This is the monthly networking meeting for faculty and staff affiliated with NDnano. For more information on affiliating with the Center, please contact Heidi Deethardt at deethardt.1@nd.edu.

Date: Tuesday, October 1


Time: 12:00 pm - 1:00 pm



Location: 253 Nieuwland Science Hall

Presenter: Saurja DasGupta
Assistant Professor, Chemistry and Biochemistry

Title: FloureSenseRNA: A new RNA aptamer-based platform for detecting toxic heavy metals

Abstract: Heavy metal contamination is a global health concern, creating a critical need for easy-to-use and cost-effective sensors for rapid environmental monitoring. Portable and inexpensive kits would enable regular testing of water in high-risk neighborhoods and in water bodies near industrial and mining sites. Conventional methods such as AAS and ICP-MS/OES are sensitive but involve elaborate instrumentation and trained operators. While chemical color tests are easy to use, they exhibit poor sensitivity and selectivity. The lack of effective point-of-care devices for toxic heavy metal detection is due to both the absence of high-precision sensing platforms and their translation into field deployable formats. We developed FluoreSenseRNA, an RNA aptamer-based sensor platform that currently includes sensors for Pb2+ and Hg2+ that exhibit limits of detection of ~0.5 ppb for both. These are 30- and 4-fold lower than their EPA allowable limits in drinking water, respectively. Simplicity of design and use is the primary advantage of this platform: each sensor is composed of a short, easily synthesized RNA aptamer and a commercially-available fluorogenic dye. Upon binding to the analyte, the aptamer changes its structure allowing it to bind the dye and emit a bright and stable fluorescence signal.

We validated the performance of these sensors in tap water to demonstrate applicability in real-world samples. Toward our goal of field-deployment, we developed portable kits that use freeze-dried sensors, where all the user has to do is add their water sample, and shine an off-the-shelf UV light/LED: heavy metal contamination is revealed by a fluorescent glow. This freeze-dried format dramatically increases shelf-life of the sensor, and improves portability. This sensor has been integrated with a 3D-printed portable fluorescence reader (~$30), which generates accurate measurements of Pb2+ and Hg2+ levels. In parallel, we have started integrating these sensors with paper-based microfluidics and established a preliminary spot-test that will serve as a foundation for more advanced paper-based devices as point-of-care sensors. Further, we demonstrated intracellular imaging of Hg2+ in human cells using our RNA-based mercury sensor, unlocking the opportunity to study the uptake, release, and intracellular distribution of Hg2+ with implications for monitoring mercury toxicity.