title: A DNA-gold nanoparticle-based colorimetric competition assay for the detection of cysteine.
abstract: 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.
authors.affiliation: Department of Chemistry and International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, USA.
authors.forename: Jae-Seung
authors.initials: JS
authors.lastname: Lee
authors.forename: Pirmin A
authors.initials: PA
authors.lastname: Ulmann
authors.forename: Min Su
authors.initials: MS
authors.lastname: Han
authors.forename: Chad A
authors.initials: CA
authors.lastname: Mirkin
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D003124:Colorimetry / Q000295:instrumentation* / Q000379:methods; D003460:Crystallization / Q000379:methods; D003545:Cysteine / Q000032:analysis* / Q000737:chemistry; D004247:DNA / Q000737:chemistry*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006046:Gold / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D036103:Nanotechnology / Q000295:instrumentation* / Q000379:methods; D010316:Particle Size; D013499:Surface Properties
chemical_list: D046911:Macromolecular Substances; D006046:Gold; D004247:DNA; D003545:Cysteine