Highly sensitive and selective detection of Pb2+ ions using a novel and simple DNAzyme-based quartz crystal microbalance with dissipation biosensorElectronic supplementary information (ESI) available. See DOI: 10.1039/c4an00922c

• Main Authors: Teh, Hui Boon, Li, Haiyan, Yau Li, Sam Fong
• Format: Article
• Language: English
• ISSN: 0003-2654; 1364-5528
• DOI: 10.1039/c4an00922c

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. A label-free DNAzyme-based QCM-D biosensor was developed for highly sensitive and specific detection of Pb 2+ ions in drinking water.