Multifunctional oligomer immobilized on quartz crystal microbalance: a facile and stabilized molecular imprinting strategy for glycoprotein detection.

Glycoprotein detection holds great potential for early diagnosis of diverse diseases. For this purpose, the combination of quartz crystal microbalance (QCM) sensor and molecular imprinting has attracted increasing attention. Nonetheless, the recently common imprinted films fabricated on QCM electrode are thick and rigid, lacking flexibility in aqueous phase. Alternatively, small molecules immobilized on the electrode to construct molecular scale film could address this problem, while stabilization of the imprinted sites remains challenging. Herein, a co-assembly complex was obtained by the mixture of template and multifunctional oligomer, which was then immobilized on the amino-modified transducer surface through epoxy-amino reaction to form a protein-imprinted film. Afterward, the remaining epoxy groups in oligomer chains were cross-linked to conserve and stabilize the orientation of imprinted sites after template elution. Template rebinding tests show that cross-linked film has much higher imprinting factors than that of the non-cross-linked counterpart. Furthermore, control proteins that are distinct in properties and structures were employed to demonstrate the selectivity of this approach, and the imprinted assay reveals high affinity and specificity towards template protein. Graphical Abstract.