Molecularly Imprinted Tunable Binding Sites Based on Conjugated Prosthetic Groups and Ion-Paired Cofactors

Post-imprinting modification of molecularly imprinted polymer for proteins detection: A review

Inspired by protein post-translational modification (PTM), post-imprinting modification (PIM) has been proposed and developed to prepare novel molecularly imprinted polymers (MIPs), which are similar to functionalized biosynthetic proteins. The PIM involves site-directed modifications in the imprinted cavity of the MIP, such as introducing high-affinity binding sites and introducing fluorescent signal molecules. This modification makes the MIP further functionalized and improves the shortcomings of general molecular imprinting, such as single function, low selectivity, low sensitivity, and inability to fully restore the complex function of natural antibodies. This paper describes the characteristics of PIM strategies, reviews the latest research progress in the recognition and detection of protein biomarkers such as lysozyme, prostate-specific antigen, alpha-fetoprotein, human serum albumin, and peptides, and further discusses the importance, main challenges, and development prospects of PIM. The PIM technology has the potential to develop a new generation of biomimetic recognition materials beyond natural antibodies. It can be used in bioanalysis and other multitudinous fields for its unique features in molecule recognition.

A molecularly imprinted nanocavity with transformable domains that fluorescently indicate the presence of antibiotics in meat extract samples

In this study, we aimed to create synthetic polymer receptors with the fluorescence signalling ability, using molecular imprinting, precisely designed template molecules, and site-specific post-imprinting modifications, which can mimic conjugated proteins and are capable of specific molecular recognition, and wherein successful binding can be indicated by a change in fluorescence. A molecularly imprinted APO-type nanocavity with a reconstructable domain was prepared by co-polymerisation of a template molecule containing cephalexin conjugated to polymerisable groups via a Schiff base, a disulphide bond, and a cross-linker, followed by hydrolysis of the Schiff base and a disulphide exchange reaction. Fluorescence-based indication of binding was devised by the Schiff base formation reaction with 4-formylsalicylic acid, and the interacting site was introduced via a disulphide exchange reaction with 4-mercaptobenzoic acid, yielding a multifunctional mature (HOLO)-type molecularly imprinted nanocavity. The ability to indicate binding events using changes in the fluorescence of the HOLO polymer was investigated, and it was revealed that the target antibiotic cephalexin can be selectively detected in aqueous media with high affinity (K_a = 1.1 × 10⁴ M^-1). Furthermore, the proposed sensor exhibited the potential to detect spiked cephalexin in chicken extracts with a limit of detection of 18 μM (1.3 ppm). The proposed fluorescence-sensing system based on molecular imprinting and post-imprinting modification is expected to enable the development of advanced materials for the specific detection of trace antibiotics in complex samples.

A descriptive and comparative analysis on the adsorption of PPCPs by molecularly imprinted polymers

Molecularly imprinted polymers (MIPs) have aroused great attention as a new material for the removal or detection of pharmaceuticals and personal care products (PPCPs). However, it is not clear about the superiority and deficiency of MIPs in the process of removing or detecting PPCPs. Herein, we evaluated the performance of MIPs in the aspects of adsorption capacity, binding affinity, adsorption rate, and compatibility to other techniques, and proposed ways to improve its performance. Without regard to the selectivity of MIPs, for the PPCPs adsorption, MIPs surprisingly did not always perform better than the conventional adsorbents (non-imprinted polymers, biochar, activated carbon and resin), indicating that MIPs should be used where selectivity is crucial, for example recovery of specific PPCPs in an environmental sample extraction process. Compared to the traditional solid-phase extraction for PPCPs detection pretreatment, the usage of MIPs as substitute extraction agents could obtain high selectivity of specific substance, due to the uniformity and effectiveness of the specific sites. A promising development in the future would be to combine other simple and rapid quantitative technologies, such as electro/photochemical sensor and catalytic degradation, to realize rapid and sensitive detection of trace PPCPs.

Signalling molecular recognition nanocavities with multiple functional groups prepared by molecular imprinting and sequential post-imprinting modifications for prostate cancer biomarker glycoprotein detection

Novel sequential post-imprinting modifications were demonstrated on the development of multi-functionalized molecularly imprinted polymers for a biomarker glycoprotein.

Inhibition of HER2-Positive Breast Cancer Growth by Blocking the HER2 Signaling Pathway with HER2-Glycan-Imprinted Nanoparticles

Blocking the HER2 signaling pathway has been an effective strategy in the treatment of HER2-positive breast cancer. It mainly relies on the use of monoclonal antibodies and tyrosine-kinase inhibitors. Herein, we present a new strategy, the nano molecularly imprinted polymer (nanoMIP). The nanoMIPs, imprinted using HER2 N-glycans, could bind almost all HER2 glycans and suppress the dimerization of HER2 with other HER family members, blocking the downstream signaling pathways, thereby inhibiting HER2+ breast cancer growth. In vitro experiments demonstrated that the nanoMIPs specifically targeted HER2+ cells and inhibited cell proliferation by 30 %. In vivo experiments indicated that the mean tumor volume of the nanoMIP-treated group was only about half of that of the non-treated groups. This study provides not only a new possibility to treat of HER2+ breast cancer but also new evidence to boost further development of nanoMIPs for cancer therapy.

Binding-promoted chemical reaction in the nanospace of a binding site: effects of environmental constriction

Chemical reactions in a confined nanospace can be very different from those in solution. Imine formation between molecular amines and an aldehyde inside a molecularly imprinted receptor was promoted strongly by the binding. Although how well the amine fit in the binding pocket and its electronic nature both influenced the reaction, the freedom of movement for the amine was the most important factor determining the binding-normalized reactivity.

Beyond natural antibodies – a new generation of synthetic antibodies created by post-imprinting modification of molecularly imprinted polymers

Post-imprinting modification (PIM) is an innovative strategy for generating MIPs analogous to biosynthesising proteins to introduce new functionalities in a site-directed manner.

Fluorescent nanoparticle sensors with tailor-made recognition units and proximate fluorescent reporter groups

Molecular imprinting in micelles followed by covalent modification of the binding pocket yielded fluorescent sensors with precisely constructed binding pockets.

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

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.

Catalytic Formation of Disulfide Bonds in Peptides by Molecularly Imprinted Microgels at Oil/Water Interfaces

This work describes the preparation and investigation of molecularly imprinted polymer (MIP) microgel (MG) stabilized Pickering emulsions (PEs) for their ability to catalyze the formation of disulfide bonds in peptides at the O/W interface. The MIP MGs were synthesized via precipitation polymerization and a programmed initiator change strategy. The MIP MGs were characterized using DLS analysis, SEM measurement, and optical microscopy analysis. The dry and wet MIP MGs showed a hydrodynamic diameter of 100 and 280 nm, respectively. A template rebinding experiment showed that the MIP MGs bound over two times more template (24 mg g^-1) compared to the uptake displayed by a nonimprinted reference polymer (NIP) MG (10 mg g^-1) at saturation. Using the MIP MGs as stabilizers, catalytic oxidation systems were prepared by emulsifying the oil phase and water phase in the presence of different oxidizing agents. During the cyclization, the isolation of the thiol precursors and the oxidizing reagents nonselectively decreased the formation of the byproducts, while the imprinted cavities on the MIP MGs selectively promoted the intramolecular cyclization of peptides. When I₂ was used as the oxidizing agent, the MIP-PE-I₂ system showed a product yield of 50%, corresponding to a nearly 2-fold increase compared to that of the nonimprinted polymer NIP-PE-I₂ system (26%). We believe the interfacial catalysis system presented in this work may offer significant benefits in synthetic peptide chemistry by raising productivity while suppressing the formation of byproducts.

Fluorescence signaling molecularly imprinted polymers for antibiotics prepared via site-directed post-imprinting introduction of plural fluorescent reporters within the recognition cavity

An antibiotic-imprinted cavity with two different fluorescent dyes was prepared by molecular imprinting and subsequent post-imprinting modifications (PIMs), for the readout of a specific binding event as a fluorescence signal.

A molecularly imprinted nanocavity-based fluorescence polarization assay platform for cortisol sensing

The sensing nano-platform for cortisol detection was developed on the basis of the fluorescence polarization assay involving the competitive binding of dansyl-cortisol and cortisol against molecularly imprinted polymer nanoparticles.

Synthesis of Monodispersed Submillimeter-Sized Molecularly Imprinted Particles Selective for Human Serum Albumin Using Inverse Suspension Polymerization in Water-in-Oil Emulsion Prepared Using Microfluidics

We synthesized monodispersed submillimeter-sized (100 μm-1 mm) microgels by inverse suspension polymerization of water-soluble monomer species with a photoinitiator in water-in-oil (W/O) droplets formed by the microchannel. After fundamental investigations of the selection of suitable surfactants, surfactant concentration, and flow rate, we successfully prepared monodispersed submillimeter-sized W/O droplets. Because radical polymerization based on thermal initiation was not appropriated based on colloidal stability, we selected photoinitiation, which resulted in the successful synthesis of monodispersed submillimeter-sized microgels with sufficient colloidal stability. The microgel size was controlled by the flow rate of the oil phase, which maintained the monodispersity. In addition, the submillimeter-sized microgels exhibit high affinity and selective binding toward HSA utilizing molecular imprinting. We believe the monodispersed submillimeter-sized molecularly imprinted microgels can be used as affinity column packing materials without any biomolecules, such as antibodies, for sample pretreatment to remove unwanted proteins without a pump system.

Preparation of molecularly imprinted polymers for the recognition of proteins via the generation of peptide-fragment binding sites by semi-covalent imprinting and enzymatic digestion

An acryloyl protein was copolymerized with a crosslinker, followed by enzymatic digestion, yielding protein imprinted polymers bearing peptide-fragment binding sites.

Efficient passivated phthalocyanine-quantum dot solar cells

The power conversion efficiency of CdSe and CdS quantum dot sensitized solar cells is enhanced up to 45% for CdSe and 104% for CdS by passivation with an asymmetrically disulfide substituted phthalocyanine.

Molecular imprinting science and technology: a survey of the literature for the years 2004-2011

Herein, we present a survey of the literature covering the development of molecular imprinting science and technology over the years 2004-2011. In total, 3779 references to the original papers, reviews, edited volumes and monographs from this period are included, along with recently identified uncited materials from prior to 2004, which were omitted in the first instalment of this series covering the years 1930-2003. In the presentation of the assembled references, a section presenting reviews and monographs covering the area is followed by sections describing fundamental aspects of molecular imprinting including the development of novel polymer formats. Thereafter, literature describing efforts to apply these polymeric materials to a range of application areas is presented. Current trends and areas of rapid development are discussed.

Molecularly imprinted protein recognition cavities bearing exchangeable binding sites for postimprinting site-directed introduction of reporter molecules for readout of binding events

Protein-imprinted cavities bearing exchangeable domains to be used for postimprinting fluorophore introduction to transform binding events into fluorescence changes were constructed in molecularly imprinted polymer (MIPs) matrixes prepared on glass substrates. Copolymerization was performed with acrylamide, N,N'-methylenebisaclylamide, and a newly designed functional group-exchangeable monomer, ({[2-(2-methacrylamido)ethyldithio]ethylcarbamoyl}methoxy)acetic acid (MDTA), in the presence of a model basic protein, lysozyme (Lyso); MDTA can interact with Lyso and assemble close to Lyso in the resulting polymer. After removal of Lyso, followed by a disulfide reduction to cleave the (ethylcarbamoylmethoxy)acetic acid moiety from the MDTA residues, the exposed thiol groups within the imprinted cavities were modified by aminoethylpyridyldisulfide to be transformed into aminoethyl groups that function as active sites for amine-reactive fluorophores. Fluorescein isothiocyanate (FITC) was then coupled with the aminoethyl groups, yielding site specifically FITC-modified signaling imprinted cavities for Lyso binding. Because the in-cavity fluorescent labeling was achieved via a disulfide linkage, it was easy to remove, exchange, and/or replace amine-reactive fluorophores. This facilitated the screening of fluorophores to select the highest readout for binding events, replace fluorophores when photobleaching occurred, and introduce other functions. The proposed molecular imprinting process, combined with postimprinting modifications, is expected to provide an affordable route to develop multifunctional MIPs for specific detection of protein binding events.

Conjugated-protein mimics with molecularly imprinted reconstructible and transformable regions that are assembled using space-filling prosthetic groups

Conjugated-protein mimics were obtained using a new molecular imprinting strategy combined with post-imprinting modifications. An antibiotic was employed as a model template molecule, and a polymerizable template molecule was designed, which was composed of the antibiotic and two different prosthetic groups attached through a disulfide bond and Schiff base formation. After co-polymerization with a cross-linker, the template molecule was removed together with the prosthetic groups, yielding the apo-type scaffold. Through conjugation of the two different prosthetic groups at pre-determined positions within the apo-type scaffold, the apo cavity was transformed into a functionalized holo cavity, which enables the on/off switching of the molecular recognition ability, signal transduction activity for binding events, and photoresponsive activity.

Synthesis and properties of magnetic molecularly imprinted polymers based on multiwalled carbon nanotubes for magnetic extraction of bisphenol A from water

Novel magnetic molecularly imprinted polymers based on multiwalled carbon nanotubes (MWNTs@MMIPs) with specific selectivity toward bisphenol A were synthesized using bisphenol A as the template molecule, methacrylic acid, and β-cyclodextrin as binary functional monomers and ethylene glycol dimethacrylate as the cross-linker. The MWNTs@MMIPs were characterized by Fourier transform infrared, vibrating sample magnetometer, and transmission electron microscopy. Batch mode adsorption experiment was carried out to investigate the specific adsorption equilibrium and kinetics of the MWNTs@MMIPs. The MWNTs@MMIPs exhibited good affinity with a maximum adsorption capacity of 49.26 μmol g(-1) and excellent selectivity toward bisphenol A. Combined with high-performance liquid chromatography analysis, the MWNTs@MMIPs were employed to extract bisphenol A in tap water, rain water, and lake water successfully with the recoveries of 89.8-95.4, 89.9-93.4, and 87.3-94.1%, respectively.

On the influence of crosslinker on template complexation in molecularly imprinted polymers: a computational study of prepolymerization mixture events with correlations to template-polymer recognition behavior and NMR spectroscopic studies

Aspects of the molecular-level basis for the function of ethylene glycol dimethacrylate and trimethylolproprane trimethacrylate crosslinked methacrylic acid copolymers molecularly imprinted with (S)-propranolol have been studied using a series of all-component and all-atom molecular dynamics studies of the corresponding prepolymerization systems. The crosslinking agents were observed to contribute to template complexation, and the results were contrasted with previously reported template-recognition behavior of the corresponding polymers. Differences in the extent to which the two crosslinkers interacted with the functional monomer were identified, and correlations were made to polymer-ligand recognition behavior and the results of nuclear magnetic resonance spectroscopic studies studies. This study demonstrates the importance of considering the functional monomer–crosslinker interaction when designing molecularly imprinted polymers, and highlights the often neglected general contribution of crosslinker to determining the nature of molecularly imprinted polymer-template selectivity.

SPR sensing of bisphenol A using molecularly imprinted nanoparticles immobilized on slab optical waveguide with consecutive parallel Au and Ag deposition bands coexistent with bisphenol A-immobilized Au nanoparticles

A slab-type optical waveguide (s_OWG)-based microfluidic SPR measurement system for bisphenol A was developed. This s_OWG possesses consecutive parallel gold and silver deposition bands in the line of plasmon flow, allowing two individual SPR signals to be independently obtained as a result of the difference in resonant reflection spectra of these metals. As a molecular recognition element, molecularly imprinted polymer nanoparticles (MIP-Np) were employed and immobilized on the surface of each of the gold and silver deposition bands. The resonant reflection spectra were measured on the MIP-Np-immobilized consecutive parallel gold and silver deposition bands coexistent with BPA-AuNp. The Ag-based SPR spectra showed a red shift (0.7 nm) when free BPA (0.1 mM) was passed over the BPA-AuNp/immobilized MIP-Np complexes formed on the s_OWG, unlike the case for the Au deposition band, while a large excess of BPA induced a blue shift due to the competitive desorption of BPA-AuNp from the immobilized MIP-Np on the s_OWG. By using the proposed detection system, binding events of other small molecules could be monitored in conjunction with the use of MIP-Np and labeled-AuNp.