Photonics of Hydrothermally Treated β-Lactoglobulin Amyloids

Increased temperature and high pressure are applied to β-lactoglobulin fibrils in the autoclave, resulting in the acquisition of a composite material comprised of partially disassembled amyloid fibrils and carbon dots. Confirmation of the preservation of the β-sheet motif attributed to amyloids in the hydrothermally treated fibrils is obtained through wide-angle X-ray scattering and ThT assay. Z-scan analysis reveals a two-photon absorption (2PA) enhancement in the low-lying transition band (L _a) of tyrosine, while quantum chemical calculations demonstrate a correlation between the yield of 2PA and the interspace distance between aromatic residues. Overall, the intrinsic optical properties of amyloid fibrils treated in a subcritical water environment are found to be linked with the π-conjugation of tyrosine units and their through-space coupling. The resulting composite material is employed as a coating for a commercial ultraviolet light-emitting diode lamp, showcasing the potential utility of sustainable biomaterials with improved optical properties for photonics applications.