Multifunctional Hybrid Nanocomposite Nanofibers Produced by Colloid Electrospinning from Water Solutions

Few polymers with practical and technological appeal can be electrospun into nanofibers from water solutions. The production of polymer nanofibers from water solution is considered green, up-scalable and versatile. From this point of view, the use of nanoparticles in the form of water colloidal suspension instead of nano-powder should be more affordable and safer. The combination of these two aspects makes a breakthrough in materials science on electrospun nanomaterials. In this work, multi-component organic/inorganic nanofibers were produced by electrospinning water solutions of a protein extracted from wool (i.e. keratin) containing nanosols of titanium dioxide and metal silver. In order to improve electrospinnability, poly(ethylene oxide) was added to the solutions. Colloidal stability was studied in depth to preserve nanoparticle dimension as smaller as possible in the electrospinning solutions. Resulting hybrid keratin-based nanofibers were made water insoluble by treatments at high temperature, expanding the range of applications of such a nanomaterial. In this way, it was also possible to wash out poly(ethylene oxide) from nanofibers maintaining a nanofibrous structure and small-sized porosity comparable to the as-spun materials. Finally, the functional properties of electrospun hybrid nanofibers were evaluated. Both antibacterial and photo-catalytic activities of titanium dioxide nanoparticles embedded into the nanofibers were quantified, as well as antibacterial property of nano-silver. The results demonstrate that nanoparticle functionalities were maintained in electrospun keratin nanofibers.