Cyanobacteria harmful algal blooms (Cyano-HABs) are increasing in frequency and cyanotoxins have become an environmental and public concern in the U.S. and worldwide. The current detection methodologies are not providing real-time monitoring of these toxins, which compromise the successful water quality assessment and management of drinking water treatment processes.On-line advanced sensors would alert the presence of cyanotoxins in water in real-time, which is important in preventing toxins from entering a drinking water treatment plant. This oral presentation will include the successful development of a sensitive electrochemical aptamer-based biosensor in sources of drinking water, inform the challenges in developing such sensors and suggest strategies to overcome the challenges of electrochemical biosensors for cyanotoxins in surface waters. The broader impact of this presentation is to contribute to the efforts of the scientific community on addressing Cyano-HABs drinking water supply issues and prevent exposure to humans.

A novel electrochemical sensing approach has been developed. The sensor targets the point-of-use detection and quantification of the highly potent microcystin-LR (MC-LR) in water. The sensor uses hexaammineruthenium(III) chloride ([Ru(NH₃)₆]³⁺) as redox mediator and square wave voltammetry. The sensor performed well into a dynamic range of MC-LR concentrations and in drinking water samples. The limit of detection was much less than the 10-day Health Advisory released by the EPA, which leaves room for minimizing sample pretreatments and increase the sensor application for point-of-use detection and real-time application.

In an effort to develop sensors using Electrochemical impedance spectroscopy (EIS) and aptamers for the detection of MC-RR and MC-LR, a systematic study revealed fundamental understanding the EIS signal response and how to optimize the experimental conditions for development of sensitive and reproducible sensors. While nucleic-acid based sensors using EIS offer exceptional sensitivity, signal fidelity is often linked to the physical and chemical properties of the electrode-solution interface. The presented data will demonstrate the need for rigorous control experiments to ensure that the measured change in impedance is unequivocally a result of a specific interaction between the target analyte and nucleic recognition element.

Dr. Vasileia Vogiazi

Associate Service Fellow, NIOSH, CDC

Appearances