An Epitope-Imprinted Biointerface with Dynamic Bioactivity for Modulating Cell-Biomaterial Interactions

High selectivity molecularly imprinted polymer based on short amylose as bio-based functional monomers for selective extraction of λ-cyhalothrin

Nowadays, the development of sustainable molecularly imprinted polymers (MIPs) with high selectivity is still challenging due to the limitations of bio-based functional monomers. In this study, the highly selective and porous MIPs (LC-TMIPs) were designed and prepared on short amylose (SAM) as bio-based functional monomers, λ-cyhalothrin (LC) as a template molecule, and tetrafluoroterephthalonitrile as a rigid crosslinking agent. Static, dynamic, and selective adsorption experiments were conducted to investigate the adsorption performance. The results indicated that, compared to MIPs prepared using epichlorohydrin as flexible crosslinking agents, LC-TMIPs exhibited higher imprinting factor (3.93), selectivity (5.78), and adsorption capacity (35.79 mg g-1), as well as faster adsorption/desorption kinetics. The LC-TMIPs were used as sorbents for the selective determination of LC in both apple and cucumber samples by high-performance liquid chromatography. Under the optimal extraction conditions, the recoveries of the method reached 92.1-106.1 %, with a linear range of 1.5-30 ng g-1 and a detection limit of 0.5 ng g-1. The proposed preparation method of LC-TMIPs is expected to open a new way to prepare highly selective and sustainable MIPs for hydrophobic compounds.

Cell-penetrating protein-recognizing polymeric nanoparticles through dynamic covalent chemistry and double imprinting

Molecular recognition of proteins is key to their biological functions and processes such as protein-protein interactions (PPIs). The large binding interface involved and an often relatively flat binding surface make the development of selective protein-binding materials extremely challenging. A general method is reported in this work to construct protein-binding polymeric nanoparticles from cross-linked surfactant micelles. Preparation involves first dynamic covalent chemistry that encodes signature surface lysines on a protein template. A double molecular imprinting procedure fixes the binding groups on the nanoparticle for these lysine groups, meanwhile creating a binding interface complementary to the protein in size, shape, and distribution of acidic groups on the surface. These water-soluble nanoparticles possess excellent specificities for target proteins and sufficient affinities to inhibit natural PPIs such as those between cytochrome c (Cytc) and cytochrome c oxidase (CcO). With the ability to enter cells through a combination of energy-dependent and -independent pathways, they intervene apoptosis by inhibiting the PPI between Cytc and the apoptotic protease activating factor-1 (APAF1). Generality of the preparation and the excellent molecular recognition of the materials have the potential to make them powerful tools to probe protein functions in vitro and in cellulo.

Tailor-made molecular imprints for biological event intervention

Molecular imprints, which are crosslinked architectures containing specific molecular recognition cavities for targeting compounds, have recently transitioned from in vitro diagnosis to in vivo treatment. In current application scenarios, it has become an important topic to create new biomolecular recognition pathways through molecular imprinting, thereby inhibiting the pathogenesis and regulating the development of diseases. This review starts with a pathological analysis, mainly focusing on the corresponding artificial enzymes, enzyme inhibitors and antibody mimics with enhanced functions that are created by molecular imprinting strategies. Recent advances are highlighted in the use of molecular imprints as tailor-made nanomedicines for the prevention of three major diseases: metabolic syndrome, cancer, and bacterial/viral infections.

Scaffold Adhering to Peptide-Based Biomimetic Extracellular Matrix Composite Nanobioglass Promotes the Proliferation and Migration of Skin Fibroblasts Through the GSK-3β/β-Catenin Signaling Axis

Introduction

Nano-mesoporous bioactive glass and RGD peptide-coated collagen membranes have great potential in wound healing. However, the application of their compound has not been further studied. Our purpose is to prepare a novel bioactive collagen scaffold containing both NMBG stent and adhesion peptides (BM), which then proves its promising prospect the assessment of physical properties, biocompatibility, GSK-3β/β-catenin signaling axis and toxicological effects.

Methods

The structural and morphological changes of BM were analyzed using scanning electron microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). In vivo, wound healing of BM was assessed in SD rats through dynamic monitoring and calculation of wound healing rate. Immunohistofluorescence (IHF), H&E, and Masson staining were utilized; in vitro, primary cell culture, and a variety of assays including CCK-8, Transwell, Scratch, Immunocytofluorescence (ICF), and Western blot (WB) were performed, both for morphology and molecular analysis.

Results and Discussion

Preparation of BM involved attaching NMBG to RGD-exposed collagen while avoiding the use of toxic chemical reagents. BM exhibited a distinctive superficial morphology with increased Si content, indicating successful NMBG attachment. In vivo studies on SD rats demonstrated the superior wound healing capability of BM, as evidenced by accelerated wound closure, thicker epithelial layers, and enhanced collagen deposition compared to the NC group. Additionally, BM promoted skin fibroblast migration and proliferation, possibly through activation of the GSK-3β/β-catenin signaling axis, which was crucial for tissue regeneration. This study underscored the potential of BM as an effective wound-healing dressing.

Conclusion

A new method for synthesizing ECM-like membranes has been developed using nano-mesoporous bioactive glass and collagen-derived peptides. This approach enhances the bioactivity of biomaterials through surface functionalization and growth factor-free therapy.

Molecularly Targeted Fluorescent Sensors for Visualizing and Tracking Cellular Senescence

Specific identification and monitoring of senescent cells are essential for the in-depth understanding and regulation of senescence-related life processes and diseases. Fluorescent sensors providing real-time and in situ information with spatiotemporal resolution are unparalleled tools and have contributed greatly to this field. This review focuses on the recent progress in fluorescent sensors for molecularly targeted imaging and real-time tracking of cellular senescence. The molecular design, sensing mechanisms, and biological activities of the sensors are discussed. The sensors are categorized by the types of markers and targeting ligands. Accordingly, their molecular recognition and fluorescent performance towards senescence biomarkers are summarized. Finally, the perspective and challenges in this field are discussed, which are expected to assist future design of next-generation sensors for monitoring cellular senescence.

Microcontact-Imprinted Optical Sensors for Virulence Factors of Periodontal Disease

Periodontitis (gum disease) is a common biofilm-mediated oral condition, with around 7% of the adult population suffering from severe disease with risk for tooth loss. Moreover, periodontitis virulence markers have been found in atherosclerotic plaque and brain tissue, suggesting a link to cardiovascular and Alzheimer's diseases. The lack of accurate, fast, and sensitive clinical methods to identify patients at risk leads, on the one hand, to patients being undiagnosed until the onset of severe disease and, on the other hand, to overtreatment of individuals with mild disease, diverting resources from those patients most in need. The periodontitis-associated bacterium, Porphyromonas gingivalis, secrete gingipains which are highly active proteases recognized as key virulence factors during disease progression. This makes them interesting candidates as predictive biomarkers, but currently, there are no methods in clinical use for monitoring them. Quantifying the levels or proteolytic activity of gingipains in the periodontal pocket surrounding the teeth could enable early-stage disease diagnosis. Here, we report on a monitoring approach based on high-affinity microcontact imprinted polymer-based receptors for the Arg and Lys specific gingipains Rgp and Kgp and their combination with surface plasmon resonance (SPR)-based biosensor technology for quantifying gingipain levels in biofluids and patient samples. Therefore, Rgp and Kgp were immobilized on glass coverslips followed by microcontact imprinting of poly-acrylamide based films anchored to gold sensor chips. The monomers selected were N-isopropyl acrylamide (NIPAM), N-hydroxyethyl acrylamide (HEAA) and N-methacryloyl-4-aminobenzamidine hydrochloride (BAM), with N,N'-methylene bis(acrylamide) (BIS) as the crosslinker. This resulted in imprinted surfaces exhibiting selectivity towards their templates high affinity and selectivity for the templated proteins with dissociation constants (K _d) of 159 and 299 nM for the Rgp- and Kgp-imprinted, surfaces respectively. The former surface displayed even higher affinity (K _d = 71 nM) when tested in dilute cell culture supernatants. Calculated limits of detection for the sensors were 110 and 90 nM corresponding to levels below clinically relevant concentrations.

Rapid Screening and Synthesis of Abiotic Synthetic Receptors for Selective Bacterial Recognition

The major challenges that impede the preparation of abiotic synthetic receptors designed to feature selective bacterial recognition properties are the complexity, nonrobustness, and environmental adaptability of live microbes. Here, we describe a new rapid screening strategy to determine the optimal polymer formulation on 96-well plates and then produce abiotic synthetic receptors by imprinting the surface marker lipopolysaccharide (LPS) of Gram-negative bacteria. The resulting LPS-imprinted nanoparticles reveal remarkable affinity toward LPS with an equilibrium dissociation constant (K_D) value of 10^-12 M and can distinguish and selectively recognize specific bacteria in whole blood at concentrations down to 10 cells/mL. The incorporation of gold nanorods into imprinted nanoparticles allows selective microbial inactivation based on photothermal treatment. We have also demonstrated that the imprinted nanoparticles with high affinity for bacteria could induce bacteria clustering, drive the expression of quorum-sensing-controlled signal molecules, and eventually enhance the productivity of the cell factory.

MIP-on-a-chip: Artificial receptors on microfluidic platforms for biomedical applications

Lab-on-a-chip (LOC) as an alternative biosensing approach concerning cost efficiency, parallelization, ergonomics, diagnostic speed, and sensitivity integrates the techniques of various laboratory operations such as biochemical analysis, chemical synthesis, or DNA sequencing, etc. on miniaturized microfluidic single chips. Meanwhile, LOC tools based on molecularly imprinted biosensing approach permit their applications in various fields such as medical diagnostics, pharmaceuticals, etc., which are user-, and eco-friendly sensing platforms for not only alternative to the commercial competitor but also on-site detection like point-of-care measurements. In this review, we focused our attention on compiling recent pioneer studies that utilized those intriguing methodologies, the microfluidic Lab-on-a-chip and molecularly imprinting approach, and their biomedical applications.

Nanoparticle Scanners for the Identification of Key Sequences Involved in the Assembly and Disassembly of β-Amyloid Peptides

The aggregation of β-amyloid peptides (Aβ), implied in the development and progression of Alzheimer's disease, is driven by a complex set of intramolecular and intermolecular interactions involving both hydrophobic and polar residues. The key residues responsible for the forward assembling process may be different from those that should be targeted to disassemble already formed aggregates. Molecularly imprinted nanoparticle (MINP) receptors are reported in this work to strongly and selectively bind specific segments of Aβ₄₀. Combined fluorescence spectroscopy, atomic force microscopy (AFM) imaging, and circular dichroism (CD) spectroscopy indicate that binding residues 21-30 near the loop region is most effective at inhibiting the aggregation of monomeric Aβ₄₀, but residues 11-20 that include the internal β strand closer to the N-terminal represent the best target for disaggregating already formed aggregates in the polymerization phase. Once the aggregation proceeds to the saturation phase, binding residues 1-10 has the largest effect on the disaggregation, likely because of the accessibility of these amino acids relative to others to the MINP receptors.

Improving performance of cell imprinted PDMS by integrating boronate affinity and local post-imprinting modification for selective capture of circulating tumor cells from cancer patients

Efficient capture of circulating tumor cells (CTCs) from cancer patients is an important technique that may promote early diagnosis and prognosis monitoring of cancer. However, the existing systems have certain disadvantages, such as poor selectivity, low capture efficiency, consumption of antibodies, and difficulty in release of CTCs for downstream analysis. Herein, we fabricated an innovative PEGylated boronate affinity cell imprinted polydimethylsiloxane (PBACIP) for highly efficient capture of CTCs from cancer patients. The antibody-free PBACIP possessed hierarchical structure of imprinted cavities, which were inlaid with boronic acid modified SiO₂ nanoparticles (SiO₂@BA), so it could specifically capture target CTCs from biological samples due to the synergistic effect of boronate affinity and cell imprinting. Furthermore, PEGylation was accurately completed in the non-imprinted region by the template cells occupying the imprinted cavity, which not only retained the microstructure of original imprinted cavities, but also endowed PBACIP with hydrophilicity. The artificial PBACIP could efficiently capture human breast-cancer cells from biological sample. When 5 to 500 SKBR3 cells were spiked in 1 mL mice lysed blood, the capture efficiency reached 86.7 ± 11.5% to 96.2 ± 2.3%. Most importantly, the PBACIP was successfully used to capture CTCs from blood of breast cancer patients, and the captured CTCs were released for subsequent gene mutation analysis. The PBACIP can efficiently capture and release CTCs for downstream analysis, which provides a universal strategy toward individualized anti-tumor comprehensive treatments and has great potential in the future cell-based clinical applications.

Core-Shell Magnetic Imprinted Polymers for the Recognition of FLAG-Tagpeptide

FLAG^® tag (DYKDDDDK) is a small epitope peptide employed for the purification of recombinant proteins such as immunoglobulins, cytokines, and gene regulatory proteins. It provides superior purity and recoveries of fused target proteins when compared to the commonly used His-tag. Nevertheless, the immunoaffinity-based adsorbents required for their isolation are far more expensive than the ligand-based affinity resin used in combination with the His-tag. In order to overcome this limitation we report herein the development of molecularly imprinted polymers (MIPs) selective to the FLAG^® tag. The polymers were prepared by the epitope imprinting approach using a four amino acids peptide, DYKD, including part of the FLAG^® sequence as template molecule. Different kinds of magnetic polymers were synthesised in aqueous and organic media also using different sizes of magnetite core nanoparticles. The synthesised polymers were used as solid phase extraction materials with excellent recoveries and high specificity for both peptides. The magnetic properties of the polymers confer a new, effective, simple, and fast method in the purification using FLAG^® tag.

Applications of Material-Binding Peptides: A Review

Material-binding peptides (MBPs) are functionalized adhesive materials consisting of a few to several dozen amino acids. This affinity between MBPs and materials is regulated by multiple interactions, including hydrogen bonding, electrostatic, hydrophobic interactions, and π-π stacking. They show selective binding and high affinity to a diverse range of inorganic and organic materials, such as silicon-based materials, metals, metal compounds, carbon materials, and polymers. They are used to improve the biocompatibility of materials, increase the efficiency of material synthesis, and guide the controlled synthesis of nanomaterials. In addition, these can be used for precise targeting of proteins by conjugating to target biomolecules. In this review, we summarize the main designs and applications of MBPs in recent years. The discussions focus on more efficient and functional peptides, including evolution and overall design of MBPs. We have also highlighted the recent applications of MBPs, such as functionalization of material surfaces, synthesis of nanomaterials, drug delivery, cancer therapy, and plastic degradation. Besides, we also discussed the development trend of MBPs. This interpretation will accelerate future investigations to bottleneck the drawbacks of available MBPs, promoting their commercial applications.

Reversible Self-Assembled Monolayers with Tunable Surface Dynamics for Controlling Cell Adhesion Behavior

Cells adhering onto surfaces sense and respond to chemical and physical surface features. The control over cell adhesion behavior influences cell migration, proliferation, and differentiation, which are important considerations in biomaterial design for cell culture, tissue engineering, and regenerative medicine. Here, we report on a supramolecular-based approach to prepare reversible self-assembled monolayers (rSAMs) with tunable lateral mobility and dynamic control over surface composition to regulate cell adhesion behavior. These layers were prepared by incubating oxoacid-terminated thiol SAMs on gold in a pH 8 HEPES buffer solution containing different mole fractions of ω-(ethylene glycol)_2-4- and ω-(GRGDS)-, α-benzamidino bolaamphiphiles. Cell shape and morphology were influenced by the strength of the interactions between the amidine-functionalized amphiphiles and the oxoacid of the underlying SAMs. Dynamic control over surface composition, achieved by the addition of inert filler amphiphiles to the RGD-functionalized rSAMs, reversed the cell adhesion process. In summary, rSAMs featuring mobile bioactive ligands offer unique capabilities to influence and control cell adhesion behavior, suggesting a broad use in biomaterial design, tissue engineering, and regenerative medicine.

The Efficient and Convenient Extracting Uranium from Water by a Uranyl-Ion Affine Microgel Container

Uranium is an indispensable part of the nuclear industry that benefits us, but its consequent pollution of water bodies also makes a far-reaching impact on human society. The rapid, efficient and convenient extraction of uranium from water is to be a top priority. Thanks to the super hydrophilic and fast adsorption rate of microgel, it has been the ideal adsorbent in water; however, it was too difficult to recover the microgel after adsorption, which limited its practical applications. Here, we developed a uranyl-ion affine and recyclable microgel container that has not only the rapid swelling rate of microgel particles but also allows the detection of the adsorption saturation process by the naked eye.

Controlled synthesis of open-mouthed epitope-imprinted polymer nanocapsules with a PEGylated nanocore and their application for fluorescence detection of target protein

Epitope imprinting is an effective way to create artificial receptors for protein recognition. Surface imprinting with immobilized templates and sacrificial supports can generate high-quality imprinted cavities of homogeneous orientation and good accessibility, but it is still challenging to fabricate nanoscale imprinted materials by this approach. Herein, we propose a method for the controlled synthesis of open-mouthed epitope-imprinted polymer nanocapsules (OM-MIP NCs) by limiting the imprinting polymerization on the template-bearing side of the Janus nanoparticles (JNPs). Concurrent bromoacetyl (Ac–Br) and 2-bromoisobutyryl (iB–Br) functionalization of the major portion of SiO₂ nanoparticles is achieved via the molten-wax-in-water Pickering emulsion approach. The cysteinyl-derived epitope templates are immobilized through the Ac–Br groups, and then surface imprinting is fulfilled via ATRP initiated by the iB–Br groups. The SiO₂ supports are partially etched and then PEGlated, affording OM-MIP NCs with a PEGylated nanocore. The inside nanocore can facilitate collection of the NCs by centrifugation, and its PEGylation can inhibit non-specific binding. The surface imprinting can be optimized through the ATRP time, and the etching can be tailored via the concentration of NH₄HF₂ employed. For proof-of-concept, with a C-terminus nonapeptide of bovine serum albumin (BSA) chosen as a model epitope and polymerizable carbon dots added to the pre-polymerization solution, fluorescent OM-MIP NCs were fabricated for BSA sensing. The as-synthesized NCs exhibited satisfactory detection performance, with an imprinting factor of 6.1, a limit of detection of 38.1 nM, a linear range of 0.25–6 μM, and recoveries of 98.0 to 104.0% in bovine serum samples.

Surface epitope imprinting over the one side of Janus SiO₂ NPs via ATRP affords open-mouthed epitope-imprinted nanocapsules with imprinted cavities of homogeneous orientation and good accessibility for fluorescence detection of target protein.

Recent Advances in Quartz Crystal Microbalance Biosensors Based on the Molecular Imprinting Technique for Disease-Related Biomarkers

The molecular imprinting technique is a quickly developing field of interest regarding the synthesis of artificial recognition elements that enable the specific determination of target molecule/analyte from a matrix. Recently, these smart materials can be successfully applied to biomolecule detection in biomimetic biosensors. These biosensors contain a biorecognition element (a bioreceptor) and a transducer, like their biosensor analogs. Here, the basic difference is that molecular imprinting-based biosensors use a synthetic recognition element. Molecular imprinting polymers used as the artificial recognition elements in biosensor platforms are complementary in shape, size, specific binding sites, and functionality to their template analytes. Recent progress in biomolecular recognition has supplied extra diagnostic and treatment methods for various diseases. Cost-effective, more robust, and high-throughput assays are needed for monitoring biomarkers in clinical settings. Quartz crystal microbalance (QCM) biosensors are promising tools for the real-time and quick detection of biomolecules in the past two decades A quick, simple-to-use, and cheap biomarkers detection technology based on biosensors has been developed. This critical review presents current applications in molecular imprinting-based quartz crystal microbalance biosensors for the quantification of biomarkers for disease monitoring and diagnostic results.

Reversible dougong structured receptor-ligand recognition for building dynamic extracellular matrix mimics

This paper reports an exciting breakthrough in dynamic biomaterials design mimicking the reversible interlocking and remoldable structure of extracellular matrix (ECM). Specifically, we realize a nature-derived molecular recognition event (i.e., the antibiotic glycopeptide vancomycin [Van] and the dipeptide d-Ala-d-Ala [AA] receptor–ligand interaction) as a reversible strategy for fabrication of dynamic biointerface and 3D ECM mimics. We believe that the specific but reversible Van–AA molecular recognition would be a strategy for dynamic biomaterial fabrication, and that the easy-handling merit, ECM-like remoldability, and inherent antibacterial activity will bring insights to biomaterial scaffold design in tissue engineering and regenerative medicine.

Dynamic biomaterials excel at recapitulating the reversible interlocking and remoldable structure of the extracellular matrix (ECM), particularly in manipulating cell behaviors and adapting to tissue morphogenesis. While strategies based on dynamic chemistries have been extensively studied for ECM-mimicking dynamic biomaterials, biocompatible molecular means with biogenicity are still rare. Here, we report a nature-derived strategy for fabrication of dynamic biointerface as well as a three-dimensional (3D) hydrogel structure based on reversible receptor–ligand interaction between the glycopeptide antibiotic vancomycin and dipeptide d-Ala-d-Ala. We demonstrate the reversible regulation of multiple cell types with the dynamic biointerface and successfully implement the dynamic hydrogel as a functional antibacterial 3D scaffold to treat tissue repair. In view of the biogenicity and high applicability, this nature-derived reversible molecular strategy will bring opportunities for malleable biomaterial design with great potential in biomedicine.

Molecular recognition of enzymes and modulation of enzymatic activity by nanoparticle conformational sensors

Regulation of enzyme activity is key to dynamic processes in biology but is difficult to achieve with synthetic systems. We here report molecularly imprinted nanoparticles with strong binding for the N- and C-terminal peptides on lysozyme. Binding affinity for the enzyme correlated with conformational flexibility of the peptides in the protein structure. Significantly, binding at the C-terminus of lysozyme enhanced the performance of the enzyme at elevated temperatures and that at the N-terminus lowered the enzyme activity. These nanoparticles, when clicked onto magnetic nanoparticles, could also be used to fish out the protein of interest from a mixture in a single step.

A Dual-Responsive Peptide-Based Smart Biointerface with Biomimetic Adhesive Behaviors for Bacterial Isolation

As mimics of the extracellular matrix, surfaces with the capability of capturing and releasing specific cells in a smart and controllable way play an important role in bacterial isolation. In this work, we fabricated a dual-responsive smart biointerface via peptide self-assembly and reversible covalent chemistry biomimetic adhesion behavior for bacterial isolation. Compared with that of the biointerface based on a single reversible covalent bond, the bacterial enrichment efficiency obtained in this work was 2.3 times higher. Furthermore, the release of bacteria from the surface could be achieved by dual responsiveness (sugar and enzyme), which makes the biointerface more adaptable and compatible under different conditions. Finally, the reusability of the biointerface was verified via peptide self-assembly and the regenerated smart biointerface still showed good bacterial capture stability and excellent release efficiency, which was highly anticipated to be more widely applied in biomaterial science and biomedicine in the future.

Biocompatibility pathways and mechanisms for bioactive materials: The bioactivity zone

This essay analyzes the scientific evidence that forms the basis of bioactive materials, covering the fundamental understanding of bioactivity phenomena and correlation with the mechanisms of biocompatibility of biomaterials. This is a detailed assessment of performance in areas such as bone-induction, cell adhesion, immunomodulation, thrombogenicity and antimicrobial behavior. Bioactivity is the modulation of biological activity by characteristics of the interfacial region that incorporates the material surface and the immediate local host tissue. Although the term ‘bioactive material’ is widely used and has a well understood general meaning, it would be useful now to concentrate on this interfacial region, considered as ‘the bioactivity zone’. Bioactivity phenomena are either due to topographical/micromechanical characteristics, or to biologically active species that are presented in the bioactivity zone. Examples of topographical/micromechanical effects are the modulation of the osteoblast – osteoclast balance, nanotopographical regulation of cell adhesion, and bactericidal nanostructures. Regulation of bioactivity by biologically active species include their influence, especially of metal ions, on signaling pathways in bone formation, the role of cell adhesion molecules and bioactive peptides in cell attachment, macrophage polarization by immunoregulatory molecules and antimicrobial peptides. While much experimental data exists to demonstrate the potential of such phenomena, there are considerable barriers to their effective clinical translation. This essay shows that there is solid scientific evidence of the existence of bioactivity mechanisms that are associated with some types of biomaterials, especially when the material is modified in a manner designed to specifically induce that activity.

A porous molecularly imprinted nanofilm for selective and sensitive sensing of an anticancer drug ruxolitinib

A novel methodology has been applied to generate a porous molecularly imprinted material for highly selective and sensitive recognition of Janus kinase inhibitor ruxolitinib (RUX). The porous material-based nucleobase-derivative functional monomer was developed by a photopolymerization method. The thymine methacrylate (ThyM) as a functional monomer was synthesized and copolymerized with 2-hydroxyethyl methacrylate (HEMA) in the presence of ethylene glycol dimethacrylate (EGDMA) onto the glassy carbon electrode [glassy carbon electrode/molecularly imprinted polymer@poly(2-hydroxyethyl methacrylate-co-thymine methacrylate), (GCE/MIP@PHEMA-ThyM)] for the first time. The presence of ThyM results in the functional groups in imprinting binding sites, while the presence of poly(vinyl alcohol) (PVA) allows to generate porous materials for sensitive sensing. The characterization of GCE/MIP@PHEMA-ThyM was investigated by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and impedance spectroscopy technique. Then, the porous MIP modified glassy carbon electrode was optimized with effecting parameters including removal agent, removal time, and incubation time to get a better response for RUX. Under well-controlled optimum conditions, the GCE/MIP@PHEMA-ThyM linearly responded to the RUX concentration up to 0.01 pM at the limit of detection (LOD) of 0.00191 pM. The non-imprinted polymer (NIP) was also prepared to serve as a control in the same way but without the template. The proposed method improves the accessibility of binding sites by generating the porous material resulting in highly selective and sensitive recognition of drugs in the pharmaceutical dosage form and synthetic human serum samples.

Epitope-imprinted polymers: Design principles of synthetic binding partners for natural biomacromolecules

Molecular imprinting (MI) has been explored as an increasingly viable tool for molecular recognition in various fields. However, imprinting of biologically relevant molecules like proteins is severely hampered by several problems. Inspired by natural antibodies, the use of epitopes as imprinting templates has been explored to circumvent those limitations, offering lower costs and greater versatility. Here, we review the latest innovations in this technology, as well as different applications where MI polymers (MIPs) have been used to target biomolecules of interest. We discuss the several steps in MI, from the choice of epitope and functional monomers to the different production methods and possible applications. We also critically explore how MIP performance can be assessed by various parameters. Last, we present perspectives on future breakthroughs and advances, offering insights into how MI techniques can be expanded to new fields such as tissue engineering.

The promising use of nano-molecular imprinted templates for improved SARS-CoV-2 detection, drug delivery and research

Molecular imprinting (MI) is a technique that creates a template of a molecule for improving complementary binding sites in terms of size and shape to a peptide, protein, bacteria, mammalian cell, or virus on soft materials (such as polymers, hydrogels, or self-assembled materials). MI has been widely investigated for over 90 years in various industries but is now focused on improved tissue engineering, regenerative medicine, drug delivery, sensors, diagnostics, therapeutics and other medical applications. Molecular targets that have been studied so far in MI include those for the major antigenic determinants of microorganisms (like bacteria or viruses) leading to innovations in disease diagnosis via solid-phase extraction separation and biomimetic sensors. As such, although not widely investigated yet, MI demonstrates much promise for improving the detection of and treatment for the current Coronavirus Disease of 2019 (COVID-2019) pandemic as well as future pandemics. In this manner, this review will introduce the numerous applications of MI polymers, particularly using proteins and peptides, and how these MI polymers can be used as improved diagnostic and therapeutic tools for COVID-19.

Magnetic Control and Real-Time Monitoring of Stem Cell Differentiation by the Ligand Nanoassembly

Native extracellular matrix (ECM) exhibits dynamic change in the ligand position. Herein, the ECM-emulating control and real-time monitoring of stem cell differentiation are demonstrated by ligand nanoassembly. The density of gold nanoassembly presenting cell-adhesive Arg-Gly-Asp (RGD) ligand on Fe₃ O₄ (magnetite) nanoparticle in nanostructures flexibly grafted to material is changed while keeping macroscale ligand density invariant. The ligand nanoassembly on the Fe₃ O₄ can be magnetically attracted to mediate rising and falling ligand movements via linker stretching and compression, respectively. High ligand nanoassembly density stimulates integrin ligation to activate the mechanosensing-assisted stem cell differentiation, which is monitored via in situ real-time electrochemical sensing. Magnetic control of rising and falling ligand movements hinders and promotes the adhesion-mediated mechanotransduction and differentiation of stem cells, respectively. These rising and falling ligand states yield the difference in the farthest distance (≈34.6 nm) of the RGD from material surface, thereby dynamically mimicking static long and short flexible linkers, which hinder and promote cell adhesion, respectively. Design of cytocompatible ligand nanoassemblies can be made with combinations of dimensions, shapes, and biomimetic ligands for remotely regulating stem cells for offering novel methodologies to advance regenerative therapies.

Substrate Protection in Controlled Enzymatic Transformation of Peptides and Proteins

Proteins are involved in practically every single biological process. The many enzymes involved in their synthesis, cleavage, and posttranslational modification (PTM) carry out highly specific tasks with no usage of protecting groups. Yet, the chemists' strategy of protection/deprotection potentially can be highly useful, for example, when a specific biochemical reaction catalyzed by a broad-specificity enzyme needs to be inhibited, during infection of cells by enveloped viruses, in the invasion and spread of cancer cells, and upon mechanistic investigation of signal-transduction pathways. Doing so requires highly specific binding of peptide substrates in aqueous solution with biologically competitive affinities. Recent development of peptide-imprinted cross-linked micelles allows such protection and affords previously impossible ways of manipulating peptides and proteins in enzymatic transformations.

A versatile pH-responsive peptide based dynamic biointerface for tracking bacteria killing and infection resistance

Herein we reported a versatile dynamic biointerface based on pH-responsive peptide self-assembly and disassembly to capture the bacteria to avoid bacteria further infected tissue around that can release peptides from the surface in a slightly acidic environment to kill the bacteria with the specificity. The exposed biointerface still presented infection resistance.

Bioinspired peptide adhesion on Ti implants alleviates wear particle-induced inflammation and improves interfacial osteogenesis

In the inflammatory peri-implant microenvironment, excessive polarization of macrophages to the proinflammatory M1 phenotype can trigger the secretion of inflammatory cytokines, which promote bone resorption and impede osteogenesis around implants. The direct consequence of this process is the failure of prosthetic implants due to aseptic loosening. To reverse the inflammatory microenvironment and prevent prosthesis loosening, a mussel adhesion-inspired surface strategy was used for bioengineering of titanium implants with integrin-binding ability. In our design, a mussel-inspired catecholic peptide with tetravalent 3,4-dihydroxy-l-phenylalanine (DOPA) and Arg-Gly-Asp (RGD) sequences was synthesized. The peptide can easily anchor to the surface of medical titanium materials through a mussel adhesive mechanism. We found that peptide-decorated titanium implants could effectively inhibit peri-implant inflammation in a wear particle model and could promote the polarization of macrophages to a pro-healing M2 phenotype by interfering with integrin-α₂β₁ and integrin-α_vβ₃. Moreover, the peptide coating increased the adherence of osteoblasts and promoted osteogenesis on titanium implants even under inflammatory conditions. This work suggested that this biomimetic catecholic integrin-binding peptide can provide facile tactics for surface bioengineering of medical prostheses with improved interfacial osteogenesis under inflammatory conditions, which might contribute greatly to the prevention of prosthesis loosening and the improvement of clinical outcomes.

Protein Denaturation Through the Use of Magnetic Molecularly Imprinted Polymer Nanoparticles

The inhibition of the protein function for therapeutic applications remains challenging despite progress these past years. While the targeting application of molecularly imprinted polymer are in their infancy, no use was ever made of their magnetic hyperthermia properties to damage proteins when they are coupled to magnetic nanoparticles. Therefore, we have developed a facile and effective method to synthesize magnetic molecularly imprinted polymer nanoparticles using the green fluorescent protein (GFP) as the template, a bulk imprinting of proteins combined with a grafting approach onto maghemite nanoparticles. The hybrid material exhibits very high adsorption capacities and very strong affinity constants towards GFP. We show that the heat generated locally upon alternative magnetic field is responsible of the decrease of fluorescence intensity.

Novel Molecular Organic Framework Composite Molecularly Imprinted Nanofibrous Membranes with a Bioinspired Viscid Bead Structure for Selective Recognition and Separation of Atrazine

In this work, novel atrazine (ATZ) molecularly imprinted nanofibrous membranes (A-MNMs) with a molecular organic framework (MOF)-based viscid bead structure were developed based on a natural spider-web-inspired strategy for selective separation of ATZ. Poly(vinylidene fluoride)/poly(vinyl alcohol) (PVDF/PVA) blended nanofibrous membranes as the basal membrane were synthesized by electrospinning technology combined with a chemical cross-linking procedure. The most critical design is that MOF nanocrystals as the matrix of the viscid bead structure were assembled on the PVDF/PVA blended nanofibrous membrane surface and the specific recognition sites were efficiently constructed on the surface and pores of the MOF-based viscid bead structure by a surface imprinting strategy. Significantly, the as-synthesized MOF-based viscid bead structure has an enhanced specific surface area, which helps to form abundant specific recognition sites in A-MNMs. Therefore, the A-MNMs with a spider-web-like structure presented an enhanced rebinding capacity (37.62 mg g^-1) and permselectivity (permselectivity factors β were 4.21 and 4.31) toward ATZ. Moreover, the A-MNMs display strong practicability in separation of ATZ from simulated environmental water samples. The presented work has shown tremendous potential for preparing natural spider-web-like molecularly imprinted membranes (MIMs) for selective separation of environment pollutants.

Abiotic Mimic of Matrix Metalloproteinase-9 Inhibitor against Advanced Metastatic Cancer

As the most representative family of proteinases related to tumorigenesis, matrix metalloproteinase-9 (MMP-9) represents a key player in cancer cell migration and regulation of the tumor microenvironment. The inhibition of MMP-9 activity has been pursued as a target for anticancer therapy. However, most synthetic MMP-9 inhibitors have failed in clinical trials because of their lack of selectivity. Here, an abiotic mimic based on molecularly imprinted nanoparticles has been designed as an inhibitor for MMP-9. To attain fast mass transfer and facilitate multifunctional roles, we synthesized the imprinted polymer thin layer on the surface of gold nanorods by reversible addition-fragmentation chain transfer polymerization using MMP-9 as the template, which captures MMP-9 selectively and inhibits its activity by providing steric hindrance to the activity-related domain of MMP-9. In vitro cell experiments and in vivo studies in mice demonstrate that the imprinted artificial antibody suppresses the migration and growth of metastatic tumors. The tumor growth inhibition rate reaches up to 54 ± 15%. Compared with the typical photothermal therapy induced by gold nanorods, the use of MMP-9-imprinted synthetic antibody could better inhibit the lung tumor metastasis by quenching the enzyme activity of MMP-9. This study offers a new paradigm in the engineering of imprinted nanoparticles as inhibitors for cancer therapy.

Molecularly imprinted fluoroprobes doped with Ag nanoparticles for highly selective detection of oxytetracycline in real samples

A molecularly imprinted polymer (MIP), which is synthesized by a nanomolding process around a template, has emerged as a promising analytical tool for environmental quality monitoring and food safety test. In this work, a fluoroprobe with Ag-doped MIP nanolayer (16 nm thickness) is successfully prepared for the highly selective detection of oxytetracycline (OTC) in real samples (i.e. Yangtze River water, swine urine). In the MIP nanolayer, two functional monomers (i.e. 4-(2-acrylamidoethylcarbamoyl)-3-fluorophenylboronic acid, methacrylic acid) synergistically constitute the specific recognition sites. Meanwhile, the doped Ag enhances the detection sensitivity (with a detection limit of 5.38 nM) and accelerates the detection rate (within 2.5 min) even in real samples. Therefore, the present study paves the way for the preparation of MIP-based fluoroprobes, showing great prospects in environmental quality and food safety tests.

Advances in epitope molecularly imprinted polymers for protein detection: a review

Epitope molecularly imprinted polymers (EMIPs) are novel imprinted materials using short characteristic peptides as templates rather than entire proteins. To be specific, the amino acid sequence of the template peptide is the same as an exposed N- or C-terminus of a target protein, or its amino acid composition and sequence replicate a similar conformational arrangement as the same amino acid residues on the surface of the target protein. EMIPs have a good application prospect in protein research. Herein, we focus on classification of epitope imprinting techniques, methods of epitope immobilization on matrix materials including boronate affinity immobilization, covalent bonding immobilization, physical adsorption immobilization and metal ion chelation immobilization, and application of EMIPs in peptides, proteins, target imaging and target therapy fields. Finally, the main problems and future development are summarized.

Selective analysis of interferon-alpha in human serum with boronate affinity oriented imprinting based plastic antibody

Interferons are important biomolecules in human immune system. Cytokine interferon alpha (IFN-α), a type I interferon, is one of the major components of the innate immune response involved in autoimmune diseases. Thus, the analysis of interferons is of great importance for both biological and pharmaceutical purposes. In this work, an IFN-α specific plastic antibody is prepared via boronate affinity oriented surface imprinting. By combing with the magnetic nanoparticles, the imprinted material exhibits several advantages, including strong affinity (K_d: 75.2 nM), high specificity (cross reactivity<25%), excellent efficiency (imprinting efficiency: 44.1%), tolerance to interferences, and easy manipulation. By employing the prepared imprinted material as sorbent for selective enrichment of IFN-α, a good linearity is achieved in the range of 50 ng/mL-10 μg/mL, and the detection and quantifcation limits are 10 ng/mL and 50 ng/mL respectively. The recoveries of this approach are found within 75.8%-82.2% with relative standard deviations of 6.4-9.7%. Furthermore, the IFN-α in spiked human serum is analyzed with acceptable reliability (recovery: 77.3%, RSD: 7.9%). Because of these highly desirable properties, the IFN-α specific plastic antibody can find more applications in medical and pharmaceutical industry.

An Overview of Bio-Inspired Intelligent Imprinted Polymers for Virus Determination

The molecular imprinting polymers (MIPs) have shown their potential in various applications including pharmaceuticals, chemical sensing and biosensing, medical diagnosis, and environmental related issues, owing to their artificial selective biomimetic recognition ability. Despite the challenges posed in the imprinting and recognition of biomacromolecules, the use of MIP for the imprinting of large biomolecular oragnism such as viruses is of huge interest because of the necessity of early diagnosis of virus-induced diseases for clinical and point-of-care (POC) purposes. Thus, many fascinating works have been documented in which such synthetic systems undoubtedly explore a variety of potential implementations, from virus elimination, purification, and diagnosis to virus and bacteria-borne disease therapy. This study is focused comprehensively on the fabrication strategies and their usage in many virus-imprinted works that have appeared in the literature. The drawbacks, challenges, and perspectives are also highlighted.

Molecular Imprinting Strategies for Tissue Engineering Applications: A Review

Tissue Engineering (TE) represents a promising solution to fabricate engineered constructs able to restore tissue damage after implantation. In the classic TE approach, biomaterials are used alongside growth factors to create a scaffolding structure that supports cells during the construct maturation. A current challenge in TE is the creation of engineered constructs able to mimic the complex microenvironment found in the natural tissue, so as to promote and guide cell migration, proliferation, and differentiation. In this context, the introduction inside the scaffold of molecularly imprinted polymers (MIPs)—synthetic receptors able to reversibly bind to biomolecules—holds great promise to enhance the scaffold-cell interaction. In this review, we analyze the main strategies that have been used for MIP design and fabrication with a particular focus on biomedical research. Furthermore, to highlight the potential of MIPs for scaffold-based TE, we present recent examples on how MIPs have been used in TE to introduce biophysical cues as well as for drug delivery and sequestering.

Visual detection of hepatocellular carcinoma cells with cell imprinted substrate and pH-sensitive allochroic-graphene oxide

Herein, we integrate cell-imprinted substrate (CIS) and allochroic-graphene oxide (AGO) for specific visualization sorting of hepatocellular carcinoma cells. The state-of-the-art-of detection method relies on the enzyme linked immunosorbent assay (ELISA)-like sandwich strategy with hierarchical recognition. The target tumor cells are first selectively captured by the CIS based on cell imprinted recognition, and then specifically labeled with AGO by boronate affinity recognition between boronic acid on AGO and cis-diols on the surface of target cells. The selectively recognition of CIS for target template cells is verified by cell function experiments. It is also worth mentioning that the AGO can specifically recognize target tumor cells under physiological pH, and then perform signal amplification and output through pH-triggered allochroism. The CIS linked AGO for cell assay (CIS-AGO-CA) is successfully used for visualization detection of human hepatocarcinoma HLE cells from hepatocyte suspension. When the hepatocyte suspension is spiked with 1.0 × 10⁵ cells, the recoveries of CIS-AGO-CA are 80.67 ± 4.33% for target HLE cells, and only 12.00 ± 1.00% for non-target Hep3B cells. It is worth emphasizing that the CIS-AGO-CA process is antibody-free. Therefore, this novel ELISA-like sandwich strategy is high specificity, cost-efficient and easy-to-use, and exhibits great prospect in the visualization sorting of tumor subpopulation.

Molecular Imprints Frozen by Strong Intermolecular Interactions in Place of Cross-Linking

A new way to freeze molecular imprints in a polymer material is reported. So far, molecular imprinted polymers (MIP) involve copolymerization of a functional monomer and large amounts of cross-linking agent, which keeps the template shape memory in rigid molecular imprints. MIP materials are prepared herein without cross-linking agent. Stiff chains of polyaniline grafted on a solid support as a brush-like material achieve the necessary rigidity. Differential adsorption to imprinted and non-imprinted materials provides evidence of molecular imprints. A correct adsorption isotherm for mobile adsorbed layers (Volmer isotherm) is introduced instead of the popular but inadequate Langmuir isotherm. Non-selective adsorption is entropic, whereas adsorption to molecular imprints has an enthalpic contribution coming from specific interactions. Fast adsorption kinetics are a definite benefit with regards to applications such as chromatographic separations and chemical sensors.

Microwave-assisted preparation of a molecularly imprinted monolith combining an imidazolium ionic liquid and POSS for enhanced extraction of baicalin-like compounds in Scutellaria baicalensis by means of in-capillary SPME followed by on-line LC and off-line LC-MS/MS

An imidazolium-type ionic liquid and polyhedral oligomeric silsesquioxane were combined to produce an imprinted monolith in capillary endowed with wide selectivity to enrich baicalin and its analogues for analysis by multidimensional LC systems.

Thermo-responsive imprinted hydrogel with switchable sialic acid recognition for selective cancer cell isolation from blood

In this work, a sialic acid (SA)-imprinted thermo-responsive hydrogel layer was prepared for selective capture and release of cancer cells. The SA-imprinting process was performed at 37 °C using thermo-responsive functional monomer, thus generating switchable SA-recognition sites with potent SA binding at 37 °C and weak binding at a lower temperature (e.g., 25 °C). Since SA is often overexpressed at the glycan terminals of cell membrane proteins or lipids, the SA-imprinted hydrogel layer could be used for selective cancer cell recognition. Our results confirmed that the hydrogel layer could efficiently capture cancer cells from not only the culture medium but also the real blood samples. In addition, the captured cells could be non-invasively released by lowing the temperature. Considering the non-invasive processing mode, considerable capture efficiency, good cell selectivity, as well as the more stable and durable SA-imprinted sites compared to natural antibodies or receptors, this thermo-responsive hydrogel layer could be used as a promising and general platform for cell-based cancer diagnosis.

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Thermo-responsive sialic acid (SA)-imprinted hydrogel layer was prepared.

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The hydrogel layer could efficiently and selective capture cancer cells at 37 °C.

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The captured cancer cells could be released at a lower temperature (e.g., 25 °C).

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The hydrogel layer could be used for capture and release cancer cells from blood.

Molecularly Imprinted Synthetic Antibodies: From Chemical Design to Biomedical Applications

Billions of dollars are invested into the monoclonal antibody market every year to meet the increasing demand in clinical diagnosis and therapy. However, natural antibodies still suffer from poor stability and high cost, as well as ethical issues in animal experiments. Thus, developing antibody substitutes or mimics is a long-term goal for scientists. The molecular imprinting technique presents one of the most promising strategies for antibody mimicking. The molecularly imprinted polymers (MIPs) are also called "molecularly imprinted synthetic antibodies" (MISAs). The breakthroughs of key technologies and innovations in chemistry and material science in the last decades have led to the rapid development of MISAs, and their molecular affinity has become comparable to that of natural antibodies. Currently, MISAs are undergoing a revolutionary transformation of their applications, from initial adsorption and separation to the rising fields of biomedicine. Herein, the fundamental chemical design of MISAs is examined, and then current progress in biomedical applications is the focus. Meanwhile, the potential of MISAs as qualified substitutes or even to transcend the performance of natural antibodies is discussed from the perspective of frontier needs in biomedicines, to facilitate the rapid development of synthetic artificial antibodies.

Selective Binding of Dopamine and Epinephrine in Water by Molecularly Imprinted Fluorescent Receptors

Catecholamines play important roles in biology but their structural similarity makes it challenging to construct synthetic receptors with selective binding. A combination of covalent and noncovalent binding groups in the hydrophobic core of water-soluble nanoparticles enabled them to recognize dopamine and epinephrine with an association constant (Ka ) of 3-4×104  M-1 in water, an order of magnitude higher than those of previously reported synthetic hosts. In addition, minute structural changes among analogues were detected including the addition or removal of a single hydroxyl or methyl group.