Preparation and Characterization of Long-Term Antibacterial and Temperature-Responsive Chitosan-g-PNIPAm @ Mugwort Oil Microcapsules

First, biocompatible temperature-responsive polymer chitosan- graft - N -isopropylacrylamide (CS- g -PNIPAm) synthesized via ATRP. Second, mugwort oil (MO) was encapsultated with CS- g -PNIPAm as shell materials to form long-term anti-bacterial agents and temperature responsive microcapsules. The CS- g -PNIPAm@MO (CSPN@MO) microcapsules were prepared via single coacervation method and solvent evaporation method. The chemical structures of CS 0.1 - g -PNIPAm 22 was confirmed by 1 H NMR and FTIR. And the copolymer micelles were characterized by UV, laser particle-size analysis, and TEM. The results indicated that the copolymer had temperature-responsive behaviors. The microcapsules were characterized by laser particle-size analyzers (LPSA), scanning electron microscopy (SEM), TG and anti-bacterial agents performance testing. The results showed that the average particle size of microcapsules was 0.28 μm, and the encapsulation efficiency and drug loading efficiency of MO reached 60.2 and 44.5%. After 48 h of release in media at different temperature (20, 40 and 60 °C) still sequestered 79.2, 92.2 and 96.1% of MO which approved the shell of microcapsules responded to different temperature. The morphology of CSPN@MO microcapsules revealed that the microcapsules presented smooth and firm structure. Antibacterial test for Artemisia argyi of CSPN@MO implied that the bacteriostatic rate reached 99.2 and 96.2% after 1 day and 10 days respectively. Bio-based macromolecular modification strategies can provide inspiration for the development of green microcapsules. Graphical Abstract