Electrically conductive lignin reinforced PAA/HA scaffolds with enhanced biological activity via polyelectrolyte multilayer coatings for tissue engineering applications

In this study, a layer-by-layer deposition of poly(L-lysine) and hyaluronic acid (HA) as a polyelectrolyte multilayer (PEM) film on polyacrylic acid (PAA) /HA/ lignin (LIG) disc shaped scaffolds is presented to increase the biological activity of the scaffolds for tissue engineering applications. These scaffolds are electrically conductive via the introduction poly(3,4-ethylene dioxythiophene):hyaluronic acid (PEDOT:HA) nanoparticles (NPs), with a diameter of 10 mm and thickness of 3-4 mm. The multilayer film formation was confirmed through contact angle measurements, fluorescence microscopy and scanning electron microscopy (SEM) imaging. It was found that the PEM layers had the unexpected benefit of increased compression strength and decreased swelling as the layers tend to reinforce the struts of the scaffolds whilst possibly interfering with diffusion pathways. Importantly, results show statistically significant improved attachment and proliferation of L929 fibroblast cells on the surface of the scaffolds. Furthermore, the effect of varied PEDOT:HA NP addition was assessed and it was concluded that samples containing 1% (w/v) of nanoparticles exhibited a desirable balance between good mechanical characteristics, high conductivity, high cell adhesion and cell proliferation. These novel conductive PEM composite scaffolds offer future potential in biomedical applications such as tissue engineering, wound healing and biosensors.