Scientists have recently developed electrochemical immunosensors based on graphene oxide−gold (GO−Au) nanocomposites. These immunosensors are highly sensitive with dual function, i.e., they can detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigen and antibody. This study is available in the journal ACS Applied Bio Materials.
Impact of Global Outbreak of Diseases
In the last century, the world has witnessed several global outbreaks that include influenza, severe acute respiratory syndrome coronavirus (SARS-CoV), middle east respiratory syndrome coronavirus (MERS), and most recently, SARS-CoV-2. The ongoing coronavirus disease 2019 (COVID-19) pandemic, caused by SARS-CoV-2, has drastically impacted the global healthcare system and economy. To date, this virus has claimed more than 6.2 million lives and infected around 517 million individuals worldwide.
Scientists worldwide have worked extensively to develop effective preventive measures and sensitive diagnostic tools for fast and accurate detection of the SARS-CoV-2 virus. Early detection of the disease would help prevent further transmission of the virus in the community.
Diagnostic Tools for SARS-CoV-2
Although reverse transcriptase-polymerase chain reaction (RT-PCR) can accurately detect the SARS-CoV-2 virus by identifying viral genomic RNA, it requires expensive setups and highly skilled personnel for its operation. Scientists have stated serological-based methods, e.g., enzyme-linked immunosorbent assay (ELISA), for the detection of SARS-CoV-2 antibodies, are mind-numbing and time-consuming, which restricts their usage for mass testing for COVID-19 antibodies.
Previous studies have reported the development of biosensors, based on field-effect transistor (FET), electrochemical, and fluorescence, to detect COVID-19 disease. Electrochemical biosensors could be extremely advantageous over other biosensors because of their high sensitivity, accuracy, easy operation, and rapid detection processes. Scientists have stated that there is a need to develop superior electrochemical biosensors with greater transducing capabilities, applicability, and high active surface area.
Previous studies have shown that several nanomaterials and nanocomposites, for example, gold nanoparticles (AuNPs), graphene oxide (GO), and reduced graphene oxide (RGO), are promising constituents for novel electrochemical biosensors.
Development of Highly Sensitive Electrochemical Immunosensor for SARS-CoV-2: A New Study
Scientists have synthesized GO−Au nanocomposites to fabricate two immunosensors used to detect SARS-CoV-2 antigen and antibody. The newly developed GO−Au nanocomposites possess high conductivity, a large surface to area ratio, and several functional groups for their binding with biomolecules.
The authors have characterized the newly synthesized nanocomposites using UV−Vis spectroscopy, transmission electron microscopy (TEM), and X-ray diffraction (XRD). The average particle size of the AuNPs in the nanocomposite was measured to be 12.1 nm. UV-Vis analysis revealed the presence of characteristic peaks of GO (265 nm) and Au (538 nm) in the synthesized GO-Au nanocomposite. Interestingly, XRD analysis showed a peak at 26.4°, which implied a partial reduction of GO in the nanocomposite. TEM image indicated a uniform dispersion of AuNPs in the nanocomposite as well as its polycrystalline nature.
The electrochemical activity of GO-Au nanocomposite and fabricated immunosensors were analyzed through differential pulse voltammetry (DPV), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) techniques. Scientists performed all electrochemical measurements in redox electrolytes.
CV helped determine SARS-CoV-2 antibody−antigen interaction on electrode surfaces. Both CV and DPV results revealed effective fabrication of the SARS-CoV-2 antibody immunosensor.
In this study, researchers reported that the SARS-CoV-2 antigen immunosensor exhibited excellent sensitivity with a linear detection range between 10.0 ag mL–1 and 50.0 ng mL–1. They further estimated the detection range of antibody immunosensor to be between 1.0 fg mL–1 and 1.0 ng mL–1. For the SARS-CoV-2 antibody immunosensor, the limit of detection (LOD) was measured to be 1 fg mL−1. Similarly, the LOD of the SARS-CoV-2 antigen immunosensor was estimated to be 3.99 ag mL−1.
Synthetic samples were used initially to analyze both the immunosensors and the results were later validated using serum and nasopharyngeal swab samples of COVID-19 patients. They obtained samples from nine different COVID-19 patients to validate their findings. Both DPV analysis and voltammetric characterization showed that the SARS-CoV-2 antibody immunosensor and SARS-CoV-2 antigen immunosensor could be effectively utilized to study clinical samples.
To further determine the sensitivity of the immunosensors, scientists used nasopharyngeal samples of seven different patients (four SARS-CoV-2 negatives and three positives). The results obtained in this study were consistent with the RT-PCR test.
Conclusion
In this study, the authors developed electrochemical immunosensor platforms based on newly developed GO−Au nanocomposites. These immunosensors have a dual function, i.e., detection of both SARS-CoV-2 antibodies as well as antigen. In the future, these immunosensors could be used to develop portable point of contact (POC) devices for accurate detection of the SARS-CoV-2 virus.
News
Emission of Fe- and Ti-Containing Nanoparticles from Coal-Fired Power Plants
In an article published in the journal Science of the Total Environment, researchers have highlighted the significance and potential risks associated with the release of nanoparticles from coal-fired power plants. Applying the single-particle inductively coupled plasma mass [...]
Covalent Organic Framework Nanofluidic Hybrid Membrane for Osmotic Energy Generation
A paper recently published in the journal ACS Applied Energy Materials demonstrated the feasibility of using a covalent organic framework (COF)-based nanofluidic hybrid membranes (NHMs) to attain enhanced interfacial ion transport for the generation of osmotic [...]
Degradable Nanocomposite Removes Antibiotics from Contaminated Water
The excess fluoroquinolones (FQs) discharged into the aquatic environment due to human activities must be removed cost-effectively. In an article published in the Journal of Cleaner Production, the authors fabricated an environment-friendly dealkaline lignin-grafted Fe3O4 nanoparticles [...]
Light-controlled reactions at the nanoscale
Controlling strong electromagnetic fields on nanoparticles is the key to triggering targeted molecular reactions on their surfaces. Such control over strong fields is achieved via laser light. Although laser-induced formation and breaking of molecular [...]
Bright Future for Nanophotonic Chips with Topological Rainbow Device
A paper recently published in the journal Nature Communications demonstrated an effective method to realize on-chip nanophotonic topological rainbow devices using the concept of synthetic dimensions. Importance of Synthetic Dimensions for the Construction of Topological Nanophotonics [...]
Green Approach to Silver Nanoparticle Fabrication with Citrus Fruits
In a study available in the journal Materials Today: Proceedings, silver nanoparticles (Ag NPs) were fabricated using a green method using Citrus X sinensis. Methylthioninium Chloride (MB) Dyes Threatening the Environment Dye and sewage drainage into [...]
Coronavirus ‘ghosts’ found lingering in the gut
Scientists are studying whether long COVID could be linked to viral fragments found in the body months after initial infection. In the chaos of the first months of the coronavirus pandemic, oncologist and geneticist [...]
Experts perplexed over number of people getting long COVID
Public health experts are divided over how many people are getting long COVID-19, a potentially debilitating condition that comes after a patient has recovered from the coronavirus. Ill effects from the condition can include [...]
Four strange COVID symptoms you might not have heard about
Well over two years into the pandemic, hundreds of thousands of COVID cases continue to be recorded around the world every day. With the rise of new variants, the symptoms of COVID have also evolved. Initially, [...]
A new method for exploring the nano-world
Nanoparticles are everywhere. They are in our body as protein aggregates, lipid vesicles, or viruses. They are in our drinking water in the form of impurities. They are in the air we breath as [...]
Breast Cancer Drug Resistance Tackled By Polymer Nanoparticles
Drug resistance is a common phenomenon, with drugs becoming less and less effective as their usage increases. To address this issue, a novel technique employing conjugated polymer-based nanoparticles is presented in the study published [...]
New imaging method makes microrobots visible in the body
Microrobots have the potential to revolutionize medicine. Researchers at the Max Planck ETH Centre for Learning Systems have now developed an imaging technique that for the first time recognises cell-sized microrobots individually and at [...]
Multifunctional Nanocrystals Enhance Cancer Cell Killing Therapies
Scientists have recently developed multifunctional hexagonal NaxWO3 nanocrystals that can serve as microwave sensitizers to kill cancer cells as well as improve the overall chemodynamic therapy (CDT). This study is available as a pre-proof in Chemical Engineering Journal. [...]
Biotech, nanomedicine, and AI combine for health breakthrough predicted by Apple genius Steve Jobs
Apple’s visionary founder, the late Steve Jobs once said, “the biggest innovations of the 21st century will be at the intersection of biology and technology”. And that prediction is coming true in the drug [...]
Making chemical separation more eco-friendly with nanotechnology
Chemical separation processes are essential in the manufacturing of many products from gasoline to whiskey. Such processes are energetically costly, accounting for approximately 10–15 percent of global energy consumption. In particular, the use of [...]
Dual Function SARS-CoV-2 Sensor for Point of Contact Testing
Scientists have recently developed electrochemical immunosensors based on graphene oxide−gold (GO−Au) nanocomposites. These immunosensors are highly sensitive with dual function, i.e., they can detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigen and antibody. [...]
