Structuring of bioactive glass surfaces at the micrometer scale by direct casting intended to influence cell response

Defect-free bioactive glass surfaces with a grooved microstructure at the low micrometer scale were achieved by a mold casting process. The process was applied to the well-known glass compositions 45S5 and 13–93. Such microstructured surfaces may exhibit especially favorable conditions for bone cell orientation and growth. The aim of the study was to assess the parameter range for a successful casting process and thus to produce samples suitable to investigate the interaction between structured surfaces and relevant cells. Viscous flow in its temperature dependence and thermal analysis were analyzed to identify a suitable process window and to design a manageable time-temperature process scheme. Counteracting effects such as formation of chill ripples, mold sticking and build-up of permanent thermal stress in the glass had to be overcome. A platinum gold alloy was chosen as mold material with the mold surface bearing the mother shape of the microstructure to be imprinted on the glass surface. First experiments studying the behavior of osteoblast-like cells, seeded on these microstructured glass surfaces revealed excellent viability and an orientation of the cells along the microgrooves. The presented results show that direct casting is a suitable process to produce defined microstructures on bioactive glass surfaces