Label-Free Colorimetric Detection of Lead Ions with a Nanomolar Detection Limit and Tunable Dynamic Range by using Gold Nanoparticles and DNAzyme

Authors

  • Zidong Wang,

    1. Department of Materials Science and Engineering, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana–Champaign Urbana, IL 61801 (USA)
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  • Jung Heon Lee,

    1. Department of Materials Science and Engineering, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana–Champaign Urbana, IL 61801 (USA)
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  • Yi Lu

    Corresponding author
    1. Department of Materials Science and Engineering, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana–Champaign Urbana, IL 61801 (USA)
    2. Department of Chemistry, University of Illinois at Urbana–Champaign, Urbana, IL 61801 (USA)
    • Department of Materials Science and Engineering, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana–Champaign Urbana, IL 61801 (USA).
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  • Z. W. and J. H. L. contributed equally to this work. We thank Dr. Juewen Liu and Dr. Geng Lu for helpful discussions. This work has been supported by the US Department of Energy (DE-FG02-01-ER63179), the NSF (DMR-0117792, CTS-0120978 and DMI-0328162), and the Illinois Waste Management and Research Center (WMRC).

Abstract

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In the presence of Pb2+, a cleaved enzyme–substrate complex releases ssDNA that adsorbs onto and stabilizes gold nanoparticles (AuNPs) against salt-induced aggregation. In the absence of Pb2+, the uncleaved complex can not stabilize the AuNPs, resulting in purple–blue AuNP aggregates (see figure). The sensor has a low detection limit of 3 nM, a high selectivity, and a tunable dynamic range.

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