Highly efficient red-emitting carbon dots as a turn-on temperature probe in living cells

Nanothermometers, which can precisely detect the intracellular temperature changes, have great potential to solve questions concerning the cellular processes. Thus, the temperature sensors that provide fluorescent turn on signals in the biological transparency window are of highly desirable. To meet these criteria, this work reported a new turn-on carbon dot (CD)-based fluorescent nanothermometry device for sensing temperature in living cells. The CDs that emit bright red fluorescence (R-CDs; lambda(max) = 610 nm in water) were synthesized with o- phenylenediamine as carbon precursor via a facile solvothermal method. The R-CDs in water were almost nonfluorescent at 15 ?C. As the temperature increased, the fluorescence intensity of R-CDs exhibited a gradual increase and the final enhancement factor was greater than 21-fold. The fluorescence intensity exhibited a linear response to temperature and a high-sensitive variation of asymptotic to 13.3 % ?C-1 was detected within a broad temperature range of 28-60 ?C. Moreover, the R-CD thermal sensors also exhibited high storage stability, excellent response reversibility and superior photo-and thermo-stability. Due to its good biocompatibility and intelligent response to external temperature, the nanothermometer could be applied for sensing temperature changes in biological media.

Automated summary

This study reported a new fluorescent carbon dot-based nanothermometer for sensing temperature changes in living cells. The nanothermometer exhibited high temperature stability, reversibility, and photo-thermo stability. It showed intelligent response to external temperature changes.