Oriented, molecularly imprinted cavities with dual binding sites for highly sensitive and selective recognition of cortisol

Abstract

Novel, molecularly imprinted polymers (MIPs) were developed for the highly sensitive and selective recognition of the stress marker cortisol. Oriented, homogeneous cavities with two binding sites for cortisol were fabricated by surface-initiated atom transfer radical polymerization, using a cortisol motif template molecule (TM1) which consists of a polymerizable moiety attached at the 3-carbonyl group of cortisol via an oxime linkage and an adamantane carboxylate moiety coupled with the 21-hydroxyl group. TM1 was orientationally immobilized on a β-cyclodextrin (β-CD)-grafted gold-coated sensor chip by inclusion of the adamantane moiety of TM1, followed by copolymerization of a hydrophilic comonomer, 2-methacryloyloxyethyl phosphorylcholine, with or without a cross-linker, N,N′-methylenebisacrylamide. Subsequent cleavage of the oxime linkage leaves the imprinted cavities that contain dual binding sites—namely, the aminooxy group and β-CD—capable of oxime formation and hydrophobic interaction, respectively. As an application, MIP-based picomolar level detection of cortisol was demonstrated by a competitive binding assay using a fluorescent competitor. Cross-linking of the MIP imparts rigidity to the binding cavities, and improves the selectivity and sensitivity significantly, reducing the limit of detection to 4.8 pM. In addition, detection of cortisol in saliva samples was demonstrated as a feasibility study.

Recent Advances of Molecularly Imprinted Polymers Based on Cyclodextrin

“…Relying on the inclusion of guest molecules by supramolecular β‐CD, Suda et al. [ 90 ] constructed a MIP thin layer with directional binding cavity to cortisol based on a new type of cortisol motif template molecule (TM1). In the TM1, an adamantane moiety was introduced to interact with β‐CD by esterification of the 21‐hydroxyl group of the cortisol molecule with 1‐adamantane carboxylic acid, while a reversible oxime bond was constructed by linking a 2‐aminooxy‐ N ‐(4‐vinylphenyl) acetamide at the 3‐carbonyl group of the cortisol molecule to enables the removal of TM1 from the MIP ( Figure A).…”

“…Reproduced under terms of the CC‐BY license. [ 90 ] Copyright 2017, the Authors. Published by The Royal Society.…”

Multi-Functional Nanocavities Fabricated Using Molecular Imprinting and Post-Imprinting Modifications for Efficient Biomarker Detection

“…A PSA-immobilized substrate was prepared by utilizing a cyclic di-ester formation reaction between phenylboronic acid (introduced on the substrate) and the cis-diol of the sugar chain on PSA. As a result, PSA was immobilized on the substrate with the sugar chain facing down, this would be helped to form homogeneous imprinted cavity [12,13]. A polymer matrix was fabricated on the PSA-immobilized substrate through the surface-initiated atom transfer radical polymerization (SI-ATRP) [14].…”

Molecularly Imprinted Polymer-Based Hybrid Materials for the Development of Optical Sensors

“…In some cases, polymerization control is achieved by functionalization of the support with functional monomers or with templates that allow a superficial imprinting [67]. Suda et al [68] functionalized a gold chip with a complex molecule formed by a cyclodextrin, cortisol as template molecule and a functional monomer with a polymerizable group. In this way they develop a competitive fluorescent sensor for cortisol determination using a fluorescent probe.…”