Spatial Control of Cell-Nanosurface Interactions by Tantalum Oxide Nanodots for Improved Implant Geometry

Nanotopological cues can be exploited to understand the nature of interactions between cells and their microenvironment to generate superior implant geometries. Nanosurface parameters which modulate the cell behavior and characteristics such as focal adhesions, cell morphology are not clearly understood. Here, we studied the role of different nanotopographic dimensions in modulating the cell behavior, characteristics and ultimately the cell fate and accordingly, a methodology to improve implant surface geometry is proposed. Tantalum oxide nanodots of 50, 100nm dot diameter with an inter-dot spacing of 20, 70nm and heights 40, 100nm respectively, were engineered on Silicon substrates. MG63 cells were cultured for 72 hours and the modulation in morphology, focal adhesions, cell extensible area, cell viability, transcription factors and genes responsible for bone protein secretion as a function of the nanodot diameter, inter-dot distance and nanodot height were evaluated. Nanodots of 50nm diameter with a 20nm inter-dot spacing and 40nm height enhanced cell spreading area by 40%, promoted cell viability by 70% and upregulated transcription factors and genes twice as much, as compared to the 100nm nanodots with 70nm inter-dot spacing and 100nm height. Favorable interactions between cells and all dimensions of 50nm nanodot diameter were observed, determined with Scanning electron microscopy and Immunofluorescence staining. Nanodot height played a vital role in controlling the cell fate. Dimensions of nanodot features which triggered a transition in cell characteristics or behavior was also defined through statistical analysis. The findings of this study provide insights in the parameters of nanotopographic features which can vitally control the cell fate and should therefore be taken into account when designing implant geometries.