Platform and Reagent Optimization Towards Detection of PFOA With a Simple Lateral Flow Assay

Abstract

Current methods to detect PFOA in drinking water require expensive, specialized equipment and trained operators. This research builds on previous research with the goal of creating a low-cost flow rate based microfluidic assay to test water for PFOA. The aims of this research include creating a platform for repeatable capillary flow rate-based testing and to determine the optimal reagents that interact with PFOA. Utilizing System Automated Loading for Sample Analysis (SALSA), the platform achieved greater consistency within individual chip channels and across multiple chips, evidenced by reduced standard deviation when compared to traditional pipetting techniques. Additionally, the platform demonstrated improved k-value consistency over successive uses relative to manual pipetting. The research also evaluated seven reagents for their effectiveness in detecting perfluorooctanoic acid (PFOA) in deionized water samples. Of these reagents, glutamine and L-lysine showed no statistically significant differences between PFOA-spiked samples and controls, indicating they may not significantly alter k-values for further assay development. In contrast, larger proteins such as bovine serum albumin (BSA) and lysozyme yielded promising results for PFOA detection. BSA displayed linear detection within the range of 100 ag/µL to 1 pg/µL PFOA, enabling approximate concentration measurement. This study identifies five reagents—BSA, lysozyme, myoglobin, glycine, and L-aspartic acid—as suitable for PFOA detection in water samples using a flow rate-based assay. The potential for further refinement of the assay towards cost-effectiveness and specificity, as well as the application of machine learning for enhanced data analysis, is highlighted. In initial ML trails using XGBoost, samples spiked with PFOA were differentiated from a DI control with 95% accuracy. Notably, the SALSA platform provides a viable solution for consistent chip loading in various flow rate-based assays, offering rapid performance and cost-efficiency without the need for target-specific antibodies.