A new nanomaterial based on PSS- [Tb2(TCAn)2] was synthesized by solvent-induced nanoprecipitation for highly sensitive intracellular temperature monitoring within the physiological 303-313 K range. The degree of bromination of TCA ligands was found to play a dramatic role in control of thermoresponsive behavior of PSS-[Tb2(TCAn)2] particles. Tetra-brominated thiacalix arene based nanoparticles provided the most sensitive response to the heating, but restricts their applicability to the single use. However, the di-brominated ligands provide the optimal ligand environment of the Tb3+ ions in the nanoparticles for the recurrent temperature measurements for the five “heating-cooling” cycles at least. Effective cell internalization, low cytotoxicity, and bright green Tb3+-luminescence provides great potential for in vivo intracellular monitoring of temperature changes induced by hyperthermia or pathological processes in narrow range of physiological temperatures with unprecedented sensitivity (SI=5.25%K-1), and may represent a significant step forward for accurate 2D temperature mapping. Aiming at ratiometric temperature sensing, second luminescent component, namely carbon dots (CDs), was introduced to the nanoparticles. Resulting hybrid PSS-[TbL CD] nanoparticles showed excellent colloidal stability, bright and reversible thermo responsive and pH responsive functions in green (545 nm, 5D4-7F5 transition of Tb3+) and blue (450 nm, designated to CD fluorescence) regions of spectrum, correspondingly. Temperature sensing was achieved via green peak reversible quenching, while blue peak remained unchanged. Oppositely, CD fluorescence peak demonstrates sensitivity to pH changes in the range of 5-7.5 where 545 nm peak shows constant intensity. Dual function nanosensor constructed via combination of Tb3+ chelate and CDs within one nanoarchitecture allows remote real-time monitoring of two main parameters, temperature and pH, in cells at nanoscale dimensions.
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