A dip-and-read optical aptasensor for detection of tau protein

Real-time detection of Tau-381 protein using liquid crystal-based sensors for Alzheimer's disease diagnosis

Tau is a protein found in the central nervous system (CNS) and is involved in stabilizing microtubules in axons. Given the link between Tau levels in the body and Alzheimer's disease (AD), there is a demand for straightforward and precise strategies to detect Tau in body fluids. In this study, we report liquid crystal (LC)-based sensors for the real-time detection of Tau protein, a well-known AD biomarker. The sensor uses a detection method based on the orientation change of the LC because of the competitive biomolecular interaction between Tau and Tau aptamers with the cationic polymer poly-L-lysine (PLL). Tau and its aptamers form stable complexes through electrostatic interactions. Owing to the consumption of the aptamer, the positively charged PLL fails to interact with the aptamer but binds to the negatively charged 1.2-dioleoyl-sn-glycero-3-phospho-(1'-rac-glycerol) sodium salt (DOPG). The PLL and DOPG complex alters the orientation of the LC to ensure a planar anchoring of the 4-cyano-4'-pentylbiphenyl (5CB)/aqueous interface; this anchoring intensifies with increasing Tau concentration, thus enabling the observation of a bright optical image. Our LC-based sensor demonstrated a low detection limit of 2.77 pg/mL in phosphate buffered saline (PBS) and 10.86 pg/mL and 19.31 pg/mL in human serum and plasma, respectively. Moreover, it is anticipated to be suitable for point-of-care diagnosis of AD because it does not require specialized analytical equipment and only requires microliters of sample.

Optical fiber biosensors toward in vivo detection

This review takes stock of the various optical fiber-based biosensors that could be used for in vivo applications. We discuss the characteristics that biosensors must have to be suitable for such applications and the corresponding transduction modes. In particular, we focus on optical fiber biosensors based on fluorescence, evanescent wave, plasmonics, interferometry, and Raman phenomenon. The operational principles, implemented solutions, and performances are described and debated. The different sensing configurations, such as the side- and tip-based fiber biosensors, are illustrated, and their adaptation for in vivo measurements is discussed. The required implementation of multiplexed biosensing on optical fibers is shown. In particular, the use of multi-fiber assemblies, one of the most optimal configurations for multiplexed detection, is discussed. Different possibilities for multiple localized functionalizations on optical fibers are presented. A final section is devoted to the practical in vivo use of fiber-based biosensors, covering regulatory, sterilization, and packaging aspects. Finally, the trends and required improvements in this promising and emerging field are analyzed and discussed.

Label-Free Biochemical Sensing Using Processed Optical Fiber Interferometry: A Review

Over the last 20 years, optical fiber-based devices have been exploited extensively in the field of biochemical sensing, with applications in many specific areas such as the food processing industry, environmental monitoring, health diagnosis, bioengineering, disease diagnosis, and the drug industry due to their compact, label-free, and highly sensitive detection. The selective and accurate detection of biochemicals is an essential part of biosensing devices, which is to be done through effective functionalization of highly specific recognition agents, such as enzymes, DNA, receptors, etc., over the transducing surface. Among many optical fiber-based sensing technologies, optical fiber interferometry-based biosensors are one of the broadly used methods with the advantages of biocompatibility, compact size, high sensitivity, high-resolution sensing, lower detection limits, operating wavelength tunability, etc. This Review provides a comprehensive review of the fundamentals as well as the current advances in developing optical fiber interferometry-based biochemical sensors. In the beginning, a generic biosensor and its several components are introduced, followed by the fundamentals and state-of-art technology behind developing a variety of interferometry-based fiber optic sensors. These include the Mach-Zehnder interferometer, the Michelson interferometer, the Fabry-Perot interferometer, the Sagnac interferometer, and biolayer interferometry (BLI). Further, several technical reports are comprehensively reviewed and compared in a tabulated form for better comparison along with their advantages and disadvantages. Further, the limitations and possible solutions for these sensors are discussed to transform these in-lab devices into commercial industry applications. At the end, in conclusion, comments on the prospects of field development toward the commercialization of sensor technology are also provided. The Review targets a broad range of audiences including beginners and also motivates the experts helping to solve the real issues for developing an industry-oriented sensing device.

Protein aggregation and neurodegenerative disease: Structural outlook for the novel therapeutics

Before the controversial approval of humanized monoclonal antibody lecanemab, which binds to the soluble amyloid-β protofibrils, all the treatments available earlier, for Alzheimer's disease (AD) were symptomatic. The researchers are still struggling to find a breakthrough in AD therapeutic medicine, which is partially attributable to lack in understanding of the structural information associated with the intrinsically disordered proteins and amyloids. One of the major challenges in this area of research is to understand the structural diversity of intrinsically disordered proteins under in vitro conditions. Therefore, in this review, we have summarized the in vitro applications of biophysical methods, which are aimed to shed some light on the heterogeneity, pathogenicity, structures and mechanisms of the intrinsically disordered protein aggregates associated with proteinopathies including AD. This review will also rationalize some of the strategies in modulating disease-relevant pathogenic protein entities by small molecules using structural biology approaches and biophysical characterization. We have also highlighted tools and techniques to simulate the in vivo conditions for native and cytotoxic tau/amyloids assemblies, urge new chemical approaches to replicate tau/amyloids assemblies similar to those in vivo conditions, in addition to designing novel potential drugs.

A New Optical Interferometric Biosensing System Enhanced with Nanoparticles for Alzheimer's Disease in Serum

In this scientific work, we demonstrate, for the first time, a new biosensing system and procedure to measure specifically the total Tau (T-Tau) protein in serum, one of the most relevant biomarkers of Alzheimer's disease (AD). AD is a progressive brain disorder that produces neuronal and cognitive dysfunction and affects a high percentage of people worldwide. For this reason, diagnosing AD at the earliest possible stage involves improving diagnostic systems. We report on the use of interferometric bio-transducers integrated with 65 microwells forming diagnostic KITs read-out by using the Interferometric Optical Detection Method (IODM). Moreover, biofunctionalized silicon dioxide (SiO₂) nanoparticles (NPs) acting as interferometric enhancers of the bio-transducers signal allow for the improvement of both the optical read-out signal and its ability to work with less-invasive biological samples such as serum instead of cerebrospinal fluid (CSF). As a result, in this paper, we describe for the first time a relevant diagnostic alternative to detect Tau protein at demanding concentrations of 10 pg/mL or even better, opening the opportunity to be used for detecting other relevant AD-related biomarkers in serum, such as β-amyloid and phosphorylated Tau (P-Tau), neurofilaments, among others that can be considered relevant for AD.

Tau Protein Biosensors in the Diagnosis of Neurodegenerative Diseases

Tau protein plays a crucial role in diagnosing neurodegenerative diseases. However, performing an assay to detect tau protein on a nanoscale is a great challenge for early diagnosis of diseases. Enzyme-linked immunosorbent assay (ELISA), western-blotting, and molecular-based methods, e.g., PCR and real-time PCR, are the most widely used methods for detecting tau protein. These methods are subject to certain limitations: the need for advanced equipment, low sensitivity, and specificity, to name a few. With the above said, it is necessary to discover advanced and novel methods for monitoring tau protein. Counted among remarkable approaches adopted by researchers, biosensors can largely eliminate the difficulties and limitations associated with conventional methods. The main objective of the present study is to review the latest biosensors developed to detect the tau protein. Furthermore, the problems and limitations of conventional diagnosis methods were discussed in detail.

Paper-Based Biosensors for the Detection of Nucleic Acids from Pathogens

Paper-based biosensors are microfluidic analytical devices used for the detection of biochemical substances. The unique properties of paper-based biosensors, including low cost, portability, disposability, and ease of use, make them an excellent tool for point-of-care testing. Among all analyte detection methods, nucleic acid-based pathogen detection offers versatility due to the ease of nucleic acid synthesis. In a point-of-care testing context, the combination of nucleic acid detection and a paper-based platform allows for accurate detection. This review offers an overview of contemporary paper-based biosensors for detecting nucleic acids from pathogens. The methods and limitations of implementing an integrated portable paper-based platform are discussed. The review concludes with potential directions for future research in the development of paper-based biosensors.

One-step high-throughput detection of low-abundance biomarker BDNF using a biolayer interferometry-based 3D aptasensor

Although biosensors for signal monitoring have been extensively developed, their application in one-step high-throughput detection of low-abundance disease biomarkers remains challenging. This study presents a 3D aptasensor based on a biolayer interferometry (BLI) technique, followed by the sensitive and rapid detection of the specific biomarker brain-derived neurotrophic factor (BDNF) for early screening of glaucoma, an irreversible disease that causes blindness. The developed 3D aptasensor enabled one-step batch conversion of the low-abundance biomarker BDNF binding into optical interference signal, which was mainly attributed to the following factors: (1) A dimeric aptamer with extremely high targeting affinity was constructed as a biorecognition molecule, (2) highly sensitive 3D matrix sensors were integrated as signal transduction elements, and (3) the BLI Octet system with automated, high-throughput, and real-time online monitoring capabilities was used for reporting. The 3D aptasensor exhibited a broad detection window from 0.41 to 250 ng/mL BDNF, with a limit of detection of 0.2 ng/mL. Furthermore, detection of BDNF in glaucoma patient serum using the aptasensor showed good agreement with ELISA findings as well as the clinical diagnosis of the patient, demonstrating the feasibility of the system as a screening tool for glaucoma. This one-step high-throughput screening approach provides a valuable solution for the early diagnosis of glaucoma and may reduce the risk of blindness in visually impaired people.

Construction of ssDNA-Attached LR-Chimera Involving Z-DNA for ZBP1 Binding Analysis

The binding of proteins to Z-DNA is hard to analyze, especially for short non-modified DNA, because it is easily transferred to B-DNA. Here, by the hybridization of a larger circular single-stranded DNA (ssDNA) with a smaller one, an LR-chimera (involving a left-handed part and a right-handed one) with an ssDNA loop is produced. The circular ssDNAs are prepared by the hybridization of two ssDNA fragments to form two nicks, followed by nick sealing with T4 DNA ligase. No splint (a scaffold DNA for circularizing ssDNA) is required, and no polymeric byproducts are produced. The ssDNA loop on the LR-chimera can be used to attach it with other molecules by hybridization with another ssDNA. The gel shift binding assay with Z-DNA specific binding antibody (Z22) or Z-DNA binding protein 1 (ZBP1) shows that stable Z-DNA can form under physiological ionic conditions even when the extra ssDNA part is present. Concretely, a 5'-terminal biotin-modified DNA oligonucleotide complementary to the ssDNA loop on the LR-chimera is used to attach it on the surface of a biosensor inlaid with streptavidin molecules, and the binding constant of ZBP1 with Z-DNA is analyzed by BLI (bio-layer interferometry). This approach is convenient for quantitatively analyzing the binding dynamics of Z-DNA with other molecules.

Recent advances in aptamer applications for analytical biochemistry

Aptamers are typically defined as relatively short (20-60 nucleotides) single-stranded DNA or RNA molecules that bind with high affinity and specificity to various types of targets. Aptamers are frequently referred to as "synthetic antibodies" but are easier to obtain, less expensive to produce, and in several ways more versatile than antibodies. The beginnings of aptamers date back to 1990, and since then there has been a continual increase in aptamer publications. The intent of the present account was to focus on recent original research publications, i.e., those appearing in 2019 through April 2020, when this account was written. A Google Scholar search of this recent literature was performed for relevance-ranking of articles. New methods for selection of aptamers were not included. Nine categories of applications were organized and representative examples of each are given. Finally, an outlook is offered focusing on "faster, better, cheaper" application performance factors as key drivers for future innovations in aptamer applications.

Biosensor approaches on the diagnosis of neurodegenerative diseases: Sensing the past to the future

Early diagnosis of neurodegeneration-oriented diseases that develop with the aging world is essential for improving the patient's living conditions as well as the treatment of the disease. Alzheimer's and Parkinson's diseases are prominent examples of neurodegeneration characterized by dementia leading to the death of nerve cells. The clinical diagnosis of these diseases only after the symptoms appear, delays the treatment process. Detection of biomarkers, which are distinctive molecules in biological fluids, involved in neurodegeneration processes, has the potential to allow early diagnosis of neurodegenerative diseases. Studies on biosensors, whose main responsibility is to detect the target analyte with high specificity, has gained momentum in recent years with the aim of high detection of potential biomarkers of neurodegeneration process. This study aims to provide an overview of neuro-biosensors developed on the basis of biomarkers identified in biological fluids for the diagnosis of neurodegenerative diseases such as Alzheimer's disease (AD), and Parkinson's disease (PD), and to provide an overview of the urgent needs in this field, emphasizing the importance of early diagnosis in the general lines of the neurodegeneration pathway. In this review, biosensor systems developed for the detection of biomarkers of neurodegenerative diseases, especially in the last 5 years, are discussed.

Current progress in aptamer-based sensing tools for ultra-low level monitoring of Alzheimer's disease biomarkers

Alzheimer's disease (AD) as common late-life dementia is pathologically associated with the irreversible and progressive disorder, misfolding, deposition, and accumulation of the brain proteins. Especially, the formation of fibrous amyloid plaques by aggregation of amyloid-β peptides is the pathological cause of this neurologic disorder disease. Besides, tau protein isoforms destabilize the microtubule filaments through post-translational modifications and induce nerve cells' death. Amyloid-β peptides and tau proteins are considered as the critical symptom and reliable molecular biomarkers for the early diagnosis of AD. AD is characterized by impaired thinking proficiencies, cognitive decline, memory loss, and behavioral disability. Since there is no efficacious therapy for AD at present, the development of precise sensing tools for the early diagnosis of this disease is essential and crucial. Aptamer-based biosensors (aptasensors) have acquired utmost importance in the field of AD healthcare, due to excellent sensitivity and specificity, ease-of-use, cost-effectiveness, portability, and rapid assay time. Here, we highlight the recent developments and novel perspectives in the field of aptasensor design to quantitatively monitor the AD biomarkers. Finally, some results are represented to achieve a promising viewpoint for introducing the novel aptasensor test kits in the future.

Lab-on-a-ZnO-Submicron-Particle Sensor Array for Monitoring AD upon Cd2+ Exposure with CSF Tau441% as an Effective Hallmark

In this study, based on the posttreatment strategy, blue-color-emissive ZnO submicron particles (B-ZnO SMPs) and red-color-emissive ZnO submicron particles (R-ZnO SMPs) were obtained from rationally designed Zn-infinite coordination polymer (ICP) precursors. After modification of thiol-containing aptamers, diverse spectral changes in the ultraviolet and visible regions of B- and R-ZnO SMPs toward different tau species were explored to construct a lab-on-a-ZnO-submicron-particle sensor array. Assisted by principal component analysis (PCA), the unique fingerprints of the sensor array enabled the simultaneous differentiation and quantitative detection of different tau species (tau381, tau410, and tau441) for the first time. Furthermore, the dynamic changes of tau441% (the ratio of the two most reported representative 4R isoform (full-length tau441) and 3R isoform (tau381)) in cerebrospinal fluid (CSF) during the Alzheimer's disease (AD) onset of Cd²⁺-exposed rats could also be monitored by the lab-on-a-ZnO-submicron-particle sensor array, which was supposed to be an effective hallmark and highly correlated with the formation of neurofibrillary tangles (NFTs). This study not only provides a further insight into the involvement of subchronic Cd²⁺ exposure in the tau etiology of AD but also offers more comprehensive and effective information about the asymptomatic stage of AD upon environmental risk, which has potential applications in the early diagnosis and therapy.

Advances in the development paradigm of biosample-based biosensors for early ultrasensitive detection of alzheimer's disease

This review highlights current developments, challenges, and future directions for the use of invasive and noninvasive biosample-based small biosensors for early diagnosis of Alzheimer's disease (AD) with biomarkers to incite a conceptual idea from a broad number of readers in this field. We provide the most promising concept about biosensors on the basis of detection scale (from femto to micro) using invasive and noninvasive biosamples such as cerebrospinal fluid (CSF), blood, urine, sweat, and tear. It also summarizes sensor types and detailed analyzing techniques for ultrasensitive detection of multiple target biomarkers (i.e., amyloid beta (Aβ) peptide, tau protein, Acetylcholine (Ach), microRNA137, etc.) of AD in terms of detection ranges and limit of detections (LODs). As the most significant disadvantage of CSF and blood-based detection of AD is associated with the invasiveness of sample collection which limits future strategy with home-based early screening of AD, we extensively reviewed the future trend of new noninvasive detection techniques (such as optical screening and bio-imaging process). To overcome the limitation of non-invasive biosamples with low concentrations of AD biomarkers, current efforts to enhance the sensitivity of biosensors and discover new types of biomarkers using non-invasive body fluids are presented. We also introduced future trends facing an infection point in early diagnosis of AD with simultaneous emergence of addressable innovative technologies.

Recent Developments in Aptasensors for Diagnostic Applications

Aptamers are exciting smart molecular probes for specific recognition of disease biomarkers. A number of strategies have been developed to convert target-aptamer binding into physically detectable signals. Since the aptamer sequence was first discovered, a large variety of aptamer-based biosensors have been developed, with considerable attention paid to their potential applications in clinical diagnostics. So far, a variety of techniques in combination with a wide range of functional nanomaterials have been used for the design of aptasensors to further improve the sensitivity and detection limit of target determination. In this paper, the advantages of aptamers over traditional antibodies as the molecular recognition components in biosensors for high-throughput screening target molecules are highlighted. Aptamer-target pairing configurations are predominantly single- or dual-site binding; the design of recognition modes of each aptamer-target pairing configuration is described. Furthermore, signal transduction strategies including optical, electrical, mechanical, and mass-sensitive modes are clearly explained together with examples. Finally, we summarize the recent progress in the development of aptamer-based biosensors for clinical diagnosis, including detection of cancer and disease biomarkers and in vivo molecular imaging. We then conclude with a discussion on the advanced development and challenges of aptasensors.

Nanomaterial-based Optical and Electrochemical Biosensors for Amyloid beta and Tau: Potential for early diagnosis of Alzheimer's Disease

INTRODUCTION

Alzheimer's disease (AD), a heterogeneous pathological process representing the most common causes of dementia worldwide, has required early and accurate diagnostic tools. Neuropathological hallmarks of AD involve the aberrant accumulation of Amyloid beta (Aβ) into Amyloid plaques and hyperphosphorylated Tau into neurofibrillary tangles, occurring long before the onset of brain dysfunction.Areas covered:Considering the significance of Aβ and Tau in AD pathogenesis, these proteins have been adopted as core biomarkers of AD, and their quantification has provided precise diagnostic information to develop next-generation AD therapeutic approaches. However, conventional diagnostic methods may not suffice to achieve clinical criteria that are acceptable for proper diagnosis and treatment. The advantages of nanomaterial-based biosensors including facile miniaturization, mass fabrication, ultra-sensitivity, make them useful to be promising tools to measure Aβ and Tau simultaneously for accurate validation of low-abundance yet potentially informative biomarkers of AD..

EXPERT OPINION

The study has identified the potential application of advanced biosensors as standardized clinical diagnostic tools for AD, evolving the way for new and efficient AD control with minimum economic and social burden. After clinical trial, nanobiosensors for measuring Aβ and Tau simultaneously possess innovative diagnosis of AD to provide significant contributions to primary Alzheimer's care intervention.

Rapid and sensitive detection of SARS-CoV-2 antibodies by biolayer interferometry

Serological testing to evaluate antigen-specific antibodies in plasma is generally performed by rapid lateral flow test strips that lack quantitative results or by high complexity immunoassays that are time- and labor-intensive but provide semi-quantitative results. Here, we describe a novel application of biolayer interferometry for the rapid detection of antigen-specific antibody levels in plasma samples, and demonstrate its utility for quantification of SARS-CoV-2 antibodies. Our biolayer interferometry immunosorbent assay (BLI-ISA) utilizes single-use biosensors in an automated "dip-and-read" format, providing real-time optical measurements of antigen loading, plasma antibody binding, and antibody isotype detection. Complete semi-quantitative results are obtained in less than 20 min. BLI-ISA meets or exceeds the performance of high complexity methods such as Enzyme-Linked Immunosorbent Assay (ELISA) and Chemiluminescent Immunoassay. Importantly, our method can be immediately implemented on existing BLI platforms for urgent COVID-19 studies, such as serosurveillance and the evaluation of vaccine candidates. In a broader sense, BLI-ISA can be developed as a novel diagnostic platform to evaluate antibodies and other biomolecules in clinical specimens.

Polyvalent Biotinylated Aptamer Scaffold for Rapid and Sensitive Detection of Tau Proteins

Biomimetic construction of artificial scaffolds has attracted increasing attention. However, the construction methods usually require redundant materials and procedures, which is inconvenient for further application. Herein, inspired by the polyvalent multifunctional structure in nature, we have designed a polyvalent biotinylated aptamer scaffold (PBAS) which can conduct analytical performance with high sensitivity and simplified procedures. To construct a PBAS, the aptamers are designed to hybridize with prepared linker probes to form polyvalent biotinylated scaffolds, which contain both multiple aptamers and signal labels. Therefore, multifunctional scaffolds can be constructed with high recognition and capture efficiency as well as significant signal amplification. Furthermore, the scaffold can be used for the assay of some disease marker proteins. By taking tau proteins as an example, the proposed aptasensor can exhibit excellent performance with a low detection limit of 153 pg mL^-1 and a short assay time of 50 min, which is much better than most of the previous methods. By assays of tau proteins in both serum and artificial cerebro spinal fluid, the PBAS-based aptasensor can work well. Therefore, the scaffold may be expected to be a powerful analytical tool which may have wide applications in the detection of a variety of analytes.

Label-Free Optical Resonator-Based Biosensors

The demand for biosensor technology has grown drastically over the last few decades, mainly in disease diagnosis, drug development, and environmental health and safety. Optical resonator-based biosensors have been widely exploited to achieve highly sensitive, rapid, and label-free detection of biological analytes. The advancements in microfluidic and micro/nanofabrication technologies allow them to be miniaturized and simultaneously detect various analytes in a small sample volume. By virtue of these advantages and advancements, the optical resonator-based biosensor is considered a promising platform not only for general medical diagnostics but also for point-of-care applications. This review aims to provide an overview of recent progresses in label-free optical resonator-based biosensors published mostly over the last 5 years. We categorized them into Fabry-Perot interferometer-based and whispering gallery mode-based biosensors. The principles behind each biosensor are concisely introduced, and recent progresses in configurations, materials, test setup, and light confinement methods are described. Finally, the current challenges and future research topics of the optical resonator-based biosensor are discussed.

Fluorescent aptasensor based on G-quadruplex-assisted structural transformation for the detection of biomarker lipocalin 1

Diabetic retinopathy (DR) is the leading global cause of blindness in the working-age population. Early diagnosis and intervention can effectively reduce the risk for blindness. However, the current diagnostic methods in clinical practice remain constrained by nonquantitative examinations and individual ophthalmologists' experiences. Sensitive, specific and accurate detection of DR-specific biomarkers is an important approach to achieve its early and rapid diagnosis. In this study, a high-affinity aptamer APT12TM that specifically binds to the tear-derived DR biomarker lipocalin 1 was obtained. The aptamer APT12TM can be folded into a stable B-DNA structure, and its strong interaction with LCN 1, including hydrogen bonding and hydrophobic interactions, is an important factor for targeted recognition and high-affinity binding. A G-rich DNA fragment was further assembled at both ends of the aptamer APT12TM, and the B-DNA form was successfully converted into a parallel G-quadruplex. Most importantly, LCN 1 could induce further transformation of the G-quadruplex structure. Therefore, a fluorescent aptasensor based on G-quadruplex-assisted structural transformation was developed through the Thioflavin T mediator. The aptasensor exhibited a broad detection window from 0.25 to 1000 nM LCN 1, with a limit of detection of 0.2 nM. Furthermore, the aptasensor was applied to LCN 1 detection in artificial tear samples and displayed good reproducibility and stability. These results show that the developed aptasensor has significant potential for sensitive, specific and convenient detection of the DR-specific biomarker LCN 1.

Rapid and sensitive detection of SARS-CoV-2 antibodies by biolayer interferometry

Serological testing to evaluate antigen-specific antibodies in plasma is generally performed by rapid lateral flow test strips that lack quantitative results or by high complexity immunoassays that are time- and labor-intensive but provide quantitative results. Here, we describe a novel application of biolayer interferometry for the rapid detection of antigen-specific antibody levels in plasma samples, and demonstrate its utility for quantification of SARS-CoV-2 antibodies. Our biolayer interferometry immunosorbent assay (BLI-ISA) utilizes single-use biosensors in an automated "dip-and-read" format, providing real-time optical measurements of antigen loading, plasma antibody binding, and antibody isotype detection. Complete quantitative results are obtained in less than 20 minutes. BLI-ISA meets or exceeds the performance of high complexity methods such as Enzyme-Linked Immunosorbent Assay (ELISA) and Chemiluminescent Immunoassay. Importantly, our method can be immediately implemented on existing BLI platforms for urgent COVID-19 studies, such as serosurveillance and the evaluation of vaccine candidates. In a broader sense, BLI-ISA can be developed as a novel diagnostic platform to evaluate antibodies and other biomolecules in clinical specimens.

The application of antibody-aptamer hybrid biosensors in clinical diagnostics and environmental analysis

The growing number of various diseases and the increase of environmental contamination are the causes for the development of novel methods for their detection. The possibility of the application of affinity-based biosensors for such purposes seems particularly promising as they provide high selectivity and low detection limits. Recently, the usage of hybrid antibody-aptamer sandwich constructs was shown to be more advantageous in terms of working parameters in comparison to aptamer-based and immune-based biosensors. This review is focused on the usage of hybrid antibody-aptamer receptor layers for the determination of clinically and environmentally important target molecules. In this work, antibodies and aptamer molecules are characterized and the methods of their immobilization as well as analytical signal generation are shown. This is followed by the critical presentation of examples of hybrid sandwich biosensors that have been elaborated in the past 12 years.