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.　©　2025