Hemin as a UCNP quencher for constructing a NIR-excitable nanoprobe for peroxynitrite

The advancement of novel detection strategies, especially those activatable by near-infrared (NIR) light, is of great importance for advancing biomedical sensing. Herein, we report a rationally designed, NIR-excitable nanoprobe, UCNP‑hemin@F127, for the sensitive detection and imaging of peroxynitrite (ONOO - ). The central design feature is the dual role of the biological molecule hemin, which acts simultaneously as a luminescence resonance energy transfer (LRET) acceptor to quench the emission of core‑shell upconversion nanoparticles (UCNP) and as a specific recognition unit for ONOO - . Co‑encapsulated with the UCNP donor within an amphiphilic F127 matrix, hemin enables a highly efficient “turn‑on” sensing mechanism. Upon interaction with ONOO - , the porphyrin ring of hemin is cleaved, disrupting the LRET process and restoring the fluorescence. This nanoprobe allows rapid, selective, and sensitive detection of ONOO - in solution, achieving a detection limit of 37.41 nM and a signal enhancement of up to 7.7‑fold. It demonstrates good biocompatibility and has been successfully applied for visualizing both exogenous and endogenous ONOO - in live cells under 980 nm excitation. This integrated quencher‑sensor strategy, employing a native biomolecule as a key functional module, provides a reliable tool for monitoring ONOO - and offers a versatile design platform for the development of advanced LRET‑based bio-probes.