Recent Advances of Representative Optical Biosensors for Rapid and Sensitive Diagnostics of SARS-CoV-2

Evaluation and comparison of one-step real-time PCR and one-step RT-LAMP methods for detection of SARS-CoV-2

BACKGROUND

There is an increasing disease trend for SARS-COV-2, so need a quick and affordable diagnostic method. It should be highly accurate and save costs compared to other methods. The purpose of this research is to achieve these goals.

METHODS

This study analyzed 342 samples using TaqMan One-Step RT-qPCR and fast One-Step RT-LAMP (Reverse Transcriptase Loop-Mediated Isothermal Amplification). The One-Step LAMP assay was conducted to assess the sensitivity and specificity.

RESULTS

The research reported positive samples using two different methods. In the RT-LAMP method, saliva had 92 positive samples (26.9%) and 250 negative samples (73.09%) and nasopharynx had 94 positive samples (27.4%) and 248 negative samples (72.51%). In the RT-qPCR method, saliva had 86 positive samples (25.1%) and 256 negative samples (74.8%) and nasopharynx had 93 positive samples (27.1%) and 249 negative samples (72.8%). The agreement between the two tests in saliva and nasopharynx samples was 93% and 94% respectively, based on Cohen's kappa coefficient (κ) (P < 0.001). The rate of sensitivity in this technique was reported at a dilution of 1 × 101 and 100% specificity.

CONCLUSIONS

Based on the results of the study the One-Step LAMP assay has multiple advantages. These include simplicity, cost-effectiveness, high sensitivity, and specificity. The One-Step LAMP assay shows promise as a diagnostic tool. It can help manage disease outbreaks, ensure prompt treatment, and safeguard public health by providing rapid, easy-to-use testing.

Enhancing the understanding of SARS-CoV-2 protein with structure and detection methods: An integrative review

As the rapid and accurate screening of infectious diseases can provide meaningful information for outbreak prevention and control, as well as owing to the existing limitations of the polymerase chain reaction (PCR), it is imperative to have new and validated detection techniques for SARS-CoV-2. Therefore, the rationale for outlining the techniques used to detect SARS-CoV-2 proteins and performing a comprehensive comparison to serve as a practical benchmark for future identification of similar viral proteins is clear. This review highlights the urgent need to strengthen pandemic preparedness by emphasizing the importance of integrated measures. These include improved tools for pathogen characterization, optimized societal precautions, the establishment of early warning systems, and the deployment of highly sensitive diagnostics for effective surveillance, triage, and resource management. Additionally, with an improved understanding of the virus' protein structure, considerable advances in targeted detection, treatment, and prevention strategies are expected to greatly improve our ability to respond to future outbreaks.

Optical biosensors for diagnosis of COVID-19: nanomaterial-enabled particle strategies for post pandemic era

The COVID-19 pandemic underlines the need for effective strategies for controlling virus spread and ensuring sensitive detection of SARS-CoV-2. This review presents the potential of nanomaterial-enabled optical biosensors for rapid and low-cost detection of SARS-CoV-2 biomarkers, demonstrating a comprehensive analysis including colorimetric, fluorescence, surface-enhanced Raman scattering, and surface plasmon resonance detection methods. Nanomaterials including metal-based nanomaterials, metal-organic frame-based nanoparticles, nanorods, nanoporous materials, nanoshell materials, and magnetic nanoparticles employed in the production of optical biosensors are presented in detail. This review also discusses the detection principles, fabrication methods, nanomaterial synthesis, and their applications for the detection of SARS-CoV-2 in four categories: antibody-based, antigen-based, nucleic acid-based, and aptamer-based biosensors. This critical review includes reports published in the literature between the years 2021 and 2024. In addition, the review offers critical insights into optical nanobiosensors for the diagnosis of COVID-19. The integration of artificial intelligence and machine learning technologies with optical nanomaterial-enabled biosensors is proposed to improve the efficiency of optical diagnostic systems for future pandemic scenarios.

Graphene transistor-based biosensors for rapid detection of SARS-CoV-2

Field-effect transistor (FET) biosensors use FETs to detect changes in the amount of electrical charge caused by biomolecules like antigens and antibodies. COVID-19 can be detected by employing these biosensors by immobilising bio-receptor molecules that bind to the SARS-CoV-2 virus on the FET channel surface and subsequent monitoring of the changes in the current triggered by the virus. Graphene Field-effect Transistor (GFET)-based biosensors utilise graphene, a two-dimensional material with high electrical conductivity, as the sensing element. These biosensors can rapidly detect several biomolecules including the SARS-CoV-2 virus, which is responsible for COVID-19. GFETs are ideal for real-time infectious illness diagnosis due to their great sensitivity and specificity. These graphene transistor-based biosensors could revolutionise clinical diagnostics by generating fast, accurate data that could aid pandemic management. GFETs can also be integrated into point-of-care (POC) diagnostic equipment. Recent advances in GFET-type biosensors for SARS-CoV-2 detection are discussed here, along with their associated challenges and future scope.

Rapid Nucleic Acid Diagnostic Technology for Pandemic Diseases

The recent global pandemic of coronavirus disease 2019 (COVID-19) has enormously promoted the development of diagnostic technology. To control the spread of pandemic diseases and achieve rapid screening of the population, ensuring that patients receive timely treatment, rapid diagnosis has become the top priority in the development of clinical technology. This review article aims to summarize the current rapid nucleic acid diagnostic technologies applied to pandemic disease diagnosis, from rapid extraction and rapid amplification to rapid detection. We also discuss future prospects in the development of rapid nucleic acid diagnostic technologies.

Machine Learning for COVID-19 Determination Using Surface-Enhanced Raman Spectroscopy

The rapid, low cost, and efficient detection of SARS-CoV-2 virus infection, especially in clinical samples, remains a major challenge. A promising solution to this problem is the combination of a spectroscopic technique: surface-enhanced Raman spectroscopy (SERS) with advanced chemometrics based on machine learning (ML) algorithms. In the present study, we conducted SERS investigations of saliva and nasopharyngeal swabs taken from a cohort of patients (saliva: 175; nasopharyngeal swabs: 114). Obtained SERS spectra were analyzed using a range of classifiers in which random forest (RF) achieved the best results, e.g., for saliva, the precision and recall equals 94.0% and 88.9%, respectively. The results demonstrate that even with a relatively small number of clinical samples, the combination of SERS and shallow machine learning can be used to identify SARS-CoV-2 virus in clinical practice.

Recent advances in point-of-care testing of COVID-19

Advances in microfluidic device miniaturization and system integration contribute to the development of portable, handheld, and smartphone-compatible devices. These advancements in diagnostics have the potential to revolutionize the approach to detect and respond to future pandemics. Accordingly, herein, recent advances in point-of-care testing (POCT) of coronavirus disease 2019 (COVID-19) using various microdevices, including lateral flow assay strips, vertical flow assay strips, microfluidic channels, and paper-based microfluidic devices, are reviewed. However, visual determination of the diagnostic results using only microdevices leads to many false-negative results due to the limited detection sensitivities of these devices. Several POCT systems comprising microdevices integrated with portable optical readers have been developed to address this issue. Since the outbreak of COVID-19, effective POCT strategies for COVID-19 based on optical detection methods have been established. They can be categorized into fluorescence, surface-enhanced Raman scattering, surface plasmon resonance spectroscopy, and wearable sensing. We introduced next-generation pandemic sensing methods incorporating artificial intelligence that can be used to meet global health needs in the future. Additionally, we have discussed appropriate responses of various testing devices to emerging infectious diseases and prospective preventive measures for the post-pandemic era. We believe that this review will be helpful for preparing for future infectious disease outbreaks.

Flow injection analysis coupled with photoelectrochemical immunoassay for simultaneous detection of anti-SARS-CoV-2-spike and anti-SARS-CoV-2-nucleocapsid antibodies in serum samples

A thin-layer flow cell of low internal volume (12 μL) is incorporated in a flow injection analysis (FIA) system for simultaneous and real-time photoelectrochemical (PEC) immunoassay of anti-SARS-CoV-2 spike 1 (S1) and anti-SARS-CoV-2 nucleocapsid (N) antibodies. Covalent linkage of S1 and N proteins to two separate polyethylene glycol (PEG)-covered gold nanoparticles (AuNPs)/TiO2 nanotube array (NTA) electrodes affords 10 consecutive analyses with surface regenerations in between. An indium tin oxide (ITO) allows visible light to impinge onto the two electrodes. The detection limits for anti-S1 and anti-N antibodies were estimated to be 177 and 97 ng mL-1, respectively. Such values compare well with those achieved with other reported methods and satisfy the requirement for screening convalescent patients with low antibody levels. Additionally, our method exhibits excellent intra-batch (RSD = 1.3%), inter-batch (RSD = 3.4%), intra-day (RSD = 1.0%), and inter-day (RSD = 1.6%) reproducibility. The obviation of an enzyme label and continuous analysis markedly decreased the assay cost and duration, rendering this method cost-effective. The excellent anti-fouling property of PEG enables accuracy validation by comparing our PEC immunoassays of patient sera to those of ELISA. In addition, the simultaneous detection of two antibodies holds great potential in disease diagnosis and immunity studies.

Two-Dimensional (2D) materials in the detection of SARS-CoV-2

The SARS-CoV-2 pandemic has resulted in a devastating effect on human health in the last three years. While tremendous effort has been devoted to the development of effective treatment and vaccines against SARS-CoV-2 and controlling the spread of it, collective health challenges have been encountered along with the concurrent serious economic impacts. Since the beginning of the pandemic, various detection methods like PCR-based methods, isothermal nucleic acid amplification-based (INAA) methods, serological methods or antibody tests, and evaluation of X-ray chest results have been exploited to diagnose SARS-CoV-2. PCR-based detection methods in these are considered gold standards in the current stage despite their drawbacks, including being high-cost and time-consuming procedures. Furthermore, the results obtained from the PCR tests are susceptible to sample collection methods and time. When the sample is not collected properly, obtaining a false result may be likely. The use of specialized lab equipment and the need for trained people for the experiments pose additional challenges in PCR-based testing methods. Also, similar problems are observed in other molecular and serological methods. Therefore, biosensor technologies are becoming advantageous with their quick response, high specificity and precision, and low-cost characteristics for SARS-CoV-2 detection. In this paper, we critically review the advances in the development of sensors for the detection of SARS-CoV-2 using two-dimensional (2D) materials. Since 2D materials including graphene and graphene-related materials, transition metal carbides, carbonitrides, and nitrides (MXenes), and transition metal dichalcogenides (TMDs) play key roles in the development of novel and high-performance electrochemical (bio)sensors, this review pushes the sensor technologies against SARS-CoV-2 detection forward and highlights the current trends. First, the basics of SARS-CoV-2 detection are described. Then the structure and the physicochemical properties of the 2D materials are explained, which is followed by the development of SARS-CoV-2 sensors by exploiting the exceptional properties of the 2D materials. This critical review covers most of the published papers in detail from the beginning of the outbreak.

Multiplexed Biosensing of Proteins and Virions with Disposable Plasmonic Assays

Our growing ability to tailor healthcare to the needs of individuals has the potential to transform clinical treatment. However, the measurement of multiple biomarkers to inform clinical decisions requires rapid, effective, and affordable diagnostics. Chronic diseases and rapidly evolving pathogens in a larger population have also escalated the need for improved diagnostic capabilities. Current chemical diagnostics are often performed in centralized facilities and are still dependent on multiple steps, molecular labeling, and detailed analysis, causing the result turnaround time to be over hours and days. Rapid diagnostic kits based on lateral flow devices can return results quickly but are only capable of detecting a handful of pathogens or markers. Herein, we present the use of disposable plasmonics with chiroptical nanostructures as a platform for low-cost, label-free optical biosensing with multiplexing and without the need for flow systems often required in current optical biosensors. We showcase the detection of SARS-CoV-2 in complex media as well as an assay for the Norovirus and Zika virus as an early developmental milestone toward high-throughput, single-step diagnostic kits for differential diagnosis of multiple respiratory viruses and any other emerging diagnostic needs. Diagnostics based on this platform, which we term "disposable plasmonics assays," would be suitable for low-cost screening of multiple pathogens or biomarkers in a near-point-of-care setting.

Simultaneous Detection of SARS-CoV-2 Nucleoprotein and Receptor Binding Domain by a Multi-Area Reflectance Spectroscopy Sensor

The COVID-19 pandemic has emphasized the urgent need for point-of-care methods suitable for the rapid and reliable diagnosis of viral infections. To address this demand, we report the rapid, label-free simultaneous determination of two SARS-CoV-2 proteins, namely, the nucleoprotein and the receptor binding domain peptide of S1 protein, by implementing a bioanalytical device based on Multi Area Reflectance Spectroscopy. Simultaneous detection of these two proteins is achieved by using silicon chips with adjacent areas of different silicon dioxide thickness on top, each of which is modified with an antibody specific to either the nucleoprotein or the receptor binding domain of SARS-CoV-2. Both areas were illuminated by a single probe that also collected the reflected light, directing it to a spectrometer. The online conversion of the combined reflection spectra from the two silicon dioxide areas into the respective adlayer thickness enabled real-time monitoring of immunoreactions taking place on the two areas. Several antibodies have been tested to define the pair, providing the higher specific signal following a non-competitive immunoassay format. Biotinylated secondary antibodies and streptavidin were used to enhance the specific signal. Both proteins were detected in less than 12 min, with detection limits of 1.0 ng/mL. The assays demonstrated high repeatability with intra- and inter-assay coefficients of variation lower than 10%. Moreover, the recovery of both proteins from spiked samples prepared in extraction buffer from a commercial self-test kit for SARS-CoV-2 collection from nasopharyngeal swabs ranged from 90.0 to 110%. The short assay duration in combination with the excellent analytical performance and the compact instrument size render the proposed device and assay suitable for point-of-care applications.

A Surface-Enhanced Raman Spectroscopy-Based Biosensor for the Detection of Biological Macromolecules: The Case of the Lipopolysaccharide Endotoxin Molecules

The development of sensitive methods for the detection of endotoxin molecules, such as lipopolysaccharides (LPS), is essential for food safety and health control. Conventional analytical methods used for LPS detection are based on the pyrogen test, plating and culture-based methods, and the limulus amoebocyte lysate method (LAL). Alternatively, the development of reliable biosensors for LPS detection would be highly desirable to solve some critical issues, such as high cost and a long turnaround time. In this work, we present a label-free Surface-Enhanced Raman Spectroscopy (SERS)-based method for LPS detection in its free form. The proposed method combines the benefits of plasmonic enhancement with the selectivity provided by a specific anti-lipid A antibody (Ab). A high-enhancing nanostructured silver substrate was coated with Ab. The presence of LPS was quantitatively monitored by analyzing the changes in the Ab spectra obtained in the absence and presence of LPS. A limit of detection (LOD) and quantification (LOQ) of 12 ng/mL and 41 ng/mL were estimated, respectively. Importantly, the proposed technology could be easily expanded for the determination of other biological macromolecules.

Recent development of surface-enhanced Raman scattering for biosensing

Surface-Enhanced Raman Scattering (SERS) technology, as a powerful tool to identify molecular species by collecting molecular spectral signals at the single-molecule level, has achieved substantial progresses in the fields of environmental science, medical diagnosis, food safety, and biological analysis. As deepening research is delved into SERS sensing, more and more high-performance or multifunctional SERS substrate materials emerge, which are expected to push Raman sensing into more application fields. Especially in the field of biological analysis, intrinsic and extrinsic SERS sensing schemes have been widely used and explored due to their fast, sensitive and reliable advantages. Herein, recent developments of SERS substrates and their applications in biomolecular detection (SARS-CoV-2 virus, tumor etc.), biological imaging and pesticide detection are summarized. The SERS concepts (including its basic theory and sensing mechanism) and the important strategies (extending from nanomaterials with tunable shapes and nanostructures to surface bio-functionalization by modifying affinity groups or specific biomolecules) for improving SERS biosensing performance are comprehensively discussed. For data analysis and identification, the applications of machine learning methods and software acquisition sources in SERS biosensing and diagnosing are discussed in detail. In conclusion, the challenges and perspectives of SERS biosensing in the future are presented.

Emerging trends in point-of-care biosensing strategies for molecular architectures and antibodies of SARS-CoV-2

COVID-19, a highly contagious viral infection caused by the occurrence of severe acute respiratory syndrome coronavirus (SARS-CoV-2), has turned out to be a viral pandemic then ravaged many countries worldwide. In the recent years, point-of-care (POC) biosensors combined with state-of-the-art bioreceptors, and transducing systems enabled the development of novel diagnostic tools for rapid and reliable detection of biomarkers associated with SARS-CoV-2. The present review thoroughly summarises and discusses various biosensing strategies developed for probing SARS-CoV-2 molecular architectures (viral genome, S Protein, M protein, E protein, N protein and non-structural proteins) and antibodies as a potential diagnostic tool for COVID-19. This review discusses the various structural components of SARS-CoV-2, their binding regions and the bioreceptors used for recognizing the structural components. The various types of clinical specimens investigated for rapid and POC detection of SARS-CoV-2 is also highlighted. The importance of nanotechnology and artificial intelligence (AI) approaches in improving the biosensor performance for real-time and reagent-free monitoring the biomarkers of SARS-CoV-2 is also summarized. This review also encompasses existing practical challenges and prospects for developing new POC biosensors for clinical monitoring of COVID-19.

Diffusive Formation of Au/Ag Alloy Nanoparticles of Governed Composition in Glass

For the first time we show that the introduction of silver ions in the glass containing gold nanoparticles (NPs) and additional heat treatment of the glass in the air lead to the formation of Au/Ag alloy NPs. The proposed approach makes it possible to position localized surface plasmon resonance of the NPs by selecting the heat treatment temperature, which determines the silver proportion in the alloy NPs. This allows for expanding customizability of NPs for applications in surface-enhanced Raman scattering spectroscopy, catalysis and biochemistry. Developed technique benefits from the presence of silver in the glass in ionic form, which prevents the oxidation of silver and provides stable preparation of Au/Ag alloy NPs.