Developing antibacterial superhydrophobic coatings based on polydimethylsiloxane/silver phosphate nanocomposites: Assessment of surface morphology, roughness and chemistry

Nanocomposite coatings based on polydimethylsiloxane (PDMS) and silver phosphate (Ag₃PO₄) nanoparticles were developed to achieve superhydrophobicity, antibacterial behavior and low protein adsorption. Since the as-synthesized nanoparticles were hydrophilic, octadecanethiol was added into the coatings’ solutions. Wettability results demonstrated that the higher the nanoparticle content, the higher the water contact angle (WCA). The highest WCA was observed for 7 wt% inclusion of nanoparticles (152°). Morphological analysis revealed the surface localization of nanoparticles and a packed structure in case of 7 wt% nanoparticle inclusion. From the roughness results, the ratio of texture surface area to cross-sectional area was found to be notably increased at higher nanoparticle contents. The presence of Ag₃PO₄ nanoparticles at the coatings’ top layer was confirmed by X-ray photoelectron spectroscopy. Antibacterial activity of the coatings significantly enhanced upon increasing the nanoparticle content. As a result of a true superhydrophobic (roll-off) behavior for 7 wt% nanoparticle inclusion, the protein adsorption was highly reduced (∼83 %) due to the enclosed air layer within the surface cavities leading to a lowered contact area of proteins with the coating's surface. The combination of superhydrophobicity, antibacterial behavior and low protein adsorption leads to a biocompatible coating which could have many biomedical applications needing further investigations.