Fluorescent and thermoresponsive tetraphenylethene-based cross-linked poly(N-isopropylacrylamide)s: Synthesis, thermal/AIE properties, and cell viability

Background: The synthesis, thermal properties, and aggregation-induced emission (AIE)-responsive properties of a series of tetraphenylethene (TPE)-based cross-linked poly(N-isopropylacrylamide)s (PNIPAms) consisting of a hydrophilic/thermosensitive NIPAm monomer and AIE-responsive/hydrophobic TPE derivative through reversible addition-fragmentation chain transfer polymerization was investigated in this study. Methods: The AIE effect was investigated in a H2O/THF mixture via photoluminescence intensity measurements, and the polymers showed emission (lambda(em) = 485 +/- 5 nm). When the water fraction was 90%, the PL intensity was enhanced to the highest value. Significant findings: Polymers P1-P3 showed the low critical solution temperature (LCST) at approximately 33.5, 32.4, and 28.1 degrees C, respectively, and deformed at P4 and P5. From dynamic light scattering, the hydrodynamic diameters of P0 and P1-P2 at a temperature higher than the LCST decreased from 564.0 to 159.6 nm, 417.4 to 126.7 nm, and 469.4 to 134.5 nm (P0, P1, and P2, respectively), indicating the thermoresponsive property. A MTT assay was used for HepG2 liver cancer cells at a concentration of 2 mu g/mL, and all the polymers showed cell viability over 80%. P2 and P3 showed emission in the living HepG2 cells for 96 h of incubation. These findings suggest that the synthesized polymers have potential as drug carriers. (c) 2022 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.