One-step rapid quantification of SARS-CoV-2 virus particles via low-cost nanoplasmonic sensors in generic microplate reader and point-of-care device.

Optical biosensors based on refractometric sensing schemes: A review.

The global sanitary crisis caused by the emergence of the respiratory virus SARS-CoV-2 and the COVID-19 outbreak has revealed the urgent need for rapid, accurate, and affordable diagnostic tests to broadly and massively monitor the population in order to properly manage and control the spread of the pandemic. Current diagnostic techniques essentially rely on polymerase chain reaction (PCR) tests, which provide the required sensitivity and specificity. However, its relatively long time-to-result, including sample transport to a specialized laboratory, delays massive detection. Rapid lateral flow tests (both antigen and serological tests) are a remarkable alternative for rapid point-of-care diagnostics, but they exhibit critical limitations as they do not always achieve the required sensitivity for reliable diagnostics and surveillance. Next-generation diagnostic tools capable of overcoming all the above limitations are in demand, and optical biosensors are an excellent option to surpass such critical issues. Label-free nanophotonic biosensors offer high sensitivity and operational robustness with an enormous potential for integration in compact autonomous devices to be delivered out-of-the-lab at the point-of-care (POC). Taking the current COVID-19 pandemic as a critical case scenario, we provide an overview of the diagnostic techniques for respiratory viruses and analyze how nanophotonic biosensors can contribute to improving such diagnostics. We review the ongoing published work using this biosensor technology for intact virus detection, nucleic acid detection or serological tests, and the key factors for bringing nanophotonic POC biosensors to accurate and effective COVID-19 diagnosis on the short term.

/pdf/how-nanophotonic-label-free-biosensors-can-contribute-to-2j9g4xhos7.pdf

How Nanophotonic Label-Free Biosensors Can Contribute to Rapid and Massive Diagnostics of Respiratory Virus Infections: COVID-19 Case.

The recent events of outbreaks related to different respiratory viruses in the past few years, exponentiated by the pandemic caused by the coronavirus disease 2019 (COVID-19), reported worldwide caused by SARS-CoV-2, raised a concern and increased the search for more information on viruses-based diseases. The detection of the virus with high specificity and sensitivity plays an important role for an accurate diagnosis. Despite the many efforts to identify the SARS-CoV-2, the diagnosis still relays on expensive and time-consuming analysis. A fast and reliable alternative is the use of low-cost biosensor for in loco detection. This review gathers important contributions in the biosensor area regarding the most current respiratory viruses, presents the advances in the assembly of the devices and figures of merit. All information is useful for further biosensor development for the detection of respiratory viruses, such as for the new coronavirus.

Biosensors for the detection of respiratory viruses: a review

Biosensors are measurement devices that can sense several biomolecules, and are widely used for the detection of relevant clinical pathogens such as bacteria and viruses, showing outstanding results. Because of the latent existing risk of facing another pandemic like the one we are living through due to COVID-19, researchers are constantly looking forward to developing new technologies for diagnosis and treatment of infections caused by different bacteria and viruses. Regarding that, nanotechnology has improved biosensors' design and performance through the development of materials and nanoparticles that enhance their affinity, selectivity, and efficacy in detecting these pathogens, such as employing nanoparticles, graphene quantum dots, and electrospun nanofibers. Therefore, this work aims to present a comprehensive review that exposes how biosensors work in terms of bacterial and viral detection, and the nanotechnological features that are contributing to achieving a faster yet still efficient COVID-19 diagnosis at the point-of-care.

https://www.mdpi.com/1424-8220/20/23/6926/pdf

Biosensors for the Detection of Bacterial and Viral Clinical Pathogens.

In 2013 a new reassortant avian influenza A H7N9 virus emerged in China, causing human infection with high mortality. An accurate and timely diagnosis is crucial for controlling the outbreaks of the disease. We therefore propose a simple strategy for rapidly and sensitively detecting the H7N9 virus using an intensity-modulated surface plasmon resonance (IM-SPR) biosensor integrated with a new generated monoclonal antibody. The novel antibody exhibits significant specificity to recognize H7N9 virus compared with other clinical human influenza isolates (p < 0.01). Experimentally, the detection limit of the proposed approach for H7N9 virus detection is estimated to be 144 copies/mL, which is a 20-fold increase in sensitivity compared with homemade target-captured ELISA using the identical antibody. For the measurement of mimic clinical specimens containing the H7N9 virus mixed with nasal mucosa from flu-like syndrome patients, the detection limit is calculated to be 402 copies/mL, which is better than conven...

Simple Strategy for Rapid and Sensitive Detection of Avian Influenza A H7N9 Virus Based on Intensity-Modulated SPR Biosensor and New Generated Antibody

Human immunodeficiency virus type 1 (HIV-1) has developed many unique strategies to evade the immune system, one of which is via cell-to-cell transfer through a virological synapse (VS). Cell-to-cell transmission results in more efficient virus transmission than infection with cell-free virions. Cell-to-cell transmission occurs at the VS, where a tight cleft forms between HIV-1-infected cells (effectors) and receptor-expressing (target) cells. Upon VS formation, viral budding polarizes toward target cells; the budding virus, viral RNA, and virus-related proteins are likely transmitted to target cells via this cleft. Furthermore, the movement of HIV-1 across an adhesive junction might help to protect the virus from attack by humoral factors, such as antibodies or complements. Therefore, cell-to-cell transfer is considered to be the predominant mechanism of viral spread during infection.1

Recent reports have shown that cell-to-cell spread of HIV-1 between T cells is more efficient than the equivalent cell-free infection.1,2 Normally, T cells are not inherently polarized and do not display front–rear polarity in the absence of stimulation. However, T cells can adapt and show front–rear polarity during stimulation, including cell–cell contact with antigen-presenting cells at the immunological synapse (IS), T cell migration, and chemokine or cytokine stimulation. IS formation triggers cytoplasmic and membrane remodeling within the T cell and recruits organelles, such as the secretory apparatus, signaling machinery, and mitochondria, to the contact region.

Mitochondria has been reported to play an important role in the formation of IS by promoting sustained calcium influx to support synaptic signaling.3 VS formation shares many similarities with the IS.2 Mitochondria have long been known to be essential organelles that provide metabolic energy. They are involved in many physical functions and regulations including cellular signaling pathways, apoptosis, autophagy, and innate immunity.3 There is limited information regarding the role of mitochondria in VS.

To address this question, we used transmission electron microscopy (TEM) to observe the location of mitochondria during HIV-1 VS formation using HIV-1-infected Jurkat T cells cocultured with uninfected Jurkat T cells. Our results illustrated in Fig. 1 showed that mitochondria were polarized and were engaged primarily in the contact regions of the HIV-1-infected T cells (effectors) during cell-to-cell contact. Recently, Groppelli et al. also indicated that polarization of mitochondria supports HIV-1 VS formation.2 Lee-Huang and Huang used live-cell real-time imaging to observe mitochondria in HIV-1-infected cells.4



FIG. 1.

Cell-to-cell contact between HIV-1-infected (the lower cell) and HIV-uninfected (the upper cell) Jurkat T cells under transmission electron microscopy (TEM).



We therefore suggest that mitochondria are important for VS formation and supply energy for cell-to-cell transmission of HIV-1. At present, the detailed mechanism of VS formation and cell-to-cell transmission is still not fully understood. These findings provide further insight into intercellular interactions and organelle localization during HIV-1 VS formation.

Yi Wei Hong

Papers

Simple Strategy for Rapid and Sensitive Detection of Avian Influenza A H7N9 Virus Based on Intensity-Modulated SPR Biosensor and New Generated Antibody

Mitochondria polarization in the contact regions of virus-infected effector cells during cell-to-cell transmission of HIV-1.