Temperature-sensitive hydrogel modified by polymerizable liquid crystal AAc-Brij-58: Optical and protein adsorption/desorption behaviors

To avoid template-like action of polyoxyethylene 20 cetyl ether (Brij-58) in hydrogel matrix, a polymerizable liquid crystal AAc-Brij-58 based acrylic acid (AAc) and Brij-58, and poly(NIPAm-co-AAc-Brij-58) (ACHX) hydrogels based on N-isopropylacrylamide (NIPAm) and AAc-Brij-58 were synthesized by esterification and free-radical polymerization. The chemical structures of resulting ACHX hydrogels were confirmed by FTIR and 1H NMR. The optical property of ACHX pre-polymerization solution was monitored by ultraviolet-visible spectrophotometry (UV/Vis). The pore structure was observed by scanning electron microscopy (SEM). The adsorption and desorption behaviors of Bovine Serum Albumin (BSA) were investigated by temperature-oscillating between 37 °C and 25 °C. The result shows that AAc-Brij-58 and ACHX hydrogels have been successfully synthesized. With increasing mass percent of AAc-Brij-58/NIPAm from 0 to 10 wt%, the transparency of ACH01-10 hydrogel decreases to 0 at 20, 17, 14, 12 and 16 min, respectively. The interior of ACHX hydrogels presents honeycomb structure with thick pore wall with pore size from 120 to 600 μm, but shows vent-like structure on the outer surface after copolymerization by AAc-Brij-58. The adsorption and desorption of ACHX hydrogels exhibit reversible temperature oscillation responsibility between 37 °C and 25 °C. As mass percent of AAc-Brij-58/NIPAm is 1 wt%, ACH01 hydrogel presents highest adsorbed BSA amount, about 1090 ± 24 mg/g at 37 °C. After desorption at 25 °C, columniform BSA aggregates on the surface of ACHX hydrogels were not observed.