Water-insensitive down-shifting nanoparticles for sensitive biosensing.

Conventional optical probes suffer from signal degradation in aqueous media, hindering sensitive biodetection. To overcome this, newly developed water-insensitive down-shifting nanoparticles (WINPs) possess superior photophysical properties in the NIR-I window, including high quantum yield and negligible thermal effects, permitting stable, high-contrast signal generation under low excitation power. This advantage facilitated a low-power lateral flow assay capable of highly sensitive avian influenza virus (AIV) detection in the opaque biological matrices (such as avian swabs), mitigating interference issues relying on visible-range signals.