Aspirin-loaded chitosan nanoparticles and polydopamine modified titanium sheets improve osteogenic differentiation
Li Rui, Liu Zhen, Guo Zige, Lu Ruijie, Wang Chen
Hospital of Stomatology, Tianjin Medical University, Tianjin 300070, China
Abstract: BACKGROUND: Titanium as a bone substitute material has been widely used in the field of oral implant devices, but its bioinert would affect the stable combination with bone tissue at the early stage of implantation. Therefore, exploring to improve the osteogenic properties of titanium through surface modification is necessary.
OBJECTIVE: To investigate the effect of composite coating of aspirin loaded chitosan nanoparticles and polydopamine on the viability of osteoblasts in vitro.
METHODS: The titanium sheets modified by polydopamine coating as well as aspirin loaded chitosan nanoparticles and polydopamine composite coating were constructed. The surface morphology and microstructure of the coatings were characterized by scanning electron microscopy. In vitro sustained-release properties of aspirin nanosphere coatings on pure titanium were detected. Rat bone marrow mesenchymal stem cells were seeded and cultured on the pure titanium sheet and the two kinds of modified titanium sheets. The spreading morphology of rat bone marrow mesenchymal stem cells on the surface of titanium sheets was observed by cytoskeleton staining. Cell proliferation was determined by CCK-8 assay. The osteogenic differentiation of rat bone marrow mesenchymal stem cells on titanium sheets was measured using alkaline phosphatase staining and immunofluorescence staining.
RESULTS AND CONCLUSION: (1) Scanning electron microscope images showed that the pure titanium surface was relatively smooth, and deposits as well as grain appeared after the dopamine polymerization. Aspirin microspheres were spherical with uniform size distribution. The hydrophilicity of the nanoparticles immobilized titanium surfaces and the polydopamine coating modified titanium surfaces were better than that of the pure titanium sheets (P < 0.05). The aspirin appeared to be slow and sustained under the encapsulation of chitosan nanoparticles. (2) As observed by cytoskeleton staining, the cells showed insufficient cell expansion on the surface of the pure titanium sheets and formed a few filopodia on the dopamine modified titanium sheets. The cells on nanoparticles modified sheets showed perfect expansion. (3) CCK-8 assay showed that the titanium sheets had no obvious cytotoxicity, and the cell proliferation rate of the nanoparticles modified titanium sheets displayed higher rates of proliferation than that of the dopamine coated and pure titanium sheets with increasing cell culture time (P < 0.05). (4) Alkaline phosphatase activity was highest on the surfaces of nanoparticles modified sheets. Immunofluorescence showed that the fluorescence intensity of alkaline phosphatase was strongest. (5) The results showed that the sustained-release coating of aspirin loaded chitosan nanoparticles on the titanium surfaces could enhance the proliferation and adhesion of rat bone marrow mesenchymal stem cells and promote osteogenic differentiation.
Key words: titanium, surface modification, dopamine, aspirin, chitosan nanoparticle, bone marrow mesenchymal stem cells, cell adhesion, osteogenic differentiation