Living cell intracellular temperature imaging with biocompatible dye-conjugated carbon dots

Within living cells, the biological functions of subcellular organelles are highly dependent on the distribution of local temperature. In this regard, sensitive and accurate measurement of cellular temperature with subcellular resolution is fundamentally and practically significant. In this work, we demonstrated a fluorescence-based self-calibration method for the quantitative analysis of living cell temperature. A ratiometric temperature sensor was designed by conjugating a temperature sensitive dye, Rhodamine B (RhB), with biocompatible carbon dots (CDs) via a covalent bond. The as-prepared CDs-RhB probe showed excellent ratiometric temperature sensing capability in solution under a single wavelength excitation and displayed a linear temperature sensing range from 5 to 50 °C, which matches the requirement well for the physiologically relevant temperature assay. Furthermore, this probe was applied to map intracellular temperature inside living cells. The fast and accurate temperature response of the probe makes it a promising tool for monitoring the intracellular temperature change, which will promote a better understanding of the temperature relevant biological processes inside living cells.