ZnO nanoparticle-incorporated native collagen films with electro-conductive properties.

Collagen obtained from bovine skin was mechanically pre-treated with the aim of preserving the triple helix structure of native collagen. Furthermore, zinc oxide nanoparticles were incorporated into film forming formulations due to their inherent biological properties, which are of great relevance for biomedical applications. All the films showed good mechanical properties with a predominant elastic behavior, as shown by dynamic mechanical analysis (DMA) curves, and collagen films were easy to handle in both dry and wet states. It is worth noting that the integrity in the wet state was achieved without incorporating chemical crosslinkers, in contrast to chemically treated collagen that must be crosslinked chemically due to collagen denaturation after the pre-treatment. As shown by Fourier Transform Infrared (FTIR) spectroscopy analysis, collagen preserved the triple helix structure, although a slight decrease was observed with the increase of zinc oxide nanoparticles (ZnO NPs) content, which slightly increased the equilibrium swelling values and also caused some changes in the denaturation collagen peak observed above 200 °C by Differential Scanning Calorimetry (DSC) measurements. Additionally, collagen films showed good barrier properties, protection again Ultraviolet (UV) light and optimal Water Vapor Permeability (WVP) values (occlusivity) for biomedical purposes such as wound healing, since the WVP values measured would allow exudates' absorption. Regarding electrical conductivity, collagen films presented a semiconductor behavior and memory properties and, thus, these films could be used as biosensors.