Pyridoxal conjugated gold nanoparticles for distinct colorimetric detection of chromium(III) and iodide ions in biological and environmental fluids

We developed pyridoxal conjugated gold nanoparticles (CAPy-AuNPs) for the selective colorimetric detection of Cr³⁺ and iodide ions in an aqueous medium. The CAPy decorated AuNPs showed selective aggregation in the presence of Cr³⁺ and I^- ions, resulting in a distinct color change from red to blue, which was in response to the surface plasmon resonance absorption of dispersed or aggregated nanoparticles. An assay was used to detect the concentrations of Cr³⁺ and I^- in real samples, such as liquid milk, milk power, river and tap water, and urine, and the recoveries ranged from 90 to 123.6%, indicating that the method could be used for extensive practical applications in complicated environmental and biological samples.