Internet-of-medical-things integrated point-of-care biosensing devices for infectious diseases: Toward better preparedness for futuristic pandemics.

Microbial pathogens have threatened the world due to their pathogenicity and ability to spread in communities. The conventional laboratory-based diagnostics of microbes such as bacteria and viruses need bulky expensive experimental instruments and skilled personnel which limits their usage in resource-limited settings. The biosensors-based point-of-care (POC) diagnostics have shown huge potential to detect microbial pathogens in a faster, cost-effective, and user-friendly manner. The use of various transducers such as electrochemical and optical along with microfluidic integrated biosensors further enhances the sensitivity and selectivity of detection. Additionally, microfluidic-based biosensors offer the advantages of multiplexed detection of analyte and the ability to deal with nanoliters volume of fluid in an integrated portable platform. In the present review, we discussed the design and fabrication of POCT devices for the detection of microbial pathogens which include bacteria, viruses, fungi, and parasites. The electrochemical techniques and current advances in this field in terms of integrated electrochemical platforms that include mainly microfluidic- based approaches and smartphone and Internet-of-things (IoT) and Internet-of-Medical-Things (IoMT) integrated systems have been highlighted. Further, the availability of commercial biosensors for the detection of microbial pathogens will be briefed. In the end, the challenges while fabrication of POC biosensors and expected future advances in the field of biosensing have been discussed. The integrated biosensor-based platforms with the IoT/IoMT usually collect the data to track the community spread of infectious diseases which would be beneficial in terms of better preparedness for current and futuristic pandemics and is expected to prevent social and economic losses.

Polydopamine decorated MoS2 nanosheet based electrochemical immunosensor for sensitive detection of SARS-CoV-2 nucleocapsid protein in clinical samples.

The outbreak of the highly contagious disease COVID-19, which is triggered by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), demands a rapid, low-cost, and highly sensitive immunosensor that can detect and identify the virus efficiently. Here, an electrochemical immunosensor based on a nanocomposite consisting of molybdenum disulfide nanosheets decorated with polydopamine (MoS2-PDA) is developed for highly sensitive detection of SARS-CoV-2 nucleocapsid protein (N protein). The MoS2-PDA nanocomposite possesses various hydroxyl and amine groups that have excellent chemistry with crosslinkers and act as adhesive agents to bind with the working electrode surface. Furthermore, the optical, functional, structural, vibrational, and morphological properties of the MoS2-PDA nanocomposite are studied using various characterization techniques such as UV-vis, FTIR, and Raman spectroscopies, XRD, and TEM. The electrochemical immunosensor is fabricated by functionalizing the MoS2-PDA nanocomposite with anti-SARS-CoV-2 nucleocapsid IgG antibody (Ab) and has a very high sensitivity against the N protein with a linear range between 10 ag mL-1 and 100 ng mL-1. The electrochemical immunosensor exhibits a lowest limit of detection (LOD) of 2.80 ag mL-1 and a limit of quantification (LOQ) of 8.48 ag mL-1via electrochemical impedance spectroscopy (EIS). Furthermore, the electrochemical immunosensor is successfully employed to detect the N protein in nasopharyngeal swab specimens and displays good consistency with the conventional RT-PCR test results. The results show that the MoS2-PDA nanocomposite-based electrochemical platform can serve as a highly sensitive and selective detector of N protein and will pave the way for the development of a point-of-care (POC) electrochemical immunosensor for rapid detection of other infectious viruses.

SERS Based Lateral Flow Immunoassay for Point-of-Care Detection of SARS-CoV-2 in Clinical Samples.

The current scenario, an ongoing pandemic of COVID-19, places a dreadful burden on the healthcare system worldwide. Subsequently, there is a need for a rapid, user-friendly, and inexpensive on-site monitoring system for diagnosis. The early and rapid diagnosis of SARS-CoV-2 plays an important role in combating the outbreak. Although conventional methods such as PCR, RT-PCR, and ELISA, etc., offer a gold-standard solution to manage the pandemic, they cannot be implemented as a point-of-care (POC) testing arrangement. Moreover, surface-enhanced Raman spectroscopy (SERS) having a high enhancement factor provides quantitative results with high specificity, sensitivity, and multiplex detection ability but lacks in POC setup. In contrast, POC devices such as lateral flow immunoassay (LFIA) offer rapid, simple-to-use, cost-effective, reliable platform. However, LFIA has limitations in quantitative and sensitive analyses of SARS-CoV-2 detection. To resolve these concerns, herein we discuss a unique modality that is an integration of SERS with LFIA for quantitative analyses of SARS-CoV-2. The miniaturization ability of SERS-based devices makes them promising in biosensor application and has the potential to make a better alternative of conventional diagnostic methods. This review also demonstrates the commercially available and FDA/ICMR approved LFIA kits for on-site diagnosis of SARS-CoV-2.

Point-of-Care Biosensor-Based Diagnosis of COVID-19 Holds Promise to Combat Current and Future Pandemics.

Efficient and rapid detection of viruses plays an extremely important role in disease prevention, diagnosis, and environmental monitoring. Early screening of viral infection among the population has the potential to combat the spread of infection. However, the traditional methods of virus detection being used currently, such as plate culturing and quantitative RT-PCR, give promising results, but they are time-consuming and require expert analysis and costly equipment and reagents; therefore, they are not affordable by people in low socio-economic groups in developing countries. Further, mass or bulk testing chosen by many governments to tackle the pandemic situation has led to severe shortages of testing kits and reagents and hence are affecting the demand and supply chain drastically. We tried to include all the reported current scenario-based biosensors such as electrochemical, optical, and microfluidics, which have the potential to replace mainstream diagnostic methods and therefore could pave the way to combat COVID-19. Apart from this, we have also provided information on commercially available biosensors for detection of SARS-CoV-2 along with the challenges in development of better diagnostic approaches. It is therefore expected that the content of this review will help researchers to design and develop more sensitive advanced commercial biosensor devices for early diagnosis of viral infection, which can open up avenues for better and more specific therapeutic outcomes.