Fluorescence enhancement thermoresponsive polymer luminescent sensors based on BODIPY for intracellular temperature

Abstract Herein, A water soluble, visible excited and simple-structured copolymer hydrogel, poly(NIPAM- co -BODIPY-AA), consisting of N -isopropylacrylamide (NIPAM) and derivative of 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) units as thermoresponsive and polarity sensitive fluorescent signalling parts, respectively, has been synthesized. The copolymer exhibits weak fluorescence at temperature low than 35 °C in aqueous solution, whereas the red fluorescence intensity (λ em  = 605 nm) increases with a 10 folds rise in temperature up to 47 °C with an increase of average lifetime from 0.68 ns up to 2 ns in the thermal transition processes. The fluorescence intensity increased linearly with increasing physiology temperature (37–42 °C). The resultant nanothermometer could feature a high and spontaneous uptaking into the BHK cells. The prepared nanothermometer which is user friendly can provide tools for unveiling intrinsic relationship between the intracellular temperature and could be used in further applications for the fluorescent temperature sensing included parts of physiological temperature range in living cells.