Site-specific post-imprinting modification of molecularly imprinted polymer nanocavities with a modifiable functional monomer for prostate cancer biomarker recognition

Abstract

Recognition of glycans of glycoproteins using biotic materials such as antibodies is challenging due to lack of antigenicity. Polymeric materials suitable for the molecular recognition of glycoproteins have attracted considerable attention. In this study, we aimed to develop abiotic molecular materials for the recognition of prostate-specific antigen (PSA), a known biomarker for prostate cancer. We used a non-covalent bonding-based molecular imprinting technique to introduce post-imprinting poly(ethylene glycol)-based capping agent into a lowaffinity recognition cavity. Details of the binding properties of these groups were investigated to optimize their affinity and selectivity for PSA. Molecularly imprinted polymers (MIPs) were prepared using a bottom-up approach based on surface-initiated atom transfer radical polymerization from a PSA-conjugated sensor chip with a functional monomer-bearing carboxy and secondary amine groups as interaction and post-imprinting modification (PIM) sites, respectively. PSA was orientationally conjugated on the sensor chip through diesters between the immobilized 3-fluorophenyl boronic acid and the cis-diol groups of PSA glucans. Treatment with the capping agent selectively inactivated low-affinity recognition cavities while protecting high-affinity cavities with the addition of a low concentration of PSA as a dynamic protection agent. The MIP thickness is critical in the present molecular imprinting, as a value of less than 5 nm can enable high selectivity. We believe that the proposed strategy based on a non-covalent molecular imprinting approach combined with a PIM-based capping treatment provides a novel method for the development of highly sensitive and selective glycoprotein recognition materials for use in biomarker sensing.

Differential Refractometric Biosensor for Reliable Human IgG Detection: Proof of Concept

“…After template extraction, as described in Section 2.3 , a decreasing of the RI around the LPFG (shifting 300 pm to higher wavelengths) was observed which can be related to the IgG molecules removal from the MIP layer ( Figure 4 d). In literature, similar procedures to remove electrostatically immobilized templates using NaCl were reported by other authors, e.g., by Schwark et al to remove IgG molecules from imprinted macroporous membranes; Matsumoto et al to remove prostate-specific antigen (PSA) from a synthesized MIP layer on an SPR chip; and by Yang et al when developing a selective and sensitive impedance sensor targeting the BSA protein, using a NaCl/SDS solution in the template extraction stage [ 58 , 59 , 60 ]. The resulted MIP receptors were tested in the presence of IgG antibodies and competitors.…”

Fluorescent Signaling of Molecularly Imprinted Nanogels Prepared via Postimprinting Modifications for Specific Protein Detection

“…However, such undesirable PIM sites in incomplete imprinted cavities can be hindered before introducing the fluorescence dye by a previously reported multistep PIM, called a capping treatment. [ 35,46 ]…”

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

“…We employed the PIM strategy to reduce non-specific binding. Specifically, we designed and synthesized 4-[2-(Nmethacrylamido)ethylaminomethyl]benzoic acid (MABA), a functional monomer [10] (Fig. 2), bearing a benzoic acid unit capable of interacting with target molecules, and secondary amino groups.…”