Self-assembled gold nanoparticles and amphiphile peptides: a colorimetric probe for copper(ii) ion detection. Issue 45 (5th May 2020)

• Record Type: Journal Article
• Authors: Pelin, Juliane N. B. D.; Edwards-Gayle, Charlotte J. C.; Martinho, Herculano; Gerbelli, Barbara B.; Castelletto, Valeria; Hamley, Ian W.; Alves, Wendel A.
• Is Part Of: Dalton transactions. Volume 49:Issue 45(2020)
• Page Start: 16226
• Page End: 16237
• Publication Date: 2020-05-05
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/d0dt00844c
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : We show that arginine/phenylalanine based peptides can be used to control the aggregation of gold nanoparticles in different ways. The arrangement provides a colorimetric approach to detect Cu 2+ ions in water. Abstract : Morphological, spectroscopic and scattering studies of the self-assembly and aggregation process of hybrids containing gold nanoparticles (AuNPs) and the amyloid peptides [RF]4 and P[RF]4 (where R = arginine; F = phenylalanine; P = proline) in aqueous solution were performed. Two methodologies were tested for the AuNP nucleation, using sodium borohydride (NaBH4 ) or epigallocatechin gallate (EGCG) as a reducing agent. This led to remarkable distinct modes of assembly, AuNP decorated fibrils with NaBH4 reduction or isolated AuNPs with EGCG reduction. For both methodologies, the presence of spherical AuNPs was observed by plasmonic resonance bands in absorption spectra at ∼520 nm. Zeta potential measurements confirmed stable systems, with a similar aggregation state. Circular dichroism spectra revealed an antiparallel β-sheet conformation of the peptides. The transmission electron microscopy (TEM) images showed the coexistence of nanometer fibers and globular nanoparticles with 20 nm size. The small-angle X-ray scattering (SAXS) results show that the NaBH4 systems presented large cylindrical structures, while with increasing P[RF]4 content, a decrease in radius was observed. However, the EGCG-AuNPs were characterized by spherical particles, with a radius of 10–20 nm. Also, the colorimetric efficiency of the hybrids in the capture of Cu 2+ ions in solution was monitored. Raman spectroscopy data confirmed the conformation/structure of self-assembled samples. Moreover, there are indications for a surface-enhanced Raman spectroscopy (SERS) effect for Cu 2+ sites. The set of results indicates that these systems could act as a promising sensitive metal concentration probes.