Nanothermometer with Temperature Induced Reversible Emission for Evaluation of Intracellular Thermal Dynamics

Abstract

Temperature dynamics reflect the physiological state of cells, and accurate measurement of intracellular temperature helps to understand the biological processes. Herein, we report a novel nanothermometer by conjugating a fluorescent probe 3-ethyl-2-[4-(1,2,2-triphenylvinyl)styryl]benzothiazol-3-ium iodide (TPEBT) with a thermoresponsive polymer poly(N-isopropylacrylamide-co-tetrabutylphosphonium styrenesulfonate) [P-(NIPAM-co-TPSS)]. The derived nanoprobe TPEBT-P(NIPAM-co-TPSS) self-assembles into micelles with TPEBT as hydrophobic core and PNIPAM as hydrophilic shell. It exhibits aggregation-induced emission (AIE) at λ ex /λ em = 420/640 nm in aqueous medium with a quantum yield of Φ F 11.9%. The rise in temperature transforms PNIPAM chains from linear to compact spheres to serve as the core of micelles, and meanwhile converts TPEBT from the state of aggregation to dispersion and redistributes in the micellar shell. Temperaturedriven phase transition of P(NIPAM-co-TPSS) mediates the reversible aggregation and disaggregation of TPEBT and endows the nanothermometer with temperature-dependent AIE features and favorable sensitivity for temperature sensing in 32−40 °C. TPEBT-P(NIPAM-co-TPSS) is taken up by HeLa cells to distribute mainly in lysosomes. It enables quantitative visualization of in situ thermal dynamics in response to stimuli from carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone, oligomycin, genipin, and lipopolysaccharide. The real-time monitoring of photothermalinduced intracellular temperature variation is further conducted.

Water-Soluble Cationic Eu3+-Metallopolymer with High Quantum Yield and Sensitivity for Intracellular Temperature Sensing

“…Particularly, the proton signal from VTPE unit can be detected within the range of 6.9−7.2 ppm at 45 °C, indicating that the protons from the VTPE unit are not shielded, suggesting that the VTPE units are relieved from the core of the nano particle at higher temperature. 55 It is worth noting that this phenomenon is different from the previously reported thermoresponsive polymer with TPE units, where the fluorescence intensity increased with the enhancement of the temperature. 56 The opposite phenomenon in the present case might be owing to the presence of the ionic ammonium salt, which leads to the linear, mild, and incomplete phase transition of the Poly-Eu-NPs.…”

“…These results can be ascribed to the more crowded microenvironment for the protons upon the conformation change of the polymer main chain. Particularly, the proton signal from VTPE unit can be detected within the range of 6.9–7.2 ppm at 45 °C, indicating that the protons from the VTPE unit are not shielded, suggesting that the VTPE units are relieved from the core of the nano particle at higher temperature . It is worth noting that this phenomenon is different from the previously reported thermoresponsive polymer with TPE units, where the fluorescence intensity increased with the enhancement of the temperature .…”

Light, pH, and Temperature Triple-Responsive Magnetic Composites for Highly Efficient Phosphopeptide Enrichment

“…The isomerization of SPA to MCH + under acid and UV stimuli promotes the selective separation of phosphates based on electrostatic interactions. pNIPAm has hydrophilicity at room temperature, which also favors phosphate adsorption …”

“…When SP is combined with other molecules, a synergistic effect can be expected to confer the composite with more sensitive response properties. , For example, NIPAm, a widely investigated thermoresponsive polymer containing both hydrophilic amide and hydrophobic isopropyl groups, − can be polymerized with SP-based monomer to obtain stimuli-responsive materials. The polymerization of pNIPAm with SP-based monomer can be facilitated by surface-initiated atom transfer radical polymerization (SI-ATRP).…”

Aggregation-induced emission-active micelles: synthesis, characterization, and applications

“…10f). 102 The resulting nanoprobe could self-assemble into micelles with PNIPAM as the hydrophilic shell and TPEBT as the hydrophobic core. The aggregation of the TPEBT molecules induced strong fluorescence emission at 640 nm.…”