Orientationally Fabricated Zwitterionic Molecularly Imprinted Nanocavities for Highly Sensitive Glycoprotein Recognition

Preparation of lysozyme-imprinted mesoporous Zr-based metal-organic frameworks with remarkable specific recognition

The development of high-performance protein-imprinted materials remains challenging due to defects concerning high mass transfer resistance and non-specific binding, which are crucial for protein purification and enrichment. In this paper, lysozyme-imprinted mesoporous Zr-based MOF (mesoUiO-66-NH2@MIPs) with specific and selective recognition of lysozyme (Lyz) were prepared by surface imprinting technology. In particular, the excellent hydrophilicity mesoporous MOFs (mesoUiO-66-NH2) with a pore size of 10 nm was prepared as a carrier for Lyz immobilization by an auxiliary modulation strategy to regulate the microporous structure of UiO-66-NH2 with the propionic acid solution, enabling massive loading of the macromolecular protein Lyz. The mesoUiO-66-NH2@MIPs reached a maximum saturation adsorption of 206.54 mg g-1 on Lyz in 20 min at 25 °C with an imprinting factor of 2.57 and selection factors of 2.02, 2.34, and 2.45 for cytochrome c (Cyt c), bovine serum albumin (BSA) and bovine hemoglobin (BHb), respectively. More importantly, the mesoUiO-66-NH2@MIPs could specifically recognize Lyz from the mixed protein system. The adsorption capacity of Lyz could still reach 78.55% after 5 cycles with good cyclic regeneration performance. This provides a new research option for developing and applying novel porous MOF in biomolecule imprinting technology and the specific separation of biomolecules.

Microfluidic synthesis of pH-responsive molecularly imprinted silica nanospheres for fluorescence sensing target glycoprotein

Here, fluorescent artificial antibodies for sensing ovalbumin in food were synthesized by molecular imprinting technique in a microfluidic reactor. A phenylboronic acid-functionalized silane was employed as the functional monomer to enable the polymer has pH-responsive property. Fluorescent molecularly imprinted polymers (FMIPs) could be produced continuously in a short time. Both fluorescein isothiocyanate (FITC) and rhodamine B isothiocyanate (RB)-based FMIPs can specifically recognize the target ovalbumin, particularly FITC-based FMIP, giving an imprinting factor of 2.5 and cross-reactivity factors of 2.7 (ovotransferrin), 2.8 (β-lactoglobulin) and 3.4 (bovine serum albumin), and was applied for the detection of ovalbumin in milk powder with recovery rates of 93-110%; moreover, the FMIP can be reused at least four times. Such FMIPs have promising future in replacing the fluorophore-labelled antibodies to fabricate fluorescent sensing devices or establish immunoassay methods, which have extra merits of low-cost, high stability and recyclability, easy to carry and store at ambient environments.

Cell-membrane-inspired polymers for constructing biointerfaces with efficient molecular recognition

Fabrication of devices that accurately recognize, detect, and separate target molecules from mixtures is a crucial aspect of biotechnology for applications in medical, pharmaceutical, and food sciences. This technology has also been recently applied in solving environmental and energy-related problems. In molecular recognition, biomolecules are typically complexed with a substrate, and specific molecules from a mixture are recognized, captured, and reacted. To increase sensitivity and efficiency, the activity of the biomolecules used for capture should be maintained, and non-specific reactions on the surface should be prevented. This review summarizes polymeric materials that are used for constructing biointerfaces. Precise molecular recognition occurring at the surface of cell membranes is fundamental to sustaining life; therefore, materials that mimic the structure and properties of this particular surface are emphasized in this article. The requirements for biointerfaces to eliminate nonspecific interactions of biomolecules are described. In particular, the major issue of protein adsorption on biointerfaces is discussed by focusing on the structure of water near the interface from a thermodynamic viewpoint; moreover, the structure of polymer molecules that control the water structure is considered. Methodologies enabling stable formation of these interfaces on material surfaces are also presented.

Nanoscale SPR sensor for the ultrasensitive detection of the ovarian cancer marker carbohydrate antigen 125

In this study, a nanoscale surface plasmon resonance (SPR) sensor was developed to determine the ovarian cancer marker carbohydrate antigen (CA) 125 level in serum utilizing the molecular imprinting method.

Recent progress and perspectives in applications of 2-methacryloyloxyethyl phosphorylcholine polymers in biodevices at small scales

Bioinspired materials have attracted attention in a wide range of fields. Among these materials, a polymer family containing 2-methacryloyloxyethyl phosphorylcholine (MPC), which has a zwitterionic phosphorylcholine headgroup inspired by the...

Fighting Antibiotic-Resistant Bacteria : Promising Strategies Orchestrated by Molecularly Imprinted Polymers

Infections caused by antibiotic-resistant bacteria are difficult and sometimes impossible to treat, making them one of the major public health problems of our time. We highlight how one unique material , molecularly imprinted polymers (MIPs), can orchestrate several strategies to fight this major societal issue. MIPs are tailor-made biomimetic supramolecular receptors that recognize and bind target molecules with a high affinity and selectivity, comparable to those of antibodies. While research on MIPs for combatting cancer has been constantly flourishing, comprehensive work on their involvement in combatting resistant superbugs has been rather scarce. This review aims at filling this gap. We will describe what are the causes of bacterial resistance and at which level MIPs can deploy their weapons. MIPs' targets can be biofilm constituents, quorum sensing messengers, bacterial surface proteins and antibiotic-deactivating enzymes, among others. We will conclude on the current challenges and future developments in this field.

Molecularly imprinted colloidal array with multi-boronic acid sites for glycoprotein detection under neutral pH

Glycoproteins play vital roles in living organisms and often serve as biomarkers for some disease. However, due to the low content of glycoprotein in biological fluids, selective detection of glycoproteins is still a challenging issue that needs to be addressed. In this study, molecularly imprinted colloidal array with multi-boronic acid sites for glycoprotein detection under physiological pH was proposed. Monodispersed glycoprotein imprinted particles (SiO₂@PEI/MIPs) was first prepared based on surface imprinting strategy using horseradish peroxidase (HRP) as template, and polyethyleneimine (PEI) was used to increase the number of boronic acid groups. The binding experiment indicated that the SiO₂@PEI/MIPs hold satisfactory adsorption capacity (1.41 μmol/g), rapid adsorption rate (40 min) and preferable selectivity toward HRP. Then the SiO₂@PEI/MIPs was assembled into close-packed colloidal array to construct a label free optical sensor (denoted as GICA). Benefiting from the high ordered photonic crystal structure, binding of HRP onto the GICA could be directly readout from the changes in structure color and diffracted wavelength. The structure color of the GICA changed from bright blue to yellow with the diffraction wavelength red shifted 59 nm when the HRP concentration increased from 2.5 to 15 μmol/L. Importantly, the GICA was capable of detecting HRP from human serum samples. All those results indicated the potential of the GICA for naked-eye detection of glycoprotein.

Fabrication of Raspberry-like Cytochrome C Surface-Imprinted Nanoparticles Based on MOF Composites for High-Performance Protein Separation

The development of high-performance protein-imprinted materials is vital to meet the requirements of proteomics research but remains a challenge. Herein, a new type of raspberry-like cytochrome C-imprinted nanoparticle was first designed and fabricated via surface imprinting technology combined with a template immobilization strategy. In particular, the state-of-the-art metal-organic framework (MOF)/carbon nanoparticle (CN) composites were selected as protein immobilization carriers for two advantages: (1) the composites reflected the intrinsic characteristics of MOFs including flexible design, facile preparation, and extensive interactions with proteins and (2) the utilization of composites also overcame the issue associated with the severe agglomeration of individual MOFs during the post-use process. Therefore, the as-prepared composites exhibited a regular raspberry-like shape with good dispersion (polydispersity index (PDI) < 0.25), high specific surface area (551.4 m² g^-1), and outstanding cytochrome C immobilization capacity (900 mg g^-1). Furthermore, a zwitterionic monomer was chosen to participate in the synthesis of an imprinting layer to reduce the nonspecific binding with proteins. As a result, the unique design presented here in both the protein immobilization carrier and the selected polymer composition endowed the imprinted material (noted as CN@UIO-66@MIPs) with the excellent ability for cytochrome C enrichment with extremely high recognition ability (imprinting factor (IF) = 6.1), rapid adsorption equilibrium time (40 min), and large adsorption capacity (815 mg g^-1). Furthermore, encouraged by the experimental results, we successfully used CN@UIO-66@MIPs to specifically capture cytochrome C in mixed protein solutions and biological samples, which proved them to be a potential candidate for protein separation and purification.

Protein-imprinted polymer films prepared via cavity-selective multi-step post-imprinting modifications for highly selective protein recognition

The use of molecularly imprinted polymers (MIPs) for achieving synthetic receptors capable of selective molecular recognition is promising; however, these polymers exhibit low selectivity derived from the heterogeneity of their created, imprinted cavities. To achieve highly selective protein recognition, we herein report the cavity-selective, multi-step, post-imprinting modification of MIPs. An MIP film for lysozyme was prepared by the copolymerization of {[2-(2-methacrylamido)ethyldithio]ethylcarbamoyl}methoxy acetic acid, a functional monomer possessing a modifiable disulfide bond, with acrylamide and N,N'-methylenebisacrylamide in the presence of lysozyme. After the removal of lysozyme, the disulfide bonds were cleaved by treatment with a reductant. A low concentration of lysozyme was then added to occupy the high-affinity cavities of the polymer and sterically protect the thiol groups within them. A poly(ethylene glycol)-based capping agent was reacted with the thiol groups residing in low-affinity cavities to hinder them. After the regeneration of the high-affinity cavities by washing out the bound lysozyme, the remaining thiol groups were reacted with 3-(2-pyridyldithio)propionic acid to introduce interacting groups, which produced capped MIPs. Comparing the capped and uncapped MIPs revealed that off-target protein binding was effectively suppressed by the capping treatment without any reduction in binding affinity (1.1 × 10⁹ M^-1). Further investigation revealed that the lysozyme concentration during the capping process is critical for the selectivity of the capped MIP. In this case, highly selective MIPs were achieved when the lowest lysozyme concentration (100 nM) was used. This facile process for creating highly selective, synthetic polymer receptors is a powerful approach for achieving plastic antibodies.

Oriented Immobilization of Protein Templates: A New Trend in Surface Imprinting

In this Review, we have summarized recent trends in protein template imprinting. We emphasized a new trend in surface imprinting, namely, oriented protein immobilization. Site-directed proteins were assembled through specially selected functionalities. These efforts resulted in a preferably oriented homogeneous protein construct with decreased protein conformation changes during imprinting. Moreover, the maximum functionality for protein recognition was utilized. Various strategies were exploited for oriented protein immobilization, including covalent immobilization through a boronic acid group, metal coordinating center, and aptamer-based immobilization. Moreover, we have discussed the involvement of semicovalent as well as covalent imprinting. Interestingly, these approaches provided additional recognition sites in the molecular cavities imprinted. Therefore, these molecular cavities were highly selective, and the binding kinetics was improved.

Molecularly Imprinted Nanogels Possessing Dansylamide Interaction Sites for Controlling Protein Corona In Situ by Cloaking Intrinsic Human Serum Albumin

Nanomaterials have become increasingly promising for biomedical applications owing to their specific biological characteristics. As drug delivery vehicles, nanomaterials have to circulate in the bloodstream to deliver the encapsulated components to the target tissues. Protein corona regulation is one of the promising approaches that gives stealth capability to avoid immune response. The aim of this study was to develop molecularly imprinted polymer nanogels (MIP-NGs) capable of protein corona regulation, using intrinsic human serum albumin (HSA) and with a functional monomer, dansylamide ethyl acrylamide (DAEAm), the dansylamide group serving as a ligand for HSA. The recognition capability of HSA for MIP-NGs was investigated by isothermal titration calorimetry (ITC). The affinity of the MIP-NGs prepared with DAEAm was then compared to that of the reference MIP-NGs prepared with pyrrolidyl acrylate developed in our previous study. Furthermore, we demonstrated that the concurrent use of these two different functional monomers for molecular imprinting was further effective to construct high-affinity recognition nanocavities for HSA and to form HSA-rich protein corona in the human plasma owing to the different interaction modes of the monomers. We believe that the molecular imprinting strategy developed through the use of ligand-based functional monomer is an effective strategy to create artificial molecular recognition materials.

Molecular Imprinted Polymers Coupled to Photonic Structures in Biosensors: The State of Art

Optical sensing, taking advantage of the variety of available optical structures, is a rapidly expanding area. Over recent years, whispering gallery mode resonators, photonic crystals, optical waveguides, optical fibers and surface plasmon resonance have been exploited to devise different optical sensing configurations. In the present review, we report on the state of the art of optical sensing devices based on the aforementioned optical structures and on synthetic receptors prepared by means of the molecular imprinting technology. Molecularly imprinted polymers (MIPs) are polymeric receptors, cheap and robust, with high affinity and selectivity, prepared by a template assisted synthesis. The state of the art of the MIP functionalized optical structures is critically discussed, highlighting the key progresses that enabled the achievement of improved sensing performances, the merits and the limits both in MIP synthetic strategies and in MIP coupling.

Molecularly Imprinted Nanogels Capable of Porcine Serum Albumin Detection in Raw Meat Extract for Halal Food Control

Accurate, simple, and valuable analytical methods for detection of food contamination are rapidly expanding to evaluate the validity of food product quality because of ethnic considerations and food safety. Herein molecularly imprinted nanogels (MIP-NGs), capable of porcine serum albumin (PSA) recognition, were prepared as artificial molecular recognition elements. The MIP-NGs were immobilized on a quartz crystal microbalance (QCM) sensor for detection of pork contamination in real beef extract samples. The MIP-NGs-based QCM sensor showed high affinity and excellent selectivity toward PSA compared to reference serum albumins from five different animals. The high PSA specificity of MIP-NGs led to the detection of pork contamination with a detection limit of 1% (v/v) in real beef extract samples. We believe the artificial molecular recognition materials prepared by molecular imprinting are a promising candidate for halal food control.

Creation of glycoprotein imprinted self-assembled monolayers with dynamic boronate recognition sites and imprinted cavities for selective glycoprotein recognition

Glycoproteins are involved in the pathogenesis and development of many diseases and are used as biomarkers for disease diagnosis. It is highly desirable to develop highly sensitive and selective methods for the detection of glycoproteins without the use of antibodies. Imprinting of proteins represents one of the most challenging tasks. Glycoprotein imprinted self-assembled monolayers (SAMs) were created, for the first time, from an oligo(ethylene glycol) (OEG) terminated 1,2-dithiolane derivative linked through an alkyl chain incorporated with two amide groups (DHAP) and combined functional thiols of p-mercaptophenylboronic acid (PMBA) and p-aminothiophenol (PATP) in aqueous media, without the use of polymerization initiators. Combined action of PMBA and PATP was essential for the development of boronate recognition sites for glycoproteins at the physiological pH, attributed to the water molecule-mediated Lewis acid-base interactions between the electron-deficient PMBA and the electron-rich PATP. DHAP played key roles not only in cementation of imprinted cavities by means of double hydrogen bond networks through the amide groups but also in resistance to nonspecific protein binding by terminal OEG moieties, as well as hydrogen bond binding sites from the amide groups exposed to imprinted cavities. The created glycoprotein imprinted SAMs showed excellent recognition selectivity of target glycoproteins. The strategy for tailor-made glycoprotein imprinted SAMs explores a new avenue to the creation of intelligent biomaterials and fabrication of chemosensors.

Hexagonally Packed Macroporous Molecularly Imprinted Polymers for Chemosensing of Follicle-Stimulating Hormone Protein

Homogenous nanostructuration of molecularly imprinted polymer (MIP) films for follicle-stimulating hormone (FSH)-sensing was achieved by using optimized colloidal crystals as a hard mold. Introduction of a heating step after assembling colloidal crystals of silica beads promoted their adhesion. Thus, precise assembling of beads was not disturbed during further multisteps of surface imprinting, and crack-free hexagonal packing was maintained. Scanning electron microscopy imaging confirmed hexagonal packing of silica colloidal crystals as well as homogenous nanostructuration in MIP films. FSH immobilization over silica beads and later its derivatization with electroactive functional monomers was confirmed by X-ray photoelectron spectroscopy analysis. The nanostructured molecular recognition films prepared in this way were combined with an electrochemical transducer in order to design a capacitive impedimetry-based chemosensing system. It was tested for the determination of FSH in the range from 0.1 fM to 100 pM in 10 mM 2-(N-morpholino) ethane sulfonic acid buffer (pH = 4.2). The detection limit of the chemosensor was 0.1 fM, showing a high selectivity with respect to common protein interferences as well as other protein hormones of the gonadotropin family.

Fluorescent nanosensor designing via hybrid of carbon dots and post-imprinted polymers for the detection of ovalbumin

We reported a facile strategy to assemble a ratiometric nanosensor for the ovalbumin (OVA) fluorescence determination and meanwhile it can be utilized for selective visual identification by naked eyes with fluorescent test papers under 365 nm UV lamp. The nanosensor was prepared through simply mixing blue color carbon dots (CDs) and green color core-shell imprinted polymers. Blue CDs were used directly as the internal reference without participating in the imprinting process and modified molecularly imprinted polymers (MIPs) were synthesized by post-imprinting, using fluorescein isothiocyanate (FITC) as fluorescence enhanced signal. Upon the addition of different concentrations of OVA, the fluorescence intensity of FITC was enhanced, while the fluorescence intensity of CDs was almost unchanged, leading to a detection limit as low as 15.4 nM. Accordingly, the fluorescence color was gradually changed from blue to dark olive green to green with naked eyes observation. Moreover, the ratiometric nanosensor was successfully applied to detect OVA in the human urine samples with satisfactory recoveries attaining of 92.0-104.0% with relative standard deviation (RSD) of 3.3-3.9% and 93.3-101.0% with RSDs of 2.7-3.8% for the spiked chicken egg white samples. This strategy reported here opens a novel pathway for biomacromolecule detection in real applications and can realize the visual observation on fluorescent test papers.

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.

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

We report on the development of new optical sensors using molecularly imprinted polymers (MIPs) combined with different materials and explore the novel strategies followed in order to overcome some of the limitations found during the last decade in terms of performance. This review pretends to offer a general overview, mainly focused on the last 3 years, on how the new fabrication procedures enable the synthesis of hybrid materials enhancing not only the recognition ability of the polymer but the optical signal. Introduction describes MIPs as biomimetic recognition elements, their properties and applications, emphasizing on each step of the fabrication/recognition procedure. The state of the art is presented and the change in the publication trend between electrochemical and optical sensor devices is thoroughly discussed according to the new fabrication and micro/nano-structuring techniques paving the way for a new generation of MIP-based optical sensors. We want to offer the reader a different perspective based on the materials science in contrast to other overviews. Different substrates for anchoring MIPs are considered and distributed in different sections according to the dimensionality and the nature of the composite, highlighting the synergetic effect obtained as a result of merging both materials to achieve the final goal.

Towards Detection of Glycoproteins Using Molecularly Imprinted Nanoparticles and Boronic Acid-Modified Fluorescent Probe

Glycoproteins represent a group of important biomarkers for cancer and other life-threatening diseases. Selective detection of specific glycoproteins is an important step for early diagnosis. Traditional glycoprotein assays are mostly based on lectins, antibodies, and enzymes, biochemical reagents that are costly and require special cold chain storage and distribution. To address the shortcomings of the existing glycoprotein assays, we propose a new approach using protein-imprinted nanoparticles to replace the traditional lectins and antibodies. Protein-imprinted binding sites were created on the surface of silica nanoparticles by copolymerization of dopamine and aminophenylboronic acid. The imprinted nanoparticles were systematically characterized by dynamic light scattering, scanning and transmission electron microscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy, and elemental analysis. A boronic acid-modified fluorescent probe was used to detect the target glycoprotein captured by the imprinted nanoparticles. Using horseradish peroxidase as a model glycoprotein, we demonstrated that the proposed method can be applied to detect target protein containing multiple glycosylation sites. Because of their outstanding stability and low cost, imprinted nanoparticles and synthetic probes are attractive replacements of traditional biochemical reagents to develop simpler, faster, and more cost-effective analytical methods for glycoproteins.