Natural Melanin Composites by Layer-by-Layer Assembly

Melanin is an electrically conductive biomaterial from human skin, eyes, brain, and beyond, because their conjugated backbone structures provide conducting pathways. Thus, there is a potential of using as materials for the neural interfaces and the body implantable devices. Extracted from Sepia officinalis ink, our natural melanin was uniformly dispersed in polar solvents such as water and alcohols. Then, the dispersed melanin was further fabricated to nano-thin layered composites by the layer-by-layer (LBL) assembly technique. Combined with polyvinyl alcohol (PVA), the melanin nanoparticles behave as an LBL component to from finely tuned nanostructured films. The LBL process can adjust the smart performances of the composites by varying the layering conditions and sandwich thickness. We further demonstrated the melanin loading degree of stacked layers, combination nanostructures, and biocompatibility of the resulting composites by UV-vis spectrophotometer, scanning electron microscope (SEM), and in-vitro cell test of PC12, respectively.