Glycan and lectin biosensors

Innovations in dengue virus detection: An overview of conventional and electrochemical biosensor approaches

Globally, people are in great threat due to the highly spreading of viral infectious diseases. Every year like 100-300 million cases of infections are found, and among them, above 80% are not recognized and irrelevant. Dengue virus (DENV) is an arbovirus infection that currently infects people most frequently. DENV encompasses four viral serotypes, and they each express comparable sign. From a mild febrile sickness to a potentially fatal dengue hemorrhagic fever, dengue can induce a variety of symptoms. Presently, the globe is being challenged by the untimely identification of dengue infection. Therefore, this review summarizes advances in the detection of dengue from conventional methods (nucleic acid-based, polymerase chain reaction-based, and serological approaches) to novel biosensors. This work illustrates an extensive study of the current designs and fabrication approaches involved in the formation of electrochemical biosensors for untimely identifications of dengue. Additionally, in electrochemical sensing of DENV, we skimmed through significances of biorecognition molecules like lectins, nucleic acid, and antibodies. The introduction of emerging techniques such as the CRISPR/Cas' system and their integration with biosensing platforms has also been summarized. Furthermore, the review revealed the importance of electrochemical approach compared with traditional diagnostic methods.

CA19-9 and CEA biosensors in pancreatic cancer

Cancer is a complex pathophysiological condition causing millions of deaths each year. Early diagnosis is essential especially for pancreatic cancer. Existing diagnostic tools rely on circulating biomarkers such as Carbohydrate Antigen 19-9 (CA19-9) and Carcinoembryonic Antigen (CEA). Unfortunately, these markers are nonspecific and may be increased in a variety of disorders. Accordingly, diagnosis of pancreatic cancer generally involves more invasive approaches such as biopsy as well as imaging studies. Recent advances in biosensor technology have allowed the development of precise diagnostic tools having enhanced analytical sensitivity and specificity. Herein we examine these advances in the detection of cancer in general and in pancreatic cancer specifically. Furthermore, we highlight novel technologies in the measurement of CA19-9 and CEA and explore their future application in the early detection of pancreatic cancer.

Interdigitated impedimetric-based Maackia amurensis lectin biosensor for prostate cancer biomarker

Highly specific detection of tumor-associated biomarkers remains a challenge in the diagnosis of prostate cancer. In this research, Maackia amurensis (MAA) was used as a recognition element in the functionalization of an electrochemical impedance-spectroscopy biosensor without a label to identify cancer-associated aberrant glycosylation prostate-specific antigen (PSA). The lectin was immobilized on gold-interdigitated microelectrodes. Furthermore, the biosensor's impedance response was used to assess the establishment of a complex binding between MAA and PSA-containing glycans. With a small sample volume, the functionalized interdigitated impedimetric-based (IIB) biosensor exhibited high sensitivity, rapid response, and repeatability. PSA glycoprotein detection was performed by measuring electron transfer resistance values within a concentration range 0.01-100 ng/mL, with a detection limit of 3.574 pg/mL. In this study, the ability of MAA to preferentially recognize α2,3-linked sialic acid in serum PSA was proven, suggesting a potential platform for the development of lectin-based, miniaturized, and cost effective IIB biosensors for future disease detection.

Linking aberrant glycosylation of plasma glycoproteins with progression of myelodysplastic syndromes: a study based on plasmonic biosensor and lectin array

Aberrant glycosylation of glycoproteins has been linked with various pathologies. Therefore, understanding the relationship between aberrant glycosylation patterns and the onset and progression of the disease is an important research goal that may provide insights into cancer diagnosis and new therapy development. In this study, we use a surface plasmon resonance imaging biosensor and a lectin array to investigate aberrant glycosylation patterns associated with oncohematological disease-myelodysplastic syndromes (MDS). In particular, we detected the interaction between the lectins and glycoproteins present in the blood plasma of patients (three MDS subgroups with different risks of progression to acute myeloid leukemia (AML) and AML patients) and healthy controls. The interaction with lectins from Aleuria aurantia (AAL) and Erythrina cristagalli was more pronounced for plasma samples of the MDS and AML patients, and there was a significant difference between the sensor response to the interaction of AAL with blood plasma from low and medium-risk MDS patients and healthy controls. Our data also suggest that progression from MDS to AML is accompanied by sialylation of glycoproteins and increased levels of truncated O-glycans and that the number of lectins that allow discriminating different stages of disease increases as the disease progresses.

Biofunctionalization of Multiplexed Silicon Photonic Biosensors

Silicon photonic (SiP) sensors offer a promising platform for robust and low-cost decentralized diagnostics due to their high scalability, low limit of detection, and ability to integrate multiple sensors for multiplexed analyte detection. Their CMOS-compatible fabrication enables chip-scale miniaturization, high scalability, and low-cost mass production. Sensitive, specific detection with silicon photonic sensors is afforded through biofunctionalization of the sensor surface; consequently, this functionalization chemistry is inextricably linked to sensor performance. In this review, we first highlight the biofunctionalization needs for SiP biosensors, including sensitivity, specificity, cost, shelf-stability, and replicability and establish a set of performance criteria. We then benchmark biofunctionalization strategies for SiP biosensors against these criteria, organizing the review around three key aspects: bioreceptor selection, immobilization strategies, and patterning techniques. First, we evaluate bioreceptors, including antibodies, aptamers, nucleic acid probes, molecularly imprinted polymers, peptides, glycans, and lectins. We then compare adsorption, bioaffinity, and covalent chemistries for immobilizing bioreceptors on SiP surfaces. Finally, we compare biopatterning techniques for spatially controlling and multiplexing the biofunctionalization of SiP sensors, including microcontact printing, pin- and pipette-based spotting, microfluidic patterning in channels, inkjet printing, and microfluidic probes.

Nanotechnology‐based electrochemical biosensors for monitoring breast cancer biomarkers

Breast cancer is categorized as the most widespread cancer type among women globally. On-time diagnosis can decrease the mortality rate by making the right decision in the therapy procedure. These features lead to a reduction in medication time and socioeconomic burden. The current review article provides a comprehensive assessment for breast cancer diagnosis using nanomaterials and related technologies. Growing use of the nano/biotechnology domain in terms of electrochemical nanobiosensor designing was discussed in detail. In this regard, recent advances in nanomaterial applied for amplified biosensing methodologies were assessed for breast cancer diagnosis by focusing on the advantages and disadvantages of these approaches. We also monitored designing methods, advantages, and the necessity of suitable (nano) materials from a statistical standpoint. The main objective of this review is to classify the applicable biosensors based on breast cancer biomarkers. With numerous nano-sized platforms published for breast cancer diagnosis, this review tried to collect the most suitable methodologies for detecting biomarkers and certain breast cancer cell types.

Glycan-Based Electrochemical Biosensors: Promising Tools for the Detection of Infectious Diseases and Cancer Biomarkers

Glycan-based electrochemical biosensors are emerging as analytical tools for determining multiple molecular targets relevant to diagnosing infectious diseases and detecting cancer biomarkers. These biosensors allow for the detection of target analytes at ultra-low concentrations, which is mandatory for early disease diagnosis. Nanostructure-decorated platforms have been demonstrated to enhance the analytical performance of electrochemical biosensors. In addition, glycans anchored to electrode platforms as bioreceptors exhibit high specificity toward biomarker detection. Both attributes offer a synergy that allows ultrasensitive detection of molecular targets of clinical interest. In this context, we review recent advances in electrochemical glycobiosensors for detecting infectious diseases and cancer biomarkers focused on colorectal cancer. We also describe general aspects of structural glycobiology, definitions, and classification of electrochemical biosensors and discuss relevant works on electrochemical glycobiosensors in the last ten years. Finally, we summarize the advances in electrochemical glycobiosensors and comment on some challenges and limitations needed to advance toward real clinical applications of these devices.

An insight into new glycotherapeutics in glial inflammation: Understanding the role of glycosylation in mitochondrial function and acute to the chronic phases of inflammation

INTRODUCTION

Glycosylation plays a critical role during inflammation and glial scar formation upon spinal cord injury (SCI) disease progression. Astrocytes and microglia are involved in this cascade to modulate the inflammation and tissue remodeling from acute to chronic phases. Therefore, understating the glycan changes in these glial cells is paramount.

METHOD AND RESULTS

A lectin microarray was undertaken using a cytokine-driven inflammatory mixed glial culture model, revealing considerable differential glycosylation from the acute to the chronic phase in a cytokine-combination generated inflamed MGC model. It was found that several N- and O-linked glycans associated with glia during SCI were differentially regulated. Pearson's correlation hierarchical clustering showed that groups were separated into several clusters, illustrating the heterogenicity among the control, cytokine combination, and LPS treated groups and the day on which treatment was given. Control and LPS treatments were observed to be in dense clusters. This was further confirmed with lectin immunostaining in which GalNAc, GlcNAc, mannose, fucose and sialic acid-binding residues were detected in astrocytes and microglia. However, the sialyltransferase inhibitor inhibited this modification (upregulation of the sialic acid expression), which indeed modulates the mitochondrial functions.

CONCLUSIONS

The present study is the first functional investigation of glycosylation modulation in a mixed glial culture model, which elucidates the role of the glycome in neuroinflammation in progression and identified potential therapeutic targets for future glyco therapeutics in neuroinflammation.

Review of Label-Free Monitoring of Bacteria: From Challenging Practical Applications to Basic Research Perspectives

Novel biosensors already provide a fast way to detect the adhesion of whole bacteria (or parts of them), biofilm formation, and the effect of antibiotics. Moreover, the detection sensitivities of recent sensor technologies are large enough to investigate molecular-scale biological processes. Usually, these measurements can be performed in real time without using labeling. Despite these excellent capabilities summarized in the present work, the application of novel, label-free sensor technologies in basic biological research is still rare; the literature is dominated by heuristic work, mostly monitoring the presence and amount of a given analyte. The aims of this review are (i) to give an overview of the present status of label-free biosensors in bacteria monitoring, and (ii) to summarize potential novel directions with biological relevancies to initiate future development. Optical, mechanical, and electrical sensing technologies are all discussed with their detailed capabilities in bacteria monitoring. In order to review potential future applications of the outlined techniques in bacteria research, we summarize the most important kinetic processes relevant to the adhesion and survival of bacterial cells. These processes are potential targets of kinetic investigations employing modern label-free technologies in order to reveal new fundamental aspects. Resistance to antibacterials and to other antimicrobial agents, the most important biological mechanisms in bacterial adhesion and strategies to control adhesion, as well as bacteria-mammalian host cell interactions are all discussed with key relevancies to the future development and applications of biosensors.

Effect of Interfacial Properties on Impedimetric Biosensing of the Sialylation Process with a Biantennary N-Glycan-Based Monolayer

Sensing enzymatic sialylation provides new tools for the evaluation of pathological events and pathogen invasion. Enzymatic sialylation is usually monitored via fluorescence or metabolic labeling, which requires relatively large amounts of the glycan substrate with limited availability. Using a label-free biosensor requires smaller quantities of substrates because the interactions induce measurable changes to an interface, which can be translated into a signal. The downside of label-free biosensors is that they are very sensitive to changes at the interface, and the properties of the surface layer can play a major role. Electrochemical impedance spectroscopy was used here to follow the enzymatic sialylation of a biantennary N-glycan acceptor in mixed monolayers. The surfaces contained either neutral, positively or negatively charged, or zwitterionic functional groups. The systems were characterized by contact potential difference, ellipsometry, and contact angle analyses. We found that the characteristics of the mixed monolayer have a profound effect on the biosensing of the enzymatic sialylation. Positively charged layers were found to adsorb the enzyme under the reaction conditions. Negatively charged and zwitterionic surfaces were nonresponsive to enzymatic sialylation. Only the neutral mixed monolayers provided signals that were related directly to enzymatic sialylation. This work demonstrates the importance of appropriate interface properties for monitoring enzymatic sialylation processes.

Lectins applied to diagnosis and treatment of prostate cancer and benign hyperplasia: A review

Environmental factors, as well as genetic factors, contribute to the increase in prostate cancer cases (PCa), the second leading cause of cancer death in men. This fact calls for the development of more reliable, quick and low-cost early detection tests to distinguish between malignant and benign cases. Abnormal cell glycosylation pattern is a promising PCa marker for this purpose. Proteins, such as lectins can decode the information contained in the glycosylation patterns. Several studies have reported on applications of plant lectins as diagnostic tools for PCa considering the ability to differentiate it from benign cases. In addition, they can be used to detect, separate and differentiate the glycosylation patterns of cells or proteins present in serum, urine and semen. Herein, we present an overview of these studies, showing the lectins that map glycans differentially expressed in PCa, as well as benign hyperplasia (BPH). We further review their applications in biosensors, histochemical tests, immunoassays, chromatography, arrays and, finally, their therapeutic potential. This is the first study to review vegetable lectins applied specifically to PCa.

Systematic review on lectin-based electrochemical biosensors for clinically relevant carbohydrates and glycoconjugates

Carbohydrates and glycoconjugates are involved in numerous natural and pathological metabolic processes, and the precise elucidation of their biochemical functions has been supported by smart technologies assembled with lectins, i.e., ubiquitous proteins of nonimmune origin with carbohydrate-specific domains. When lectins are anchored on suitable electrochemical transducers, sensitive and innovative bioanalytical tools (lectin-based biosensors) are produced, with the ability to screen target sugars at molecular levels. In addition to the remarkable electroanalytical sensitivity, these devices associate specificity, precision, stability, besides the possibility of miniaturization and portability, which are special features required for real-time and point-of-care measurements. The mentioned attributes can be improved by combining lectins with biocompatible 0-3D semiconductors derived from carbon, metal nanoparticles, polymers and their nanocomposites, or employing labeled biomolecules. This systematic review aims to substantiate and update information on the progress made with lectin-based biosensors designed for electroanalysis of clinically relevant carbohydrates and glycoconjugates (glycoproteins, pathogens and cancer biomarkers), highlighting their main detection principles and performance in highly complex biological milieus. Moreover, particular emphasis is given to the main advantages and limitations of the reported devices, as well as the new trends for the current demands. We believe that this review will support and encourage more cutting-edge research involving lectin-based electrochemical biosensors.

Glycosylated biomarker sensors: advancements in prostate cancer diagnosis

Prostate cancer is currently diagnosed using the conventional gold standard methods using prostate-specific antigen (PSA) as the selective biomarker. However, lack of precision in PSA screening has resulted in needless biopsies and delays the treatment of potentially fatal prostate cancer. Thus, identification of glycans as novel biomarkers for the early detection of prostate cancer has attracted considerable attention due to their reliable diagnostic platform compared with the current PSA systems. Therefore, biosensing technologies that provide point-of-care diagnostics have demonstrated the ability to detect various analytes, including glycosylated micro- and macro-molecules, thereby enabling versatile detection methodologies. This highlight article discusses recent advances in the biosensor-based detection of prostate cancer glycan biomarkers and the innovative strategies for the conjugation of nanomaterials adapted to biosensing platforms. Finally, the article is concluded with prospects and challenges of prostate cancer biosensors and recommendations to overcome the issues associated with prostate cancer diagnosis.

Surface plasmon resonance study for a reliable determination of the affinity constant of multivalent grafted beads

In this study, galactose-grafted beads were prepared using the main design principle of the cluster effect. Galactose was chosen as the sugar for investigation because it acts as the main building block of long glycan chains and because a simple and fast protocol is still required for its immobilization. For the analysis, the lectin, ligand of the galactose, was immobilized on a gold plasmonic substrate. After preliminary characterization of the galactose-grafted beads, the investigation of the surface plasmon surface behavior of the system was carried out, for studying the affinity constant of the multivalent beads. The results of steady-state and of the kinetics analysis evidenced a higher affinity of the galactose-grafted beads over the beadless galactose solution. For the association kinetics analysis, a Langmuir isotherm was applied to the data. The analysis of the rate of dissociation evidenced the most important differences between the two samples, based on the more difficult release of the galactose-grafted beads during washing. To confirm the influence of the glycoside cluster effect, a low-density lectin substrate was tested, and the results evidenced that the characteristic size of the molecules determines a threshold for the cluster density. The calculated detection limit and dissociation constants were 3.5 μM and 40.2 μM, respectively. Considering those results, the evaluation of the affinities toward the receptors depends on the cluster density and then, it should be designed for mimicking the biological samples.

Reversible Lectin Binding to Glycan-Functionalized Graphene

The monolayer character of two-dimensional materials predestines them for application as active layers of sensors. However, their inherent high sensitivity is always accompanied by a low selectivity. Chemical functionalization of two-dimensional materials has emerged as a promising way to overcome the selectivity issues. Here, we demonstrate efficient graphene functionalization with carbohydrate ligands—chitooligomers, which bind proteins of the lectin family with high selectivity. Successful grafting of a chitooligomer library was thoroughly characterized, and glycan binding to wheat germ agglutinin was studied by a series of methods. The results demonstrate that the protein quaternary structure remains intact after binding to the functionalized graphene, and that the lectin can be liberated from the surface by the addition of a binding competitor. The chemoenzymatic assay with a horseradish peroxidase conjugate also confirmed the intact catalytic properties of the enzyme. The present approach thus paves the way towards graphene-based sensors for carbohydrate–lectin binding.

Label-Free Protein Glycosylation Analysis Using NanoMonitor-An Ultrasensitive Electrochemical Biosensor

Glycans (oligosaccharide chains attached to glycoproteins) are a promising class of biomarkers, found in body fluids such as serum, saliva, urine, etc., that can be used for the diagnosis of disease conditions. Subtle changes in glycans resulting from altered glycosylation machinery have been reported during various diseases, including carcinogenesis. In this article, we detail protocols for the rapid, label-free analysis of glycans using a previously developed highly sensitive and selective electrochemical impedance spectroscopy-based biosensing diagnostic platform called "NanoMonitor." The glycosensor operation is based on the specific affinity capture of the target glycans on the sensor surface by glycan-binding proteins known as lectins. This glycan-lectin binding activity modulates the impedance of the electrical double layer at the buffer-electrode interface. Protocols for the preparation of glycoprotein samples and glycosylation analysis using NanoMonitor and lectin-based ELISA are described here. The data obtained using these protocols show that NanoMonitor is capable of distinguishing between glycoform variants of the glycoprotein fetuin and glycoproteins derived from cultured human pancreatic cancer cells with high sensitivity (orders of magnitude higher than lectin-based ELISA) and selectivity. The results obtained indicate that NanoMonitor protocols can be further developed to enable use of NanoMonitor as a handheld electronic biosensor device for routine multiplexed detection of glycan biomarkers from clinical samples. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Preparing the NanoMonitor surface for glycan biosensing Support Protocol: Synthesis of glycoform variants of fetuin Basic Protocol 2: Performing Electrochemical Impedance Spectroscopy (EIS) for analyzing glycoprotein structures.

Electrochemical biosensors for neglected tropical diseases: A review

A group of infectious and parasitic diseases with prevalence in tropical and subtropical regions of the planet, especially in places with difficult access, internal conflicts, poverty, and low visibility from the government and health agencies are classified as neglected tropical diseases. While some well-intentioned isolated groups are making the difference on a global scale, the number of new cases and deaths is still alarming. The development and employment of low-cost, miniaturized, and easy-to-use devices as biosensors could be the key to fast diagnosis in such areas leading to a better treatment to further eradication of such diseases. Therefore, this review contains useful information regarding the development of such devices in the past ten years (2010-2020). Guided by the updated list from the World Health Organization, the work evaluated the new trends in the biosensor field applied to the early detection of neglected tropical diseases, the efficiencies of the devices compared to the traditional techniques, and the applicability on-site for local distribution. So, we focus on Malaria, Chagas, Leishmaniasis, Dengue, Zika, Chikungunya, Schistosomiasis, Leprosy, Human African trypanosomiasis (sleeping sickness), Lymphatic filariasis, and Rabies. Few papers were found concerning such diseases and there is no available commercial device in the market. The works contain information regarding the development of point-of-care devices, but there are only at proof of concepts stage so far. Details of electrode modification and construction of electrochemical biosensors were summarized in Tables. The demand for the eradication of neglected tropical diseases is increasing. The use of biosensors is pivotal for the cause, but appliable devices are scarce. The information present in this review can be useful for further development of biosensors in the hope of helping the world combat these deadly diseases.

In depth analysis on the carbohydrate-binding properties of a vasorelaxant lectin from Dioclea lasiophylla Mart Ex. Benth seeds

Lectins are a class of proteins or glycoproteins capable of recognizing and interacting with carbohydrates in a specific and reversible manner. Owing to this property, these proteins can interact with glycoconjugates present on the cell surface, making it possible to decipher the glycocode, as well as elicit biological effects, such as inflammation and vasorelaxation. Here, we report a structural and biological study of the mannose/glucose-specific lectin from Dioclea lasiophylla seeds, DlyL. The study aimed to evaluate in detail the interaction of DlyL with Xman and high-mannose N-glycans (MAN3, MAN5 and MAN9) by molecular dynamics (MD) and the resultant in vitro effect on vasorelaxation using rat aortic rings. In silico analysis of molecular docking was performed to obtain the initial coordinates of the DlyL complexes with the carbohydrates to apply as inputs in MD simulations. The MD trajectories demonstrated the stability of DlyL over time as well as different profiles of interaction with Xman and N-glycans. Furthermore, aortic rings assays demonstrated that the lectin could relax pre-contracted aortic rings with the participation of the carbohydrate recognition domain (CRD) and nitric oxide (NO) when endothelial tissue is preserved. These results confirm the ability of DlyL to interact with high-mannose N-glycans with its expanded CRD, supporting the hypothesis that DlyL vasorelaxant activity occurs primarily through its interaction with cell surface glycosylated receptors.Communicated by Ramaswamy H. Sarma.

Novel urinary glycan profiling by lectin array serves as the biomarkers for predicting renal prognosis in patients with IgA nephropathy

In IgA nephropathy (IgAN), IgA1 molecules are characterized by galactose deficiency in O-glycans. Here, we investigated the association between urinary glycosylation profile measured by 45 lectins at baseline and renal prognosis in 142 patients with IgAN. The primary outcome was estimated glomerular filtration rate (eGFR) decline (> 4 mL/min/1.73 m²/year), or eGFR ≥ 30% decline from baseline, or initiation of renal replacement therapies within 3 years. During follow-up (3.4 years, median), 26 patients reached the renal outcome (Group P), while 116 patients were with good renal outcome (Group G). Multivariate logistic regression analyses revealed that lectin binding signals of Erythrina cristagalli lectin (ECA) (odds ratio [OR] 2.84, 95% confidence interval [CI] 1.11–7.28) and Narcissus pseudonarcissus lectin (NPA) (OR 2.32, 95% CI 1.11–4.85) adjusted by age, sex, eGFR, and urinary protein were significantly associated with the outcome, and they recognize Gal(β1-4)GlcNAc and high-mannose including Man(α1-6)Man, respectively. The addition of two lectin-binding glycan signals to the interstitial fibrosis/tubular atrophy score further improved the model fitness (Akaike’s information criterion) and incremental predictive abilities (c-index, net reclassification improvement, and integrated discrimination improvement). Urinary N-glycan profiling by lectin array is useful in the prediction of IgAN prognosis, since ECA and NPA recognize the intermediate glycans during N-glycosylation of various glycoproteins.

Implications of Glycosylation in Alzheimer's Disease

Alzheimer's disease (AD) is the most common cause of dementia, affecting millions of people worldwide, and no cure is currently available. The major pathological hallmarks of AD are considered to be amyloid beta plaques and neurofibrillary tangles, generated by respectively APP processing and Tau phosphorylation. Recent evidence imply that glycosylation of these proteins, and a number of other AD-related molecules is altered in AD, suggesting a potential implication of this process in disease pathology. In this review we summarize the understanding of glycans in AD pathogenesis, and discuss how glycobiology can contribute to early diagnosis and treatment of AD, serving as potential biomarkers and therapeutic targets. Furthermore, we look into the potential link between the emerging topic neuroinflammation and glycosylation, combining two interesting, and until recent years, understudied topics in the scope of AD. Lastly, we discuss how new model platforms such as induced pluripotent stem cells can be exploited and contribute to a better understanding of a rather unexplored area in AD.

A bi-specific lectin from the mushroom Boletopsis grisea and its application in glycoanalytical workflows

The BLL lectin from the edible Japanese "Kurokawa" mushroom (Boletopsis leucomelaena) was previously reported to bind to N-glycans harboring terminal N-acetylglucosamine (GlcNAc) and to induce apoptosis in a leukemia cell line. However, its gene has not been reported. In this study, we used a transcriptomics-based workflow to identify a full-length transcript of a BLL functional ortholog (termed BGL) from Boletopsis grisea, a close North American relative of B. leucomelaena. The deduced amino acid sequence of BGL was an obvious member of fungal fruit body lectin family (Pfam PF07367), a highly conserved group of mushroom lectins with a preference for binding O-glycans harboring the Thomsen-Friedenreich antigen (TF-antigen; Galβ1,3GalNAc-α-) and having two ligand binding sites. Functional characterization of recombinant BGL using glycan microarray analysis and surface plasmon resonance confirmed its ability to bind both the TF-antigen and β-GlcNAc-terminated N-glycans. Structure-guided mutagenesis of BGL's two ligand binding clefts showed that one site is responsible for binding TF-antigen structures associated with O-glycans, whereas the second site specifically recognizes N-glycans with terminal β-GlcNAc. Additionally, the two sites show no evidence of allosteric communication. Finally, mutant BGL proteins having single functional bindings site were used to enrich GlcNAc-capped N-glycans or mucin type O-glycopeptides from complex samples in glycomics and glycoproteomics analytical workflows.

Recent advances and challenges in electrochemical biosensors for emerging and re-emerging infectious diseases

The rise of emerging infectious diseases (EIDs) as well as the increase in spread of existing infections is threatening global economies and human lives, with several countries still fighting repeated onslaught of a few of these epidemics. The catastrophic impact a pandemic has on humans and economy should serve as a reminder to be better prepared to the advent of known and unknown pathogens in the future. The goal of having a set of initiatives and procedures to tackle them is the need of the hour.

Rapid detection and point-of-care (POC) analysis of pathogens causing these diseases is not only a problem entailing the scientific community but also raises challenges in tailoring appropriate treatment strategies to the healthcare sector. Among the various methods used to detect pathogens, Electrochemical Biosensor Technology is at the forefront in the development of POC devices. Electrochemical Biosensors stand in good stead due to their rapid response, high sensitivity and selectivity and ease of miniaturization to name a few advantages.

This review explores the innovations in electrochemical biosensing based on the various electroanalytical techniques including voltammetry, impedance, amperometry and potentiometry and discusses their potential in diagnosis of emerging and re-emerging infectious diseases (Re-EIDs), which are potential pandemic threats.

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This review offers a detailed description of the latest developments in electrochemical biosensors for emerging and re-emerging infectious diseases.

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Advantages and limitations of various types of electrochemical biosensor techniques are demonstrated.

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Discusses the latest electrochemical biosensors for COVID-19.

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Challenges and future prospects of electrochemical biosensors have been discussed in this review.

Glycoprotein- and Lectin-Based Approaches for Detection of Pathogens

Infectious diseases alone are estimated to result in approximately 40% of the 50 million total annual deaths globally. The importance of basic research in the control of emerging and re-emerging diseases cannot be overemphasized. However, new nanotechnology-based methodologies exploiting unique surface-located glycoproteins or their patterns can be exploited to detect pathogens at the point of use or on-site with high specificity and sensitivity. These technologies will, therefore, affect our ability in the future to more accurately assess risk. The critical challenge is making these new methodologies cost-effective, as well as simple to use, for the diagnostics industry and public healthcare providers. Miniaturization of biochemical assays in lab-on-a-chip devices has emerged as a promising tool. Miniaturization has the potential to shape modern biotechnology and how point-of-care testing of infectious diseases will be performed by developing smart microdevices that require minute amounts of sample and reagents and are cost-effective, robust, and sensitive and specific. The current review provides a short overview of some of the futuristic approaches using simple molecular interactions between glycoproteins and glycoprotein-binding molecules for the efficient and rapid detection of various pathogens at the point of use, advancing the emerging field of glyconanodiagnostics.

Electrochemical Biosensors for Determination of Colorectal Tumor Biomarkers

The accurate determination of specific tumor markers associated with cancer with non-invasive or minimally invasive procedures is the most promising approach to improve the long-term survival of cancer patients and fight against the high incidence and mortality of this disease. Quantification of biomarkers at different stages of the disease can lead to an appropriate and instantaneous therapeutic action. In this context, the determination of biomarkers by electrochemical biosensors is at the forefront of cancer diagnosis research because of their unique features such as their versatility, fast response, accurate quantification, and amenability for multiplexing and miniaturization. In this review, after briefly discussing the relevant aspects and current challenges in the determination of colorectal tumor markers, it will critically summarize the development of electrochemical biosensors to date to this aim, highlighting the enormous potential of these devices to be incorporated into the clinical practice. Finally, it will focus on the remaining challenges and opportunities to bring electrochemical biosensors to the point-of-care testing.

Different liposome patterns to detection of acute leukemia based on electrochemical cell sensor

Leukemia is the worst type of malignancy in children which its proper diagnosis can be used in the treatment. We design the turn-off sensor by using the different electrochemical patterns of liposomes to the detection of acute lymphoblastic leukemia cells. Our design is first sandwiched by lectin liposome which increases the electrochemical exchange on the electrode. With the addition of Molt-4 cells, the bonding connection between the n-glycan and lectin can also increase the electrochemical exchange with the high detection cells. Subsequently, the addition of boronic acid liposomes decreases the resistance due to covering glycosylation bond and the sensor is turn-off. But stable and specific binding with the sialic acid causes the higher detection of Molt-4 cells. The electrochemical measurements are performed between the potentials at -0.4 V and +0.4 V with 1 mM [Fe(CN)₆] ^-3/-4. So, for the first time, we designed a cells sensor based on the different patterns of liposomes to screening the N-glycan cells, which can be used in the point of care tests with higher sensitivity.

Early Stage Glycosylation Biomarkers in Alzheimer's Disease

Alzheimer's disease (AD) is of great cause for concern in our ageing population, which currently lacks diagnostic tools to permit accurate and timely diagnosis for affected individuals. The development of such tools could enable therapeutic interventions earlier in the disease course and thus potentially reducing the debilitating effects of AD. Glycosylation is a common, and important, post translational modification of proteins implicated in a host of disease states resulting in a complex array of glycans being incorporated into biomolecules. Recent investigations of glycan profiles, in a wide range of conditions, has been made possible due to technological advances in the field enabling accurate glycoanalyses. Amyloid beta (Aβ) peptides, tau protein, and other important proteins involved in AD pathogenesis, have altered glycosylation profiles. Crucially, these abnormalities present early in the disease state, are present in the peripheral blood, and help to distinguish AD from other dementias. This review describes the aberrant glycome in AD, focusing on proteins implicated in development and progression, and elucidates the potential of glycome aberrations as early stage biomarkers of AD.

Electrospun Nanofibers for Label-Free Sensor Applications

Electrospinning is a simple, low-cost and versatile method for fabricating submicron and nano size fibers. Due to their large surface area, high aspect ratio and porous structure, electrospun nanofibers can be employed in wide range of applications. Biomedical, environmental, protective clothing and sensors are just few. The latter has attracted a great deal of attention, because for biosensor application, nanofibers have several advantages over traditional sensors, including a high surface-to-volume ratio and ease of functionalization. This review provides a short overview of several electrospun nanofibers applications, with an emphasis on biosensor applications. With respect to this area, focus is placed on label-free sensors, pertaining to both recent advances and fundamental research. Here, label-free sensor properties of sensitivity, selectivity, and detection are critically evaluated. Current challenges in this area and prospective future work is also discussed.

Electrochemical biosensing of mosquito-borne viral disease, dengue: A review

Dengue virus is a mosquito-borne, single positive-stranded RNA virus that spread human being through infected female Aedes mosquito bite and causes dengue fever. The demand for early detection of this virus has increased to control the widespread of infectious diseases and protect humankind from its harmful effects. Recently, biosensors are found to the potential tool to detect and quantify the virus with fast detection, relatively cost-effective, high sensitivity and selectivity than the conventional diagnostic methods such as immunological and molecular techniques. Mostly, the biosensors employ electrochemical detection technique with transducers, owing to its easy construction, low-cost, ease of use, and portability. Here, we review the current trends and advancement in the electrochemical diagnosis of dengue virus and discussed various types of electrochemical biosensing techniques such as; amperometric, potentiometric, impedometric, and voltammetric sensing. Apart from these, we discussed the role of biorecognition molecules such as nucleic acid, antibodies, and lectins in electrochemical sensing of dengue virus. In addition, the review highlighted the benefits of the electrochemical approach in comparison with traditional diagnostic methods. We expect that these dengue virus diagnostic techniques will continue to evolve and grow in future, with exciting new possibilities stemming from advancement in the rational design of electrochemical biosensors.

Identification of Critical Surface Parameters Driving Lectin-Mediated Capture of Bacteria from Solution

Lectin-functional interfaces are useful for isolation of bacteria from solution because they are low-cost and allow nondestructive, reversible capture. This study provides a systematic investigation of physical and chemical surface parameters that influence bacteria capture over lectin-functionalized polymer interfaces and then applies these findings to construct surfaces with significantly enhanced bacteria capture. The designer block copolymer poly(glycidyl methacrylate)- block-poly(vinyldimethyl azlactone) was used as a lectin attachment layer, and lectin coupling into the polymer film through azlactone-lectin coupling reactions was first characterized. Here, experimental parameters including polymer areal chain density, lectin molecular weight, and lectin coupling buffer were systematically varied to identify parameters driving highest azlactone conversions and corresponding lectin surface densities. To introduce physical nanostructures into the attachment layer, nanopillar arrays (NPAs) of varied heights (300 and 2100 nm) were then used to provide an underlying surface template for the functional polymer layer. Capture of Escherichia coli on lectin-polymer surfaces coated over both flat and NPA surfaces was then investigated. For flat polymer interfaces, bacteria were detected on the surface after incubation at a solution concentration of 10³ cfu/mL, and a corresponding detection limit of 1.7 × 10³ cfu/mL was quantified. This detection limit was 1 order of magnitude lower than control lectin surfaces functionalized with standard, carbodiimide coupling chemistry. NPA surfaces containing 300 nm tall pillars further improved the detection limit to 2.1 × 10² cfu/mL, but also reduced the viability of captured cells. Finally, to investigate the impact of cell surface parameters on capture, we used Agrobacterium tumefaciens cells genetically modified to allow manipulation of exopolysaccharide adhesin production levels. Statistical analysis of surface capture levels revealed that lectin surface density was the primary factor driving capture, as opposed to exopolysaccharide adhesin expression. These findings emphasize the critical importance of the synthetic interface and the development of surfaces that combine high lectin densities with tailored physical features to drive high levels of capture. These insights will aid in design of biofunctional interfaces with physicochemical surface properties favorable for capture and isolation of bacteria cells from solutions.

'Clickable lectins': bioorthogonal reactive handles facilitate the directed conjugation of lectins in a modular fashion

Lectins are carbohydrate-binding proteins with specificity for their target ligands. They play diverse roles in cellular recognition and signalling processes, as well as in infections and cancer metastasis. Owing to their specificity, lectins find application in biotechnology and medicine, e.g. for blood group typing, purification of glycoproteins or lipids and as markers that target cancer cells. For some applications, lectins are immobilized on a solid support, or they are conjugated with other molecules. Classical protein conjugation reactions at nucleophilic amino acids such as cysteine or lysine are often non-selective, and the site of conjugation is difficult to pre-define. Random conjugation, however, can interfere with protein function. Therefore, we sought to equip lectins with a unique reactive handle, which can be conjugated with other molecules in a pre-defined manner. We site-specifically introduced non-canonical amino acids carrying bioorthogonal reactive groups into several lectins. As a proof of principle, we conjugated these 'clickable lectins' with small molecules. Furthermore, we conjugated lectins with different ligand specificities with one another to produce superlectins. The 'clickable lectins' might be useful for any process where lectins shall be conjugated with another module in a selective, pre-defined and site-specific manner.

Identification of Novel Urinary Biomarkers for Predicting Renal Prognosis in Patients With Type 2 Diabetes by Glycan Profiling in a Multicenter Prospective Cohort Study: U-CARE Study 1

OBJECTIVE

Because quantifying glycans with complex structures is technically challenging, little is known about the association of glycosylation profiles with the renal prognosis in diabetic kidney disease (DKD).

RESEARCH DESIGN AND METHODS

In 675 patients with type 2 diabetes, we assessed the baseline urinary glycan signals binding to 45 lectins with different specificities. The end point was a decrease of estimated glomerular filtration rate (eGFR) by ≥30% from baseline or dialysis for end-stage renal disease.

RESULTS

During a median follow-up of 4.0 years, 63 patients reached the end point. Cox proportional hazards analysis revealed that urinary levels of glycans binding to six lectins were significantly associated with the outcome after adjustment for known indicators of DKD, although these urinary glycans, except that for DBA, were highly correlated with baseline albuminuria and eGFR. Hazard ratios for these lectins were (+1 SD for the glycan index) as follows: SNA (recognizing glycan Siaα2-6Gal/GalNAc), 1.42 (95% CI 1.14-1.76); RCA120 (Galβ4GlcNAc), 1.28 (1.01-1.64); DBA (GalNAcα3GalNAc), 0.80 (0.64-0.997); ABA (Galβ3GalNAc), 1.29 (1.02-1.64); Jacalin (Galβ3GalNAc), 1.30 (1.02-1.67); and ACA (Galβ3GalNAc), 1.32 (1.04-1.67). Adding these glycan indexes to a model containing known indicators of progression improved prediction of the outcome (net reclassification improvement increased by 0.51 [0.22-0.80], relative integrated discrimination improvement increased by 0.18 [0.01-0.35], and the Akaike information criterion decreased from 296 to 287).

CONCLUSIONS

The urinary glycan profile identified in this study may be useful for predicting renal prognosis in patients with type 2 diabetes. Additional investigation of glycosylation changes and urinary glycan excretion in DKD is needed.

MCAW-DB: A glycan profile database capturing the ambiguity of glycan recognition patterns

Glycan-binding protein (GBP) interaction experiments, such as glycan microarrays, are often used to understand glycan recognition patterns. However, oftentimes the interpretation of glycan array experimental data makes it difficult to identify discrete GBP binding patterns due to their ambiguity. It is known that lectins, for example, are non-specific in their binding affinities; the same lectin can bind to different monosaccharides or even different glycan structures. In bioinformatics, several tools to mine the data generated from these sorts of experiments have been developed. These tools take a library of predefined motifs, which are commonly-found glycan patterns such as sialyl-Lewis X, and attempt to identify the motif(s) that are specific to the GBP being analyzed. In our previous work, as opposed to using predefined motifs, we developed the Multiple Carbohydrate Alignment with Weights (MCAW) tool to visualize the state of the glycans being recognized by the GBP under analysis. We previously reported on the effectiveness of our tool and algorithm by analyzing several glycan array datasets from the Consortium of Functional Glycomics (CFG). In this work, we report on our analysis of 1081 data sets which we collected from the CFG, the results of which we have made publicly and freely available as a database called MCAW-DB. We introduce this database, its usage and describe several analysis results. We show how MCAW-DB can be used to analyze glycan-binding patterns of GBPs amidst their ambiguity. For example, the visualization of glycan-binding patterns in MCAW-DB show how they correlate with the concentrations of the samples used in the array experiments. Using MCAW-DB, the patterns of glycans found to bind to various GBP-glycan binding proteins are visualized, indicating the binding "environment" of the glycans. Thus, the ambiguity of glycan recognition is numerically represented, along with the patterns of monosaccharides surrounding the binding region. The profiles in MCAW-DB could potentially be used as predictors of affinity of unknown or novel glycans to particular GBPs by comparing how well they match the existing profiles for those GBPs. Moreover, as the glycan profiles of diseased tissues become available, glycan alignments could also be used to identify glycan biomarkers unique to that tissue. Databases of these alignments may be of great use for drug discovery.

Analytical Application of Lectins

This review is devoted to the analytical application of carbohydrate-binding proteins called lectins. The nature of lectins and the regularities of their specificity with respect to simple sugars and complex carbohydrate-containing biomolecules are discussed. The main areas of the modern analytical application of lectins are described. Lectin-affinity chromatography, histo- and cytochemical approaches, lectin blotting, microarray, and biosensor technologies as well as microplate analysis are considered in detail. Data on the use of lectins for the detection of cells and microorganisms as well as the study of protein glycosylation are summarized. The large potential of lectins as components of analytical systems used for the identification of glycans and the characteristics of their structure are substantiated.

Post-translational modifications in tumor biomarkers: the next challenge for aptamers?

Advances in proteomics have fueled the search for novel cancer biomarkers with higher selectivity. Differential expression of low abundant proteins has been the usual way of finding those biomarkers. The existence of a selective receptor for each biomarker is compulsory for their use in diagnostic/prognostic assays. Antibodies are the receptors of choice in most cases although aptamers are becoming familiar because of their facile and reproducible synthesis, chemical stability as well as comparable affinity and selectivity. In recent years, it has been reported that the pattern of post-translational modifications, altered under neoplastic disease, is a better predictive biomarker than the total protein level. Among others, abnormal glycosylation is attracting great attention. Lectins and antibodies are being used for identification and detection of the carbohydrate moiety with low level of discrimination among various glycoproteins. Such level of selectivity is critical to bring next-generation biomarkers to the clinic. Aptamers that can be rationally tailored for a certain molecule domain can become the golden receptor to specifically detect aberrant glycosylation at each protein or even at each glycosylation site, providing new diagnostic tools for early detection of cancer. Graphical abstract Aptamers may specifically differentiate normal from aberrant glycoproteins.

Antiviral lectins: Selective inhibitors of viral entry

Many natural lectins have been reported to have antiviral activity. As some of these have been put forward as potential development candidates for preventing or treating viral infections, we have set out in this review to survey the literature on antiviral lectins. The review groups lectins by structural class and class of source organism we also detail their carbohydrate specificity and their reported antiviral activities. The review concludes with a brief discussion of several of the pertinent hurdles that heterologous proteins must clear to be useful clinical candidates and cites examples where such studies have been reported for antiviral lectins. Though the clearest path currently being followed is the use of antiviral lectins as anti-HIV microbicides via topical mucosal administration, some investigators have also found systemic efficacy against acute infections following subcutaneous administration.