Redox response, antibacterial and drug package capacities of chitosan-α-lipoic acid conjugates

Chitosan-α-lipoic acid (CS-LA) conjugates were prepared by amino reaction. The methotrexate (MTX) was successfully loaded within CS-LA copolymer by the ring-opening polymerizations of disulfide bond under the action of reducing agent. The obtained copolymer was investigated by fourier transform infrared spectrometer (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and nuclear magnetic resonance (1H NMR) analysis. The ring-opening polymerization process effected on rheological properties were studied. The graft of LA increased the apparent viscosity of CS-LA, and the loaded of MTX by redox reduced its apparent viscosity enormously. The load of MTX under the action of DTT decreased the apparent viscosity and moduli of CS-LA-MTX hydrogel. In dynamic oscillatory experiment, the package of MTX reduced the rigidity of CS-LA and damaged the gel structure of CS-LA. The antimicrobial ability of CS-LA against E. coli was processed by the inhibition zone and growth curves. The modification of LA raised the antibacterial activity of CS-LA. The cytotoxicity assay of CS-LA-MTX to prostate cancer cells (RM-1) was examined. The load of MTX within CS-LA-MTX greatly enhanced the cytotoxicity to RM-1 cells. In summary, CS-LA hydrogel may provide a new copolymer carrier for drug package in food and biomedical application.