Optimization of mucin and mucin/keratin nanofibers’ fabrication for antimicrobial applications

Background and aims One of the principal components of mucus, responsible for its gel-like, viscous, and barrier properties, is mucin, a high-molecular-weight glycoprotein often engineered to create nanoparticles, but underexplored for its potential in nanofiber shape.1 Other biopolymers are indeed commonly prepared as nanofibers, among which keratin stands out as a cysteine-rich protein (able to create disulfide bonds) that possesses several bio-related properties and is obtainable from discarded wool, one of the major textile industry's by-products.2,3 A promising technique to produce nanofibers is electrospinning, which exploits an electric field that induces a polymer solution/melt to deposit on a conductive collector.4 The scope of this work was to prepare optimized electrospun nanofibers based on mucin (alone and blended with keratin) as drug-free systems to fight microbial infections. Methods Several electrospinning procedures were tested to adjust process parameters, namely protein(s) concentration, solvent, flow rate, tip-collector distance, voltage. The stabilization to make the mucin-based mats insoluble was also the object of trials: the as-prepared nanofibers were soaked in different solvents/reactants and/or subjected to heat. The nanofibers were characterized by SEM, ATR-FTIR, DSC, wettability measures, plus antimicrobial tests through the inhibition area caused by mucin-based mats on the skin microbiota of healthy volunteers. Results A mucin/keratin formulation annealed at 180°C was proved to be stable, allowing application tests. Blend characterizations revealed the mucin-keratin chemical interactions and their synergy in inducing the microbiota growth inhibition (18 mm2) (Figs.1-2). Conclusion This work widens the mucin-based nanomaterials’ scenario, deepening preparation, characterization and application of mucin(keratin) nanofibers as drug-free substrates with intrinsic antimicrobial properties.