Ultrasensitive Detection of COVID-19 Causative Virus (SARS-CoV-2) Spike Protein Using Laser Induced Graphene Field-Effect Transistor

2D Materials in Advanced Electronic Biosensors for Point-of-Care Devices

Since two-dimensionalal (2D) materials have distinct chemical and physical properties, they are widely used in various sectors of modern technologies. In the domain of diagnostic biodevices, particularly for point-of-care (PoC) biomedical diagnostics, 2D-based field-effect transistor biosensors (bio-FETs) demonstrate substantial potential. Here, in this review article, the operational mechanisms and detection capabilities of biosensing devices utilizing graphene, transition metal dichalcogenides (TMDCs), black phosphorus, and other 2D materials are addressed in detail. The incorporation of these materials into FET-based biosensors offers significant advantages, including low detection limits (LOD), real-time monitoring, label-free diagnosis, and exceptional selectivity. The review also highlights the diverse applications of these biosensors, ranging from conventional to wearable devices, underscoring the versatility of 2D material-based FET devices. Additionally, the review provides a comprehensive assessment of the limitations and challenges faced by these devices, along with insights into future prospects and advancements. Notably, a detailed comparison of FET-based biosensors is tabulated along with various other biosensing platforms and their working mechanisms. Ultimately, this review aims to stimulate further research and innovation in this field while educating the scientific community about the latest advancements in 2D materials-based biosensors.

Engineered two-dimensional nanomaterials based diagnostics integrated with internet of medical things (IoMT) for COVID-19

More than four years have passed since an inimitable coronavirus disease (COVID-19) pandemic hit the globe in 2019 after an uncontrolled transmission of the severe acute respiratory syndrome (SARS-CoV-2) infection. The occurrence of this highly contagious respiratory infectious disease led to chaos and mortality all over the world. The peak paradigm shift of the researchers was inclined towards the accurate and rapid detection of diseases. Since 2019, there has been a boost in the diagnostics of COVID-19 via numerous conventional diagnostic tools like RT-PCR, ELISA, etc., and advanced biosensing kits like LFIA, etc. For the same reason, the use of nanotechnology and two-dimensional nanomaterials (2DNMs) has aided in the fabrication of efficient diagnostic tools to combat COVID-19. This article discusses the engineering techniques utilized for fabricating chemically active E2DNMs that are exceptionally thin and irregular. The techniques encompass the introduction of heteroatoms, intercalation of ions, and the design of strain and defects. E2DNMs possess unique characteristics, including a substantial surface area and controllable electrical, optical, and bioactive properties. These characteristics enable the development of sophisticated diagnostic platforms for real-time biosensors with exceptional sensitivity in detecting SARS-CoV-2. Integrating the Internet of Medical Things (IoMT) with these E2DNMs-based advanced diagnostics has led to the development of portable, real-time, scalable, more accurate, and cost-effective SARS-CoV-2 diagnostic platforms. These diagnostic platforms have the potential to revolutionize SARS-CoV-2 diagnosis by making it faster, easier, and more accessible to people worldwide, thus making them ideal for resource-limited settings. These advanced IoMT diagnostic platforms may help with combating SARS-CoV-2 as well as tracking and predicting the spread of future pandemics, ultimately saving lives and mitigating their impact on global health systems.

Laser-Induced Graphene-Based Sensors in Health Monitoring: Progress, Sensing Mechanisms, and Applications

The rising global population and improved living standards have led to an alarming increase in non-communicable diseases, notably cardiovascular and chronic respiratory diseases, posing a severe threat to human health. Wearable sensing devices, utilizing micro-sensing technology for real-time monitoring, have emerged as promising tools for disease prevention. Among various sensing platforms, graphene-based sensors have shown exceptional performance in the field of micro-sensing. Laser-induced graphene (LIG) technology, a cost-effective and facile method for graphene preparation, has gained particular attention. By converting polymer films directly into patterned graphene materials at ambient temperature and pressure, LIG offers a convenient and environmentally friendly alternative to traditional methods, opening up innovative possibilities for electronic device fabrication. Integrating LIG-based sensors into health monitoring systems holds the potential to revolutionize health management. To commemorate the tenth anniversary of the discovery of LIG, this work provides a comprehensive overview of LIG's evolution and the progress of LIG-based sensors. Delving into the diverse sensing mechanisms of LIG-based sensors, recent research advances in the domain of health monitoring are explored. Furthermore, the opportunities and challenges associated with LIG-based sensors in health monitoring are briefly discussed.

Improving high throughput manufacture of laser-inscribed graphene electrodes via hierarchical clustering

Laser-inscribed graphene (LIG), initially developed for graphene supercapacitors, has found widespread use in sensor research and development, particularly as a platform for low-cost electrochemical sensing. However, batch-to-batch variation in LIG fabrication introduces uncertainty that cannot be adequately tracked during manufacturing process, limiting scalability. Therefore, there is an urgent need for robust quality control (QC) methodologies to identify and select similar and functional LIG electrodes for sensor fabrication. For the first time, we have developed a statistical workflow and an open-source hierarchical clustering tool for QC analysis in LIG electrode fabrication. The QC process was challenged with multi-operator cyclic voltammetry (CV) data for bare and metalized LIG. As a proof of concept, we employed the developed QC process for laboratory-scale manufacturing of LIG-based biosensors. The study demonstrates that our QC process can rapidly identify similar LIG electrodes from large batches (n ≥ 36) of electrodes, leading to a reduction in biosensor measurement variation by approximately 13% compared to the control group without QC. The statistical workflow and open-source code presented here provide a versatile toolkit for clustering analysis, opening a pathway toward scalable manufacturing of LIG electrodes in sensing. In addition, we establish a data repository for further study of LIG variation.

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.

Ultrasensitive Biochemical Sensing Platform Enabled by Directly Grown Graphene on Insulator

To fabricate label-free and rapid-resulting semiconducting biosensor devices incorporating graphene, it is pertinent to directly grow uniform graphene films on technologically important dielectric and semiconducting substrates. However, it has long been intuitively believed that the nonideal disordered structures formed during direct growth, and the resulted inferior electrical properties will inevitably lead to deteriorated sensing performance. Here, graphene biosensor chips are constructed based on direct plasma-enhanced chemical vapor deposition (PECVD) grown graphene on a 4-inch silicon wafer with excellent film uniformity and high yield. To surprise, optimal operations of graphene biosensors permit ultrasensitive detection of SARS-CoV-2 virus nucleocapsid protein with dilutions down to sub-femtomolar concentrations. Such impressive limit of detection (LOD) is comparable to or even outperforms that of the state-of-the-art biosensor devices based on high-quality graphene. Further noise spectral characterizations and analysis confirms that the LOD is limited by molecular diffusion and/or known interference signals such as drift and instability of the sensors, rather than the electrical merits of the graphene devices along. Hence, result sheds light on processing directly grown PECVD graphene into high-performance sensor devices with important economic benefits and social significance.

The Application of Graphene Field-Effect Transistor Biosensors in COVID-19 Detection Technology: A Review

Coronavirus disease 2019 (COVID-19) is a disease caused by the infectious agent of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2). The primary method of diagnosing SARS-CoV-2 is nucleic acid detection, but this method requires specialized equipment and is time consuming. Therefore, a sensitive, simple, rapid, and low-cost diagnostic test is needed. Graphene field-effect transistor (GFET) biosensors have become the most promising diagnostic technology for detecting SARS-CoV-2 due to their advantages of high sensitivity, fast-detection speed, label-free operation, and low detection limit. This review mainly focus on three types of GFET biosensors to detect SARS-CoV-2. GFET biosensors can quickly identify SARS-CoV-2 within ultra-low detection limits. Finally, we will outline the pros and cons of the diagnostic approaches as well as future directions.

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.

Carbon-based biosensors: Next-generation diagnostic tool for target-specific detection of SARS-CoV-2 (COVID-19)

Severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) was declared a global pandemic in 2020. Having rapidly spread around the globe, with the emergence of new variants, there is a crucial need to develop diagnostic kits for its rapid detection. Since it validated accuracy and reliability, the reverse transcription polymerase chain reaction (RT-PCR) test has been declared the gold standard for disease detection. However, despite its reliability, the requirement of specialized facilities, reagents, and duration of a PCR run limits its usage for rapid detection. There is thus a continuous increase in the design and development of rapid, point-of-care (PoC), and cost-effective diagnostic kits. In this review, we discuss the potential of carbon-based biosensors for target-specific detection of coronavirus disease 19 (COVID-19) and present an overview of investigation within the timeframe of the last four years (2019-2022), which have developed novel platforms using carbon nanomaterial-based approaches for viral detection. The approaches discussed offer rapid, accurate, and cost-effective strategies for COVID-19 detection for healthcare personnel and research workers.

Batteryless wireless magnetostrictive Fe30Co70/Ni clad plate for human coronavirus 229E detection

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been garnered increasing for its rapid worldwide spread. Each country had implemented city-wide lockdowns and immigration regulations to prevent the spread of the infection, resulting in severe economic consequences. Materials and technologies that monitor environmental conditions and wirelessly communicate such information to people are thus gaining considerable attention as a countermeasure. This study investigated the dynamic characteristics of batteryless magnetostrictive alloys for energy harvesting to detect human coronavirus 229E (HCoV-229E). Light and thin magnetostrictive Fe-Co/Ni clad plate with rectification, direct current (DC) voltage storage capacitor, and wireless information transmission circuits were developed for this purpose. The power consumption was reduced by improving the energy storage circuit, and the magnetostrictive clad plate under bending vibration stored a DC voltage of 1.9 V and wirelessly transmitted a signal to a personal computer once every 5 min and 10 s under bias magnetic fields of 0 and 10 mT, respectively. Then, on the clad plate surface, a novel CD13 biorecognition layer was immobilized using a self-assembled monolayer of -COOH groups, thus forming an amide bond with -NH₂ groups for the detection of HCoV-229E. A bending vibration test demonstrated the resonance frequency changes because of HCoV-229E binding. The fluorescence signal demonstrated that HCoV-229E could be successfully detected. Thus, because HCoV-229E changed the dynamic characteristics of this plate, the CD13-modified magnetostrictive clad plate could detect HCoV-229E from the interval of wireless communication time. Therefore, a monitoring system that transmits/detects the presence of human coronavirus without batteries will be realized soon.

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.

Ultrasensitive Antibiotic Perceiving Based on Aptamer-Functionalized Ultraclean Graphene Field-Effect Transistor Biosensor

Antibiotics are powerful tools to treat bacterial infections, but antibiotic pollution is becoming a severe threat to the effective treatment of human bacterial infections. The detection of antibiotics in water has been a crucial research area for bioassays in recent years. There is still an urgent need for a simple ultrasensitive detection approach to achieve accurate antibiotic detection at low concentrations. Herein, a field-effect transistor (FET)-based biosensor was developed using ultraclean graphene and an aptamer for ultrasensitive tetracycline detection. Using a newly designed camphor-rosin clean transfer (CRCT) scheme to prepare ultraclean graphene, the carrier mobility of the FET is found to be improved by more than 10 times compared with the FET prepared by the conventional PMMA transfer (CPT) method. Based on the FET, aptamer-functionalized transistor antibiotic biosensors were constructed and characterized. A dynamic detection range of 5 orders of magnitude, a sensitivity of 21.7 mV/decade, and a low detection limit of 100 fM are achieved for the CRCT-FET biosensors with good stability, which are much improved compared with the biosensor prepared by the CPT method. The antibiotic sensing and sensing performance enhancement mechanisms for the CRCT-FET biosensor were studied and analyzed based on experimental results and a biosensing model. Finally, the CRCT-FET biosensor was verified by detecting antibiotics in actual samples obtained from the entrances of Bohai Bay.

Flexible biochemical sensors for point-of-care management of diseases: a review

Health problems have been widely concerned by all mankind. Real-time monitoring of disease-related biomarkers can feedback the physiological status of human body in time, which is very helpful to the diseases management of healthcare. However, conventional non-flexible/rigid biochemical sensors possess low fit and comfort with the human body, hence hindering the accurate and comfortable long-time health monitoring. Flexible and stretchable materials make it possible for sensors to be continuously attached to the human body with good fit, and more precise and higher quality results can be obtained. Thus, tremendous attention has been paid to flexible biochemical sensors in point-of-care (POC) for real-time monitoring the entire disease process. Here, recent progress on flexible biochemical sensors for management of various diseases, focusing on chronic and communicable diseases, is reviewed, and the detection principle and performance of these flexible biochemical sensors are discussed. Finally, some directions and challenges are proposed for further development of flexible biochemical sensors.

Advancement and Challenges of Biosensing Using Field Effect Transistors

Field-effect transistors (FETs) have become eminent electronic devices for biosensing applications owing to their high sensitivity, faster response and availability of advanced fabrication techniques for their production. The device physics of this sensor is now well understood due to the emergence of several numerical modelling and simulation papers over the years. The pace of advancement along with the knowhow of theoretical concepts proved to be highly effective in detecting deadly pathogens, especially the SARS-CoV-2 spike protein of the coronavirus with the onset of the (coronavirus disease of 2019) COVID-19 pandemic. However, the advancement in the sensing system is also accompanied by various hurdles that degrade the performance. In this review, we have explored all these challenges and how these are tackled with innovative approaches, techniques and device modifications that have also raised the detection sensitivity and specificity. The functional materials of the device are also structurally modified towards improving the surface area and minimizing power dissipation for developing miniaturized microarrays applicable in ultra large scale integration (ULSI) technology. Several theoretical models and simulations have also been carried out in this domain which have given a deeper insight on the electron transport mechanism in these devices and provided the direction for optimizing performance.

Aerosol-jet-printed graphene electrochemical immunosensors for rapid and label-free detection of SARS-CoV-2 in saliva

Rapid, inexpensive, and easy-to-use coronavirus disease 2019 (COVID-19) home tests are key tools in addition to vaccines in the world-wide fight to eliminate national and local shutdowns. However, currently available tests for SARS-CoV-2, the virus that causes COVID-19, are too expensive, painful, and irritating, or not sufficiently sensitive for routine, accurate home testing. Herein, we employ custom-formulated graphene inks and aerosol jet printing (AJP) to create a rapid electrochemical immunosensor for direct detection of SARS-CoV-2 Spike Receptor-Binding Domain (RBD) in saliva samples acquired non-invasively. This sensor demonstrated limits of detection that are considerably lower than most commercial SARS-CoV-2 antigen tests (22.91 ± 4.72 pg/mL for Spike RBD and 110.38 ± 9.00 pg/mL for Spike S1) as well as fast response time (~30 mins), which was facilitated by the functionalization of printed graphene electrodes in a single-step with SARS-CoV-2 polyclonal antibody through the carbodiimide reaction without the need for nanoparticle functionalization or secondary antibody or metallic nanoparticle labels. This immunosensor presents a wide linear sensing range from 1 to 1000 ng/mL and does not react with other coexisting influenza viruses such as H1N1 hemagglutinin. By combining high-yield graphene ink synthesis, automated printing, high antigen selectivity, and rapid testing capability, this work offers a promising alternative to current SARS-CoV-2 antigen tests.

Microfluidics-Based Biosensing Platforms: Emerging Frontiers in Point-of-Care Testing SARS-CoV-2 and Seroprevalence

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused the ongoing COVID-19 (coronavirus disease-2019) outbreak and has unprecedentedly impacted the public health and economic sector. The pandemic has forced researchers to focus on the accurate and early detection of SARS-CoV-2, developing novel diagnostic tests. Among these, microfluidic-based tests stand out for their multiple benefits, such as their portability, low cost, and minimal reagents used. This review discusses the different microfluidic platforms applied in detecting SARS-CoV-2 and seroprevalence, classified into three sections according to the molecules to be detected, i.e., (1) nucleic acid, (2) antigens, and (3) anti-SARS-CoV-2 antibodies. Moreover, commercially available alternatives based on microfluidic platforms are described. Timely and accurate results allow healthcare professionals to perform efficient treatments and make appropriate decisions for infection control; therefore, novel developments that integrate microfluidic technology may provide solutions in the form of massive diagnostics to control the spread of infectious diseases.

Laser-Induced Graphene (LIG) as a Smart and Sustainable Material to Restrain Pandemics and Endemics: A Perspective

A healthy environment is necessary for a human being to survive. The contagious COVID-19 virus has disastrously contaminated the environment, leading to direct or indirect transmission. Therefore, the environment demands adequate prevention and control strategies at the beginning of the viral spread. Laser-induced graphene (LIG) is a three-dimensional carbon-based nanomaterial fabricated in a single step on a wide variety of low-cost to high-quality carbonaceous materials without using any additional chemicals potentially used for antiviral, antibacterial, and sensing applications. LIG has extraordinary properties, including high surface area, electrical and thermal conductivity, environmental-friendliness, easy fabrication, and patterning, making it a sustainable material for controlling SARS-CoV-2 or similar pandemic transmission through different sources. LIG's antiviral, antibacterial, and antibiofouling properties were mainly due to the thermal and electrical properties and texture derived from nanofibers and micropores. This perspective will highlight the conducted research and the future possibilities on LIG for its antimicrobial, antiviral, antibiofouling, and sensing applications. It will also manifest the idea of incorporating this sustainable material into different technologies like air purifiers, antiviral surfaces, wearable sensors, water filters, sludge treatment, and biosensing. It will pave a roadmap to explore this single-step fabrication technique of graphene to deal with pandemics and endemics in the coming future.

The role of electrochemical biosensors in SARS-CoV-2 detection: a bibliometrics-based analysis and review

The global pandemic of COVID-19, which began in late 2019, has resulted in extremely high morbidity and severe mortality worldwide, with important implications for human health, international trade, and national politics. Severe acute respiratory syndrome coronavirus (SARS-CoV-2) is the primary pathogen causing COVID-19. Analytical chemistry played an important role in this global epidemic event, and detection of SARS-CoV-2 even became a part of daily life. Analytical chemists have devoted much effort and enthusiasm to this event, and different analytical techniques have shown very rapid development. Electrochemical biosensors are highly efficient, sensitive, and cost-effective and have been used to detect many highly pathogenic viruses long before this event. However, another fact is that electrochemical biosensors are not the technology of choice for most detection applications. This review describes for the first time the role played by electrochemical biosensors in SARS-CoV-2 detection from a bibliometric perspective. This paper analyzed 254 relevant research papers up to June 2022. The contributions of different countries and institutions to this topic were analyzed. Keyword analysis was used to explore different methodological attempts of electrochemical detection techniques. More importantly, we are trying to find an answer to the question: do electrochemical biosensors have the potential to become a genuinely employable detection technology in an outbreak of infectious disease?

This review describes for the first time the role played by electrochemical biosensors in SARS-CoV-2 detection from a bibliometric perspective.