Organic Electrochemical Transistors functionalized with Protein Minibinders for Sensitive and Specific Detection of SARS-CoV-2

There is a need for rapid, sensitive, specific, and low-cost virus sensors. Recent work has demonstrated that organic electrochemical transistors (OECTs) can detect the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein. Here, a simple and low-cost approach to the fabrication of OECT devices with excellent stability and unprecedented sensitivity and specificity for the detection of SARS-CoV-2 virus is demonstrated. The devices rely on the engineered protein minibinder LCB1, which binds strongly to SARS-CoV-2. The resulting devices exhibit excellent sensitivity for the detection of SARS-CoV-2 virus and SARS-CoV-2 spike protein receptor binding domain (RBD). These results demonstrate a simple, effective, and low-cost biomolecular sensor applicable to the real-time detection of SARS-CoV-2 virus and a general strategy for OECT device design that can be applied for the detection of other pathogenic viruses.

A Surge in Malaria Cases in the Eastern Health Region of Saudi Arabia During the COVID-19 Pandemic.

Background Malaria transmission was stopped on most of the vast area of the Kingdom of Saudi Arabia. However, the pandemic of coronavirus disease (COVID-19) has negatively affected the efforts to control malaria. For instance, COVID-19 was reported to induce a relapse of malaria that is caused by Plasmodium vivax. Furthermore, physicians' attention toward COVID-19 can only result in neglect and delayed diagnosis of complicated malaria cases. These factors, among others, might have contributed to an increase of malaria cases in Dammam, Saudi Arabia. Thus, this study was conducted to examine the effects of COVID-19 on malarial cases. Methods The medical records of all patients who were treated at Dammam Medical Complex for malaria between July 1, 2018, and June 30, 2022, were reviewed. Malaria cases were compared between the pre-COVID-19 period (between July 1, 2018, and June 30, 2020) and the COVID-19 period (between July 1, 2020, and June 30, 2022). Results A total of 92 malaria cases occurred in the total study period. There were 60 cases of malaria in the COVID-19 period as opposed to only 32 cases in the pre-COVID-19 period. All the cases were imported from the endemic Saudi southern areas or from outside the country. Eighty-two patients (89.1%) were males. Most of them were Sundaneses (39 patients, 42.4%), Saudis (21 patients, 22.8%), and tribal peoples (14 patients, 15.2%). Fifty-four patients (58.7%) were infected with Plasmodium falciparum. Seventeen patients (18.5%) were infected with Plasmodium vivax. Another 17 patients (18.5%) had a mixed infection with both Plasmodium falciparum and Plasmodium vivax. A trend toward more infected stateless tribal patients was observed in the COVID-19 period compared to the pre-COVID-19 period (21.7% vs 3.1%). A similar trend was noticed for mixed malarial infections with both Plasmodium falciparum and Plasmodium vivax (29.8% vs 0%) with a P value of less than 0.01. Conclusion Malaria cases were almost doubled during the COVID-19 pandemic as compared to the pre-pandemic era signifying the negative effects of the pandemic on malaria epidemiology. The cases increased for a variety of causes that include alternation of health-seeking behaviors, changes in healthcare structures and regulations, and the interruption of malaria preventive services. Future research is needed to study the long-term effects of the changes imposed by the COVID-19 pandemic and to mitigate the effects of any future pandemic on malaria control. As two patients from our cohort were diagnosed with malaria based on blood smears, although they had negative rapid detection tests (RDTs), we recommend testing all the patients who are suspected to have malaria with both RDTs and peripheral blood smears.

Functional Nanomaterials for Electrochemical SRAS-CoV-2 Biosensors: a Review

The pandemic outbreak of COVID-19 has posed a threat to public health globally, and rapid and accurate identification of the viruses is crucial for controlling COVID-19. In recent years, nanomaterial-based electrochemical sensing techniques hold immense potential for molecular diagnosis with high sensitivity and specificity. In this review, we briefly introduced the structural characteristics and routine detection methods of SARS-CoV-2, then summarized the associated properties and mechanisms of the electrochemical biosensing methods. On the above basis, the research progress of electrochemical biosensors based on gold nanomaterials, oxide nanomaterials, carbon-based nanomaterials and other nanomaterials for rapid and accurate detection of virus were reviewed. Finally, the future applications of nanomaterial-based biosensors for biomolecular diagnostics were pointed out.

The Application of Biosensors in the Detection of SARS-CoV-2

Since the outbreak of COVID-19, it is becoming important to screen SARS-CoV-2 with high accuracy, high efficiency, and rapidness, for epidemic prevention and control. Conventional detection technologies can not satisfy the requirements of examining massive people in a very short time. Biosensor technology, with the advantages of high sensitivity, good selectivity, low cost, easy miniaturization, and short detection time, is being used to develop real-time detection equipment, thus as a potential alternative for real-time detection of SARS-CoV-2 in clinical diagnosis. In the present study, the authors summarized the construction methods and principles for optical biosensors, electrochemical biosensors, wearable biosensors, magnetic biosensors, gold nanoparticle biosensors, and aptamer biosensors, followed by the introduction of the current application of multiple biosensors in SARS-CoV-2 detection. Conclusively, the technical bottlenecks and future development trends of biosensors in SARS-CoV-2 detection are proposed.

Multipurpose advanced split T7 promoter-based transcription amplification for ultrasensitive molecular diagnostics

An accurate, convenient, and rapid diagnostic platform, which can be applied in facility-limited or point-of-care (POC) settings, is essential to help prevent the spread of infectious diseases and enable the most effective treatment to be selected. In this study, we describe the development of a new isothermal molecular diagnostic system named multipurpose advanced split T7 promoter-based transcription amplification (MASTER) for the rapid and ultrasensitive detection of various pathogens containing single-stranded RNA and double-stranded DNA. MASTER produces a large number of RNA amplicons in the presence of target pathogens, which generate fluorescence or colorimetric signals based on light-up RNA aptamers or lateral flow assays. Implementing MASTER at 37 °C for<1 h achieved the detection of a single copy per reaction without cross-reactivity. Moreover, the testing of 40 clinical samples revealed that MASTER exhibited excellent accuracy with 100% sensitivity and specificity for SARS-CoV-2 diagnosis. Furthermore, a one-pot MASTER system capable of accelerating practical applications was demonstrated, indicating that the MASTER system is a promising platform for the effective surveillance of various pathogens. © 2023 Elsevier B.V.

Functional Nanomaterials for Electrochemical SRAS-CoV-2 Biosensors: a Review

The pandemic outbreak of COVID-19 has posed a threat to public health globally, and rapid and accurate identification of the viruses is crucial for controlling COVID-19. In recent years, nanomaterial-based electrochemical sensing techniques hold immense potential for molecular diagnosis with high sensitivity and specificity. In this review, we briefly introduced the structural characteristics and routine detection methods of SARS-CoV-2, then summarized the associated properties and mechanisms of the electrochemical biosensing methods. On the above basis, the research progress of electrochemical biosensors based on gold nanomaterials, oxide nanomaterials, carbon-based nanomaterials and other nanomaterials for rapid and accurate detection of virus were reviewed. Finally, the future applications of nanomaterial-based biosensors for biomolecular diagnostics were pointed out. © 2023 Science Press. All rights reserved.

A real-time monitoring platform of colorimetric LAMP for developing rapid visual detection kits of SARS-CoV-2

Visual detection of nucleic acids is important to diagnose the serious acute infectious diseases such as coronavirus disease 2019 (COVID-19). During this pandemic, reliable visual detection kits have been in high demand for screening and prevention of the virus. While developing these visual detection kits, a real-time monitoring platform is usually applied to study the amplification and detection processes of nucleic acids and optimize the detecting conditions. Herein, we developed a real-time monitoring platform of colorimetric loop-mediated isothermal amplification (LAMP) to investigate the amplification and detection processes of nucleic acids. Using this platform, we could obtain the real-time amplification curves, and optimize the reaction temperature, color change, and detection time. Based on the optimized conditions, a visual detection kit for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was successfully developed with a sensitivity of 102 copies µL−1 in 12 min. This real-time monitoring platform has advantages of simple construction, steady performance, high sensitivity, and outstanding anti-pollution capability, and could replace the traditional colorimetric methods by photographing and reading values. This platform would accelerate the development of visual detection kits for colorimetric LAMP, help to explore the amplification and transcription of nucleic acids, and provide support for the prevention of emerging biological threats. © 2023

Amplification-Free Detection of SARS-CoV-2 Down to Single Virus Level by Portable Carbon Nanotube Biosensors.

The rapid and sensitive detection of trace-level viruses in a simple and reliable way is of great importance for epidemic prevention and control. Here, a multi-functionalized floating gate carbon nanotube field effect transistor (FG-CNT FET) based biosensor is reported for the single virus level detection of SARS-CoV-2 virus antigen and RNA rapidly with a portable sensing platform. The aptamers functionalized sensors can detect SARS-CoV-2 antigens from unprocessed nasopharyngeal swab samples within 1 min. Meanwhile, enhanced by a multi-probe strategy, the FG-CNT FET-based biosensor can detect the long chain RNA directly without amplification down to single virus level within 1 min. The device, constructed with packaged sensor chips and a portable sensing terminal, can distinguish 10 COVID-19 patients from 10 healthy individuals in clinical tests both by the RNAs and antigens by a combination detection strategy with an combined overall percent agreement (OPA) close to 100%. The results provide a general and simple method to enhance the sensitivity of FET-based biochemical sensors for the detection of nucleic acid molecules and demonstrate that the CNT FG FET biosensor is a versatile and reliable integrated platform for ultrasensitive multibiomarker detection without amplification and has great potential for point-of-care (POC) clinical tests.

A Microfluidic Biosensor for Rapid Detection of Covid-19

We have designed, fabricated, and tested a MEMS-based impedance biosensor for accurate and rapid detection of severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) using of clinical samples. The device consists of focusing region that concentrate low quantities of the virus present in the samples to a detectable threshold, trap region hat maximize the captured virus, and detection region to detect the virus with high selectivity and sensitivity, using an array of interdigitated electrodes (IDE) coated with a specific antibody. Changes in the impedance value due to the binding of the SARS-COV-2 antigen to the antibody will indicate positive or negative result. The device was able to detect inactivated SARS-COV-2 antigen present in phosphate buffer saline (PBS) with a concentration as low as 50 TCID50/ml in 30 minutes. In addition, the biosensor was able to detect SARS-COV-2 in clinical samples (swabs) with a sensitivity of 84 TCID50/ml, also in 30 minutes. © 2023 IEEE.

Functional Nanomaterials for Electrochemical SRAS-CoV-2 Biosensors: a Review

The pandemic outbreak of COVID-19 has posed a threat to public health globally, and rapid and accurate identification of the viruses is crucial for controlling COVID-19. In recent years, nanomaterial-based electrochemical sensing techniques hold immense potential for molecular diagnosis with high sensitivity and specificity. In this review, we briefly introduced the structural characteristics and routine detection methods of SARS-CoV-2, then summarized the associated properties and mechanisms of the electrochemical biosensing methods. On the above basis, the research progress of electrochemical biosensors based on gold nanomaterials, oxide nanomaterials, carbon-based nanomaterials and other nanomaterials for rapid and accurate detection of virus were reviewed. Finally, the future applications of nanomaterial-based biosensors for biomolecular diagnostics were pointed out. © 2023 Science Press. All rights reserved.

Covid-19 Identification through Chest X-ray Images using Deep Learning Classifiers

In the context of the nidovirales order, the coronavirus (Covid-19) is a virus family i.e. extracted from Ribonucleic Acid (RNA) viruses. The pandemic ensued due to it has already infected 9,716,060 people across the globe and is still causing problems with mutations of concern. Because of the immense number of infected patients, and the resulting deficiency of testing kits in hospitals;a rapid, reliable, and automatic detection system is in extreme need to curb the numbers. SARS-Cov-2 is an influenza kind of virus that can be detected using imaging techniques. It is important to distinguish between Covid-19 (caused by SARS-Cov-2) disease against pneumonia disease infected patients and healthy person's chest x-ray scans respectively. Advanced computational techniques like ML (machine learning) and DL (deep learning) had proven to be extremely useful in image processing, especially for the processing of medical images. In this work, 2906 images were taken from the publically available datasets. Various transfer learning-based DL models are applied to these images. Resulting that the ML-based classifiers effectively categorizing the input images (normal/Covid-19/pneumonia). The model achieves 96.3% accuracy with the VGG19 model and Logistic Regression (LR) classifier. This model proves to be highly convenient in treating this pandemic disease Covid-19. © 2022 IEEE.

COVID-19 Diagnostic Classification from Chest X-Ray Scan Images Based on Random Forest and DenseNet

The outbreak of the coronavirus disease 2019 (i.e. COVID-19) pandemic has made an extremely serious impact on the world, and the false positive rate of X-ray images in the diagnosis of COVID-19 is a challenge for the management of the pandemic. To better assist doctors in the rapid detection of patients with COVID-19 patients, 9, 208 chest X-Ray images in 4 types of pneumonia patients, including'COVID-19','Normal','Viral-caused Pneumonia' and'Bacterial-caused Pneumonia' are implemented to build the models via DenseNet and Random Forest to classify whether a patient has signs of infection. The accuracy of the Densenet and Random Forest models is 82.03% and 88% separately according to the experimental results. Based on it, a conclusion can be summarized that when the sample size is very small, random forest is a better model than the DenseNet (i.e. Convolution Neural Network Model), which demonstrates the potential of traditional machine learning methods. © 2022 Association for Computing Machinery.

A study of Real-Time Non-invasive Detection Techniques to Identify COVID-19 contagious person

The whole world has witnessed the global pandemic situation caused and hampered very badly due to COVID-19. We had seen the adverse effect globally, in terms of health, economy, social lifestyle. So, it's an urgent need to find a rapid detection technique/test to avoid the spread of the virus. The most effective and world-wide accepted detection method of COVID-19 is the RT-PCR. But due to its slow detection time and False-negative rates, researchers and scientists are trying different detection methods such as use of GC-MS, E-nose, Electrochemical method, use of nanomaterial-based sensor arrays. But all these have limitations in terms of real time sensing, detection time, sample preparation, etc. In order to overcome said drawbacks and to get real-time analysis, we are proposing a concept for COVID-19 detection based on the reported literature. As per recent advancement researchers have evident the presence of VOCs in COVID-19 infected person's breath by GC-MS method. A real time system is very much necessary to detect the VOCs in the Exhaled breath of the COVID-19 infected person to minimize the burden of healthcare system. In this article we will discuss and propose the probable detection techniques for real time sensing of the VOCs presence in the Exhaled breath of the COVID-19 infected person. © Published under licence by IOP Publishing Ltd.

Copper Sulfate-Induced Diphenylamine for Rapid Colorimetric Point-of-Care Detection of Contagious Pathogens Combined with Loop-Mediated Isothermal Amplification

Here, we developed a copper sulfate (CuSO4)-initiated diphenylamine (DPA)-based colorimetric strategy coupled with loop-mediated isothermal amplification (LAMP) for rapid detection of two critical contagious pathogens, SARS-CoV-2 and Enterococcus faecium. To detect the DNA, acid hydrolysis of LAMP amplicons was executed, enabling the development of a blue color. In the LAMP amplicons, the bond between the purines and deoxyribose is extremely labile. It can be broken using 70% sulfuric acid followed by phosphate group elimination, which generates a highly active keto aldehyde group. CuSO4 plays an imperative role inducing DPA to rapidly react with the keto aldehyde group, producing an intense blue color within 5 min. Moreover, low quantities such as 103 copies μL-1 of SARS-CoV-2 RNA and 102 CFU mL-1 of E. faecium were successfully detected, revealing the advantages of the introduced method. To confirm practical applicability, multiplex detection of pathogens was performed using a foldable microdevice comprising reaction and detection zones. Various reactions such as DNA extraction, LAMP, and acid hydrolysis occurred in the reaction zone. Then, colorimetric reagents (DPA, CuSO4, and ethylene glycol) contained in the detection zone were mixed with the keto aldehyde group by simply folding the microdevice, which was heated at 65 °C for 5 min for colorimetric detection. An intense blue color was developed where the target DNA was present. These results indicate that the method proposed in this study is highly suitable for point-of-care applications, especially in resource-limited settings for the rapid detection of harmful pathogens. © 2023 American Chemical Society.

Gargle sample is an effective option in a novel fully automated molecular point-of-care test for influenza: a multicenter study.

BACKGROUND: We conducted a multicenter study to evaluate the performance of a novel fully automated molecular point-of-care test using transcription-reverse transcription concerted reaction that can detect influenza A and B within 15 min in nasopharyngeal swabs and gargle samples (TRCsatFLU). METHODS: Patients who visited or were hospitalized at eight clinics and hospitals with influenza-like illnesses between December 2019 and March 2020 participated in this study. We collected nasopharyngeal swabs from all patients and gargle samples from patients whom the physician judged fit to perform gargling. The result of TRCsatFLU was compared to a conventional reverse transcription-polymerase chain reaction (RT-PCR). If the results of TRCsatFLU and conventional RT-PCR were different, the samples were analyzed by sequencing. RESULTS: We evaluated 233 nasopharyngeal swabs and 213 gargle samples from 244 patients. The average age of the patients was 39.3 ± 21.2. Of the patients, 68.9% visited a hospital within 24 h of symptom onset. The most common symptoms were fever (93.0%), fatigue (79.5%), and nasal discharge (64.8%). All patients in whom the gargle sample was not collected were children. Influenza A or B was detected in 98 and 99 patients in nasopharyngeal swabs and gargle samples using TRCsatFLU, respectively. Four and five patients in nasopharyngeal swabs and gargle samples, respectively, with different TRCsatFLU and conventional RT-PCR results. Influenza A or B was detected using sequencing in all samples with different results. Based on the combined conventional RT-PCR and sequencing results, the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of TRCsatFLU for influenza detection in nasopharyngeal swabs were 0.990, 1.000, 1.000, and 0.993, respectively. In the gargle samples, the sensitivity, specificity, PPV, and NPV of the TRCsatFLU for detecting influenza were 0.971, 1.000, 1.000, and 0.974, respectively. CONCLUSIONS: The TRCsatFLU showed great sensitivity and specificity for the detection of influenza in nasopharyngeal swabs and gargle samples. TRIAL REGISTRATION: This study was registered in the UMIN Clinical Trials Registry (reference number: UMIN000038276) on October 11, 2019. Before sample collection, written informed consent for the participation and publication of this study was obtained from all participants.

Rapid detection of mpox virus using recombinase aided amplification assay.

A recent, unprecedented outbreak of human mpox virus infection has led to cases in non-African nations, and the number of confirmed or suspected cases outside of Africa has exceeded 1,000 within 5 weeks. Mpox may pose a double threat to public health in the context of the ongoing COVID-19 pandemic. It is difficult to distinguish mpox virus infection from other diseases in the early stages, and patients are contagious from the onset of nonspecific symptoms; therefore, it is crucial to develop rapid and specific diagnostic methods. The diagnosis of mpox relies on real-time polymerase chain reaction, a time-consuming method that requires a highly sophisticated thermal cycler, which makes it unsuitable for widespread use in underdeveloped areas, where the outbreak is still severe. In this study, we developed a recombinase-aided amplification (RAA) assay that can detect mpox virus within 5-10 minutes. The conserved regions of the A27L gene and F3L gene were selected as targets, as they amplify well from different mpox virus clades with no cross-reaction from other pathogens. The sensitivity of this RAA assay is 10 copies/reaction for the A27L gene and 102 copies/reaction for the F3L gene. When applied to simulated clinical samples, both targets showed 100% specificity, and the detection limits were consistent with the sensitivity results. Moreover, through clinical blinded sample detection, RAA exhibits the same detection power as RT-PCR. In summary, the RAA mpox assay described here exhibits rapid detection, high sensitivity and specificity, and low operational difficulty, making it suitable for mpox virus detection in less developed countries and regions.

Insight of smart biosensors for COVID-19: A review.

The review discusses the diagnostic application of biosensors as point-of-care devices in the COVID-19 pandemic. Biosensors are important analytical tools that can be used for the robust and effective detection of infectious diseases in real-time. In this current scenario, the utilization of smart, efficient biosensors for COVID-19 detection is increasing and we have included a few smart biosensors such as smart and intelligent based biosensors, plasmonic biosensors, field effect transistor (FET) biosensors, smart optical biosensors, surface enhanced Raman scattering (SERS) biosensor, screen printed electrode (SPE)-based biosensor, molecular imprinted polymer (MIP)-based biosensor, MXene-based biosensor and metal-organic frame smart sensor. Their significance as well as the benefits and drawbacks of each kind of smart sensor are mentioned in depth. Furthermore, we have compiled a list of various biosensors which have been developed across the globe for COVID-19 and have shown promise as commercial detection devices. Significant challenges in the development of effective diagnostic methods are discussed and recommendations have been made for better diagnostic outcomes to manage the ongoing pandemic effectively.

Isothermal nucleic acid amplification technology for rapid detection of virus.

While the research field and industrial market of in vitro diagnosis (IVD) thrived during and post the COVID-19 pandemic, the development of isothermal nucleic acid amplification test (INAAT) based rapid diagnosis was engendered in a global wised large measure as a problem-solving exercise. This review systematically analyzed the recent advances of INAAT strategies with practical case for the real-world scenario virus detection applications. With the qualities that make INAAT systems useful for making diagnosis relevant decisions, the key performance indicators and the cost-effectiveness of enzyme-assisted methods and enzyme-free methods were compared. The modularity of nucleic acid amplification reactions that can lead to thresholding signal amplifications using INAAT reagents and their methodology design were examined, alongside the potential application with rapid test platform/device integration. Given that clinical practitioners are, by and large, unaware of many the isothermal nucleic acid test advances. This review could bridge the arcane research field of different INAAT systems and signal output modalities with end-users in clinic when choosing suitable test kits and/or methods for rapid virus detection.

Rapid and Easy-Read Porcine Circovirus Type 4 Detection with CRISPR-Cas13a-Based Lateral Flow Strip.

First identified as a new circovirus in Hunan Province in China in 2019, porcine circovirus (PCV4) is now widely detected in other Chinese provinces and South Korea. In recent years, the virus has threatened pig health and operations in the pig industry. Hence, early PCV4 detection and regular surveillance are required to control the spread of infection and prevent collateral damage to the industry. Due to PCV4 being difficult to isolate in vitro, molecular detection methods, such as conventional PCR and real-time PCR, and serological assays are currently the main methods used for the detection of PCV4 infection. However, they are time-consuming, labor-intensive, and complex and require professional personnel. To facilitate rapid pen-side PCV4 diagnoses, we used clustered regularly interspaced short palindromic repeats (CRISPR) and Cas13a technology to develop a quick testing kit. Five recombinase-aided amplification (RPA) primer sets were designed based on the conserved PCV4-Cap gene nucleotide region, which were used to determine several key lateral flow strip (LFD) characteristics (sensitivity, specificity, and accuracy). The results showed that the RPA-Cas13a-LFD reaction could detect PCV4 within 1.5 h in genomic DNA harboring a minimum of a single copy. Furthermore, the assay showed good specificity and absence of cross-reactivity with PCV2, PCV3, or other porcine viruses. When we tested 15 clinical samples, a high accuracy was also recorded. Therefore, we successfully developed a detection assay that was simple, fast, accurate, and suitable for on-site PCV4 testing.

Electronic Sensors to Detect SARS-CoV-2 Viruses in Real Time

Sensors with 60 nm gap junctions coated with aptamers that bind with S1 and S2 spiking proteins of the SARS-CoV-2 virus were developed. Sensor impedance changes with virus enabling rapid (∼1 min), point-of-care detection. Exosomes and other nanoparticles in the saliva produce false positive signals but do not bind with aptamers and are easily removed to achieve 6% false positivity rates. A positive sensor voltage is used to attract negatively charged SARS-CoV-2 viruses to the junction and reduce sensor false negativity rates to below 7%. The limit of detection of the sensor is 1000 viruses and can be altered by changing the sensor's lateral dimensions and its transduction noise level. © 2001-2012 IEEE.