Multifunctional Tannic Acid and Polyamino Acid Layer-by-Layer Coatings for Tailored Implant Surfaces

Polyphenols are attractive candidates for biological surface modifications due to their adhesive, antioxidant, anti-inflammatory, and antimicrobial properties. However, the uncontrolled release of polyphenols, such as tannic acid (TA), from the surface may lead to adverse biological responses. Polyamino acids (PAAs), such as poly-l-lysine (PLL) and poly-l-arginine (PLR), improve wound healing and act as antimicrobial agents, but their high positive charge can result in cytotoxicity. In this study, TA and PAAs were combined in layer-by-layer (LbL) coatings to take advantage of the beneficial biological properties of these molecules while limiting their release and the potential damage they can cause to the surrounding tissues. Coating formation was monitored using a quartz crystal microbalance with dissipation. Linear growth of the TA thickness versus time was observed for most of the studied conditions. TA/PLR coatings resulted in higher dissipation shifts compared with TA/PLL, indicating that PLR results in more viscoelastic coatings. Dissipation progressively increased with the number of deposited bilayers, the increase being more noticeable for TA/PLR. Modeled thickness of the coatings was greater for TA/PLR than for TA/PLL coatings. The interaction between TA and PAAs in the LbL coatings was found to be noncovalent, as determined by Fourier transform infrared (FTIR) and Ultraviolet-visible (UV-vis) spectroscopy. The addition of PAAs to the coatings prevented the release of TA but reduced their antioxidant capacity. Human gingival fibroblasts (hGFs) showed a higher viability on TA/PLL than on TA/PLR coatings. Cells adhered to both multilayer types and formed multiple focal adhesions (FA), which are essential for proper cell function.