Synthesis and Fluorescent Thermoresponsive Properties of Tetraphenylethylene‐Labeled Methylcellulose

Abstract

Functional polymer, especially the one based on renewable and sustainable materials, has attracted increasing attention to satisfy the growing demand for the design of stimuli‐responsive devices. Methylcellulose (MC) is a water‐soluble derivative of cellulose, which has been widely used in many fields for its biocompatibility and biological inertness. In this work, MC is labeled by tetraphenylethylene (TPE) via azide–alkyne click reaction to obtain a fluorescent cellulose‐based derivative of MC‐TPE. The degree of substitution of MC‐TPE is determined to be 0.074, which can be self‐assembled into micelles in water with the size of 42 ± 6 nm. MC‐TPE shows thermoresponsivity and thermoreversibility in size, transmittance, and fluorescence, enabling it to work as a fluorescent thermosensor. Moreover, MC‐TPE exhibits nontoxicity and biocompatibility, allowing its application in MCF‐7 cell imaging. Therefore, this newly functional natural polymer shows promising potentials in the fields of sensing and bioimaging.

Facile Fabrication of Fluorescent Cellulose with Aggregation‐Induced Emission Characteristic in a CO2 Switchable Solvent

“…Increasing the molar ratio to 2.5, the DS TPE can be increased to 0.220, which is 2 times higher than that reported in the literature. [ 21 ] Therefore, TPE‐CH 2 Br can be considered as a more effective reagent for the fabrication of fluorescent cellulose with AIE property, compared with those TPE derivatives with COOH, [ 10 ] NCS [ 4 ] and OCHCH [ 21 ] functional groups. Interestingly, all C‐ g ‐PLLA/TPE samples have a similar amount of grafted PLLA side chains, with W PLLA of around 0.70, which indicated that the grafting of TPE to the cellulose backbone by nucleophilic substitution reaction does not affect the existing side groups in the cellulose backbone.…”

“…[2] For example, Tang group fabricated AIE bioconjugates with chitosan and TPE derivative with -NCS group (TPE-NCS). [4,[18][19][20] In another example, Wang and coauthors [21] converted -OH group in the methylcellulose to -N 3 group, and then grafted TPE via azide-alkyne click reaction with alkynyl TPE (TPE-OCH≡CH). The resulting product had DS of the TPE of 0.074.…”

“…The resulting product had DS of the TPE of 0.074. [ 21 ] In these studies, transformation of hydroxyl groups in the cellulose to other more reactive groups was necessary, and the preparation of TPE derivatives was complicated, but the resulting fluorescent cellulose had low DS of TPE. Therefore, a facile strategy for the fabrication of fluorescent cellulose with AIE property is strongly demanded.…”