Revealing the regulation of water dipole potential to aggregation of amyloid-β42 at chiral interface by surface-enhanced infrared absorption spectroscopy

Surface chirality plays an important role in determining the biological effect,but the molecular nature beyond stereoselectivity is still unknown.Herein,through surface-enhanced infrared absorption spectroscopy,electrochemistry,and theoretical simulations,we found diasteromeric monolayers induced by assembled density on chiral gold nanofilm and identified the positive contribution of water dipole poten-tial at chiral interface and their different interfacial interactions,which result in a difference both in the positive dipoles of interfacial water compensating the negative surface potential of the SAM and in the hindrance effect of interface dehydration,thereby regulating the interaction between amyloid-βpeptide(Aβ)and N-isobutyryl-cysteine(NIBC).Water on L-NIBC interface which shows stronger positive dipole potential weakens the negative surface potential,but its local weak binding to the isopropyl group facilitates hydrophobic interaction between Aβ42 and L-NIBC and resultedfiber aggregate.Conversely,electrostatic interaction between Aβ42 and D-NIBC induces spherical oligomer.Thesefindings provide new insight into molecular nature of chirality-regulated biological effect.