Dual effect of 2D WS2 nanoparticles on the lysozyme conformation.

In the present work we studied the effect of 2D WS2 nanoparticles on the conformational changes in lysozyme protein at different pH values (2.0-11.5). The contributions of various structural conformations (α-helix, β-sheets parallel and antiparallel, unordered structure and side groups) were determined by decomposition of Amid I absorbance bands. The 2D WS2 were shown to have different impact on secondary structure depending on pH of the solution and protein concentration. The amyloid fibril presence was confirmed with confocal microscopy enhanced by gold support, and fluorescent spectroscopy with amyloid-sensitive dye Thioflavin T. Our data show that WS2 can both inhibit and stimulate amyloid formation. Additionally, we have also reported an unusual spectroscopic behavior displayed by lysozyme, indicated by narrowing of Amide I and Amide II bands at pH 2.5 and 3.5 when incubated with 2D WS2 nanoparticles.