Colorimetric detection of cysteine based on dispersion - aggregation of chitosan stabilized gold nanoparticles

A simple and selective colorimetric method of detection of cysteine using chitosan stabilized gold nanoparticles has been developed. L-cysteine is a sulfur containing amino acid. Cysteine binds with the gold nanoparticles through sulfur group and induces aggregation of the nanoparticles which leads to an apparently visible color change from pale red to blue. A good linearity was observed from 0.1 to 30 ÂľM (R=0.9958) cysteine and the limit of detection was found to be 0.1ÂľM. The gold nanoparticles showed a high selectivity towards the detection of cysteine even in the presence of 10,000 fold higher concentration of common interferences such as glutathione, methionine and homocysteine. A plausible mechanism for the selective detection of cysteine in presence of interferences based on a dispersion-aggregation mechanism has been proposed.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author