Antibacterial free-standing polysaccharide composite films inspired by the sea

The adhesive capabilities of marine mussel proteins are well-known, exhibiting the ability to stick to different underwater substrates, either inorganic or organic. These unique adhesive properties are due to the high levels of amino acid, 3,4-dihydroxyphenyl-l-alanine (DOPA), which presents the reactive catechol group. Herein, novel antibacterial free-standing (FS) films were developed with natural polymers, namely chitosan (CHT) and hyaluronic acid (HA), being the catechol-functionalized hyaluronic acid (HA-DN) also included to provide wet adhesive properties. In order to obtain composite films, silver doped bioglass nanoparticles (Ag-BGs) were incorporated to promote bactericidal and bioactive properties, being tested four distinct formulations of FS films. Their surface morphology and topography, wettability, weight loss, swelling, mechanical, adhesion and bioactivity was analyzed. In particular, bioactivity tests revealed that upon immersion in simulated body fluid, there was the formation of a bone-like apatite layer. Moreover, upon 16 h in direct contact with Staphylococcus aureus and Escherichia coli cultures, these FS films exhibited a clear antibacterial effect. Therefore, such bioactive, antibacterial and adhesive free-standing films could potentially be used as temporary guided bone regeneration films, in particular to regenerate small bone defects and also periodontal tissues.