Fabrication of thermoresponsive micelles by functionalizing hydroxypropyl cellulose via azide‐alkyne click reaction

Abstract

In this work, we functionalized hydroxypropyl cellulose (HPC) by attaching tetraphenylethylene (TPE) via copper‐catalyzed azide‐alkyne cycloaddition (CuAAC). The obtained HPC‐TPE samples displayed water‐solubility, biocompatibility, fluorescence and thermoresponsive properties. The degree of substitution (DSTPE) of HPC‐TPE1 ~ 4 was determined to be 0.002, 0.006, 0.025, and 0.053, respectively. HPC‐TPE could self‐assemble into micelles in water with the hydrodynamic radius (Rh) ranging from 164 to 190 nm. Under different DSTPE, HPC‐TPE samples showed different lower critical solution temperature (LCST) behaviors in light transmittance, Rh and fluorescence. The critical transition temperatures in light transmittance for HPC‐TPE1 ~ 4 solutions were 55–49 °C during the heating process, and were 44–40 °C during the cooling process, respectively. Moreover, HPC‐TPE demonstrated a rapid and sensitive response to Fe3+ with ignoring interferences in the presence of other common metal ions, and could also be used to image 4T1 cells. Therefore, this work offered a general approach for the synthesis of functionalized polymers with promising applications in sensing and bioimaging.