Abstract: Objective: To prepare the lithium-doped poly-glycerol sebacate (PGS-Li) scaffold using the specific effects of lithium ions and the excellent performance of PGS, and to provide the basis for its application prospects in cementation tissue engineeringscaffold.Methods: The scaffolds were divided into two groups. The PGS-Li scaffolds prepared by adding lithium phosphate during the PGS cross-linking process were used as PGS-Li group, and the PGS scaffolds synthesized by the equal-purification of sebacic acid and glycerol were used as PGS group. The molecular weights of the scaffolds in two groups were determined by gel permeation chromatography. The structures of the scaffolds in two groups were analyzed by fourier transform infrared spectroscope. The surface morphology and the porosities and the pore sizes of the scaffolds in two groups were observed by scanning electron microscope. X-ray photoelectron(XPS) spectroscope and inductively coupled plasma optical emission spectrometer were used to determine the Li ion contents in the scaffolds in two groups. Thermogravimetric analyzer was used to analyze the thermal stabilities of the scaffolds in two groups. Contact angle measuring instrument was used to compare the hydrophilicities of the scaffolds in two groups. In vitro weight loss test was used to determine the degradation rates of the scaffolds in two groups. The OCCM-30 cells were divided into experimental group (added with PGS-Li scaffold extract), PGS group (added with PGS scaffold extract) and blank control group (added with DMEM culture medium). MTT assay was used to detect the proliferation activities of cells in various groups at different time (24, 48 and 72 h);the cell morphology was observed by calcein-AM staining.Results: The gel permeation chromatography results showed that the molecular weight of the PGS-Li scaffold was slightly larger than that of the PGS scaffold. The specific absorption peak of phosphate was detected in the fourier infrared spectrum of the PGS-Li scaffold. The scaffolds in two groups had irregular three-dimensional network structures under scanning electron microscope,and the pore size was 20-160 μm, the porosity of PGS scaffold was (53.92±2.18)%, and the porosity of PGS-Li scaffold was (53.58±1.73)%, there was no statistical difference between two groups (P>0.05). The XPS results showed that a peak appeared at 54.9 eV in PGS-Li group, which coincided with the Li 1s binding energy, while the inductively coupled plasma emission spectrometer results showed that the Li ion content in the PGS-Li scaffold was 0.084%. The thermogravimetric analysis results showed that PGS-Li scaffolds began to degrade at a higher temperature and ceased at a lower temperature compared with PGS scaffolds. The contact angle measurement results indicated that both the materials were hydrophilic materials; the contact angle of PGS scaffold meterial was 78.26°±2.00°, and the contact angle of the PGS-Li scaffold material was 69.78°±1.15°; there was statistical difference between two groups (P<0.05). The in vitro degradation experiments showed that the degradation rate of PGS-Li scaffolds was faster than that of PGS scaffolds.The proliferation activity of OCCM-30 cells in PGS-Li group had no significant difference compared with PGS group and blank control group(P>0.05). The calcein-AM staining results showed the green fluorescence in the OCCM-30 cells in PGS and PGS-Li groups,and there were no significant changes in the morphology of cementoblasts.Conclusion: PGS-Li scaffolds have similar composition and structure to PGS scaffolds, and have better performance in hydrophilicity and thermal stability. PGS-Li scaffolds have no effect on the proliferation of cementoblasts and have broad application prospects in cementum tissue engineering.

Key words: lithium, poly-glycerol sebacate, tissue engineering, dental cementum