Chemical Antibody Mimics Inhibit Cadherin‐Mediated Cell–Cell Adhesion: A Promising Strategy for Cancer Therapy

Double Imprinted Nanoparticles for Sequential Membrane-to-Nuclear Drug Delivery

Efficient and site-specific delivery of therapeutics drugs remains a critical challenge in cancer treatment. Traditional drug nanocarriers such as antibody-drug conjugates are not generally accessible due to their high cost and can lead to serious side effects including life-threatening allergic reactions. Here, these problems are overcome via the engineering of supramolecular agents that are manufactured with an innovative double imprinting approach. The developed molecularly imprinted nanoparticles (nanoMIPs) are targeted toward a linear epitope of estrogen receptor alfa (ERα) and loaded with the chemotherapeutic drug doxorubicin. These nanoMIPs are cost-effective and rival the affinity of commercial antibodies for ERα. Upon specific binding of the materials to ERα, which is overexpressed in most breast cancers (BCs), nuclear drug delivery is achieved via receptor-mediated endocytosis. Consequentially, significantly enhanced cytotoxicity is elicited in BC cell lines overexpressing ERα, paving the way for precision treatment of BC. Proof-of-concept for the clinical use of the nanoMIPs is provided by evaluating their drug efficacy in sophisticated three-dimensional (3D) cancer models, which capture the complexity of the tumor microenvironment in vivo without requiring animal models. Thus, these findings highlight the potential of nanoMIPs as a promising class of novel drug compounds for use in cancer treatment.

Reversible Photoregulation of Cell-Cell Adhesions With Opto-E-cadherin

The cell-cell adhesion molecule E-cadherin has been intensively studied due to its prevalence in tissue function and its spatiotemporal regulation during epithelial-to-mesenchymal cell transition. Nonetheless, regulating and studying the dynamics of it has proven challenging. We developed a photoswitchable version of E-cadherin, named opto-E-cadherin, which can be toggled OFF with blue light illumination and back ON in the dark. Herein, we describe easy-to-use methods to test and characterise opto-E- cadherin cell clones for downstream experiments. Key features • This protocol describes how to implement optogenetic cell-cell adhesion molecules effectively (described here on the basis of opto-E-cadherin), while highlighting possible pitfalls. • Utilises equipment commonly found in most laboratories with high ease of use. • Phenotype screening is easy and done within a few hours (comparison of cell clusters in the dark vs. blue light in an aggregation assay). • Three different functionality assay systems are described. • After the cell line is established, all experiments can be performed within three days.

Multifunctional Self-Signaling nanoMIP and Its Application for a Washing-Free Assay of Human Angiotensin-Converting Enzyme 2

Molecular imprinting techniques have attracted a lot of attention as a potential biomimetic technology, but there are still challenges in protein imprinting. Herein, multifunctional nanosized molecularly imprinted polymers (nanoMIPs) for human angiotensin-converting enzyme 2 (ACE2) were prepared by epitope imprinting of magnetic nanoparticles-anchored peptide (magNP-P) templates, which were further applied to construct a competitive displacement fluorescence assay toward ACE2. A cysteine-flanked dodecapeptide sequence was elaborately selected as an epitope for ACE2, which was immobilized onto the surface of magnetic nanoparticles and served as a magNP-P template for imprinting. During polymerization, fluorescent monomers were introduced to endow fluorescence responsiveness to the prepared self-signaling nanoMIPs. A competitive displacement fluorescence assay based on the nanoMIPs was established and operated in a washing-free manner, yielding a wide range for ACE2 (0.1-6.0 pg/mL) and a low detection limit (0.081 pg/mL). This approach offers a promising avenue in the preparation of nanoMIPs for macromolecule recognition and expands potential application of an MIP in the detection of proteins as well as peptides.

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.

Unveiling a pH-Responsive Dual-Androgen-Blocking Magnetic Molecularly Imprinted Polymer for Enhanced Synergistic Therapy of Prostate Cancer

Prostate cancer is the most common malignancy diagnosed in men. Androgens are directly related to its pathogenesis. Inhibition of the androgen receptor (AR) is considered to be the most promising therapeutic approach for the treatment of prostate cancer. In this study, a new type of pH-responsive dual androgen-blocking nanodrug (FASC MIPs) based on a molecularly imprinted polymer has been designed and synthesized. The nanodrug could selectively sequester testosterone from the prostate tumor through specific molecular imprinting sites and simultaneously deliver the AR inhibitory drug bicalutamide, which ultimately leads to enhanced synergistic therapy of prostate cancer. FASC MIPs demonstrate excellent pH responsiveness in a simulated tumor microenvironment due to the presence of chitosan and significantly inhibit the growth of prostate cancer cells (LNCaP cells) by blocking the G1 phase of cytokinesis. Additionally, the nanodrug also displayed excellent antitumor properties in a xenograft mouse model of prostate cancer without any sign of detrimental effects on healthy tissues and organs. Both in vitro and in vivo studies verified the augmented and synergistic therapeutic effects of FASC MIPs, and the proposed dual-androgen-blocking strategy could explore novel avenues in prostate cancer treatment.

In situ digestion-assisted multi-template imprinted nanoparticles for efficient analysis of protein phosphorylation

A new general approach called in situ digestion-assisted multi-template imprinting is proposed for preparation of phospho-specific molecularly imprinted nanoparticles. Through the novel templating strategy and controllable imprinting process, imprinted nanoparticles specific to the intact phosphoprotein and its phosphopeptides were synthesized. The prepared imprinted nanoparticles exhibited excellent specificity (cross reactivity < 10%), high affinity (10-6 M), high efficiency (47.5%), and good generality (both intact phosphoprotein and phosphopeptides). We also realized the fine tuning of the recognition at peptide level of the imprinted nanoparticles by adjusting the imprinting time. Based on the selective enrichment of the imprinted nanoparticles, the MS identification of both the intact phosphoprotein (Tau) and phosphopeptides (angiotensin II and peptides of Tau) in real complex samples could be achieved. Therefore, we believe that the in situ digestion-assisted multi-template imprinting strategy holds promising future in both phosphorylation analysis and proteomics applications.

Reversible photoregulation of cell-cell adhesions with opto-E-cadherin

E-cadherin-based cell-cell adhesions are dynamically and locally regulated in many essential processes, including embryogenesis, wound healing and tissue organization, with dysregulation manifesting as tumorigenesis and metastasis. However, the lack of tools that would provide control of the high spatiotemporal precision observed with E-cadherin adhesions hampers investigation of the underlying mechanisms. Here, we present an optogenetic tool, opto-E-cadherin, that allows reversible control of E-cadherin-mediated cell-cell adhesions with blue light. With opto-E-cadherin, functionally essential calcium binding is photoregulated such that cells expressing opto-E-cadherin at their surface adhere to each other in the dark but not upon illumination. Consequently, opto-E-cadherin provides remote control over multicellular aggregation, E-cadherin-associated intracellular signalling and F-actin organization in 2D and 3D cell cultures. Opto-E-cadherin also allows switching of multicellular behaviour between single and collective cell migration, as well as of cell invasiveness in vitro and in vivo. Overall, opto-E-cadherin is a powerful optogenetic tool capable of controlling cell-cell adhesions at the molecular, cellular and behavioural level that opens up perspectives for the study of dynamics and spatiotemporal control of E-cadherin in biological processes.

Imprinted Hydrogel Nanoparticles for Protein Biosensing: A Review

Over the past decade, molecular imprinting (MI) technology has made tremendous progress, and the advancements in nanotechnology have been the major driving force behind the improvement of MI technology. The preparation of nanoscale imprinted materials, i.e., molecularly imprinted polymer nanoparticles (MIP NPs, also commonly called nanoMIPs), opened new horizons in terms of practical applications, including in the field of sensors. Currently, hydrogels are very promising for applications in bioanalytical assays and sensors due to their high biocompatibility and possibility to tune chemical composition, size (microgels, nanogels, etc.), and format (nanostructures, MIP film, fibers, etc.) to prepare optimized analyte-responsive imprinted materials. This review aims to highlight the recent progress on the use of hydrogel MIP NPs for biosensing purposes over the past decade, mainly focusing on their incorporation on sensing devices for detection of a fundamental class of biomolecules, the peptides and proteins. The review begins by directing its focus on the ability of MIPs to replace biological antibodies in (bio)analytical assays and highlight their great potential to face the current demands of chemical sensing in several fields, such as disease diagnosis, food safety, environmental monitoring, among others. After that, we address the general advantages of nanosized MIPs over macro/micro-MIP materials, such as higher affinity toward target analytes and improved binding kinetics. Then, we provide a general overview on hydrogel properties and their great advantages for applications in the field of Sensors, followed by a brief description on current popular routes for synthesis of imprinted hydrogel nanospheres targeting large biomolecules, namely precipitation polymerization and solid-phase synthesis, along with fruitful combination with epitope imprinting as reliable approaches for developing optimized protein-imprinted materials. In the second part of the review, we have provided the state of the art on the application of MIP nanogels for screening macromolecules with sensors having different transduction modes (optical, electrochemical, thermal, etc.) and design formats for single use, reusable, continuous monitoring, and even multiple analyte detection in specialized laboratories or in situ using mobile technology. Finally, we explore aspects about the development of this technology and its applications and discuss areas of future growth.

Synthetic Peptide Antibodies as TNF-α Inhibitors: Molecularly Imprinted Polymer Nanogels Neutralize the Inflammatory Activity of TNF-α in THP-1 Derived Macrophages

Tumor Necrosis Factor-α (TNF-α) is a cytokine that is normally produced by immune cells when fighting an infection. But, when too much TNF-α is produced as in autoimmune diseases, this leads to unwanted and persistent inflammation. Anti-TNF-α monoclonal antibodies have revolutionized the therapy of these disorders by blocking TNF-α and preventing its binding to TNF-α receptors, thus suppressing the inflammation. Herein, we propose an alternative in the form of molecularly imprinted polymer nanogels (MIP-NGs). MIP-NGs are synthetic antibodies obtained by nanomoulding the 3-dimensional shape and chemical functionalities of a desired target in a synthetic polymer. Using an in-house developed in silico rational approach, epitope peptides of TNF-α were generated and 'synthetic peptide antibodies' were prepared. The resultant MIP-NGs bind the template peptide and recombinant TNF-α with high affinity and selectivity, and can block the binding of TNF-α to its receptor. Consequently they were applied to neutralize pro-inflammatory TNF-α in the supernatant of human THP-1 macrophages, leading to a downregulation of the secretion of pro-inflammatory cytokines. Our results suggest that MIP-NGs, which are thermally and biochemically more stable and easier to manufacture than antibodies, and cost-effective, are very promising as next generation TNF-α inhibitors for the treatment of inflammatory diseases.

Hierarchically Structured Molecularly Imprinted Nanotransducers for Truncated HER2-Targeted Photodynamic Therapy of Therapeutic Antibody-Resistant Breast Cancer

Antibodies have been a mainstream class of therapeutics for clinical treatment of various diseases, especially cancers. However, mutation in cancer cells leads to resistance to therapeutic antibodies, hyperactivity of proliferation of cancer cells, and difficulty in the development of therapeutic antibodies. Herein, we present a strategy termed molecularly imprinted nanotransducer (MINT) for targeted photodynamic therapy (PDT) of mutated cancers. The MINT is a rationally engineered nanocomposite featuring a core of an upconversion nanoparticle, a shell of a thin layer of molecularly imprinted polymer, and a photosensitizer modified on the surface. As a proof-of-principle, truncated HER2 (P95HER2) overexpressed breast cancer, a challenging cancer lacking effective targeted therapeutics, was used as the cancer model. The designed structure, properties, functions, and anticancer efficacy of MINT were systematically investigated and experimentally confirmed. The MINT could not only specifically target P95HER2+ cancer cells in vitro and in vivo but also efficiently transfer the irradiated light and generate excited-state oxygen, resulting in efficient targeted cancer killing. Therefore, the MINT strategy provides a promising therapeutic for targeted PDT of drug-resistant cancers caused by target mutation.

Tumor microenvironment promotes lymphatic metastasis of cervical cancer: its mechanisms and clinical implications

Although previous studies have shed light on the etiology of cervical cancer, metastasis of advanced cervical cancer remains the main reason for the poor outcome and high cancer-related mortality rate. Cervical cancer cells closely communicate with immune cells recruited to the tumor microenvironment (TME), such as lymphocytes, tumor-associated macrophages, and myeloid-derived suppressor cells. The crosstalk between tumors and immune cells has been clearly shown to foster metastatic dissemination. Therefore, unraveling the mechanisms of tumor metastasis is crucial to develop more effective therapies. In this review, we interpret several characteristics of the TME that promote the lymphatic metastasis of cervical cancer, such as immune suppression and premetastatic niche formation. Furthermore, we summarize the complex interactions between tumor cells and immune cells within the TME, as well as potential therapeutic strategies to target the TME.

Molecularly Imprinted Polymers as Synthetic Antibodies for Protein Recognition: The Next Generation

Molecularly imprinted polymers (MIPs) are chemical antibody mimics obtained by nanomoulding the 3D shape and chemical functionalities of a desired target in a synthetic polymer. Consequently, they possess exquisite molecular recognition cavities for binding the target molecule, often with specificity and affinity similar to those of antigen-antibody interactions. Research on MIPs targeting proteins began in the mid-90s, and this review will evaluate the progress made till now, starting from their synthesis in a monolith bulk format through surface imprinting to biocompatible soluble nanogels prepared by solid-phase synthesis. MIPs in the latter format will be discussed more in detail because of their tremendous potential of replacing antibodies in the biomedical domain like in diagnostics and therapeutics, where the workforce of antibodies is concentrated. Emphasis is also put on the development of epitope imprinting, which consists of imprinting a short surface-exposed fragment of a protein, resulting in MIPs capable of selectively recognizing the whole macromolecule, amidst others in complex biological media, on cells or tissues. Thus selecting the 'best' peptide antigen is crucial and in this context a rational approach, inspired from that used to predict peptide immunogens for peptide antibodies, is described for its unambiguous identification.

Epitope imprinted polymeric materials: application in electrochemical detection of disease biomarkers

Epitope imprinting is a promising method for creating specialized recognition sites that resemble natural biorecognition elements. Epitope-imprinted materials have gained a lot of attention recently in a variety of fields, including bioanalysis, drug delivery, and clinical therapy. The vast applications of epitope imprinted polymers are due to the flexibility in choosing monomers, the simplicity in obtaining templates, specificity toward targets, and resistance to harsh environments along with being cost effective in nature. The "epitope imprinting technique," which uses only a tiny subunit of the target as the template during imprinting, offers a way around various drawbacks inherent to biomacromolecule systems i.e., traditional molecular imprinting techniques with regards to the large size of proteins, such as the size, complexity, accessibility, and conformational flexibility of the template. Electrochemical based sensors are proven to be promising tool for the quick, real-time monitoring of biomarkers. This review unravels epitope imprinting techniques, approaches, and strategies and highlights the applicability of these techniques for the electrochemical quantification of biomarkers for timely disease monitoring. In addition, some challenges are discussed along with future prospective developments.

Molecularly Imprinted Nanomaterials with Stimuli Responsiveness for Applications in Biomedicine

The review aims to summarize recent reports of stimuli-responsive nanomaterials based on molecularly imprinted polymers (MIPs) and discuss their applications in biomedicine. In the past few decades, MIPs have been proven to show widespread applications as new molecular recognition materials. The development of stimuli-responsive nanomaterials has successfully endowed MIPs with not only affinity properties comparable to those of natural antibodies but also the ability to respond to external stimuli (stimuli-responsive MIPs). In this review, we will discuss the synthesis of MIPs, the classification of stimuli-responsive MIP nanomaterials (MIP-NMs), their dynamic mechanisms, and their applications in biomedicine, including bioanalysis and diagnosis, biological imaging, drug delivery, disease intervention, and others. This review mainly focuses on studies of smart MIP-NMs with biomedical perspectives after 2015. We believe that this review will be helpful for the further exploration of stimuli-responsive MIP-NMs and contribute to expanding their practical applications especially in biomedicine in the near future.

Application of Molecularly Imprinted Electrochemical Biomimetic Sensors for Detecting Small Molecule Food Contaminants

Environmental chemical contaminants in food seriously impact human health and food safety. Successful detection methods can effectively monitor the potential risk of emerging chemical contaminants. Among them, molecularly imprinted polymers (MIPs) based on electrochemical biomimetic sensors overcome many drawbacks of conventional detection methods and offer opportunities to detect contaminants with simple equipment in an efficient, sensitive, and low-cost manner. We searched eligible papers through the Web of Science (2000-2022) and PubMed databases. Then, we introduced the sensing mechanism of MIPs, outlined the sample preparation methods, and summarized the MIP characterization and performance. The classification of electrochemistry, as well as its advantages and disadvantages, are also discussed. Furthermore, the representative application of MIP-based electrochemical biomimetic sensors for detecting small molecular chemical contaminants, such as antibiotics, pesticides, toxins, food additives, illegal additions, organic pollutants, and heavy metal ions in food, is demonstrated. Finally, the conclusions and future perspectives are summarized and discussed.

pH-Responsive epitope-imprinted magnetic nanoparticles for selective separation and extraction of chlorogenic acid and caffeic acid in traditional Chinese medicines

Chlorogenic acid and caffeic acid often coexist in traditional Chinese medicines (TCMs) and play roles as antioxidation, antiviral, antitumor and anti-inflammatory agents. Due to their low content and the presence of structural analogues, they cannot be effectively separated by conventional extraction methods. Molecularly imprinted polymers, as synthesized receptors with antibody-like binding properties, have significant advantages in separating structural analogues. However, the harsh imprinting conditions easily induced the degradation of chlorogenic acid. Therefore, caffeic acid was used as an epitope template to replace chlorogenic acid for imprinting. Boronic acid-functionalized magnetic nanoparticles (MNPs) were selected as substrates, which could not only facilitate the immobilization and removal of the templates by pH regulation, but also achieve rapid separation under an external magnetic field. Tetraethyl orthosilicate was selected as an imprinting monomer which allowed for precise control of the thickness of the imprinting layer by adjusting the imprinting time. The prepared epitope-imprinted MNPs showed excellent specificity, in combination with high performance liquid chromatography, have been successfully applied to the selective separation and detection of chlorogenic acid and caffeic acid in TCMs.

New Azido Coumarins as Potential Agents for Fluorescent Labeling and Their "Click" Chemistry Reactions for the Conjugation with closo-Dodecaborate Anion

Novel fluorescent 7-methoxy- and 7-(diethylamino)-coumarins modified with azido-group on the side chain have been synthesized. Their photophysical properties and single crystals structure characteristics have been studied. In order to demonstrate the possibilities of fluorescent labeling, obtained coumarins have been tested with closo-dodecaborate derivative bearing terminal alkynyl group. Cu^I catalyzed Huisgen 1,3-dipolar cycloaddition reaction has led to fluorescent conjugates formation. The absorption-emission spectra of the formed conjugates have been presented. The antiproliferative activity and uptake of compounds against several human cell lines were evaluated.

Boosting Chemodynamic Therapy by Tumor-Targeting and Cellular Redox Homeostasis-Disrupting Nanoparticles

Chemodynamic therapy (CDT) that kills tumor cells by converting low-reactivity H₂O₂ into highly toxic hydroxyl radicals (•OH) is an emerging tumor therapeutic modality, but its therapeutic efficacy is largely limited by both the lack of tumor targeting and redox homeostasis in tumor cells. Herein, we report Cu²⁺-encapsulated and GalNAc-imprinted biodegradable silica nanoparticles (nanoMIP) for boosting CDT. In this strategy, the Cu²⁺ was first encapsulated into disulfide-bridged silica nanoparticles with a high loading capacity of ∼18.3%, followed by in situ functionalization via molecular imprinting using GalNAc as a template. Such a nanovector could specifically target tumor cells overexpressing the Tn antigen to promote the cellular uptake. After internalization into tumor cells, the degradation of nanoMIP occurred in response to the tumor microenvironment, spontaneously releasing Cu²⁺/Cu⁺ via redox cycles, which in turn promoted highly potent GSH depletion and triggered •OH generation by a Fenton-like reaction. Notably, we found that the catalase activity could be effectively inhibited by the produced Cu⁺, which indirectly upregulated the endogenous H₂O₂ level. As a result, the "maladjusted" tumor cells lost the resistance against •OH damage, finally resulting in the apoptosis of tumor cells. In vitro and in vivo experiments demonstrated that our nanoMIP exhibited excellent cytotoxicity against tumor cells and high efficacy of tumor inhibition in the xenograft tumor model with negligible side effects. Taken together, our study provides not only a promising strategy for maximizing the CDT efficacy but also a new insight for developing MIP-based nanomedicine.

Binding of Proteins to Copolymers of Varying Charges and Hydrophobicity: A Molecular Mechanism and Computational Strategies

Because of their ability to selectively bind to a target protein, copolymer nanoparticles (NPs) containing a selected combination of hydrophobic and charged groups have been frequently reported as potent antibody-like analogues. However, due to the intrinsic disorder of the copolymer NP in terms of its random monomer sequence and the cross-linked copolymer matrix, the copolymer NP is indeed strikingly different from a well-folded protein antibody and the complexation between the copolymer NP and a target protein is likely not due to a lock-key type of interaction but possibly due to a novel and unexplored molecular mechanism. Here, we study a key biomarker protein, vimentin, interacting with a set of random copolymer chains using implicit-water explicit-ion coarse-grained (CG) molecular dynamics (MD) simulations along with biolayer interferometry (BLI) analysis. Due to the charge and hydrophobicity anisotropy on the vimentin dimer (VD) surface, a set of bound copolymers are found inhomogenously adsorbed on the VD, with energetic heterogeneity for different binding sites and cooperative effect in the adsorption. Increasing the charge or hydrophobicity of the copolymer may have different consequences on the adsorption. In this study, we found that with more copolymer charges, the protein coverage increases for copolymers of low hydrophobicity and decreases of high hydrophobicity, which is explained by the distribution and size of various functional patches on the VD in loading those copolymers. Employing a coverage-dependent Langmuir model, we propose a simulation protocol to address the full profile of the copolymer binding free energy through the fit to the simulated binding isotherm. The obtained results correlate well with those from the BLI experiment, indicating the significance of this method for the rational design of the copolymer NP with engineered protein binding affinity.

Protein-Mimicking Nanoparticles in Biosystems

Proteins are essential elements for almost all life activities. The emergence of nanotechnology offers innovative strategies to create a diversity of nanoparticles (NPs) with intrinsic capacities of mimicking the functions of proteins. These artificial mimics are produced in a cost-efficient and controllable manner, with their protein-mimicking performances comparable or superior to those of natural proteins. Moreover, they can be endowed with additional functionalities that are absent in natural proteins, such as cargo loading, active targeting, membrane penetrating, and multistimuli responding. Therefore, protein-mimicking NPs have been utilized more and more often in biosystems for a wide range of applications including detection, imaging, diagnosis, and therapy. To highlight recent progress in this broad field, herein, representative protein-mimicking NPs that fall into one of the four distinct categories are summarized: mimics of enzymes (nanozymes), mimics of fluorescent proteins, NPs with high affinity binding to specific proteins or DNA sequences, and mimics of protein scaffolds. This review covers their subclassifications, characteristic features, functioning mechanisms, as well as the extensive exploitation of their great potential for biological and biomedical purposes. Finally, the challenges and prospects in future development of protein-mimicking NPs are discussed.

How Molecularly Imprinted Polymers can be Used for Diagnostic and Treatment of Tropical Diseases?

Molecularly imprinted polymers (MIPs) have been widely used in nanomedicine in the last few years. However, their use for diagnostic and treatment of tropical diseases is limited. Through this review, we aim to illustrate how MIPs were used to detect tropical disease and we show that they are not exploited enough in treatment. We finally show how MIPs could be used in the future in the treatment of tropical disease.

Hydrazone bond-oriented molecularly imprinted nanocomposites for the selective separation of protein via the well-defined recognition sites

The development of hydrazone bond-oriented epitope imprinting strategy is reported to synthesize the polymeric binders for the selective recognition of a protein-β₂-microglobulin through either its N- or C-terminal epitope. The dynamic reversibility of hydrazone bond facilitated not only the oriented assembly of the template peptide hydrazides onto the substrate but also the efficient removal of them from the imprinted cavities. The well-defined surface imprinted layer was successfully constructed through the precise control over the polymerization of silicate esters. Binding performance of the C-terminal peptide imprinted nanocomposite was significantly improved after tuning the non-covalent interactions using the sequence-matching aromatic co-monomers. The dissociation constant (K_d) between the optimized nanocomposite and epitope peptide was 0.5 µmol L^-1. The nanomaterial was utilized for the selective extraction and determination of β₂-microglobulin from human urine by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and HPLC-UV with satisfied recoveries of 93.1-112.3% in a concentration range 1.0-50.0 μg⋅mL^-1.

Molecularly imprinted polymer nanogels targeting the HAV motif in cadherins inhibit cell-cell adhesion and migration

Cadherins are cell-surface proteins that mediate cell-cell adhesion. By regulating their grip formation and strength, cadherins play a pivotal role during normal tissue morphogenesis and homeostasis of multicellular organisms. However, their dysfunction is associated with cell migration and proliferation, cancer progression and metastasis. The conserved amino acid sequence His-Ala-Val (HAV) in the extracellular domain of cadherins is implicated in cadherin-mediated adhesion and migration. Antagonists of cadherin adhesion such as monoclonal antibodies and small molecule inhibitors based on HAV peptides, are of high therapeutic value in cancer treatment. However, antibodies are not stable outside their natural environment and are expensive to produce, while peptides have certain limitations as a drug as they are prone to proteolysis. Herein, we propose as alternative, a synthetic antibody based on molecularly imprinted polymer nanogels (MIP-NGs) to target the HAV domain. The MIP-NGs are biocompatible, have high affinity for N-cadherin and inhibit cell adhesion and migration of human cervical adenocarcinoma (HeLa) cells, as demonstrated by cell aggregation and Matrigel invasion assays, respectively. The emergence of MIPs as therapeutics for fighting cancer is still in its infancy and this novel demonstration reinforces the fact that they have a rightful place in cancer treatment.

Rationally Screened and Designed ABCG2-Binding Aptamers for Targeting Cancer Stem Cells and Reversing Multidrug Resistance

The ATP-binding cassette, subfamily G, isoform 2 protein (ABCG2), as an important member of ABC transporters, plays a key role in multidrug resistance (MDR) in cancer and has been widely considered as a marker of cancer stem cells (CSC). Reagents capable of simultaneously targeting ABCG2 and reversing MDR have great clinical application values, but their development is highly challenging. Herein, ABCG2 glycosylated extracellular region-binding aptamers were efficiently screened by a cladded molecularly imprinted polymer (cMIP)-based in vitro screening method and further rationally engineered into cyclic bivalent aptamers. Experiments showed that both the monovalent and cyclic bivalent aptamers could specifically bind ABCG2 and thereby specially target CSC of human colorectal carcinomas (CoCSC), while the latter could effectively reverse MDR in drug-resistant liver cancer cells (HepG2/ADR). Different from currently predominant small molecule inhibitors, the reversal of MDR relied on a different mechanism; the cyclic bivalent aptamers bound the two monomers of ABCG2 dimers simultaneously and thereby blocked the ABCG2-mediated drug-pumping channel, resulting in increased intracellular accumulation of substrate drugs. This study opened a new access to the development of affinity reagents for targeting CSC and reversing MDR, holding great prospects in cancer diagnosis and treatment.

Recent advances in protein-imprinted polymers: synthesis, applications and challenges

The molecular imprinting technique (MIT), also described as the "lock to key" method, has been demonstrated as an effective tool for the creation of synthetic polymers with antibody-like sites to specifically recognize target molecules. To date, most successful molecular imprinting researches were limited to small molecules (<1500 Da); biomacromolecule (especially protein) imprinting remains a serious challenge due to their large size, chemical and structural complexity, and environmental instability. Nevertheless, protein imprinting has achieved some significant breakthroughs in imprinting methods and applications over the past decade. Some special protein-imprinted materials with outstanding properties have been developed and exhibited excellent potential in several advanced fields such as separation and purification, proteomics, biomarker detection, bioimaging and therapy. In this review, we critically and comprehensively surveyed the recent advances in protein imprinting, particularly emphasizing the significant progress in imprinting methods and highlighted applications. Finally, we summarize the major challenges remaining in protein imprinting and propose its development direction in the near future.

Molecular imprinting and cladding produces antibody mimics with significantly improved affinity and specificity

Molecularly imprinted polymers (MIPs), as important mimics of antibodies, are chemically synthesized by polymerization in the presence of a target compound. MIPs have found wide applications in important fileds. However, the current molecular imprinting technology suffers from a dilemma; there is often a compromise between the best affinity and the best specificity for MIPs prepared under optimized conditions. Herein, we proposed a new strategy called molecular imprinting and cladding (MIC) to solve this issue. The principle is straightforward; after molecular imprinting, a chemically inert cladding thinlayer is generated to precisely cover non-imprinted area. We further proposed a special MIC approach for controllably engineering protein binders. The prepared cladded MIPs (cMIPs) exhibited significantly improved affinity and specificity. The general applicability of the proposed strategy and method was verified by engineering of cMIPs for the recognition of a variety of different proteins. The feasibility of cMIPs for real applications was demonstrated by fluorescence imaging of cancer cells against normal cells and immunoassay of C-peptide in human urine. This study opened up a new avenue for controllably engineering protein-specific antibody mimics with excellent recognition properties, holding great prospective in important applications such as disease diagnosis and nanomedicine.

The Evolution of Molecular Recognition: From Antibodies to Molecularly Imprinted Polymers (MIPs) as Artificial Counterpart

Molecular recognition is a useful property shared by various molecules, such as antibodies, aptamers and molecularly imprinted polymers (MIPs). It allows these molecules to be potentially involved in many applications including biological and pharmaceutical research, diagnostics, theranostics, therapy and drug delivery. Antibodies, naturally produced by plasma cells, have been exploited for this purpose, but they present noticeable drawbacks, above all production cost and time. Therefore, several research studies for similar applications have been carried out about MIPs and the main studies are reported in this review. MIPs, indeed, are more versatile and cost-effective than conventional antibodies, but the lack of toxicity studies and their scarce use for practical applications, make it that further investigations on this kind of molecules need to be conducted.

Rational development of molecularly imprinted nanoparticles for blocking PD-1/PD-L1 axis

Blocking the PD-1/PD-L1 immune checkpoint has emerged as a promising strategy in cancer immunotherapy, in which monoclonal antibodies are predominately used as inhibitors. Despite their remarkable success, monoclonal antibody-based therapeutics suffer from drawbacks due to the use of antibodies, such as high cost, low stability and high frequency of immune-related adverse effects. Therefore, novel anti-PD-1/PD-L1 therapeutics that can address these issues are of significant importance. Herein, we report a molecularly imprinted polymer (MIP) based PD-1 nano inhibitor for blocking the PD-1/PD-L1 axis. The anti-PD-1 nanoMIP was rationally designed and engineered by epitope imprinting using the N-terminal epitope of PD-1 as the binding site. The anti-PD-1 nanoMIP showed good specificity and high affinity towards PD-1, yielding a disassociation constant at the 10⁻⁸ M level, much better than that between PD-1 and PD-L1. Via steric hindrance, this inhibitor could effectively block PD-1/PD-L1 interaction. Besides, it could effectively reactivate T cells and reverse the chemoresistance of tumor cells. Therefore, this present study not only provides a novel and promising immune checkpoint blockade inhibitor but also boosts further development of MIPs for cancer immunotherapy.

A nanoscale molecularly imprinted polymer (MIP) for blocking the PD-1/PD-L1 axis was rationally developed. The anti-PD-1 nanoMIP was able to effectively block PD-1/PD-L1 interaction, reactivate T cells and reverse the chemoresistance of tumor cells.

Construction of DNA ligase-mimicking nanozymes via molecular imprinting

Enzyme mimics are of significant importance due to their facile preparation, low cost and stability to rigorous environment. Molecularly imprinted polymers (MIPs) have been important synthetic mimics of enzymes. However,...

Molecularly Imprinted Polymer Hydrogel Nanoparticles: Synthetic Antibodies for Cancer Diagnosis and Therapy

Cancer is a leading cause of death worldwide and according to the World Health Organization (WHO) accounted for 10 million deaths in 2020. Promising theranostic (therapy and diagnostic) agents in the treatment of cancer are nanomaterials, which have come to the forefront because of their small size approaching those of protein complexes in the human body, and of their easy functionalization giving access to nanocomposite materials with diverse functions (fluorescence, magnetic, stimuli-responsiveness, etc.), and improved biocompatibility. Among them, affinity nanoparticles, often decorated with highly specific targeting ligands such as antibodies, aptamers, lectins and peptides, have enabled enhanced binding and exquisite recognition of biomarkers overexpressed in cancer cells. In this review, we describe an emerging class of targeting ligands, molecularly imprinted polymer hydrogel nanoparticles for their application in the early detection of disease, with the aim to improve diagnosis and treatment.

Controllable Engineering and Functionalizing of Nanoparticles for Targeting Specific Proteins towards Biomedical Applications

Nanoparticles have been widely used in important biomedical applications such as imaging, drug delivery, and disease therapy, in which targeting toward specific proteins is often essential. However, current targeting strategies mainly rely on surface modification with bioligands, which not only often fail to provide desired properties but also remain challenging. Here an unprecedented approach is reported, called reverse microemulsion-confined epitope-oriented surface imprinting and cladding (ROSIC), for facile, versatile, and controllable engineering coreless and core/shell nanoparticles with tunable monodispersed size as well as specific targeting capability toward proteins and peptides. Via engineering coreless imprinted and cladded silica nanoparticles, the effectiveness and superiority over conventional imprinting of the proposed approach are first verified. The prepared nanoparticles exhibit both high specificity and high affinity. Using quantum dots, superparamagnetic nanoparticles, silver nanoparticles, and upconverting nanoparticles as a representative set of core substrates, a variety of imprinted and cladded single-core/shell nanoparticles are then successfully prepared. Finally, using imprinted and cladded fluorescent nanoparticles as probes, in vitro targeted imaging of triple-negative breast cancer (TNBC) cells and in vivo targeted imaging of TNBC-bearing mice are achieved. This approach opens a new avenue to engineering of nanoparticles for targeting specific proteins, holding great prospects in biomedical applications.

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.

Evolution of Molecularly Imprinted Enzyme Inhibitors: From Simple Activity Inhibition to Pathological Cell Regulation

Molecular imprinting represents one of the most promising strategies to design artificial enzyme inhibitors. However, the study of molecularly imprinted enzyme inhibitors (MIEIs) remains at a primary stage. Advanced applications of MIEIs for cell regulation have rarely been explored. Using a solid-phase oriented imprinting strategy so as to leave the active site of the enzymes accessible, we synthesized two MIEIs that exhibit high specificity and potent inhibitory effects (inhibition constant at low nM range) towards trypsin and angiogenin. The trypsin MIEI inhibits trypsin activity, tryptic digestion-induced extracellular matrix lysis and cell membrane destruction, indicating its utility in the treatment of active trypsin-dependent cell injury. The angiogenin MIEI blocks cancer cell proliferation by suppressing the ribonuclease activity of angiogenin and decreasing the angiogenin level inside and outside HeLa cells. Our work demonstrates the versatility of MIEIs for both enzyme inhibition and cell fate manipulation, showing their great potential as therapeutic drugs in biomedicine.

Emerging strategies in developing multifunctional nanomaterials for cancer nanotheranostics

Cancer involves a collection of diseases with a common trait - dysregulation in cell proliferation. At present, traditional therapeutic strategies against cancer have limitations in tackling various tumors in clinical settings. These include chemotherapeutic resistance and the inability to overcome intrinsic physiological barriers to drug delivery. Nanomaterials have presented promising strategies for tumor treatment in recent years. Nanotheranostics combine therapeutic and bioimaging functionalities at the single nanoparticle level and have experienced tremendous growth over the past few years. This review highlights recent developments of advanced nanomaterials and nanotheranostics in three main directions: stimulus-responsive nanomaterials, nanocarriers targeting the tumor microenvironment, and emerging nanomaterials that integrate with phototherapies and immunotherapies. We also discuss the cytotoxicity and outlook of next-generation nanomaterials towards clinical implementation.

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.

Design and development of plastic antibodies against SARS-CoV-2 RBD based on molecularly imprinted polymers that inhibit in vitro virus infection

The present research study reports the development of plastic antibodies based on Molecularly Imprinted Polymers (MIPs) capable of selectively binding a portion of the novel coronavirus SARS-CoV-2 spike protein. Indeed, molecular imprinting represents a very promising and attractive technology for the synthesis of MIPs characterized by specific recognition abilities for a target molecule. Given these characteristics, MIPs can be considered tailor-made synthetic antibodies obtained by a templating process. After in silico analysis, imprinted nanoparticles were synthesized by inverse microemulsion polymerization and their ability to prevent the interaction between ACE2 and the receptor-binding domain of SARS-CoV-2 was investigated. Of relevance, the developed synthetic antibodies are capable of significantly inhibiting virus replication in Vero cell culture, suggesting their potential application in the treatment, prevention and diagnosis of SARS-CoV-2 infection.

Molecularly imprinted polymers by epitope imprinting: a journey from molecular interactions to the available bioinformatics resources to scout for epitope templates

The molecular imprinting of proteins is the process of forming biomimetics with entailed protein-recognition by means of a template-assisted synthesis. Protein-imprinted polymers (pMIPs) have been successfully employed in separations, assays, sensors, and imaging. From a technical point of view, imprinting a protein is both costly, for protein expression and purification, and challenging, for the preservation of the protein's structural properties. In fact, the imprinting process needs to guarantee the preservation of the same protein three-dimensional conformation that later would be recognized. So far, the captivating idea to imprint just a portion of the protein, i.e., an epitope, instead of the whole, proved successful, offering reduced costs, compatibility with many synthetic conditions (solvents, pH, temperatures), and fine-tuning of the peptide sequence so to target specific physiological and functional conditions of the protein, such as post-translational modifications. Here, protein-protein interactions and the biochemical features of the epitopes are inspected, deriving lessons to prepare more effective pMIPs. Epitopes are categorized in linear or structured, immunogenic or not, located at the protein's surface or buried in its core and the imprinting strategies are discussed. Moreover, attention is given to freely available online bioinformatics resources that might offer key tools to gain further rationale amid the selection process of suitable epitopes templates.

Transition-Metal Dichalcogenide Artificial Antibodies with Multivalent Polymeric Recognition Phases for Rapid Detection and Inactivation of Pathogens

Antibodies are recognition molecules that can bind to diverse targets ranging from pathogens to small analytes with high binding affinity and specificity, making them widely employed for sensing and therapy. However, antibodies have limitations of low stability, long production time, short shelf life, and high cost. Here, we report a facile approach for the design of luminescent artificial antibodies with nonbiological polymeric recognition phases for the sensitive detection, rapid identification, and effective inactivation of pathogenic bacteria. Transition-metal dichalcogenide (TMD) nanosheets with a neutral dextran phase at the interfaces selectively recognized S. aureus, whereas the nanosheets bearing a carboxymethylated dextran phase selectively recognized E. coli O157:H7 with high binding affinity. The bacterial binding sites recognized by the artificial antibodies were thoroughly identified by experiments and molecular dynamics simulations, revealing the significance of their multivalent interactions with the bacterial membrane components for selective recognition. The luminescent WS₂ artificial antibodies could rapidly detect the bacteria at a single copy from human serum without any purification and amplification. Moreover, the MoSe₂ artificial antibodies selectively killed the pathogenic bacteria in the wounds of infected mice under light irradiation, leading to effective wound healing. This work demonstrates the potential of TMD artificial antibodies as an alternative to antibodies for sensing and therapy.

Molecularly Imprinted Polymer Nanogels for Protein Recognition: Direct Proof of Specific Binding Sites by Solution STD and WaterLOGSY NMR Spectroscopies

Molecularly imprinted polymers (MIPs) are tailor-made synthetic antibodies possessing specific binding cavities designed for a target molecule. Currently, MIPs for protein targets are synthesized by imprinting a short surface-exposed fragment of the protein, called epitope or antigenic determinant. However, finding the epitope par excellence that will yield a peptide "synthetic antibody" cross-reacting exclusively with the protein from which it is derived, is not easy. We propose a computer-based rational approach to unambiguously identify the "best" epitope candidate. Then, using Saturation Transfer Difference (STD) and WaterLOGSY NMR spectroscopies, we prove the existence of specific binding sites created by the imprinting of this peptide epitope in the MIP nanogel. The optimized MIP nanogel could bind the epitope and cognate protein with a high affinity and selectivity. The study was performed on Hepatitis A Virus Cell Receptor-1 protein, also known as KIM-1 and TIM-1, for its ubiquitous implication in numerous pathologies.

Regulation of cadherin dimerization by chemical fragments as a trigger to inhibit cell adhesion

Many cadherin family proteins are associated with diseases such as cancer. Since cell adhesion requires homodimerization of cadherin molecules, a small-molecule regulator of dimerization would have therapeutic potential. Herein, we describe identification of a P-cadherin-specific chemical fragment that inhibits P-cadherin-mediated cell adhesion. Although the identified molecule is a fragment compound, it binds to a cavity of P-cadherin that has not previously been targeted, indirectly prevents formation of hydrogen bonds necessary for formation of an intermediate called the X dimer and thus modulates the process of X dimerization. Our findings will impact on a strategy for regulation of protein-protein interactions and stepwise assembly of protein complexes using small molecules.

Molecularly Imprinted Silk Fibroin Nanoparticles

Nanosized biomimetics prepared by the strategy of molecular imprinting, that is, the stamping of recognition sites by means of a template-assisted synthesis, are demonstrating potential as plastic antibodies in medicine, proving effective for cell imaging and targeted therapies. Most molecularly imprinted nanoparticles (MIP-NPs) are currently made of soft matter, such as polyacrylamide and derivatives. Yet, MIP-NPs biocompatibility is crucial for their effective translation into clinical uses. Here, we propose the original idea to synthesize fully biocompatible molecularly imprinted nanoparticles starting from the natural polymer silk fibroin (MIP SF-NPs), which is nontoxic and highly biocompatible. The conditions to produce MIP SF-NPs of different sizes (d_mean ∼ 50 nm; d_mean ∼ 100 nm) were set using the response surface method. The stamping of a single, high affinity (K_D = 57 × 10^-9 M), and selective recognition site per silk fibroin nanoparticle was demonstrated, together with the confirmation of nontoxicity. Additionally, MIP SF-NPs were used to decorate silk microfibers and silk nanofibers, providing a general means to add entailed biofunctionalities to materials.

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.

Multivalent Nanosheet Antibody Mimics for Selective Microbial Recognition and Inactivation

Antibodies are widely used as recognition elements in sensing and therapy, but they suffer from poor stability, long discovery time, and high cost. Herein, a facile approach to create antibody mimics with flexible recognition phases and luminescent rigid scaffolds for the selective recognition, detection, and inactivation of pathogenic bacteria is reported. Tripeptides with a nitriloacetate-Cu group are spontaneously assembled on transition metal dichalcogenide (TMD) nanosheets via coordination bonding, providing a diversity of TMD-tripeptide assembly (TPA) antibody mimics. TMD-TPA antibody mimics can selectively recognize various pathogenic bacteria with nanomolar affinities. The bacterial binding sites for TMD-TPA are identified by experiments and molecular dynamics simulations, revealing that the dynamic and multivalent interactions of artificial antibodies play a crucial role for their recognition selectivity and affinity. The artificial antibodies allow the rapid and selective detection of pathogenic bacteria at single copy in human serum and urine, and their effective inactivation for therapy of infected mice. This work demonstrates the potential of TMD-TPA antibody mimics as an alternative to natural antibodies for sensing and therapy.