Figure 5: Colourimetric sensing of Cu2+.
From: Multipath colourimetric assay for copper(II) ions utilizing MarR functionalized gold nanoparticles
(A) Photographs of multiple antibiotic resistance regulator (MarR)-coated AuNP (M–AuNP) solutions with different concentrations of Cu2+ in the range from 100 nM to 20 μM. (B) UV–vis spectra of the M–AuNP solutions. (C) Plot of the A600/A520 absorbance ratios of M–AuNP solutions versus the concentrations of Cu2+. (D) Photographs of M–AuNP solutions with different concentrations of Cu2+ using a smartphone under artificial white light without flash. (E) and (F) Plot of blue/red colour values of the smartphone photographs versus the concentrations of Cu2+. Error bars at n = 3.
