Time-Resolved Ratiometric Fluorescence Nanothermometer for Real-Time Endoscopic Temperature Guidance during Tumor Ablation.

Thermal ablation is a common treatment option for early-stage cancers, but the lack of real-time temperature imaging feedback method increases the risk of incomplete or excessive ablation. Although ratiometric nanothermometer offers a rapid temperature imaging solution, accurate in vivo signal extraction remains challenging due to the autofluorescence and wavelength-dependent tissue absorption and scattering. Herein, a time-resolved ratiometric fluorescence nanothermometer composed of europium and iridium complex with identical working wavelength but distinguishing lifetimes is reported, whose well-designed structures enable 450 nm excitation of both complexes with a high quantum yield (57.8%). Based on the nanothermometer, accurate signal extraction is realized in whole blood, beneath a 2 cm tissue phantom and a 5 mm pork slice through a time-resolved ratiometric method. By leveraging the exceptional thermal sensitivity (6.9% K-1), high temperature resolution (0.02 K), and clinically relevant temperature range (30-96 °C) of the nanothermometer, a fluorescence temperature endoscopy system is further designed with a real-time temperature imaging speed of 10 fps, which is applied to minimally invasive temperature monitoring during microwave ablation of liver tumors in rabbits, realizing precise ablation control through dynamic ablation power adjustment. The real-time and accurate temperature imaging performance of the nanothermometer may offer a new perspective for intraoperative guidance.