Lanthanide-based
(Ln3+) luminescent materials are ideal
candidates for use in fluorescence intracellular temperature sensing.
However, it remains a great challenge to obtain a Ln3+-ratiometric
fluorescence thermometer with high sensitivity and quantum yield in
an aqueous environment. Herein, a cationic Eu3+-metallopolymer
was synthesized via the coordination of Eu(TTA)3·2H2O with an AIE active amphipathic polymer backbone that contains
APTMA ((3-acrylamidopropyl) trimethylammonium) and NIPAM (N-isopropylacrylamide) units, which can self-assemble into
nanoparticles in water solution with APTMA and NIPAM as the hydrophilic
shell. This polymer exhibited highly efficient dual-emissive white-light
emission (Φ = 34.3%). Particularly, when the temperature rises,
the NIPAM units will transform from hydrophilic to hydrophobic in
the spherical core of the nanoparticle, while the VTPE units are moved
from inside the nanoparticle to the shell, activating its nonradiative
transition channel and thereby decreasing its energy transfer to Eu3+ centers, endowing the Eu3+-metallopolymer with
an extremely high temperature sensing sensitivity within the physiological
temperature range. Finally, the real-time monitoring of the intracellular
temperature variation is further conducted.