TIME-DEPENDENT VARIATION OF THE SURFACE-STRUCTURE OF BIOCERAMICS IN TISSUE-CULTURE MEDIUM AND THE EFFECT ON ADHESIVENESS OF CELLS

Biocompatible ceramics made of beta-tricalcium phosphate (TCP) were fo und to be actively changing their surface characteristics in tissue cu lture medium. The time-dependent variation of the zeta potential of TC P ceramics immersed in distilled water and in culture medium with and without addition of fetal bovine serum showed that the surface was uns table with significant changes in the charge being measured. Dry TCP h ad a zeta potential of -9.3 mV, which shifted to -1.8 mV after soaking in water and to -27.6 mV in culture medium with serum. To clarify the effect of the time-dependent variation of the surface structure on gr owth and adhesion of anchorage-dependent animal cells, the zeta potent ial of ceramics in dry state was regulated from -11.5 mV to + 27.2 mV by means of silane coupling modification. After soaking in distilled w ater for six days, zeta potential of the modified TCPs shifted to betw een +7.5 mV and -7.6 mV, while they were between -9.9 mV and -23.7 mV in culture medium with serum, Concentrations of calcium and phosphate dissolved in distilled water and in culture medium showed the solubili ty of the ceramics was considerably high and depended on the pH of the surface layer. The suitable surface property for adhesion of L-929 ce lls was obtained by the most stable ceramics in the culture condition. In conclusion, the solubility of the thin surface layer of the carrie r was considered to be the dominant factor in decreasing the adhesiven ess of cells on TCP ceramics.