Dual-function Nanosensor leveraging near-infrared excitation for ultrafast and selective visualization of...

8-Hydroxyquinoline (8-HQ), a critical compound in pharmaceuticals, agriculture, and industrial applications, requires accurate detection methods. Fluorometric methods mostly rely on high-energy short-wavelength light excitation, which readily generates significant background signals and thus affects sensitivity. Herein, a novel near-infrared (NIR)-excited multimodal detection sensor was developed by combining upconversion nanoparticles with diazotized sulfanilic acid, enabling highly sensitive luminescent-colorimetric dual-mode visualization of 8-HQ. The sulfanilic acid-derived diazonium salt reacts specifically with 8-HQ under alkaline conditions, inducing selective quenching of green luminescence while red emission was preserved, thereby establishing concurrent luminescent and colorimetric sensing modalities. Under optimized conditions, the limit of detection for the luminescent mode was 68 nM, and that for the colorimetric mode was 467 nM. This method offered a rapid, sensitive, and reliable approach for 8-HQ monitoring, with broad potential applications in environmental surveillance, industrial compliance testing, and chemical safety management.