Figure 3
From: Multipath colourimetric assay for copper(II) ions utilizing MarR functionalized gold nanoparticles
(A) Optical absorption spectra of gold nanoparticle (AuNP) solutions: (a) bare AuNPs; (b) multiple antibiotic resistance regulator (MarR)-coated AuNPs (M–AuNPs); (c) AuNPs+Cu2+; (d) M–AuNPs+Cu2+. Inset of (A): photographic image of the AuNP dispersion showing that the colour change occurs only in the presence of M–AuNPs and Cu2+ (20 μM). (B) Corresponding transmission electron microscopy images (scale bars: 50 nm).
