Preparation, Characterization, and Self-assembly Behavior of a Novel MPEG/PCL-g-Chitosan Copolymer

In this article, MPEG/PCL-g-Chitosan (MPEG/PCL-g-CS) was successfully prepared via free-radical polymerization method. MPEG/PCL copolymer was first synthesized from MPEG and epsilon-caprolactone. Then, the double bond ended MPEG/PCL (MPEG/PCL macromonomer) was obtained by reaction with acryloyl chloride at 40oC in pre-dried dichloromethane. MPEG/PCL-g-CS copolymer was characterized by 1H-nuclear magnetic resonance (1H-NMR), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and differential scanning calorimeter (DSC), respectively. The obtained amphiphilic MPEG/PCL-g-CS copolymer could self-assemble into nanoparticles in aqueous solution. The critical micellar concentration (CMC) of MPEG/PCL-g-CS copolymer is about 1.78 mg/L determined by the fluorescence robe technique. In vitro cytotoxicity test revealed that MPEG/PCL-g-CS nanoparticles were low cytotoxicity against HEK293 cells after incubated for 24 h. The coupling of CS with MPEG/PCL endowed the pH sensitivity and cationic characteristics to MPEG/PCL nanoparticles. Size distribution and zeta potential of nanoparticles were greatly influenced by pH values.