Quantification of PCB72 in Water by Kinetics Exclusion Assay

The presented work addresses the need of monitoring organic pollutants in water, food, and other environmental sources. The extensive use of inert "forever chemicals" led to their continual accumulation in the environment at levels that threaten ecosystems and humans. Among those, polychlorinated biphenyls (PCB) present major health risks owing to their deleterious effects on the immune, nervous, and endocrine systems. Currently, PCBs are quantified by GC/MS and HPLC/MS, which are highly sensitive techniques but also laborious, time consuming, and expensive. To mitigate these shortcomings, our research focused on developing a procedure for quantifying PCBs in water by employing aptamers as biorecognition elements in conjunction with the Kinetics Exclusion Assay (KinExA) technology. To achieve our scientific goals, we functionalized microscopic beads with DNA molecules complementary to a fluorescent aptamer recognizing PCB72. Equilibrated aptamer (constant binding partner) and PCB72 (titrant) solutions were flown over a small pack of functionalized beads which retained a fraction of the non-bound aptamer. The standard curve showing the fluorescent signal of the captured fraction as a function of concentration was further used to determine the affinity of the aptamer for its target as well as the concentration in spiked samples. Our results demonstrate that the proposed technology has sufficient sensitivity to detect PCB72 in polluted water at levels relevant for human health.