Synthesis And Characterization Of An Injectable Bracket Material Of Tissue Engineering

Injectable scaffold materials of tissue engineering can rehabilitate or cure bone lack and bone abnormality in unharmful or tiny harmful way. Due to its advantage in therapeutics, the study of injectable scaffold materials of tissue engineering attracts increasing attention. The synthesis, characterization and crosslinkability of pre-polymers basing on fumarate-trimethylolpropane-polyethylene glycol (PEG)were studied. The acid value and viscosity of pre-polymer were monitored during polymerization to control the molecule weight; the chemical structure of the pre-polymers was characterized by gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (NMR). The low molecular weight, hydroxyl-terminal polymers were crosslinked by free radical copolymerization and N-vinylpyrrolidone (NVP) was used as crosslinking agent in order to form a suitable curing system with the characteristics of injectable scaffold materials . The result shows that, when controlling the reaction temperature between 120 ℃and 140 ℃, and the reaction time between 3 hours and 5 hours, series of pre-polymers with different molecule weight and viscosity could be synthesized. Along with the increase of reaction temperature and prolonging of reaction time, the molecule weight and viscosity of the products increase. The number molecule weight of fumarate-trimethylolpropane pre-polymers is from 2000 to 6000, and the [η] is from 10.0 to 11.0 dL·g-1. The number molecule weight of fumarate-trimethylolpropane-PEG pre-polymers is from 1500 to 2000, and the [η] is from 3.0 to 8.0 dL·g-1. Thus, the facilitation of PEG can effectively control the number molecule weight and the viscosity of pre-polymers. The crosslinking reaction of fumarate-trimethylolpropane pre-polymers was initiated by benzoyl peroxide (BPO) and vitamin C (VC). At 37℃, the highest crosslinking temperature is 39.6℃(while the highest crosslinking temperature of the polymethyl methacrylate bone cement is 96.7℃), thus various adverse effects and injuries of surrounding tissues due to excessive heat can be reduced effectively. The orthogonal experiment indicates that crosslinking-temperature influenced mainly by activator VC, while the cosslinking time influenced mainly by BPO. The crosslinking reaction of fumarate-trimethylolpropane-PEG pre-polymers was initiated by benzoyl peroxide (BPO) and N, N-Dimethylacrylamide (DMA). At 27℃, the highest crosslinking temperature is 35.3℃. The orthogonal experiment indicates that the crosslinking temperature and time influenced mainly by activator BPO, then crosslinking agent NVP, however, PEG makes nearly no impact on them.