Rapid and selective detection of cysteine based on its induced aggregates of cetyltrimethylammonium bromide capped gold nanoparticles

摘要

A detection method of cysteine is reported in this contribution with water-soluble positively charged gold nanoparticles(Au-NPs)that were prepared by seed-mediated method and capped with cetyltrimethylammonium bromide(CTAB).In aqueous medium of pH 4.2,the CTAB-capped Au-NPs display greatly different features from those of generally prepared citrate-coated Au-NPs.It was found that in a medium of high salt concentration,the presence of cysteine could induce aggregation of CTAB-capped Au-NPs,while citrate-coated Au-NPs could get aggregation soon even if without the presence of cysteine.The cysteine-induced aggregates of CTAB-capped Au-NPs display strong plasmon resonance light scattering(PRLS)signals characterized at 566.0 nm when excited by a light beam,and the PRLS intensities of the aggregates are in proportion to the concentration of cysteine in the range of 0.01-0.40 mu g mL~(-1)with the limit of detection(3 sigma)being 2.9 ng mL~(-1).No amino acids in the samples interfere with the detection,and cysteine in artificial samples could be detected with the recovery between 95.3% and 105.9%,and R.S.D.is less than 3.6%.