In-situ detection of peroxynitrite in a single living cell with electrochemical attosyringe

Peroxynitrite (ONOO⁻), a key reactive oxygen/nitrogen species, plays a crucial role in signal transduction and physiological homeostasis. However, achieving the determination of ONOO⁻ in a single living cell remains a significant challenge. In this study, we have synthesized blue-emitting carbon dots (CDs) with a specific response to ONOO⁻ via a simple Schiff base crosslinking strategy. The fluorescence of these CDs is efficiently quenched upon interaction with ONOO⁻ due to a strong nitration reaction, enabling highly sensitive and selective detection of ONOO⁻ within a concentration range of 0.06–1.0 μM, with a detection limit as low as 30 nM. Notably, we have developed an electrochemical attosyringe by loading the CDs solution into a nanopipette, facilitating in-situ detection of ONOO⁻ in a single living cell. This approach, which differs from conventional incubation methods, offers rapid infusion and ease of operation, presenting promising opportunities for advancing single-cell analysis and enhancing our understanding of cellular microenvironments.