Adhesive and biodegradable membranes made of sustainable catechol-functionalized marine collagen and chitosan.

We describe bioadhesive membranes developed from marine renewable biomaterials, namely chitosan and collagen extracted from fish skins. Collagen was functionalized with catechol groups (Coll-Cat) to provide the membranes with superior adhesive properties in a wet environment and blended with chitosan to improve the mechanical properties. The blended membranes were compared to chitosan and chitosan blended with unmodified collagen in terms of surface morphology, wettability, weight loss, water uptake, mechanical and adhesive properties. The metabolic activity, the viability and the morphology of L929 fibroblastic cells seeded on these membranes were also assessed. Our results show that the functionalization with catechol groups improves the adhesive and mechanical properties of the membranes and enhances cell attachment and proliferation. These data suggest that the developed marine origin-raw membranes present a potential towards the restoration of the structural and functional properties of damaged soft tissues.

Spin-coated freestanding films for biomedical applications.

Spin-coating is a widely employed technique for the fabrication of thin-film coatings over large areas with smooth and homogeneous surfaces. In recent years, research has extended the scope of spin-coating by developing methods involving the interface of the substrate and the deposited solution to obtain self-supported films, also called freestanding films. Thereby, such structures have been developed for a wide range of areas. Biomedical applications of spin-coated freestanding films include wound dressings, drug delivery, and biosensing. This review will discuss the fundamental physical and chemical processes governing the conventional spin-coating as well as the techniques to obtain freestanding films. Furthermore, developments within this field with a primary focus on tissue engineering applications will be reviewed.

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.