Shell Engineering on Thermal Sensitivity of Lifetime-Based NIR Nanothermometers for Accurate Temperature Measurement in Murine Internal Liver Organ

Lifetime-based NIR luminescent nanothermometry is ideally suited for temperature detection in living cells and in vivo, but the thermal sensitivity (Sr) modulation remains elusive. Herein, a thorough investigation is performed to unveil the shell effect on lifetime-based Sr by finely controlling the shell thickness of lanthanide-doped core–shell–shell nanoparticles. Owing to the space-dependent energy transfer and back energy transfer between Nd3+ and Yb3+ as well as the energy migration to surface quenchers, both active and inert shells can regulate the thermal-dependent nonradiative decays and NIR luminescence lifetime of Yb3+, which in turn modulates the Sr from 0.56% to 1.54% °C–1. After poly(acrylic acid) modification of the optimal architecture, the tiny nanoprobes possess robust stability to fluctuations in the microenvironment, which enables accurate temperature mapping of inflammation in the internal liver organ of living mouse. This work will provide new insights for optimizing Sr and guidance for precise temperature measurements in vivo.