Mucin-Inspired Single-Chain Polymer (MIP) Fibers as Potent SARS-CoV-2 Inhibitors.

Mucins are the key component of the defensive mucus barrier. They are extended fibers of very high molecular weight with diverse biological functions depending strongly on their specific structural parameters. Here, we present a mucin-inspired nanostructure, produced via a synthetic methodology to prepare methacrylate-based dendronized polysulfates (MIP-1) on a multi gram-scale with high molecular weight (MW=450 kDa) and thiol end-functionalized mucin-inspired polymer (MIP) via RAFT polymerization. Cryo-electron tomography (Cryo-ET) analysis of MIP-1 confirmed a mucin-mimetic wormlike single-chain fiber structure (length=144±59 nm) in aqueous solution. This biocompatible fiber showed promising activity against SARS-CoV-2 and its mutant strain, with a remarkable low half maximal (IC50 ) inhibitory concentration (IC50 =10.0 nM). Additionally, we investigate the impact of fiber length on SARS-CoV-2 inhibition by testing other functional polymers (MIPs) of varying fiber lengths.

Molecular imprinting-based sensors: Lab-on-chip integration and biomedical applications.

The innovative technology of a marketable lab-on-a-chip platform for point-of-care (POC) in vitro detection has recently attracted remarkable attention. The POC tests can significantly enhance the high standard of medicinal care. In the last decade, clinical diagnostic technology has been broadly advanced and successfully performed in several areas. It seems that lab-on-a-chip approaches play a significant role in these technologies. However, high-cost and time-consuming methods are increasing the challenge and the development of a cost-effective, rapid and efficient method for the detection of biomolecules is urgently needed. Recently, polymer-coated sensing platforms have been a promising area that can be employed in medical diagnosis, pharmaceutical bioassays, and environmental monitoring. The designed on-chip sensors are based on molecular imprinting polymers (MIPs) that use label-free detection technology. Molecular imprinting shines out as a potentially promising technique for creating artificial recognition material with molecular recognition sites. MIPs provide unique advantages such as excellent recognition specificity, high selectivity, and good reusability. This review article aims to define several methods using molecular imprinting for biomolecules and their incorporation with several lab-on-chip technologies to describe the most promising methods for the development of sensing systems based on molecularly imprinted polymers. The higher selectivity, more user-friendly operation is believed to provide MIP-based lab-on-a-chip devices with great potential academic and commercial value in on-site clinical diagnostics and other point-of-care assays.

Electrochemical Sensing of Favipiravir with an Innovative Water-Dispersible Molecularly Imprinted Polymer Based on the Bimetallic Metal-Organic Framework: Comparison of Morphological Effects.

Molecularly imprinted polymers (MIPs) are widely used as modifiers in electrochemical sensors due to their high sensitivity and promise of inexpensive mass manufacturing. Here, we propose and demonstrate a novel MIP-sensor that can measure the electrochemical activity of favipiravir (FAV) as an antiviral drug, thereby enabling quantification of the concentration of FAV in biological and river water samples and in real-time. MOF nanoparticles' application with various shapes to determine FAV at nanomolar concentrations was described. Two different MOF nanoparticle shapes (dodecahedron and sheets) were systematically compared to evaluate the electrochemical performance of FAV. After carefully examining two different morphologies of MIP-Co-Ni@MOF, the nanosheet form showed a higher performance and efficiency than the nanododecahedron. When MIP-Co/Ni@MOF-based and NIP-Co/Ni@MOF electrodes (nanosheets) were used instead, the minimum target concentrations detected were 7.5 × 10-11 (MIP-Co-Ni@MOF) and 8.17 × 10-9 M (NIP-Co-Ni@MOF), respectively. This is a significant improvement (>102), which is assigned to the large active surface area and high fraction of surface atoms, increasing the amount of greater analyte adsorption during binding. Therefore, water-dispersible MIP-Co-Ni@MOF nanosheets were successfully applied for trace-level determination of FAV in biological and water samples. Our findings seem to provide useful guidance in the molecularly imprinted polymer design of MOF-based materials to help establish quantitative rules in designing MOF-based sensors for point of care (POC) systems.

Molecularly imprinted miniature electrochemical biosensor for SARS-CoV-2 spike protein based on Au nanoparticles and reduced graphene oxide modified acupuncture needle.

Accurate detection of SARS-CoV-2 spike (SARS-CoV-2-S) protein is of clinical significance for early diagnosis and timely treatment of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Herein, a surface molecularly imprinted miniature biosensor was fabricated. Au nanoparticles (AuNPs), reduced graphene oxide (rGO), poly(methylene blue)/poly(ionic liquids) and poly(ionic liquids) were successively electrodeposited onto the pinpoint of an acupuncture needle (AN). The molecularly imprinted miniature biosensor was obtained after the template of SARS-CoV-2-S protein was removed, which could be used for sensitive detection of SARS-CoV-2-S protein. The linear range and limit of detection (LOD) were 0.1 âˆ¼ 1000 ng mL-1 and 38 pg mL-1, respectively, which were superior to other molecularly imprinted biosensors previously reported. The developed miniature biosensor also exhibited high specificity and stability. The reliability of the biosensor was evaluated by the detection of SARS-CoV-2-S protein in clinical serum samples.

Differential Refractometric Biosensor for Reliable Human IgG Detection: Proof of Concept.

A new sensing platform based on long-period fiber gratings (LPFGs) for direct, fast, and selective detection of human immunoglobulin G (IgG; Mw = 150 KDa) was developed and characterized. The transducer's high selectivity is based on the specific interaction of a molecularly imprinted polymer (MIPs) design for IgG detection. The sensing scheme is based on differential refractometric measurements, including a correction system based on a non-imprinted polymer (NIP)-coated LPFG, allowing reliable and more sensitive measurements, improving the rejection of false positives in around 30%. The molecular imprinted binding sites were performed on the surface of a LPFG with a sensitivity of about 130 nm/RIU and a FOM of 16 RIU-1. The low-cost and easy to build device was tested in a working range from 1 to 100 nmol/L, revealing a limit of detection (LOD) and a sensitivity of 0.25 nmol/L (0.037 µg/mL) and 0.057 nm.L/nmol, respectively. The sensor also successfully differentiates the target analyte from the other abundant elements that are present in the human blood plasma.

SARS-CoV-2 virus label-free electrochemical nanohybrid MIP-aptasensor based on Ni3(BTC)2 MOF as a high-performance surface substrate.

A dual recognition biosensor was developed via introducing aptamer strings and molecular imprinting polymer (MIP) for the selective detection of intact SARS-CoV-2 virus based on screen printed carbon electrode (SPCE) modified with nickel-benzene tricarboxylic acid-metal-organic framework (Ni3(BTC)2 MOF) synthesized by in situ growth method, SARS-CoV-2 S protein-specific amino-aptamer and electropolymerization of dopamine (ePDA). The proposed biosensor showed an excellent linear relationship between charge transfer resistance (Rct) and increase in virus concentration in the range 10 to 108 plaque-forming units/mL (PFU/mL) with a low detection limit of 3.3 ± 0.04 PFU/mL and response time of 20 min. Compared with single-element sensors (aptamer or MIP), it showed higher selectivity for  the SARS-CoV-2 virus and facilitated detection in real samples.

Computational Modelling and Sustainable Synthesis of a Highly Selective Electrochemical MIP-Based Sensor for Citalopram Detection.

A novel molecularly imprinted polymer (MIP) has been developed based on a simple and sustainable strategy for the selective determination of citalopram (CTL) using screen-printed carbon electrodes (SPCEs). The MIP layer was prepared by electrochemical in situ polymerization of the 3-amino-4 hydroxybenzoic acid (AHBA) functional monomer and CTL as a template molecule. To simulate the polymerization mixture and predict the most suitable ratio between the template and functional monomer, computational studies, namely molecular dynamics (MD) simulations, were carried out. During the experimental preparation process, essential parameters controlling the performance of the MIP sensor, including CTL:AHBA concentration, number of polymerization cycles, and square wave voltammetry (SWV) frequency were investigated and optimized. The electrochemical characteristics of the prepared MIP sensor were evaluated by both cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. Based on the optimal conditions, a linear electrochemical response of the sensor was obtained by SWV measurements from 0.1 to 1.25 µmol L-1 with a limit of detection (LOD) of 0.162 µmol L-1 (S/N = 3). Moreover, the MIP sensor revealed excellent CTL selectivity against very close analogues, as well as high imprinting factor of 22. Its applicability in spiked river water samples demonstrated its potential for adequate monitoring of CTL. This sensor offers a facile strategy to achieve portability while expressing a willingness to care for the environment.

Molecularly Imprinted Polymer Nanoparticles Enable Rapid, Reliable, and Robust Point-of-Care Thermal Detection of SARS-CoV-2.

Rapid antigen tests are currently used for population screening of COVID-19. However, they lack sensitivity and utilize antibodies as receptors, which can only function in narrow temperature and pH ranges. Consequently, molecularly imprinted polymer nanoparticles (nanoMIPs) are synthetized with a fast (2 h) and scalable process using merely a tiny SARS-CoV-2 fragment (∼10 amino acids). The nanoMIPs rival the affinity of SARS-CoV-2 antibodies under standard testing conditions and surpass them at elevated temperatures or in acidic media. Therefore, nanoMIP sensors possess clear advantages over antibody-based assays as they can function in various challenging media. A thermal assay is developed with nanoMIPs electrografted onto screen-printed electrodes to accurately quantify SARS-CoV-2 antigens. Heat transfer-based measurements demonstrate superior detection limits compared to commercial rapid antigen tests and most antigen tests from the literature for both the alpha (∼9.9 fg mL-1) and delta (∼6.1 fg mL-1) variants of the spike protein. A prototype assay is developed, which can rapidly (∼15 min) validate clinical patient samples with excellent sensitivity and specificity. The straightforward epitope imprinting method and high robustness of nanoMIPs produce a SARS-CoV-2 sensor with significant commercial potential for population screening, in addition to the possibility of measurements in diagnostically challenging environments.

Recent Advances of Point-of-Care Devices Integrated with Molecularly Imprinted Polymers-Based Biosensors: From Biomolecule Sensing Design to Intraoral Fluid Testing.

Recent developments of point-of-care testing (POCT) and in vitro diagnostic medical devices have provided analytical capabilities and reliable diagnostic results for rapid access at or near the patient's location. Nevertheless, the challenges of reliable diagnosis still remain an important factor in actual clinical trials before on-site medical treatment and making clinical decisions. New classes of POCT devices depict precise diagnostic technologies that can detect biomarkers in biofluids such as sweat, tears, saliva or urine. The introduction of a novel molecularly imprinted polymer (MIP) system as an artificial bioreceptor for the POCT devices could be one of the emerging candidates to improve the analytical performance along with physicochemical stability when used in harsh environments. Here, we review the potential availability of MIP-based biorecognition systems as custom artificial receptors with high selectivity and chemical affinity for specific molecules. Further developments to the progress of advanced MIP technology for biomolecule recognition are introduced. Finally, to improve the POCT-based diagnostic system, we summarized the perspectives for high expandability to MIP-based periodontal diagnosis and the future directions of MIP-based biosensors as a wearable format.

A Review of Sensors and Biosensors Modified with Conducting Polymers and Molecularly Imprinted Polymers Used in Electrochemical Detection of Amino Acids: Phenylalanine, Tyrosine, and Tryptophan.

Recently, the studies on developing sensors and biosensors-with an obvious interdisciplinary character-have drawn the attention of many researchers specializing in various fundamental, but also complex domains such as chemistry, biochemistry, physics, biophysics, biology, bio-pharma-medicine, and bioengineering. Along these lines, the present paper is structured into three parts, and is aimed at synthesizing the most relevant studies on the construction and functioning of versatile devices, of electrochemical sensors and biosensors, respectively. The first part presents examples of the most representative scientific research focusing on the role and the importance of the phenylalanine, tyrosine, and tryptophan amino acids, selected depending on their chemical structure and their impact on the central nervous system. The second part is dedicated to presenting and exemplifying conductor polymers and molecularly imprinted polymers used as sensitive materials in achieving electrochemical sensors and biosensors. The last part of the review analyzes the sensors and biosensors developed so far to detect amino acids with the aid of conductor polymers and molecularly imprinted polymers from the point of view of the performances obtained, with emphasis on the detection methods, on the electrochemical reactions that take place upon detection, and on the electroanalytical performances. The present study was carried out with a view to highlighting, for the benefit of specialists in medicine and pharmacy, the possibility of achieving and purchasing efficient devices that might be used in the quality control of medicines, as well as in studying and monitoring diseases associated with these amino acids.

Ultrasensitive and highly selective "turn-on" fluorescent sensor for the detection and measurement of melatonin in juice samples.

Melatonin (MLT), a hormone related to the regulation of brain functions, is directly related to sleep quality and is considered to be a possible adjuvant therapy for patients needing hospitalization for coronavirus disease 2019 pneumonia, and accurate measurement of MLT is crucial. Herein, a new, highly sensitive, and easy operation fluorescent probe was provided based on Zr metal-organic framework encapsulation into the molecularly imprinted polymer (MOF@MIP). By combining unique properties of MIP and fluorescent MOF, selectivity and operation of the applied method were significantly improved. Different characterization methods, such as XRD, FT-IR, and FE-SEM, were used to confirm the synthesis reliability. MOF@MIP was successfully used for the precise identification and ultrasensitive detection for trace amounts of MLT. The detection mechanism for the analytical system is based on the ''turn-on'' fluorescence (FL) signal in 404 nm. The findings proved that it is possible to detect trace amounts of MLT in real samples including grape, cherry, and sour cherry juice. The linear range and the limit of detection (LOD) for trace amounts of MLT were obtained as 1-100 ng/mL and 0.18 ng/mL, respectively.

Artificial Biomimetic Electrochemical Assemblies.

Rapid, selective, and cost-effective detection and determination of clinically relevant biomolecule analytes for a better understanding of biological and physiological functions are becoming increasingly prominent. In this regard, biosensors represent a powerful tool to meet these requirements. Recent decades have seen biosensors gaining popularity due to their ability to design sensor platforms that are selective to determine target analytes. Naturally generated receptor units have a high affinity for their targets, which provides the selectivity of a device. However, such receptors are subject to instability under harsh environmental conditions and have consequently low durability. By applying principles of supramolecular chemistry, molecularly imprinted polymers (MIPs) can successfully replace natural receptors to circumvent these shortcomings. This review summarizes the recent achievements and analytical applications of electrosynthesized MIPs, in particular, for the detection of protein-based biomarkers. The scope of this review also includes the background behind electrochemical readouts and the origin of the gate effect in MIP-based biosensors.

Highly sensitive electrochemical determination of the SARS-COV-2 antigen based on a gold/graphene imprinted poly-arginine sensor.

The global COVID-19 pandemic starting at 2020 induced by the severe acute respiratory syndrome coronavirus 2 virus (SARS-CoV-2) has revealed a very pressing need for rapid, affordable and effective diagnosis for epidemic management and control. Although several commercialized analytical methods (e.g., reverse transcription polymerase chain reaction and enzyme linked immunosorbent assay) have been developed for detecting SARS-CoV-2, they are expensive and time-consuming. Most recently, low-cost molecularly imprinted polymer (MIP)-based sensors have received attention. In this study, by introducing gold/graphene (Au/Gr) nanohybrids to modify a screen-printed carbon electrode (SPCE) and using arginine as the functional monomer, a simple and highly sensitive MIP sensor was proposed to detect SARS-CoV-2 nucleocapsid protein (ncovNP). By optimizing various influencing factors, the proposed MIP sensor shows wide linear range and low detection limit for ncovNP owing to excellent electrical property and large surface of Au/Gr and specific recognition ability of MIP, revealing important potential application for the effective early diagnosis of COVID-19.

An ultrasensitive molecularly imprinted polymer-based electrochemical sensor for the determination of SARS-CoV-2-RBD by using macroporous gold screen-printed electrode.

Herein, a novel molecularly imprinted polymer (MIP) based electrochemical sensor for the determination of the receptor-binding domain of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2-RBD) has been developed. For this purpose, first, a macroporous gold screen-printed electrode (MP-Au-SPE) has been fabricated. The MIP was then synthesized on the surface of the MP-Au-SPE through the electro-polymerization of ortho-phenylenediamine in the presence of SARS-CoV-2-RBD molecules as matrix polymer, and template molecules, respectively. During the fabrication process, the SARS-CoV-2-RBD molecules were embedded in the polymer matrix. Subsequently, the template molecules were removed from the electrode by using alkaline ethanol. The template molecules removal was studied using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX), and attenuated total reflectance spectroscopy (ATR). The fabricated MIP film acted as an artificial recognition element for the measurement of SARS-CoV-2-RBD. The EIS technique was used for the measurement of the SARS-CoV-2-RBD in the saliva solution. The electron transfer resistance (Ret) of the MIP-based sensor in a ferri/ferrocyanide solution increased as the SARS-CoV-2-RBD concentration increased due to the occupation of the imprinted cavities by the SARS-CoV-2-RBD. The MIP-based sensor exhibited a good response to the SARS-CoV-2-RBD in the concentration range between 2.0 and 40.0 pg mL-1 with a limit of detection of 0.7 pg mL-1. The obtained results showed that the fabricated MIP sensor has high selectivity sensitivity, and stability.

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.

Development of a portable MIP-based electrochemical sensor for detection of SARS-CoV-2 antigen.

The current COVID-19 pandemic caused by SARS-CoV-2 coronavirus is expanding around the globe. Hence, accurate and cheap portable sensors are crucially important for the clinical diagnosis of COVID-19. Molecularly imprinted polymers (MIPs) as robust synthetic molecular recognition materials with antibody-like ability to bind and discriminate between molecules can perfectly serve in building selective elements in such sensors. Herein, we report for the first time on the development of a MIP-based electrochemical sensor for detection of SARS-CoV-2 nucleoprotein (ncovNP). A key element of the sensor is a disposable sensor chip - thin film electrode - interfaced with a MIP-endowed selectivity for ncovNP and connected with a portable potentiostat. The resulting ncovNP sensor showed a linear response to ncovNP in the lysis buffer up to 111 fM with a detection and quantification limit of 15 fM and 50 fM, respectively. Notably, the sensor was capable of signaling ncovNP presence in nasopharyngeal swab samples of COVID-19 positive patients. The presented strategy unlocks a new route for the development of rapid COVID-19 diagnostic tools.

Current methods and prospects of coronavirus detection.

SARS-COV-2 is a novel coronavirus discovered in Wuhan in December 30, 2019, and is a family of SARS-COV (severe acute respiratory syndrome coronavirus), that is, coronavirus family. After infection with SARS-COV-2, patients often experience fever, cough, gas prostration, dyspnea and other symptoms, which can lead to severe acute respiratory syndrome (SARS), kidney failure and even death. The SARS-COV-2 virus is particularly infectious and has led to a global infection crisis, with an explosion in the number of infections. Therefore, rapid and accurate detection of the virus plays a vital role. At present, many detection methods are limited in their wide application due to their defects such as high preparation cost, poor stability and complex operation process. Moreover, some methods need to be operated by professional medical staff, which can easily lead to infection. In order to overcome these problems, a Surface molecular imprinting technology (SM-MIT) is proposed for the first time to detect SARS-COV-2 virus. For this SM-MIT method, this review provides detailed detection principles and steps. In addition, this method not only has the advantages of low cost, high stability and good specificity, but also can detect whether it is infected at designated points. Therefore, we think SM-MIT may have great potential in the detection of SARS-COV-2 virus.

Does the protein corona take over the selectivity of molecularly imprinted nanoparticles? The biological challenges to recognition.

"Plastic antibodies" are nano-sized biomimetics prepared by the molecular imprinting technology, which have the robustness of polymers, but specificity and selectivity alike natural receptors making them ideal for analytical uses. The current challenge is to translate plastic antibodies to in vivo applications for diagnosis, drug delivery, theranostic, therefore it is crucial to evaluate the effect of the biological sample complexity on the selectivity and the formation of protein corona (PCs), which ultimately dictate the fate of circulating nanoparticles. A set (n = 4) of plastic antibodies (nanoMIPs) against different proteins was prepared. Quantitative (iBAC) shotgun proteomics permitted to define the PC composition of nanoMIPs in human plasma, the relative protein abundances, the correlation between PC and the plasma dilution. NanoMIPs showed >200 proteins PC, while ~150 proteins were found on controls, suggesting the imprinting process influences the nanoparticle's structure hence the protein uptake. NanoMIPs and controls shared the 44% of the PC, but PC iBAQ values on nanoMIPs were 10-100 times higher than controls, suggesting PC/nanoMIPs interactions were far stronger than PC/non imprinted particles. PCs were richer in small proteins and in immunoglobulins, indicating a defensive response, while the selectivity was negatively challenged in the crowded plasma sample. SIGNIFICANCE: The formation and the composition of the protein corona (PC) is key to decide the fate of nanoparticles when in vivo, therefore there is the strong need to study the composition of the PC. To enable and to support the translation of the use of plastic antibodies (nanoMIPs), prepared by means of the molecular imprinting technique, to the clinical practice and to in vivo uses, the present work evaluates the effects of the complexity of the biological sample (plasma) on nanoMIPs composed of highly crosslinked polyacrylamide and acrylamide derivatives. Proteomic study offers an in depth insight of the protein corona formed in plasma on nanoMIPs. A set of nanoMIPs synthesized and raised to recognize either small or large proteins was tested. The selection abilities of the nanoMIPs when placed in plasma at different dilutions was studied. Quantitative shotgun proteomics allowed to define the composition of the formed protein corona (PC) enabling to detail the protein compositions, the relative abundances, its correlation to the biological sample composition and the correlation between PC and nanoMIP's imprinted template. In plasma, all the nanoMIPs gained a PC composed of more than 200 proteins. Type of protein recruited for the corona, molecular weight and abundance in the PC were studied. The PC on the nanoMIPs appeared to be driven by the protein composition of the plasma, while the template protein, towards which a nanoMIP was imprinted and that was proven to have high affinity for, did not influence the PC.