SUSTAINABLE BIOPLASTIC FOR SUN BLOCK PATCHES AND TAPES MADE FROM REGENERATED SILK AND DNA

Bioplastics made from protein, polysaccharide, etc., have been extensively investigated in the last years. Materials such as silkworm silk and DNA can be considered as inexhaustible biopolymers, as be extracted from any organisms including plants and animals. To date, these materials have not been reported for applications to protect human skin from sunlight. In this study, patches and tapes are realized as thin films or non-woven, aligned-spun fiber textile material by exploiting the dissolution of silk fibers (e. g. regenerated silk (RS)) in different solvents capable of dissolving salmon sperm DNA. Circular dichroism, infrared spectroscopy and X-ray diffraction were used to investigate the conformational transition of RS and DNA solutions in different conditions and the structure of solid RS/DNA bioplastic. The RS/DNA bioplastic are water-insoluble and thermally stable. We therefore present the validation of our proof of concept based on biological results on cellular metabolism (MTT assay) after exposures to the simultaneous combinations of solar spectrum that consist in the emission of UVB, UVA, VIS and nIR components. The obtained bioplastic absorbs UV radiation, is pressure sensitive, adhesive once applied to the skin and improves the metabolic activity of HaCat cells. This adhesive does not leave any residue on the skin after its removal. Finally, RS fibers spun by direct extrusion in the air, create a water insoluble tape with controllable secondary structure offering a useful method for packaging and storage applications.