title: Highly sensitive and selective detection of Pb2+ ions using a novel and simple DNAzyme-based quartz crystal microbalance with dissipation biosensor.
abstract: A novel, label-free DNAzyme-based quartz crystal microbalance with dissipation monitoring (QCM-D) biosensor was developed for the highly sensitive and specific detection of Pb(2+) ions. To enhance the performance of the sensor, oligonucleotide-functionalized gold nanoparticles were used for both frequency and dissipation amplification. This sensor was developed by immobilizing Pb(2+)-specific DNAzymes onto the QCM-D sensor surface and allowing them to hybridize with substrate-functionalized AuNPs. The DNAzyme catalyzed the cleavage of the substrate in the presence of Pb(2+) ions, causing the cleaved substrate-functionalized AuNPs to be removed from the sensor surface. Thus, Pb(2+) ions can be determined on-line by monitoring the change in frequency and dissipation signals. The results revealed that the sensor showed a sensitive response to Pb(2+) ions with detection limits of 14 nM and 20 nM for frequency and dissipation, respectively. This QCM-D biosensor also exhibited excellent selectivity toward Pb(2+) ions in the presence of other divalent metal ions. In addition, the approach was able to detect Pb(2+) in tap water, demonstrating its great potential for monitoring drinking water quality. The proposed sensor system described here represents a new class of lead ion sensor. Its simple detection strategy makes it feasible for 'pollution-free' detection; thus, the approach could have applications in on-line water quality monitoring.
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore. chmlifys@nus.edu.sg.
authors.forename: Hui Boon
authors.initials: HB
authors.lastname: Teh
authors.forename: Haiyan
authors.initials: H
authors.lastname: Li
authors.forename: Sam Fong
authors.initials: SF
authors.lastname: Yau Li
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods*; D021881:DNA, Catalytic / Q000737:chemistry / Q000378:metabolism; D006046:Gold / Q000737:chemistry; D007477:Ions / Q000737:chemistry; D007854:Lead / Q000032:analysis*; D053768:Metal Nanoparticles / Q000737:chemistry; D009693:Nucleic Acid Hybridization; D009841:Oligonucleotides / Q000737:chemistry / Q000378:metabolism; D058525:Quartz Crystal Microbalance Techniques; D014867:Water / Q000737:chemistry
chemical_list: D021881:DNA, Catalytic; D007477:Ions; D009841:Oligonucleotides; D014867:Water; D007854:Lead; D006046:Gold