Preparation and evaluation of highly hydrophilic aptamer-based hybrid affinity monolith for on-column specific discrimination of ochratoxin A.

Nonspecific adsorption is a challenge of specific recognition on aptamer-based affinity monoliths. Here, a novel highly hydrophilic polyhedral oligomeric silsesquioxane (POSS)-containing aptamer-based hybrid-silica affinity monolith with a good recognition nature was prepared and used for specific discrimination of ochratoxin A (OTA). A homogeneous polymerization mixture consisted of POSS chemicals, hydrophilic monomers and aptamer solution was directly polymerized via the "one-pot" method. Preparation and characterization of the resultant affinity monolith were studied in detail. A highly hydrophilic nature was obtained and the typical hydrophilic interaction liquid chromatography (HILIC) was observed when acetonitrile (ACN) content in mobile phase was 25%, which reached the highest hydrophilicity of POSS-based hybrid monoliths. By using OTA as model analyte, the nonspecific adsorption was effectively suppressed. The recovery of the analogue ochratoxin B (OTB) was only about 0.1% even if the content of OTB was 50 times more than OTA, which was much better than other POSS-containing monoliths and polar siloxane-based hybrid monoliths. Applied to beer samples, the adsorption of background materials was drastically resisted, and efficient recognition of OTA was obtained with the recoveries of 94.9-99.8%. Much less disturbance was observed than that occurred in hydrophobic POSS-based affinity monolith. It lights an attractive implement with high hydrophilicity and specificity for online selective recognition of OTA.