Early detection of the SARS-CoV-2 virus (COVID-19) is critical to stopping the spread of this contagious disease. The current diagnostic methods for COVID-19 are expensive and difficult to handle. Hence, there is a need for a quick, efficient, and user-friendly detection method.
In an article recently published in Analytica Chimica Acta, the authors fabricated a rapid and efficient nanobody-based label-free photoelectrochemical (PEC) immunosensor to detect the severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) spike protein (SP)
COVID-19 Diagnostic Methods
COVID-19, caused by the SARS-CoV-2 virus, has an enveloped structure with single-stranded ribonucleic acid (ss-RNA) as its genetic material. Currently used tests to detect COVID-19, such as reverse transcription-polymerase chain reaction (RT-PCR) and computed tomography (CT) scans are expensive and time-consuming, while the immunoassay is a cost-effective and facile method. In COVID-19 patients, the highly expressed angiotensin-converting enzyme 2 (ACE2) binds to the SP on the envelope of SARS-CoV-2 and causes infection.
Immunoassay is a biochemical method used for the qualitative and quantitative determination of biomarkers specific to antigen-antibody immunoreaction. However, in the label-free immunoassay method, the results are determined by the steric hindrance effect caused by antigen-antibody immunoreaction, which hinders the photoinduced charge diffusion to the conductive matrix, thus reducing the photoelectric current. PEC immunosensor is highly sensitive, rapid, and selective in detecting COVID-19.
Niobium (Nb) can couple with a PEC immunosensor of higher density and raise a better signal-to-noise ratio than a conventional antibody. This coupling reduces the limit of detection (LOD) and increases sensitivity for antigen realization.
Novel PEC Immunoassay for COVID-19 Diagnosis
In the present study, the authors fabricated a label-free detection, Nb-based PEC immunoassay for detecting SARS-CoV-2 SP. The nanobody was immobilized based on the advantage of the surface plasma resonance (SPR) effect of gold (Au) nanoparticles and the excellent photoelectric performance of Au-deposited titanium oxide (Au@TiO2). This nanobody anchored to Nb through conjugates results in the Nb/Au@TiO2 nanoplatform. The authors have realized the goal of enhancing SP sensitivity through the Nb-based PEC immunoassay. The fabricated immunoassay platform could detect the virus even in 0.015 to 15000 picogram per milliliter concentrations.
Nb-Based PEC Immunoassay
X-Ray diffraction studies (XRD) revealed the anatase phase of TiO2. The XRD spectral peaks of Au@TiO2 showed that deposition of Au did not affect TiO2 phase behavior. Furthermore, the peaks at 38.2, 44.4, 64.6, and 77.6 degrees confirmed the successful deposition of Au on TiO2 spheres. Scanning electron microscope (SEM) images of Au@TiO2 revealed different sized spheres and stacked nanoparticles, and diffuse reflectance spectroscopy (DRS) showed strong absorbance of Au@TiO2 in a redshift of approximately 18 nanometers.
The deposition of Au on TiO2 enhanced the solar energy utilization capability. PEC measurements prove that the presence of Au restrains the recombination of carriers from bulk and surface of TiO2.
Au@TiO2 helped enhance PEC performance, predicted based on DRS characterization and PEC measurements and thus can be used to construct a label-free PEC immunosensor. Based on Nb of the SP as a recognition site, Nb was immobilized on Au@TiO2 electrode forming Nb-Au conjugates.
The construction of Nb-based PEC immunoassay used Au@TiO2 nanomaterial as base and Nb as a recognition site for SP detection with high sensitivity. The immunoreaction between SP with Nb is because of the steric hindrance effect.
The analytical performance of Au@TiO2-based PEC immunoassay for its sensitivity towards SP was predicted by conducting optimization experiments. The results showed that photocurrent response did not correlate to Au@TiO2 dispersion. However, with increased suspension concentration, SP/Bovine serum albumin (BSA)/Nb/Au@TiO2/indium tin oxide (ITO) showed a gradual increase in photocurrent. Further, a too high suspension concentration showed a decreasing trend in photoelectric current due to the recombination of Au@TiO2 nanomaterial.
The achievement of sensitive SARS-CoV-2 SP detection by Au@TiO2-based label-free PEC immunosensor involved three steps: Firstly, introducing Au and its SPR effect boosted the efficiency of photoinduced electron transmission, which led to the superior photoelectric conversion efficiency of the nanoplatform. Secondly, the disulfide bond between Nb and Au facilitated the immobilization of Nb-Au nanoparticle conjugates. Thirdly, Nb has a high affinity toward the SP, which triggers an immunoreaction resulting in immunocomplex formation on the sensing interface.
Conclusion
In this study, a label-free PEC immunoassay was developed using the Nb/Au@TiO2 nanomaterial for SARS-CoV-2 SP identification.
The deposition of Au on TiO2 led to the Au@TiO2 nanomaterial with enhanced properties, where the SPR effect of Au boosts the photoinduced electron transmission and visible light-harvesting, resulting in an enhanced photoelectric signal than sole TiO2. This nanobody-based immunosensor paves a new way for facile and rapid PEC immunoassay for COVID-19 diagnosis.
News
Common Medication Could Save Half a Million Lives Each Year – So Why Isn’t It?
A recent study conducted by scientists at the University of Southern California sheds light on the reasons why children are not receiving an affordable and effective diarrhea treatment. Medical professionals in developing nations are [...]
X Marks the Spot: AI’s Treasure Maps Lead to Early Disease Detection
Medical diagnostics expert, doctor’s assistant, and cartographer are all fair titles for an artificial intelligence model developed by researchers at the Beckman Institute for Advanced Science and Technology. Their new model accurately identifies tumors [...]
Scientists Discover Method To Identify Alzheimer’s Disease Before It Progresses to Dementia
Researchers at Aarhus University have discovered a method to identify Alzheimer’s disease before it progresses to dementia, potentially opening up new avenues for treatment. A groundbreaking study could pave the way for early detection [...]
Startling Discovery: COVID-19 Virus Can Stay in the Body More Than a Year After Infection
The COVID-19 virus can persist in the blood and tissue of patients for more than a year after the acute phase of the illness has ended, according to new research from UC San Francisco that offers potential [...]
New bioengineered protein design shows promise in fighting COVID-19
In the wake of the COVID-19 pandemic, scientists have been racing to develop effective treatments and preventatives against the virus. A recent scientific breakthrough has emerged from the work of researchers aiming to combat [...]
Sugar-coated gold nanoparticles can quickly eliminate bacterial infections, no antibiotics required
If left to their own devices, bacteria on our teeth or wounded skin can encase themselves in a slimy scaffolding, turning into what is called biofilm. These bacteria wreak havoc on our tissue and, [...]
Liquid Lightning: Nanotechnology Unlocks New Energy
EPFL researchers have discovered that nanoscale devices harnessing the hydroelectric effect can harvest electricity from the evaporation of fluids with higher ion concentrations than purified water, revealing a vast untapped energy potential. Evaporation is a natural [...]
Unmasking the Illusion: AI-Generated Faces Challenge Perceptions
Research shows survey participants duped by AI-generated images nearly 40 percent of the time. If you recently had trouble figuring out if an image of a person is real or generated through artificial intelligence [...]
New Discovery Reveals How Cells Defend Themselves During Stressful Situations
Stress granules play a crucial role in the stress response, arising from the aggregation of non-translating mRNAs and proteins. Although significant knowledge exists about stress granules, the mechanisms behind their mRNA localization remain partially [...]
Scientists use a new type of nanoparticle that can both deliver vaccines and act as an adjuvant
Many vaccines, including vaccines for hepatitis B and whooping cough, consist of fragments of viral or bacterial proteins. These vaccines often include other molecules called adjuvants, which help to boost the immune system's response [...]
Not Science Fiction: How Optical Neural Networks Are Revolutionizing AI
A novel architecture for optical neural networks utilizes wavefront shaping to precisely manipulate the travel of ultrashort pulses through multimode fibers, enabling nonlinear optical computation. Present-day artificial intelligence systems rely on billions of adjustable [...]
Turning skin cells into limb cells sets the stage for regenerative therapy
In a collaborative study, researchers from Kyushu University and Harvard Medical School have identified proteins that can turn or “reprogram” fibroblasts — the most commonly found cells in skin and connective tissue — into [...]
AI reveals prostate cancer is not just one disease
Artificial Intelligence has helped scientists reveal a new form of aggressive prostate cancer, which could revolutionise how the disease is diagnosed and treated in the future. A Cancer Research UK-funded study, published in Cell Genomics, has revealed [...]
New Study Finds That Persistent COVID-19 Infections Are Surprisingly Common
Recent research conducted by the University of Oxford has found that a high proportion of SARS-CoV-2 infections in the general population lead to persistent infections lasting a month or more. The findings have been published in the journal Nature. [...]
Innovative nanosheet method revolutionizes brain imaging for multi-scale and long-term studies
The human brain has billions of neurons. Working together, they enable higher-order brain functions such as cognition and complex behaviors. To study these higher-order brain functions, it is important to understand how neural activity [...]
Scientists Have Discovered a Potential Universal Antivenom
Scientists at Scripps Research identified antibodies that protect against a host of lethal snake venoms. Scripps Research scientists have developed an antibody that can block the effects of lethal toxins in the venoms of [...]