity 2% Au/CeO2is higher than that of 4% Au/CeO2. And the enhancement effect of Au single atoms was not affected by the concentration of ·OH and material concentration. These results can promote the understanding of the antioxidant activity of 0.4% Au1/CeO2and promote its application.