title: Colorimetric Detection of Small Molecules in Complex Matrixes via Target-Mediated Growth of Aptamer-Functionalized Gold Nanoparticles.
abstract: A versatile and sensitive colorimetric assay that allows the rapid detection of small-molecule targets using the naked eye is demonstrated. The working principle of the assay integrates aptamer-target recognition and the aptamer-controlled growth of gold nanoparticles (Au NPs). Aptamer-target interactions modulate the amount of aptamer strands adsorbed on the surface of aptamer-functionalized Au NPs via desorption of the aptamer strands when target molecules bind with the aptamer. Depending on the resulting aptamer coverage, Au NPs grow into morphologically varied nanostructures, which give rise to different colored solutions. Au NPs with low aptamer coverage grow into spherical NPs, which produce red-colored solutions, whereas Au NPs with high aptamer coverage grow into branched NPs, which produce blue-colored solutions. We achieved visible colorimetric response and nanomolar detection limits for the detection of ochratoxin A (1 nM) in red wine samples, as well as cocaine (1 nM) and 17β-estradiol (0.2 nM) in spiked synthetic urine and saliva, respectively. The detection limits were well within clinically and physiologically relevant ranges, and below the maximum food safety limits. The assay is highly sensitive, specific, and able to detect an array of analytes rapidly without requiring sophisticated equipment, making it relevant for many applications, such as high-throughput drug and clinical screening, food sampling, and diagnostics. Furthermore, the assay is easily adapted as a chip-based platform for rapid and portable target detection.
authors.affiliation: †Department of Materials, Department of Bioengineering, and Institute of Biomedical Engineering, Imperial College London, London SW7 2AZ, London, U.K.|‡Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, The Nanos, Singapore 138669, Singapore.
authors.forename: Jun Hui
authors.initials: JH
authors.lastname: Soh
authors.affiliation: †Department of Materials, Department of Bioengineering, and Institute of Biomedical Engineering, Imperial College London, London SW7 2AZ, London, U.K.
authors.forename: Yiyang
authors.initials: Y
authors.lastname: Lin
authors.affiliation: †Department of Materials, Department of Bioengineering, and Institute of Biomedical Engineering, Imperial College London, London SW7 2AZ, London, U.K.
authors.forename: Subinoy
authors.initials: S
authors.lastname: Rana
authors.affiliation: ‡Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, The Nanos, Singapore 138669, Singapore.
authors.forename: Jackie Y
authors.initials: JY
authors.lastname: Ying
authors.affiliation: †Department of Materials, Department of Bioengineering, and Institute of Biomedical Engineering, Imperial College London, London SW7 2AZ, London, U.K.
authors.forename: Molly M
authors.initials: MM
authors.lastname: Stevens
mesh_terms: D052157:Aptamers, Nucleotide / Q000737:chemistry*; D015374:Biosensing Techniques; D003042:Cocaine / Q000737:chemistry / Q000652:urine; D003124:Colorimetry / Q000379:methods*; D004958:Estradiol / Q000737:chemistry / Q000652:urine; D006046:Gold / Q000737:chemistry*; D006801:Humans; D057230:Limit of Detection; D053768:Metal Nanoparticles / Q000737:chemistry*; D009793:Ochratoxins / Q000032:analysis; D012463:Saliva / Q000737:chemistry; D014920:Wine / Q000032:analysis
chemical_list: D052157:Aptamers, Nucleotide; D009793:Ochratoxins; C025589:ochratoxin A; D004958:Estradiol; D006046:Gold; D003042:Cocaine