Hydrogel Coatings on a NiTi-Thin films for Controlled Cell Growth
Katharina Siemsen, Rodrigo Lima de Miranda, Eckhard Quandt, Christine Selhuber-Unkel
Hydrogels and their use as coatings are promising biomaterials for mimicking the environment of cells on implant materials to control cell reactions. We here present a strategy that combines the advantages of the metallic compound, such as shape-memory effect and high strength, with the tunable stiffness and functionalization properties of hydrogels to control cell growth. Therefore, we used alginate as biomaterial scaffold and as a soft hydrated biopolymer coating material for NiTi-thin films. Alginate is investigated in its properties by changing the weight fraction, grafting with another hydrogel, degradation properties, and the concentration of the functionalization with bonding proteins to achieve cell adhesion. The coating is attained using spin coating and manual printing. A covalent bonding between NiTi-thin film and the biopolymer alginate is achieved by a surface functionalization of NiTi-thin film with APTES. Fibroblasts Ref 52 wt., i.e. cells of the extracellular matrix, and SHSy5y neuroblastoma cell, which have the characteristics of neurons, were used as reference for different properties in cell type environments. Comparing pure NiTi-thin films and hydrogel scaffolds, these different cells require different properties of samples surfaces to reach comparable cell growth. Most importantly, growth depends on type of contact towards the hydrogel, i.e. cells located on the surface or within the pores. These results show, that the control of cell growth on implant materials can be tuned with hydrogel coatings and the three-dimensional contact of the cells to the hydrogel. Moreover, further work to structure hydrogels for mimicking the natural extracellular matrix make future applications for coated medical devices feasible.