title: Colorimetric biosensors based on DNAzyme-assembled gold nanoparticles.
abstract: Taking advantage of recent developments in the field of metallic nanoparticle-based colorimetric DNA detection and in the field of in vitro selection of functional DNA/RNA that can recognize a wide range of analytes, we have designed highly sensitive and selective colorimetric biosensors for many analytes of choice. As an example of the sensor design strategy, a highly sensitive and selective colorimetric lead biosensor based on DNAzyme-directed assembly of gold nanoparticles is reviewed. The DNAzyme consists of an enzyme and a substrate strand, which can be used to assemble DNA-functionalized gold nanoparticles. The aggregation brings gold nanoparticles together, resulting in a blue-colored nanoparticle assembly. In the presence of lead, the DNAzyme catalyzes specific hydrolytic cleavage of the substrate strand, which disrupts the formation of the nanoparticle assembly, resulting in red-colored individual nanoparticles. The application of the sensor in lead detection in leaded paint is also demonstrated. In perspective, the use of allosteric DNA/RNAzymes to expand the range of the nanoparticle-based sensor design method is described.
authors.affiliation: Department of Chemistry, University of Illinois-Champaign, Urbana, Illinois 61801, USA.
authors.forename: Juewen
authors.initials: J
authors.lastname: Liu
authors.forename: Yi
authors.initials: Y
authors.lastname: Lu
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D003124:Colorimetry; D021881:DNA, Catalytic / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D007854:Lead / Q000032:analysis; D046529:Microscopy, Electron, Transmission; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D010150:Paint / Q000032:analysis; D013053:Spectrophotometry; D020349:Surface Plasmon Resonance
chemical_list: D021881:DNA, Catalytic; D007854:Lead; D006046:Gold