  Motivated by some recent works showing the ability of semiconducting
monolayers to disintegrate the structures of biological fibrils, we have
applied molecular dynamics (MD) simulations in both classical and quantum
regimes to investigate whether semiconducting Si$_3$N$_4$ monolayer has the
same ability on interaction with U-shaped amyloid beta (A$\beta$) fibril. In
agreement with the literature, we found that disintegration began from the last
chain (E) due to the rather strong interaction between the monolayer and the
fibril residues numbered from 17 to 28 on the very chain, also engaging the
next chain (D) over time. As a result, the $\beta$-sheet-rich content of chain
E considerably decreases on interaction with the monolayer, turning into other
secondary-structure types including turn and coil, in accordance with
experimental findings. Results endorse the view that semiconducting Si$_3$N$_4$
monolayer has the potential of destabilizing the structure and conformation of
U-shaped amyloid beta fibrils.
