Early adhesion of cells to ferromagnetic shape memory alloys functionalized with plasma assembled biomolecules – a single cell force spectroscopy study

Abstract Biomaterial performance and integration of prostheses in vivo strongly depend on the ability of cells to adhere. Plasma-assisted functionalization of smart metals with biopolymers, including plasma polymerized l -lysine (PPLL), constitutes a recently-developed promising approach to synthesize highly flexible, yet robust and strongly adherent protein coatings that support cell-biomaterial interaction. In the present study we employ single cell force spectroscopy to demonstrate that PPLL coatings promote early adhesion of fibroblast cells on the ferromagnetic shape memory alloy Fe Pd – a promising magnetically switchable biomaterial. By varying the contact time of a cell with the substrate surface, we show that the forces and work needed to fully detach a cell increase with time and quantify bioactivity of the material. In contrast to glass and PPLL-coated glass, cell detachment from Fe Pd requires much larger work, while a PPLL biofunctionalization further improves cell adhesion and binding affinity by an increased detachment work on short time scales. Together with a time-dependent bond model we postulate a transition from unspecific to specific cell adhesion on Fe Pd and PPLL-coated Fe Pd, while on glass detachment forces are lower and level off to a saturation regime on short times prior to the expected time necessary for specific integrin-based bond formation.