Preparation of temperature-responsive PMMA-based microspheres encapsulating erythromycin in situ by emulsion photopolymerization

Erythromycin (EM) was encapsulated into poly(methyl methacrylate) (PMMA) and poly(methyl methacrylate- co - N -vinylcaprolactam) (P(MMA-NVCL)) microspheres in situ by oil-in-water emulsion photopolymerization under green LED irradiation. The physicochemical properties of PMMA-EM and P(MMA-NVCL)-EM microspheres were characterized by SEM, FTIR, TG-DSC and DLS. P(MMA-NVCL)-EM microspheres showed temperature sensitivity, and the EM loading content of PMMA-EM and P(MMA-NVCL)-EM microspheres reached 9.7% and 15.6%, respectively. In vitro release of EM from microspheres presented good controlled release behavior in 12 h. Further release kinetic and thermodynamic investigation revealed that the release process was mainly dominated by EM concentration, accompanied by microspheres relaxation and rupture of hydrogen bonds .