Oligopeptide Helical Conformations Control Gold Nanoparticle Cross‐Linking

Abstract

Peptide sequences functionalizedw ith primary aminesa tt he N-and C-terminusa re able to induce the aggregation of gold nanoparticlesi ne thanol as ac onsequence of their foldingi nto ah elical conformation.R andomc oil peptides are unable to induce such an aggregation process. Aggregationc an be monitored spectrophotometrically by following the shift of the surfacep lasmon resonance (SPR) band of the nanoparticles and is confirmed by transmission electron microscopy and dynamic light scattering analyses. Partiald enaturation of the peptidesr esultsi nd iminished cross-linking ability.T he helicity parameter q 222 /q 208 correlates fairly well with the shift of the SPR band to longer wavelengths,s upporting the relationship between the amount of helical content of ap eptide sequence and its abilityt oinduce aggregation.

The Interaction of Amines with Gold Nanoparticles

“…The obtained profile ( Figure A) reveals the concentration at which the surface is fully saturated by the amine (surface saturation concentration, SSC) as the break point between the flat portion of the curve (fluorescence is quenched) and the steep straight line (fluorescence no longer quenched). [ 49 ] The obtained SSC is 1.64 µ m (for a 8.6 n m AuNPs [ 50 ] concentration, see the Supporting Information). For our 9.7 ± 1.3 nm AuNPs this implies a surface density of slightly less than one Py‐C 1 NH 2 molecule nm −2 .…”

Hydrolytic Nanozymes

“…The authors argued that the flexibility of functional groups leading to productive orientations for substrate binding and catalysis, thus allowing cooperativity between them, were no longer accessible in the structured coiled‐coil dimers. We had previously shown that the change of conformation of peptides grafted on a gold cluster surface dramatically changes the interaction of the constituents amino acids with the gold(0) atoms and may control also AuNPs aggregation …”