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The biomedical applications of poly(l-lactide) (PLLA) were limited by its high crystallinity. In this paper, the copolymerization of trimethylene carbonate (TMC) and l-lactide (LLA) was carried out to improve the flexibility of PLLA. The effects of feeding dose, reaction temperature and polymerization time were investigated, and the copolymers were characterized with (1)H nuclear magnetic resonance, Fourier transform infrared reflection, gel permeation chromatography differential scanning calorimetry, thermogravimetric analysis and x-ray diffraction. The copolymers were electrospun to form porous films to study their cell compatibility. The results showed that the composition of the copolymer was nearly the same as that in the feeding dose, and the molecular weight of the copolymer decreased with increasing TMC content. The decrease in the reaction temperature and polymerization time would increase the molecular weight, but the composition deviates from the feeding dose. NIH/3T3 mouse fibroblast cells were cultured on the electrospun films. The morphology and proliferation of the cells were studied. The results implied that the cell compatibility of poly(l-lactide-co-trimethylene carbonate) copolymer was much better than that of the PLLA homopolymer.

Tea polyphenol serves as an environmentally friendly ligand-exchange molecule to synthesize multifunctional metal-doped superparamagnetic iron oxide nanoparticles via a catechol-metal coordination interaction. The resultant particles not only exhibit excellent hydrophilicity and protein adsorption resistance, but also are applicable as magnetic resonance/fluorescent dual-imaging probes due to their high T₂ relaxivity, autofluorescence and large cellular uptake.