A DNA-gold nanoparticle-based colorimetric competition assay for the detection of cysteine

作者:Lee Jae Seung; Ulmann Pirmin A; Han Min Su; Mirkin Chad A*
来源:Nano Letters, 2008, 8(2): 529-533.
DOI:10.1021/nl0727563

摘要

We report the development of a highly sensitive and selective colorimetric detection method for cysteine based upon oligonucleotide-functionalized gold nanoparticle probes that contain strategically placed thymidine-thymidine (T-T) mismatches complexed with Hg2+. This assay relies upon the distance-dependent optical properties of gold nanoparticles, the sharp melting transition of oligonucleotide-linked nanoparticle aggregates, and the very selective coordination of Hg2+ with cysteine. The concentration of cysteine can be determined by monitoring with the naked eye or a UV-vis spectrometer the temperature at which the purple-to-red color change associated with aggregate dissociation takes place. This assay does not utilize organic cosolvents, enzymatic reactions, light-sensitive dye molecules, lengthy protocols, or sophisticated instrumentation thereby overcoming some of the limitations of more conventional methods.