Solid-phase synthesis of molecularly imprinted nanoparticles

Guide to the Preparation of Molecularly Imprinted Polymer Nanoparticles for Protein Recognition by Solid-Phase Synthesis

Molecularly imprinted polymers (MIPs) are synthetic antibody mimics possessing specific cavities designed for a target molecule. Nowadays, molecular imprinting of proteins still remains a challenge as the generation of selective imprinted cavities is extremely difficult, due to their flexible structure and the presence of a multitude of functional sites. To overcome this difficulty, we propose a solid-phase synthesis strategy to prepare MIPs specific for any protein that can be immobilized in an oriented way on a solid support. Trypsin and kallikrein were used as model proteins. The solid-phase support consists of glass beads functionalized with two affinity ligands of the enzymes, the competitive inhibitor p-aminobenzamidine to orient the enzymes via their active site, or a Cu²⁺chelate to orient via the surface histidine residues of the enzyme. Thermoresponsive molecularly imprinted polymer nanoparticles (MIP-NPs) are then synthesized around the immobilized enzyme. The MIP-NPs are released by a simple temperature change, resulting in protein-free polymers endowed with improved binding site homogeneity since all binding sites have the same orientation. The MIP-NPs exhibit apparent dissociation constants between 0.02 and 2nM toward their target proteins, which is comparable to those of natural antibodies. Moreover, these water-compatible polymers, targeting different domains of the enzyme, can also function as protective agents (armor), hence preventing the target proteins from denaturation by heat or pH.

Molecularly imprinted polymers for sample preparation and biosensing in food analysis: Progress and perspectives

Molecularly imprinted polymers (MIPs) are biomimetics which can selectively bind to analytes of interest. One of the most interesting areas where MIPs have shown the biggest potential is food analysis. MIPs have found use as sorbents in sample preparation attributed to the high selectivity and high loading capacity. MIPs have been intensively employed in classical solid-phase extraction and solid-phase microextraction. More recently, MIPs have been combined with magnetic bead extraction, which greatly simplifies sample handling procedures. Studies have consistently shown that MIPs can effectively minimize complex food matrix effects, and improve recoveries and detection limits. In addition to sample preparation, MIPs have also been viewed as promising alternatives to bio-receptors due to the inherent molecular recognition abilities and the high stability in harsh chemical and physical conditions. MIPs have been utilized as receptors in biosensing platforms such as electrochemical, optical and mass biosensors to detect various analytes in food. In this review, we will discuss the current state-of-the-art of MIP synthesis and applications in the context of food analysis. We will highlight the imprinting methods which are applicable for imprinting food templates, summarize the recent progress in using MIPs for preparing and analysing food samples, and discuss the current limitations in the commercialisation of MIPs technology. Finally, future perspectives will be given.

Development of molecularly imprinted polymers specific for blood antigens for application in antibody-free blood typing

A novel system for blood type testing is developed based on the first molecularly imprinted nanoparticles specific to oligosaccharides.

Replacement of Antibodies in Pseudo-ELISAs: Molecularly Imprinted Nanoparticles for Vancomycin Detection

The enzyme-linked immunosorbent assay (ELISA) is a widely employed analytical test used to quantify a given molecule. It relies on the use of specific antibodies, linked to an enzyme, to target the desired molecule. The reaction between the enzyme and its substrate gives rise to the analytical signal that can be quantified. Thanks to their robustness and low cost, molecularly imprinted polymer nanoparticles (nanoMIPs) are a viable alternative to antibodies. Herein, we describe the synthesis of nanoMIPs imprinted for vancomycin and their subsequent application in an ELISA-like format for direct replacement of antibodies.

A comparison of the performance of molecularly imprinted polymer nanoparticles for small molecule targets and antibodies in the ELISA format

Here we show that molecularly imprinted polymer nanoparticles, prepared in aqueous media by solid phase synthesis with immobilised L-thyroxine, glucosamine, fumonisin B2 or biotin as template, can demonstrate comparable or better performance to commercially produced antibodies in enzyme-linked competitive assays. Imprinted nanoparticles-based assays showed detection limits in the pM range and polymer-coated microplates are stable to storage at room temperature for at least 1 month. No response to analyte was detected in control experiments with nanoparticles imprinted with an unrelated template (trypsin) but prepared with the same polymer composition. The ease of preparation, high affinity of solid-phase synthesised imprinted nanoparticles and the lack of requirement for cold chain logistics make them an attractive alternative to traditional antibodies for use in immunoassays.

Selective extraction of proteins and other macromolecules from biological samples using molecular imprinted polymers

The accurate determination of intact macromolecules in biological samples, such as blood, plasma, serum, urine, tissue and feces is a challenging problem. The increased interest in macromolecules both as candidate drugs and as biomarkers for diagnostic purposes means that new method development approaches are needed. This review charts developments in the use of molecularly imprinted polymers first for small-molecular-mass compounds then for proteins and other macromolecules. Examples of the development of molecularly imprinted polymers for macromolecules are highlighted. The two main application areas to date are sensors and separation science, particularly SPE. Examples include peptides and polypeptides, lysozyme, hemoglobin, ovalbumin, bovine serum albumin and viruses.

Guided folding takes a start from the molecular imprinting of structured epitopes

A biomimetic route towards assisted folding was explored. Molecularly imprinted polymeric nanoparticles (MIP NPs), i.e. biomimetics with entailed molecular recognition properties made by a template assisted synthesis, were prepared to target a structured epitope: the cystine containing peptide CC9ox, which corresponds to the apical portion of the β-hairpin hormone Hepcidin-25. The structural selection was achieved by the MIP NPs; moreover, the MIP NPs demonstrated favouring the folding of the linear random peptide (CC9red) into the structured one (CC9ox), anticipating the future role of the MIP NPs as in situ nanomachines to counteract folding defects.