Highly Sensitive Colorimetric Assay for Determining Fe3+ Based on Gold Nanoparticles Conjugated with Glycol Chitosan

A highly sensitive and simple colorimetric assay for the detection of fe3+ ions was developed using gold nanoparticles (aunps) conjugated with glycol chitosan (gc). the fe3+ ion coordinates with the oxygen atoms of gc in a hexadentate manner (o-fe3+-o),decreasing the interparticle distance and inducing aggregation. time-of-flight secondary ion mass spectrometry showed that the bound fe3+ was coordinated to the oxygen atoms of the ethylene glycol in gc,which resulted in a significant color change from light red to dark midnight blue due to aggregation. using this gc-aunp probe,the quantitative determination of fe3+ in biological,environmental,and pharmaceutical samples could be achieved by the naked eye and spectrophotometric methods. sensitive response and pronounced color change of the gc-aunps in the presence of fe3+ were optimized at ph 6,70°c,and 300 mm nacl concentration. the absorption intensity ratio (a700/a510) linearly correlated to the fe3+ concentration in the linear range of 0-180 μm. the limits of detection were 11.3,29.2,and 46.0 nm for tap water,pond water,and iron supplement tablets,respectively. owing to its facile and sensitive nature,this assay method for fe3+ ions can be applied to the analysis of drinking water and pharmaceutical samples. © 2017 kyungmin kim et al.