Quantification of Hydrogen Sulfide in Single Living Cells by Azido-Functionalized Glass Nanopores

Hydrogen sulfide (H₂S) is the third gasotransmitter after nitrogen oxide and carbon monoxide, playing vital roles in physiological controls, such as angiogenesis, vascular homeostasis, thrombosis, inflammation, and remodeling. Monitoring the content level and dynamic variations of H₂S within cells will help understand its involvement and relationship in cancer proliferation and may also lead to new cancer therapy options. Herein, we developed a simple and effective approach for ionic rectification sensing detection of H₂S in single living cells using p-azidobenzoic acid (PA)-functionalized glass nanopores (PA-nanopores), in which the glass nanopores were successively functionalized with 3-aminopropyltrimethoxysilane and PA, and the exposed azido groups on the inner wall of the nanopore caused a negative rectification ratio (R) and varied upon reaction with the intracellular H₂S. In the presence of H₂S, azido groups could be reduced to amino groups, leading to a shift in the rectification ratio. The developed H₂S nanopore sensing platform showed high resolution and excellent selectivity, making it reliable for the quantification of H₂S in individual cells. The H₂S concentrations in individual HeLa cells, MCF-7 cells, and HL7702 cells were effectively quantified using the approach.