An aptamer@AuNP-modified POSS–polyethylenimine hybrid affinity monolith with a high aptamer coverage density for sensitive and selective recognition of ochratoxin A

A novel hybrid affinity monolith with a high aptamer coverage density was developed via a highly efficient modification of aptamer@gold nanoparticles (Apt@AuNPs) on a well-controlled 3D skeletal POSS-polyethylenimine (PEI) matrix. The effects of amine reagents and the skeletal structures of the hybrid monoliths on the modification efficiency of Apt@AuNPs were studied, and the resultant Apt@AuNPs@POSS-PEI1200 monolith was proposed with a high coverage density of aptamer of up to 1413 pmol μL-1, which is 4-5 times more than the coverage density when modified with Apt@AuNPs that was reported previously. Characterization including morphology, spectra analysis, mechanical stability, binding capacity and specificity studies was also carried out. Significant specific recognition targeting of ochratoxin A (OTA) was achieved with a detection limit as low as 0.06 ng mL-1. High recoveries of OTA were achieved of 92.6 ± 1.3% to 94.7 ± 1.4% (n = 3), while the cross-reactivity towards analogues such as ochratoxin B (OTB) and aflatoxin B1 (AFB1) was weak. This highlights a facile approach to POSS-based affinity monoliths with a high aptamer coverage density for sensitive and selective recognition of a trace target (OTA).