A novel and environmentally friendly colorimetric method for detection of cystine in human urine using unmodified gold nanoparticles†
Abstract
Cystine was reduced by ascorbic acid to cysteine, which induced the aggregation of unmodified gold nanoparticles. The accompanied color change was distinguishable and perceivable by the naked eye. This facile assay method was successfully applied to the detection of cystine in human urine.