The relationship between cell adhesion force activation on nano/micro-topographical surfaces and temporal dependence of cell morphology.

Interaction between adherent cells and extracellular matrix/scaffold surface features performs a crucial role in inducing physiological functions via signal transduction. Topographical design of scaffold surfaces, therefore, has the potential to promote physiological functions such as cell proliferation and differentiation. This study utilizes quantitative evaluation of cell-material interaction to identify how temporal dependence of cell morphology impacts cell adhesion force activation on nano/micro-ordered topographical surfaces. Nano-rough and micro-dot/line-patterned poly-lactic acid substrates were prepared to enable: (i) examination of the morphology of lamellipodia/filopodia, focal adhesion coupled with vinculin accumulations, and actin-filaments of osteoblast-like cells; and (ii) assay of the cell detachment force by single cell force spectroscopy. The quantitative evaluation results evidenced that in the initial period (cell adhesion time after initial attachment on any location, ta < 1 h), while nano-topographical surface enhanced detachment force of "spherical" cells, micro-topographical surfaces did not have this effect. Significantly, the identical micro-topographical surfaces were able to enhance detachment force of "spreading" cells in intermediate (1 < ta < 12 h) and long-term periods (ta > 24 h). These findings could be utilized in the design of scaffold surfaces to promote cell-material interaction (e.g. strengthening of the cell-substrate adhesion force), in tissue engineering.