Buildup of Biomimetic and Multiple Stimuli Responsive Thin Coatings of Polysaccharides and Recombinant Biopolymers

The modification of surfaces has been used in cutting-edge applications to produce smart or stimuli-responsive and patterned surfaces that may be used to develop several biomedical technologies. In this work, smart thin coatings using chitosan and recombinant elastin-like polymers (ELP) containing the cell attachment sequence RGD were fabricated in a sequential fashion through layer-by-layer adsorption. The adsorption of each layer was followed in situ using a quartz-crystal microbalance with dissipation monitoring and showed that both polymers can be successfully combined to conceive multilayer coatings.

Because ELPs are a class of biomaterials exhibiting smart properties in solution, the smart properties of the coatings were tested for their wettability by contact angle measurements (CAs) as a function of several stimuli, namely temperature, pH and ionic strength. Wettability transitions were observed from a moderate hydrophobic surface (CAs approximately from 62º to 71º) to an extremely wettable one (CA considered to be 0º) as the temperature, pH and ionic strength were raised above 50 ºC, 11, and 1.25M, respectively. Atomic force microscopy was performed to assess the coating topography, showing the formation of larger and compact micelle-like structures upon the aggregation of ELPs at the surface, increasing its water affinity.

Cell adhesion tests were conducted using a SaOS-2 cell line. Enhanced cell adhesion was observed in the coatings, as compared to a coating with a chitosan-ending film and a scrambled RDG biopolymer. The developed films have great potential as biomimetic coatings of biomaterials for different tissue engineering applications, controlled delivery systems and tunable cell adhesion.