Self-assembly and drug release control of dual-responsive copolymers based on oligo(ethylene glycol)methyl ether methacrylate and spiropyran

Abstract

To compare the synthesis and drug release of random and block copolymers, random and block copolymerizations of oligo(ethylene glycol)methyl ether methacrylate (OEGMA) and 1′-(2-methacryloxyethyl)-3′,3′-dimethyl-6-nitrospiro-(2H-1-benzopyran-2,2′-indoline) (SPMA) were carried out by atom transfer radical polymerization. The 1H NMR and GPC results indicated the targeted random and block copolymers were successfully synthesized. Critical micelle concentrations of random and block copolymers were determined as 0.0178 mg/mL and 0.0265 mg/mL, and the micelle aggregation numbers of the random and block copolymers were calculated as approximately 17 and 13, respectively, indicating that more molecular chains were required to form a stable polymeric micelle for a random than its block copolymer. A lower critical solution temperature of 37 °C, the human body temperature, was obtained for two copolymer samples, suggesting that they might have potential application in the biomedical field. During the self-assembly, the morphology of block copolymer micelles was more regular than that of random copolymer, and both copolymers exhibited the exchange of hydrophilic and hydrophobic segments called as “Schizophrenic” behavior under UV light irradiation at 50 °C. With doxorubicin as a model molecule in drug release control, heating and ultraviolet light irradiation could accelerate the drug release process to some extent, indicating the potential application of the resulting random and block copolymers in drug release and bioengineering.