Perspectives on electrochemical biosensing of COVID-19

Rapid detection of human coronavirus disease 2019, termed as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or COVID-19 infection, is urgently needed for containment strategy owing to its unprecedented spreading. Novel biosensors can be deployed in remote clinical settings without central facilities for infection screening. Electrochemical biosensors serve as analytical tools for rapid detection of viral structure proteins, mainly spike (S) and nucleocapsid (N) proteins, human immune responses, reactive oxygen species, viral ribonucleic acid, polymerase chain reaction by-products, and other potential biomarkers. The development of point-of-care testing devices is challenging due to the requirement of extensive validation, a time-consuming and expensive step. Together with specific biorecognition molecules, nanomaterial-based biosensors have emerged for the fast detection of early viral infections.     

Quantum dots as a promising agent to combat COVID-19

Approximately every 100 years, as witnessed in the last two centuries, we are facing an influenza pandemic, necessitating the need to combat a novel virus strain. As a result of the new coronavirus (severe acute respiratory syndrome coronavirus type 2 [SARS-CoV-2] outbreak in January 2020, many clinical studies are being carried out with the aim of combating or eradicating the disease altogether. However, so far, developing coronavirus disease 2019 (COVID-19) detection kits or vaccines has remained elusive. In this regard, the development of antiviral nanomaterials by surface engineering with enhanced specificity might prove valuable to combat this novel virus. Quantum dots (QDs) are multifaceted agents with the ability to fight against/inhibit the activity of COVID-19 virus. This article exclusively discusses the potential role of QDs as biosensors and antiviral agents for attenuation of viral infection.     

Exogenous pulmonary surfactant: A review focused on adjunctive therapy for severe acute respiratory syndrome coronavirus 2 including SP-A and SP-D as added clinical marker

Type I and type II pneumocytes are two forms of epithelial cells found lining the alveoli in the lungs. Type II pneumocytes exclusively secrete ‘pulmonary surfactants,’ a lipoprotein complex made up of 90% lipids (mainly phospholipids) and 10% surfactant proteins (SP-A, SP-B, SP-C, and SP-D). Respiratory diseases such as influenza, severe acute respiratory syndrome coronavirus infection, and severe acute respiratory syndrome coronavirus 2 infection are reported to preferentially attack type II pneumocytes of the lungs. After viral invasion, consequent viral propagation and destruction of type II pneumocytes causes altered surfactant production, resulting in dyspnea and acute respiratory distress syndrome in patients with coronavirus disease 2019. Exogenous animal-derived or synthetic pulmonary surfactant therapy has already shown immense success in the treatment of neonatal respiratory distress syndrome and has the potential to contribute efficiently toward repair of damaged alveoli and preventing severe acute respiratory syndrome coronavirus 2–associated respiratory failure. Furthermore, early detection of surfactant collectins (SP-A and SP-D) in the circulatory system can be a significant clinical marker for disease prognosis in the near future.     

State-of-the-art colloidal particles and unique interfaces-based SARS-CoV-2 detection methods and COVID-19 diagnosis

In March 2020, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-based infections were declared ‘COVID-19 pandemic’ by the World Health Organization. Pandemic raised the necessity to design and develop genuine and sensitive tests for precise specific SARS-CoV-2 infections detection. Nanotechnological methods offer new ways to fight COVID-19. Nanomaterials are ideal for unique sensor platforms because of their chemically versatile properties and they are easy to manufacture. In this context, selected examples for integrating nanomaterials and distinct biosensor platforms are given to detect SARS-CoV-2 biological materials and COVID-19 biomarkers, giving researchers and scientists more goals and a better forecast to design more relevant and novel sensor arrays for COVID-19 diagnosis.     

Electrochemical Biosensors for Cancer Biomarker Detection

Cancer is still one of the leading causes of death in the world. There are over 200 types of cancers currently known according to the National Cancer Institute. However, early diagnosis continues to be an important integral part of cancer treatment even though many advances in therapeutics have been made in the past decade. Quick diagnosis and early prevention are critical for the control of the disease status. Biomarkers are commonly indicative of a particular disease process and the cancer biomarkers are also widely used in oncology to help detecting the presence of various carcinomas. The detection of cancer biomarkers plays an important role in clinical diagnoses and evaluation of treatment for patients. Many immunoassay methods are developed for detection of cancer biomarkers. As the detection devices are normally viewed with high sensitivity, simple preparation and rapid response, electrochemical biosensors are increasingly used for the detection of cancer markers. This review describes the status, the latest research and trends of electrochemical sensors in the quantitation of cancer markers in recent years. In particular, the strategy to improve the sensitivities of the electrochemical biosensors by the aid of enzymatic amplification, nanoparticle amplification, ultilization of magnetic microspheres etc. is described herein. At last, we discuss some special features and limitations associated with the described systems that summarize the application and the development prospects of electrochemical immunoassay technology.     

CRISPR-Mediated Profiling of Viral RNA at Single-Nucleotide Resolution

Mass pathogen screening is critical to preventing the outbreaks and spread of infectious diseases. The large-scale epidemic of COVID-19 and the rapid mutation of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus have put forward new requirements for virus detection and identification techniques. Here, we report a CRISPR-based Amplification-free Viral RNA Electrical Detection platform (CAVRED) for the rapid detection and identification of SARS-CoV-2 variants. A series of CRISPR RNA assays were designed to amplify the CRISPR-Cas system‘s ability to discriminate between mutant and wild RNA genomes with a single-nucleotide difference. The identified viral RNA information was converted into readable electrical signals through field-effect transistor biosensors for the achievement of highly sensitive detection of single-base mutations. CAVRED can detect the SARS-CoV-2 virus genome as low as 1 cp μL⁻¹ within 20 mins without amplification, and this value is comparable to the detection limit of real-time quantitative polymerase chain reaction. Based on the excellent RNA mutation detection ability, an 8-in-1 CAVRED array was constructed and realized the rapid identification of 40 simulated throat swab samples of SARS-CoV-2 variants with a 95.0 % accuracy. The advantages of accuracy, sensitivity, and fast speed of CAVRED promise its application in rapid and large-scale epidemic screening.     

Colorimetric and Electrochemical Methods for the Detection of SARS-CoV-2 Main Protease by Peptide-Triggered Assembly of Gold Nanoparticles

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) main protease (Mpro) has been regarded as one of the ideal targets for the development of antiviral drugs. The currently used methods for the probing of Mpro activity and the screening of its inhibitors require the use of a double-labeled peptide substrate. In this work, we suggested that the label-free peptide substrate could induce the aggregation of AuNPs through the electrostatic interactions, and the cleavage of the peptide by the Mpro inhibited the aggregation of AuNPs. This fact allowed for the visual analysis of Mpro activity by observing the color change of the AuNPs suspension. Furthermore, the co-assembly of AuNPs and peptide was achieved on the peptide-covered electrode surface. Cleavage of the peptide substrate by the Mpro limited the formation of AuNPs/peptide assembles, thus allowing for the development of a simple and sensitive electrochemical method for Mpro detection in serum samples. The change of the electrochemical signal was easily monitored by electrochemical impedance spectroscopy (EIS). The detection limits of the colorimetric and electrochemical methods are 10 and 0.1 pM, respectively. This work should be valuable for the development of effective antiviral drugs and the design of novel optical and electrical biosensors.     

Development of polypyrrole (nano)structures decorated with gold nanoparticles toward immunosensing for COVID-19 serological diagnosis

The rapid and reliable detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) seroconversion in humans is crucial for suitable infection control. In this sense, many studies have focused on increasing the sensibility, lowering the detection limits and minimizing false negative/positive results. Thus, biosensors based on nanoarchitectures of conducting polymers are promising alternatives to more traditional materials since they can hold improved surface area, higher electrical conductivity and electrochemical activity. In this work, we reported the analytical comparison of two different conducting polymers morphologies for the development of an impedimetric biosensor to monitor SARS-CoV-2 seroconversion in humans. Biosensors based on polypyrrole (PPy), synthesized in both globular and nanotubular (NT) morphology, and gold nanoparticles are reported, using a self-assembly monolayer of 3-mercaptopropionic acid and covalently linked SARS-CoV-2 Nucleocapsid protein. First, the novel hybrid materials were characterized by electron microscopy and electrochemical measurements, and the biosensor step-by-step construction was characterized by electrochemical and spectroscopic techniques. As a proof of concept, the biosensor was used for the impedimetric detection of anti-SARS-CoV-2 Nucleocapsid protein monoclonal antibodies. The results showed a linear response for different antibody concentrations, good sensibility and possibility to quantify 7.442 and 0.4 ng/mL of monoclonal antibody for PPy in the globular and NT morphology, respectively. The PPy-NTs biosensor was able to discriminate serum obtained from COVID-19 positive versus negative clinical samples and is a promising tool for COVID-19 immunodiagnostic, which can contribute to further studies concerning rapid, efficient, and reliable detections.     

基于分子识别的免疫层析技术用于新冠肺炎感染的快速诊断

目前由新型冠状病毒(SARS-CoV-2)引发的新冠肺炎疫情仍在全球蔓延. 快速筛查并隔离感染者(包括无症状感染者)是遏制疫情传播的重要手段之一. 免疫层析技术是一种相对成熟的快速检测技术, 由于其操作简单、 反应时间短且结果稳定, 在生物标志物检测领域具有广阔的应用前景. 本文总结了目前免疫层析检测技术在新冠肺炎感染筛查领域的研究进展, 涵盖病毒抗体、 蛋白、 核酸等检测靶标, 并对不同检测方法的优势、 局限性进行了简要评述, 最后简单介绍了目前用于新冠肺炎感染筛查的免疫层析试纸的实际应用情况.     

多色彩可视化半定量检测方法用于COVID-19患者治疗过程中抗体浓度变化的快速监测

现场快速定量检测新型冠状病毒(SARS-CoV-2)抗体对于监测新型冠状病毒感染的肺炎患者治疗过程具有重要作用. 目前, 大多数抗体检测采用基于金纳米粒子的免疫层析定性检测, 但该方法仅表现出一种颜色变化, 无法实现现场快速定量检测. 本文采用特异性刻蚀金纳米棒(Au NRs)的方法, 实现了SARS-CoV-2抗体多色彩可视化的现场快速定量检测. 首先, 将SARS-CoV-2重组抗原固定在96孔酶标板上; 随后, 将辣根过氧化物酶标记的酶标抗体与待测抗体结合, 形成抗原-待测抗体-酶标抗体的复合三明治结构, 且酶标抗体与待测抗体浓度呈正相关; 由于酶标抗体可与3,3',5,5'-四甲基联苯胺(TMB)发生特异性反应, 生成TMB²⁺, 而TMB²⁺可选择性刻蚀Au NRs, 使得溶液产生丰富多彩的颜色, 即可通过观察溶液颜色变化实现SARS-CoV-2抗体浓度半定量检测. 在最佳条件下, 该方法对SARS-CoV-2 IgM抗体在5.00~200 IU浓度范围内呈良好线性关系, 检出限为1.29 IU, 并具有较高的灵敏度和特异性. 上述方法成功用于COVID-19患者治疗过程中SARS-CoV-2 IgM抗体浓度半定量快速检测.     

共反应试剂增强电致化学发光信号生物传感器

在电致化学发光（ECL）生物传感器的构建中,利用共反应试剂促进发光基团的发光效率是一种常见、方便且非常有效的方法. 然而,如何更好地利用共反应试剂使其更加有效地与发光基团作用是提高该类生物传感器灵敏度的重要因素. 本文结合作者课题组部分工作综述了三种共反应试剂放大ECL信号的构建：共反应试剂内置于检测底液;共反应试剂共存于电极表面;酶促生成共反应试剂,并提出了今后ECL信号放大构建的展望.     

High-Throughput Fluorescent Assay for Inhibitor Screening of Proteases from RNA Viruses

Spanish flu, polio epidemics, and the ongoing COVID-19 pandemic are the most profound examples of severe widespread diseases caused by RNA viruses. The coronavirus pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) demands affordable and reliable assays for testing antivirals. To test inhibitors of viral proteases, we have developed an inexpensive high-throughput assay based on fluorescent energy transfer (FRET). We assayed an array of inhibitors for papain-like protease from SARS-CoV-2 and validated it on protease from the tick-borne encephalitis virus to emphasize its versatility. The reaction progress is monitored as loss of FRET signal of the substrate. This robust and reproducible assay can be used for testing the inhibitors in 96- or 384-well plates.     

Middle East respiratory syndrome coronavirus: transmission,virology and therapeutic targeting to aid in outbreak control

Middle East respiratory syndrome coronavirus (MERS-CoV) causes high fever, cough, acute respiratory tract infection and multiorgan dysfunction that may eventually lead to the death of the infected individuals. MERS-CoV is thought to be transmitted to humans through dromedary camels. The occurrence of the virus was first reported in the Middle East and it subsequently spread to several parts of the world. Since 2012, about 1368 infections, including ~487 deaths, have been reported worldwide. Notably, the recent human-to-human ‘superspreading'' of MERS-CoV in hospitals in South Korea has raised a major global health concern. The fatality rate in MERS-CoV infection is four times higher compared with that of the closely related severe acute respiratory syndrome coronavirus infection. Currently, no drug has been clinically approved to control MERS-CoV infection. In this study, we highlight the potential drug targets that can be used to develop anti-MERS-CoV therapeutics.     

Repurposing metocurine as main protease inhibitor to develop novel antiviral therapy for COVID-19

Structural Chemistry - The outbreak of severe acute respiratory syndrome coronavirus-2 is causing a serious disaster through coronavirus disease-19 (COVID-19) around the globe. A large segment of...     

基于成簇的规则间隔短回文重复序列的严重急性呼吸综合征冠状病毒2检测的最新进展北大核心CSCD

严重急性呼吸综合征冠状病毒2(SARS-CoV-2)导致的新冠肺炎(COVID-19)迅速蔓延全球,给全球公共卫生系统带来了挑战。由于逆转录-定量聚合酶链反应(RT-qPCR)和抗原测试的普遍适用性和灵敏度较差,并且具有不同突变的SARS-CoV-2变体持续的出现,给疫情防控带来了更大的挑战,因此,高灵敏度、无需设备并且能够区分SARS-CoV-2变体的诊断方法亟须发展。基于成簇的规则间隔短回文重复序列(CRISPR)的诊断对设备要求低,具有可编程性、灵敏性和易用性,已经发展出多种核酸检测工具用于传染病的诊断,其在临床上具有巨大的应用潜力。文章聚焦于近期发表的基于CRISPR实现SARS-CoV-2检测和变体区分的最新技术,总结其特点并对其发展进行了展望。     

Progress in Enzyme-Based Biosensors Using Optical Transducers

Enzyme-based biosensors are well developed and relatively mature technique in the biosensing field. Biosensors that utilise enzymes as the recognition elements represent the most extensively studied area. The organisation of an enzyme-based biosensor requires the integration of the biocatalyst with the support or immobilised materials to the extent that the biocatalytic transformation is either optically or electronically transduced. Any optical or electrical changes at the support material as a result of the biocatalytic process, that is, depletion of the reactant or formation of the product, provide routes for the opto/electronic transduction of the biological process occurring at the sensing surface. This review focuses on the discussion of some enzyme immobilisation techniques including physical and chemical immobilisation. Enzyme-based biosensors using various optical detection methods such as absorptiometry, luminometry, chemiluminescence, evanescent wave, and surface plasmon resonance are also included. Finally, different types of enzyme-based optical biosensors for ascorbic acid, bilirubin, cholesterol, choline, ethanol, glucose, glutamate/glutamine, lactate, penicillin, urea, and uric acid determinations are presented.On sabbatical leave at The University of North Carolina at Chapel Hill in July 2004–July 2005     

Biomolecular interactions with nanoparticles: applications for coronavirus disease 2019

Nanoparticles are small particles sized 1–100 nm, which have a large surface-to-volume ratio, allowing efficient adsorption of drugs, proteins, and other chemical compounds. Consequently, functionalized nanoparticles have potential diagnostic and therapeutic applications. A variety of nanoparticles have been studied, including those constructed from inorganic materials, biopolymers, and lipids. In this review, we focus on recent work targeting the severe acute respiratory syndrome coronavirus 2 virus that causes coronavirus disease (COVID-19). Understanding the interactions between coronavirus-specific proteins (such as the spike protein and its host cell receptor angiotensin-converting enzyme 2) with different nanoparticles paves the way to the development of new therapeutics and diagnostics that are urgently needed for the fight against COVID-19, and indeed for related future viral threats that may emerge.     

Insights into the inhibitory potential of selective phytochemicals against Mpro of 2019-nCoV: a computer-aided study

Structural Chemistry - At the end of December 2019, a novel strain of coronavirus, given the name of 2019-nCoV, emerged for exhibiting symptoms of severe acute respiratory syndrome. The virus is...     

Screen-printed biosensors in microbiology; a review

Disposable screen-printed biosensors have been successfully employed in the development of analytical methods that respond to the growing need to perform rapid “in situ” analyses. Thus, the early detection of microorganisms, which plays an important role in the prevention of human health problems, animals and plants epidemics, has been carried out using this kind of devices. Moreover, microorganisms have been used as biological sensing elements in the development of sensitive microbial biosensors for the analysis of different analytes of interest. This review presents the electrochemical application of disposable screen-printed biosensors in the microbiology field.