Detection of Zn2+, Cd2+, Hg2+, and Pb2+ ions through label-free poly-L-glutamic acid

Jingqiu Hu; Michael S Elioff

doi:10.1016/j.talanta.2018.06.012

Detection of Zn²⁺, Cd²⁺, Hg²⁺, and Pb²⁺ ions through label-free poly-L-glutamic acid

Talanta. 2018 Oct 1:188:552-561. doi: 10.1016/j.talanta.2018.06.012. Epub 2018 Jun 5.

Authors

Jingqiu Hu¹, Michael S Elioff²

Affiliations

¹ Department of Chemistry, West Chester University of Pennsylvania, West Chester, PA 19383, United States. Electronic address: jhu@wcupa.edu.
² Department of Chemistry, Millersville University of Pennsylvania, Millersville, PA 17551, United States.

PMID: 30029412
DOI: 10.1016/j.talanta.2018.06.012

Abstract

Detection of heavy metal ions in water is important for environmental sustainability and food safety. Current fluorescent sensors interact with metal ions directly through chelation or chemical reactions. Those sensors are expensive to produce and often can detect only one ion at a time. Here we report a fluorescent turn-on sensor that can detect three group IIB metal ions and Pb²⁺ ions through label-free polypeptides in water. In our sensor-polypeptide mixture, Zn²⁺, Cd²⁺, Hg²⁺, and Pb²⁺ ions induce helix formation and inter-chain aggregation in poly-L-α-glutamic acid (PGA). The acridinium-based sensor molecules incorporate into the polypeptides and emit strongly with characteristic color for each group IIB ion under UV lamp. By adjusting the size of polypeptides or the length of the side chain carboxyl groups, we can selectively turn off or turn on the sensor emission for Hg²⁺ ions.

Keywords: Charge shift state; Chemical sensors; Fluorescent emission; Heavy metal ions; Poly-L-glutamic acids.