Investigation on microstructure, composition, and cytocompatibility of natural pumice for potential biomedical application.

In this study, the properties of Changbaishan natural pumice were characterized including the microstructure, porosity, mechanical strength, composition, harmful trace element content, and cytocompatibility. The results show that the natural pumice has a porous structure with a pore size ranging from 50 to 150 mum, an interconnective porosity of 80%, and a compressive strength of 1.72 +/- 0.12 MPa, which are adequate as a scaffold for bone tissue engineering. The natural pumice is mainly composed of silicate, and the content of harmful trace elements of arsenic (As), cadmium (Cd), and mercury (Hg) in the pumice are less than 3 ppm, whereas the content of plumbum (Pb) is less than 5 ppm, which can meet the requirement of China Medicine Standard regulation. Cytocompatibility of the pumice was also evaluated by culturing and seeding MG63 cells on the scaffold and with its medium extraction. The cells present good adhesion and proliferation and the pumice does not show a negative effect on the MG63 cells in vitro. A period of 11 days testing by 3-{4,5-dimethylthiazol-2yl}-2,5-diphenyl-2H-tetrazolium-bromide assay demonstrates that the pumice has little influence on the cell viability. This new investigation paves the way for further study on pumice's potential for biomedical applications, such as for bone tissue engineering scaffold.