Label-free electrochemical detection of Avian Influenza Virus genotype utilizing multi-walled carbon nanotubes–cobalt phthalocyanine–PAMAM nanocomposite modified glassy carbon electrode

Recent trends in carbon nanotube (CNT)-based biosensors for the fast and sensitive detection of human viruses: a critical review

The current COVID-19 pandemic, with its numerous variants including Omicron which is 50-70% more transmissible than the previously dominant Delta variant, demands a fast, robust, cheap, and easily deployed identification strategy to reduce the chain of transmission, for which biosensors have been shown as a feasible solution at the laboratory scale. The use of nanomaterials has significantly enhanced the performance of biosensors, and the addition of CNTs has increased detection capabilities to an unrivaled level. Among the various CNT-based detection systems, CNT-based field-effect transistors possess ultra-sensitivity and low-noise detection capacity, allowing for immediate analyte determination even in the presence of limited analyte concentrations, which would be typical of early infection stages. Recently, CNT field-effect transistor-type biosensors have been successfully used in the fast diagnosis of COVID-19, which has increased research and commercial interest in exploiting current developments of CNT field-effect transistors. Recent progress in the design and deployment of CNT-based biosensors for viral monitoring are covered in this paper, as are the remaining obstacles and prospects. This work also highlights the enormous potential for synergistic effects of CNTs used in combination with other nanomaterials for viral detection.

A Review on CNTs-Based Electrochemical Sensors and Biosensors: Unique Properties and Potential Applications

Carbon nanotubes (CNTs), are safe, biocompatible, bioactive, and biodegradable materials, and have sparked a lot of attention due to their unique characteristics in a variety of applications, including medical and dye industries, paper manufacturing and water purification. CNTs also have a strong film-forming potential, permitting them to be widely employed in constructing sensors and biosensors. This review concentrates on the application of CNT-based nanocomposites in the production of electrochemical sensors and biosensors. It emphasizes the synthesis and optimization of CNT-based sensors for a range of applications and outlines the benefits of using CNTs for biomolecule immobilization. In addition, the use of molecularly imprinted polymer (MIP)-CNTs in the production of electrochemical sensors is also discussed. The challenges faced by the current CNTs-based sensors, along with some the future perspectives and their future opportunities, are also briefly explained in this paper.

Electrochemical Biosensors Based on Carbon Nanomaterials for Diagnosis of Human Respiratory Diseases

In recent years, respiratory diseases have increasingly become a global concern, largely due to the outbreak of Coronavirus Disease 2019 (COVID-19). This inevitably causes great attention to be given to the development of highly efficient and minimal or non-invasive methods for the diagnosis of respiratory diseases. And electrochemical biosensors based on carbon nanomaterials show great potential in fulfilling the requirement, not only because of the superior performance of electrochemical analysis, but also given the excellent properties of the carbon nanomaterials. In this paper, we review the most recent advances in research, development and applications of electrochemical biosensors based on the use of carbon nanomaterials for diagnosis of human respiratory diseases in the last 10 years. We first briefly introduce the characteristics of several common human respiratory diseases, including influenza, COVID-19, pulmonary fibrosis, tuberculosis and lung cancer. Then, we describe the working principles and fabrication of various electrochemical biosensors based on carbon nanomaterials used for diagnosis of these respiratory diseases. Finally, we summarize the advantages, challenges, and future perspectives for the currently available electrochemical biosensors based on carbon nanomaterials for detecting human respiratory diseases.

Decadal Journey of CNT-Based Analytical Biosensing Platforms in the Detection of Human Viruses

It has been proven that viral infections pose a serious hazard to humans and also affect social health, including morbidity and mental suffering, as illustrated by the COVID-19 pandemic. The early detection and isolation of virally infected people are, thus, required to control the spread of viruses. Due to the outstanding and unparalleled properties of nanomaterials, numerous biosensors were developed for the early detection of viral diseases via sensitive, minimally invasive, and simple procedures. To that aim, viral detection technologies based on carbon nanotubes (CNTs) are being developed as viable alternatives to existing diagnostic approaches. This article summarizes the advancements in CNT-based biosensors since the last decade in the detection of different human viruses, namely, SARS-CoV-2, dengue, influenza, human immunodeficiency virus (HIV), and hepatitis. Finally, the shortcomings and benefits of CNT-based biosensors for the detection of viruses are outlined and discussed.

Movable Layer Device for Rapid Detection of Influenza a H1N1 Virus Using Highly Bright Multi-Quantum Dot-Embedded Particles and Magnetic Beads

Preventing the rapid spread of viral infectious diseases has become a major concern for global health. In this study, we present a microfluidic platform that performs an immunoassay of viral antigens in a simple, automated, yet highly sensitive manner. The device uses silica particles embedded with highly bright quantum dots (QD2) and performs the immunoassay with a vertically movable top layer and a rotating bottom layer. Through the motion of the layers and the surface tension in the liquids, reagents move from top chambers to bottom chambers and mix homogeneously. A tip in the top layer with a mobile permanent magnet moves the immune complexes comprising the magnetic beads, virus particles, and QD2 between the bottom chambers. In this way, our automated device achieves a highly sensitive magnetic bead-based sandwich immunoassay for the influenza A H1N1 virus within 32.5 min. The detection limit of our method is 5.1 × 10-4 hemagglutination units, which is 2 × 103 times more sensitive than that of the conventional hemagglutination method and is comparable to PCR. Our device is useful for the rapid and sensitive detection of infectious diseases in point-of-care applications and resource-limited environments.

Nucleic acid-based electrochemical biosensors for rapid clinical diagnosis: Advances, challenges, and opportunities

Clinical diagnostic tests should be quick, reliable, simple to perform, and affordable for diagnosis and treatment of diseases. In this regard, owing to their novel properties, biosensors have attracted the attention of scientists as well as end-users. They are efficient, stable, and relatively cheap. Biosensors have broad applications in medical diagnosis, including point-of-care (POC) monitoring, forensics, and biomedical research. The electrochemical nucleic acid (NA) biosensor, the latest invention in this field, combines the sensitivity of electroanalytical methods with the inherent bioselectivity of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). The NA biosensor exploits the affinity of single-stranded DNA/RNA for its complementary strand and is used to detect complementary sequences of NA based on hybridization. After the NA component in the sensor detects the analyte, a catalytic reaction or binding event that generates an electrical signal in the transducer ensues. Since 2000, much progress has been made in this field, but there are still numerous challenges. This critical review describes the advances, challenges, and prospects of NA-based electrochemical biosensors for clinical diagnosis. It includes the basic principles, classification, sensing enhancement strategies, and applications of biosensors as well as their advantages, limitations, and future prospects, and thus it should be useful to academics as well as industry in the improvement and application of EC NA biosensors.

Azaporphyrins Embedded on Carbon-Based Nanomaterials for Potential Use in Electrochemical Sensing-A Review

Phthalocyanines and porphyrazines as macrocyclic aza-analogues of well-known porphyrins were deposited on diverse carbon-based nanomaterials and investigated as sensing devices. The extended π-conjugated electron system of these macrocycles influences their ability to create stable hybrid systems with graphene or carbon nanotubes commonly based on π-π stacking interactions. During a 15-year period, the electrodes modified by deposition of these systems have been applied for the determination of diverse analytes, such as food pollutants, heavy metals, catecholamines, thiols, glucose, peroxides, some active pharmaceutical ingredients, and poisonous gases. These procedures have also taken place, on occasion, in the presence of various polymers, ionic liquids, and other moieties. In the review, studies are presented that were performed for sensing purposes, involving azaporphyrins embedded on graphene, graphene oxide or carbon nanotubes (both single and multi-walled ones). Moreover, possible methods of electrode fabrication, limits of detection of each analyte, as well as examples of macrocyclic compounds applied as sensing materials, are critically discussed.

Aptamer Applications in Emerging Viral Diseases

Aptamers are single-stranded DNA or RNA molecules which are submitted to a process denominated SELEX. SELEX uses reiterative screening of a random oligonucleotide library to identify high-affinity binders to a chosen target, which may be a peptide, protein, or entire cells or viral particles. Aptamers can rival antibodies in target recognition, and benefit from their non-proteic nature, ease of modification, increased stability, and pharmacokinetic properties. This turns them into ideal candidates for diagnostic as well as therapeutic applications. Here, we review the recent accomplishments in the development of aptamers targeting emerging viral diseases, with emphasis on recent findings of aptamers binding to coronaviruses. We focus on aptamer development for diagnosis, including biosensors, in addition to aptamer modifications for stabilization in body fluids and tissue penetration. Such aptamers are aimed at in vivo diagnosis and treatment, such as quantification of viral load and blocking host cell invasion, virus assembly, or replication, respectively. Although there are currently no in vivo applications of aptamers in combating viral diseases, such strategies are promising for therapy development in the future.

Recent progress in nanomaterial-based sensing of airborne viral and bacterial pathogens

Airborne pathogens are small microbes that can cause a multitude of diseases (e.g., the common cold, flu, asthma, anthrax, tuberculosis, botulism, and pneumonia). As pathogens are transmitted from infected hosts via a number of routes (e.g., aerosolization, sneezing, and coughing), there is a great demand to accurately monitor their presence and behavior. Despite such need, conventional detection methods (e.g., colony counting, immunoassays, and various molecular techniques) generally suffer from a number of demerits (e.g., complex, time-consuming, and labor-intensive nature). To help overcome such limitations, nanomaterial-based biosensors have evolved as alternative candidates to realize portable, rapid, facile, and direct on-site identification of target microbes. In this review, nano-biosensors developed for the detection of airborne pathogens are listed and discussed in reference to conventional options. The prospects for the development of advanced nano-biosensors with enhanced accuracy and portability are also discussed.

Nanobiosensors for the Detection of Novel Coronavirus 2019-nCoV and Other Pandemic/Epidemic Respiratory Viruses: A Review

The coronavirus disease 2019 (COVID-19) pandemic is considered a public health emergency of international concern. The 2019 novel coronavirus (2019-nCoV) or severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that caused this pandemic has spread rapidly to over 200 countries, and has drastically affected public health and the economies of states at unprecedented levels. In this context, efforts around the world are focusing on solving this problem in several directions of research, by: (i) exploring the origin and evolution of the phylogeny of the SARS-CoV-2 viral genome; (ii) developing nanobiosensors that could be highly effective in detecting the new coronavirus; (iii) finding effective treatments for COVID-19; and (iv) working on vaccine development. In this paper, an overview of the progress made in the development of nanobiosensors for the detection of human coronaviruses (SARS-CoV, SARS-CoV-2, and Middle East respiratory syndrome coronavirus (MERS-CoV) is presented, along with specific techniques for modifying the surface of nanobiosensors. The newest detection methods of the influenza virus responsible for acute respiratory syndrome were compared with conventional methods, highlighting the newest trends in diagnostics, applications, and challenges of SARS-CoV-2 (COVID-19 causative virus) nanobiosensors.

Ultrasensitive detection of pathogenic viruses with electrochemical biosensor: State of the art

Last few decades, viruses are a real menace to human safety. Therefore, the rapid identification of viruses should be one of the best ways to prevent an outbreak and important implications for medical healthcare. The recent outbreak of coronavirus disease (COVID-19) is an infectious disease caused by a newly discovered coronavirus which belongs to the single-stranded, positive-strand RNA viruses. The pandemic dimension spread of COVID-19 poses a severe threat to the health and lives of seven billion people worldwide. There is a growing urgency worldwide to establish a point-of-care device for the rapid detection of COVID-19 to prevent subsequent secondary spread. Therefore, the need for sensitive, selective, and rapid diagnostic devices plays a vital role in selecting appropriate treatments and to prevent the epidemics. During the last decade, electrochemical biosensors have emerged as reliable analytical devices and represent a new promising tool for the detection of different pathogenic viruses. This review summarizes the state of the art of different virus detection with currently available electrochemical detection methods. Moreover, this review discusses different fabrication techniques, detection principles, and applications of various virus biosensors. Future research also looks at the use of electrochemical biosensors regarding a potential detection kit for the rapid identification of the COVID-19.

Recent Advances in AIV Biosensors Composed of Nanobio Hybrid Material

Since the beginning of the 2000s, globalization has accelerated because of the development of transportation systems that allow for human and material exchanges throughout the world. However, this globalization has brought with it the rise of various pathogenic viral agents, such as Middle East respiratory syndrome coronavirus (MERS-CoV), severe acute respiratory syndrome coronavirus (SARS-CoV), Zika virus, and Dengue virus. In particular, avian influenza virus (AIV) is highly infectious and causes economic, health, ethnical, and social problems to human beings, which has necessitated the development of an ultrasensitive and selective rapid-detection system of AIV. To prevent the damage associated with the spread of AIV, early detection and adequate treatment of AIV is key. There are traditional techniques that have been used to detect AIV in chickens, ducks, humans, and other living organisms. However, the development of a technique that allows for the more rapid diagnosis of AIV is still necessary. To achieve this goal, the present article reviews the use of an AIV biosensor employing nanobio hybrid materials to enhance the sensitivity and selectivity of the technique while also reducing the detection time and high-throughput process time. This review mainly focused on four techniques: the electrochemical detection system, electrical detection method, optical detection methods based on localized surface plasmon resonance, and fluorescence.

RCA-Based Biosensor for Electrical and Colorimetric Detection of Pathogen DNA

For the diagnosis and prevention of diseases, a range of strategies for the detection of pathogens have been developed. In this study, we synthesized the rolling circle amplification (RCA)-based biosensor that enables detection of pathogen DNA in two analytical modes. Only in the presence of the target DNA, the template DNA can be continuously polymerized by simply carrying out RCA, which gives rise to a change of surface structure of Au electrodes and the gap between the electrodes. Electrical signal was generated after introducing hydrogen tetrachloroaurate (HAuCl4) to the DNA-coated biosensor for the improvement of the conductivity of DNA, which indicates that the presence of the pathogen DNA can be detected in an electrical approach. Furthermore, the existence of the target DNA was readily detected by the naked eyes through change in colors of the electrodes from bright yellow to orange-red after RCA reaction. The RCA-based biosensor offers a new platform for monitoring of pathogenic DNA with two different detection modes in one system.

Amperometric bioaffinity sensing platform for avian influenza virus proteins with aptamer modified gold nanoparticles on carbon chips

A sandwich assay platform involving a surface formed aptamer-protein-antibody complex was developed to obtain the highly selective and sensitive amperometric detection of H5N1 viral proteins using a gold nanoparticle (NP) modified electrode. This is the first aptamer-antibody pairing reported for the selective detection of H5N1. Nanoparticle deposited screen-printed carbon electrodes were first functionalized by the covalent immobilization of a DNA aptamer specific to H5N1 followed by the adsorption of H5N1 protein. Alkaline phosphatase (ALP) conjugated monoclonal antibody was then adsorbed to form a surface bound Au NPs-aptamer/H5N1/antiH5N1-ALP sandwich complex which was further reacted with the enzyme substrate, 4-amino phenyl phosphate (APP). The current associated with the electrocatalytic reaction of the surface bound ALP with APP increased as the H5N1 concentration increased. A lowest detectable concentration of 100 fM was obtained with a linear dynamic range of 100 fM to 10 pM using differential pulse voltammetry. As an example, the biosensor was applied to the detection of H5N1 protein in diluted human serum samples spiked with different concentrations of the viral protein target.

A packaged paper fluidic-based microdevice for detecting gene expression of influenza A virus

Pathotyping and subtyping of influenza A virus were performed with a packaged paper fluidic-based analytical microdevice (PFAM) after one-step reverse transcription-polymerase chain reaction (RT-PCR). The PFAM contains two test lines: one for detecting M gene to identify the influenza A virus and another for haemagglutinin subtyping to determine the viral strain among H1N1, H3N2, and H5N1. The M gene and the haemagglutinin gene (H1, H3, and H5 genes) were amplified by using the Digoxigenin and the Texas Red modified primers, respectively, in the multiplex RT-PCR. The amplicon products were loaded in the conjugate pad of the PFAM in which the streptavidin coated gold nanoparticles were linked with the biotin moieties that were incorporated in the middle of the DNA strands, and then captured by the anti-Digoxigenin and anti-Texas Red immobilized on the test lines. Influenza A H1N1, H3N2, and H5N1 could be identified with a limit of detection of 10(2) copies of RNA templates in 10 min. Pathotyping and subtyping of the clinical nasopharyngeal swab samples were also analyzed whose results were confirmed by real-time RT-PCR.

Label-free electrochemical impedance genosensor based on 1-aminopyrene/graphene hybrids

In this work, we proposed a novel simple protocol for preparing 1-aminopyrene/graphene (ApG) hybrids for fabricating label-free electrochemical impedance genosensor. Graphene, with the structure of a single-atom-thick sheet of sp(2)-bonded carbon atoms, was anchored to 1-aminopyrene (1-Ap) with the pyrenyl group viaπ-stacking interaction. The morphology, conductivity, and interaction of ApG hybrids were characterized by transmission electron microscopy (TEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), UV-visible (UV-vis) and fluorescence spectra. The amino-substituted oligonucleotide probe was conjugated to 1-Ap by the cross-linker glutaraldehyde. The DNA hybridization reaction of oligonucleotide probe with target DNA was monitored by EIS. Under optimum conditions, the proposed biosensor exhibited high sensitivity and a low detection limit for detecting the complementary oligonucleotide. The target oligonucleotide could be quantified in a wide range of 1.0 × 10(-12) to 1.0 × 10(-8) M with good linearity (R = 0.9900) and low detection limit of 4.5 × 10(-13) M (S/N = 3).

Electrochemical aptasensors for microbial and viral pathogens

Aptamers are DNA and RNA oligonucleotides that can bind to a variety of nonnucleic acid targets with high affinity and specificity. Pathogen detection is a promising area in aptamer research. One of its major advantages is the ability of the aptamers to target and specifically differentiate microbial and viral strains without previous knowledge of the membrane-associated antigenic determinants or molecular biomarkers present in that particular microorganism. Electrochemical sensors emerged as a promising field in the area of aptamer research and pathogen detection. An electrochemical sensor is a device that combines a recognition element and an electrochemical transduction unit, where aptamers represent the latest addition to the large catalog of recognition elements. This chapter summarizes and evaluates recent developments of electrochemical aptamer-based sensors for microbial and viral pathogen detection, viability assessment of microorganisms, bacterial typing, identification of epitope-specific aptamers, affinity measurement between aptamers and their respective targets, and estimation of the degree of aptamer protection of oncolytic viruses for therapeutic purposes.

New approaches in microbial pathogen detection

Viruses are common causes of foodborne outbreaks. Viral diseases have low fatality rates but transmission to humans via food is important due to the high probability of consuming fecally contaminated food or water because of poor food handling. Because of the low infectious doses of some foodborne viruses, there is a need for standardization and the development of new sensitive methods for detecting viruses. The focus is on molecular and non-molecular approaches, and emerging methods for the detection of foodborne viruses. The detection of noroviruses, hepatitis A and E viruses, rotaviruses and adenoviruses will be discussed. The chapter will conclude with insights into future research directions.

Carbon nanotubes and metalloporphyrins and metallophthalocyanines-based materials for electroanalysis

We discuss here the state of the art on hybrid materials made from single (SWCNT) or multi (MWCNT) walled carbon nanotubes and MN4complexes such as metalloporphyrins and metallophthalocyanines. The hybrid materials have been characterized by several methods such as cyclic voltammetry (CV), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and scanning electrochemical microscropy (SECM). The materials are employed for electrocatalysis of reactions such as oxygen and hydrogen peroxide reduction, nitric oxide oxidation, oxidation of thiols and other pollutants.

Electrochemical sensor for guanine using a self-assembled monolayer of 1,8,15,22-tetraaminophthalocyanatonickel(II) on glassy carbon electrode

This article describes the selective determination of guanine (G) using the self-assembled monolayer (SAM) of 1,8,15,22-tetraaminophthalocyanatonickel(II) (4α-Ni(II)TAPc) modified glassy carbon electrode (GCE) in 0.2 M acetate buffer solution (pH 4.0). The SAM of 4α-Ni(II)TAPc was formed on GCE by spontaneous adsorption of 1 mM 4α-Ni(II)TAPc in dimethylformamide (DMF). It shows two pairs of redox waves corresponding to Ni(III)/Ni(II) and Ni(III)Pc(-1)/Ni(III)Pc(-2) in 0.2 M acetate buffer solution. The SAM modified electrode exhibits excellent electrocatalytic activity toward the oxidation of G by enhancing its oxidation current with 150 mV less positive potential shift in contrast to bare GCE. Furthermore, the SAM modified electrode selectively determines G in the presence of high concentration of adenine (A). In differential pulse voltammetry measurements, the oxidation current response of G was increased linearly in the concentration range of 10 to 100 μM, and a detection limit was found to be 3×10(-8)M (signal/noise=3).

Dendrimers and nanotubes: a fruitful association

Dendrimers and nanotubes (particularly carbon nanotubes (CNTs)) are two types of nano-objects which have met independently a large success within the scientific community. Surprisingly, their association has been poorly studied up to now, despite some original properties recently reported and that will be emphasized in this tutorial review. One can name as a few, the elaboration of single-walled carbon nanotubes from dendrimers, CNTs functionalised with dendrimers displaying field effect transistor properties and/or used as biosensors, and modified biological properties (either enhanced biocompatibility or enhanced antimicrobial activity). However, not all the nanotubes are carbon nanotubes, and original properties were also reported for dendrimers associated with non-CNTs, such as the elaboration of specific nano-filters and of highly efficient and reusable catalysts. Furthermore, non-CNTs constituted of dendrimers, particularly those obtained by layer-by-layer deposition of positively and negatively charged dendrimers associated with quantum dots display an excellent detection limit for DNA hybridization (10 fM).