Rare earth luminescent nanothermometers for biological thermal sensing

Temperature is a fundamental parameter closely related to physiological status in various biological cycles. Due to the significant role that temperature plays in life science, thermal sensing has gained extensive attention in the field of biological detection. Thermal sensing based on luminescence signals shows certain advantages, such as being non-invasive and fast. By further reducing the size of luminescent thermometers to the nanoscale, it is expected to accurately detect temperature in small biological settings. Among several nanothermometers, rare earth luminescent nanothermometers exhibit distinctive thermal sensing properties, making them excellent for measuring biological temperatures. This review primarily discusses thermal sensing methods for optimal detection performance. The optical systems used as thermal sensing equipment and the thermal sensing evaluation indexes as the evaluation standards are subsequently summarized. For specific biological scenarios, the selection of thermal sensing methods based on the requirements of relevant biological parameters are specifically analyzed. In particular, state-of-the-art biological applications based on the unique rare earth luminescent properties are highlighted for accurate thermal measurement from the cellular level to the organism. With a multidisciplinary approach that involves material, optical, and biological analysis, the review aims to provide guidance and propose the prospects of rare earth nanothermometers for biological thermal sensing.