Tunable thermo-responsive supramolecular hydrogel: design, characterization, and drug release

During the past decade, a series of thermo-responsive hydrogels based on poly(N-isopropylacrylamide) (PNIPAM) were prepared for drug delivery. However, the release performance of those hydrogels was limited because the LCST (lower critical solution temperature) of PNIPAM (about 32 °C) is slightly lower than human body temperature, and the drug loading is complicated. To develop a new drug delivery matrix with the suitable responsive interval, a novel, temperature-sensitive copolymer with two monomers, N-isopropylacrylamide and methylacrylic polyethylene glycol monomethyl ether ester (MPEGMA) [poly(NIPAM-co-MPEGMA)], was synthesized by free radical polymerization. Then, the supramolecular hydrogels with tunable response temperature, whose structures were confirmed by X-ray diffraction (XRD), were fabricated via inclusion complexation with α-cyclodextrin (α-CD) and the copolymers in aqueous solution. The rheology results indicated that response interval could be modulated by controlling the contents of PNIPAM in the copolymers. Compared to the normal PNIPAM ge1, the succinct method of gel preparation streamlined the process of loading and made the drug loading capacity controllable. The release time was proved to be prolonged by the release kinetics of 5-fluoroucrail (5-Fu), which showed feasibility as a drug delivery.