Dual-mode monolithic column with zwitterion antifouling and aptamer affinity for online specific recognition of okadaic acid

Developing a functional media for precise identification of trace shellfish toxin would underpin the effective assessment of marine pollution. Herein, a novel monolithic column with a dual-mode strategy integrating antifouling and aptamer bionic affinity recognition was proposed for online specific identification of the marine toxin okadaic acid (OA). The zwitterionic monomer 2-(methacryloyloxy)ethylphosphorylcholine (MPC) and aptamers were synergistically employed to enable efficient reduction of matrix interferences and selective capture of target OA. Preparation optimization, characterization, and fouling-resistant mechanism of the dual-mode bionic monolith were evaluated. The zwitterion phosphorylcholine MPC introduced into the monolith significantly improved the fouling resistance to biomass substrates, meanwhile the aptamers were able to provide a high specific recognition capacity. Coupled with LC-MS, the as-prepared monolith provided an effective approach for highly selective and sensitive identification of OA. Good recovery yields of over 90 % in shellfish tissue extracts and human serum were achieved with a sensitive limit of detection (LOD) as low as 0.1 ng/mL, as well as excellent specificity and low interference from proteins, fatty acids and analogues. Applied to popular shellfishes (such as clams, mussels, and oysters) and serum samples, trace OA toxin was accurately distinguished and quantified with satisfactory recoveries as 93.8 ± 2.2 % – 99.9 ± 1.9 % (n = 3). Compared to the traditional HLB cartridge and other materials in the LC-MS method, the resulting anti-fouling aptamer monolith provided a more advanced online analysis mode with higher sensitivity and better resolution of OA in biological samples. It might provide an attractive access to an online bionic recognition platform with LC-MS for efficient, anti-interference and sensitive specific detection of trace marine toxin OA in biological samples.