Graphene-based Nanosensors for Rapid Detection of Low-concentration PFAS in Water

PROJECT SUMMARY Access to safe drinking water is critical for human health and healthy ecosystems. Per- and polyfluoroalkyl substances (PFAS) have been found to cause cancer and other health issues and it is becoming known how widespread they are in the environment. PFAS does not breakdown in the environment and slowly accumulates over time. This causes the amount of carcinogenic material in the environment to gradually accumulate over time, which increases health risks. These compounds have been used extensively for decades to manufacture products such as materials to extinguish fires, add water repellency to fabric, and in non-stick cookware. Two of the most common are perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA). These compounds are toxic and prevalent in water systems used for human consumption at low concentrations, but testing is performed infrequently on samples shipped to laboratories for analysis with expensive equipment by trained technicians. Therefore, there is an unmet need for a rapid, low-cost, point-of-use testing device. This project intends to address this unmet need through the development of graphene-based sensor chips and a portable handheld detector capable of measuring low concentrations of PFAS in water using PFOS and PFOA as model PFAS compounds. NanoAffix has developed graphene-based sensors on gold interdigitated electrodes (IDEs) that are capable of rapid detection of other contaminants in water at point-of-use. This disruptive technology takes advantage of the unique properties of graphene to detect small changes in conductivity caused by contaminants binding to the graphene-based sensor surface. This small change in conductivity can be correlated to concentration to provide quantitative results. A probe is immobilized onto the graphene-based sensor surface to add specificity to the sensors. PFAS have been shown to selectively attach to β-cyclodextrin (β-CD) due to its unique cage-like structure enabling host-guest interactions, together with electrostatic and hydrophobic interactions between PFAS and β-CD. NanoAffix has the objectives of developing a proof-of-concept technology to detect PFAS down to 1 ng/L (ppt) within 50% of results obtained by LC-MS-MS, studying the effect of potential interfering species and minimizing the impact to below 20% of the signal response, and demonstrating sensor performance with a prototype handheld testing device. The development of this prototype testing device will provide rapid and onsite results for the detection of these carcinogens in water and enable cost-effective mitigation strategies to be implemented to improve the quality and safety of drinking water.