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1.
Int J Mol Sci ; 22(19)2021 Oct 01.
Article in English | MEDLINE | ID: covidwho-1463707

ABSTRACT

The electron density of a nanoparticle is a very important characteristic of the properties of a material. This paper describes the formation of silver nanoparticles (NPs) and the variation in the electronic state of an NP's surface upon the reduction in Ag+ ions with oxalate ions, induced by UV irradiation. The calculations were based on optical spectrophotometry data. The NPs were characterized using Transmission electron microscopy and Dynamic light scattering. As ~10 nm nanoparticles are formed, the localized surface plasmon resonance (LSPR) band increases in intensity, decreases in width, and shifts to the UV region from 402 to 383 nm. The interband transitions (IBT) band (≤250 nm) increases in intensity, with the band shape and position remaining unchanged. The change in the shape and position of the LSPR band of silver nanoparticles in the course of their formation is attributable to an increasing concentration of free electrons in the particles as a result of a reduction in Ag+ ions on the surface and electron injection by CO2- radicals. The ζ-potential of colloids increases with an increase in electron density in silver nuclei. A quantitative relationship between this shift and electron density on the surface was derived on the basis of the Mie-Drude theory. The observed blue shift (19 nm) corresponds to an approximately 10% increase in the concentration of electrons in silver nanoparticles.


Subject(s)
Electricity , Electrons , Metal Nanoparticles/chemistry , Silver/chemistry , Solutions/chemistry , Chemical Phenomena , Electrochemistry , Metal Nanoparticles/ultrastructure , Microscopy, Electron, Transmission , Models, Theoretical , Particle Size , Surface Plasmon Resonance
2.
Biosens Bioelectron ; 171: 112753, 2021 Jan 01.
Article in English | MEDLINE | ID: covidwho-885210

ABSTRACT

A polyethyleneimine (PEI)-assisted copper in-situ growth (CISG) strategy was proposed as a controlled signal amplification strategy to enhance the sensitivity of gold nanoparticle-based lateral flow sensors (AuNP-LFS). The controlled signal amplification is achieved by introducing PEI as a structure-directing agent to regulate the thermodynamics of anisotropic Cu nanoshell growth on the AuNP surface, thus controlling shape and size of the resultant AuNP@Cu core-shell nanostructures and confining free reduction and self-nucleation of Cu2+ for improved reproducibility and decreased false positives. The PEI-CISG-enhanced AuNP-LFS showed ultrahigh sensitivities with the detection limits of 50 fg mL-1 for HIV-1 capsid p24 antigen and 6 CFU mL-1 for Escherichia coli O157:H7. We further demonstrated its clinical diagnostic efficacy by configuring PEI-CISG into a commercial AuNP-LFS detection kit for SARS-CoV-2 antibody detection. Altogether, this work provides a reliable signal amplification platform to dramatically enhance the sensitivity of AuNP-LFS for rapid and accurate diagnostics of various infectious diseases.


Subject(s)
Biosensing Techniques/methods , Copper/chemistry , Coronavirus Infections/diagnosis , Escherichia coli Infections/diagnosis , Gold/chemistry , HIV Infections/diagnosis , Pneumonia, Viral/diagnosis , Betacoronavirus/isolation & purification , Biosensing Techniques/instrumentation , COVID-19 , COVID-19 Testing , Clinical Laboratory Techniques , Equipment Design , Escherichia coli O157/isolation & purification , HIV Core Protein p24/analysis , HIV-1/isolation & purification , Humans , Limit of Detection , Metal Nanoparticles/chemistry , Metal Nanoparticles/ultrastructure , Oxidation-Reduction , Pandemics , Polyethyleneimine/chemistry , Reagent Strips/analysis , SARS-CoV-2
3.
Biochem Biophys Res Commun ; 533(1): 195-200, 2020 11 26.
Article in English | MEDLINE | ID: covidwho-753910

ABSTRACT

The pandemic of COVID-19 is spreading unchecked due to the lack of effective antiviral measures. Silver nanoparticles (AgNP) have been studied to possess antiviral properties and are presumed to inhibit SARS-CoV-2. Due to the need for an effective agent against SARS-CoV-2, we evaluated the antiviral effect of AgNPs. We evaluated a plethora of AgNPs of different sizes and concentration and observed that particles of diameter around 10 nm were effective in inhibiting extracellular SARS-CoV-2 at concentrations ranging between 1 and 10 ppm while cytotoxic effect was observed at concentrations of 20 ppm and above. Luciferase-based pseudovirus entry assay revealed that AgNPs potently inhibited viral entry step via disrupting viral integrity. These results indicate that AgNPs are highly potent microbicides against SARS-CoV-2 but should be used with caution due to their cytotoxic effects and their potential to derange environmental ecosystems when improperly disposed.


Subject(s)
Antiviral Agents/administration & dosage , Betacoronavirus/drug effects , Coronavirus Infections/drug therapy , Metal Nanoparticles/administration & dosage , Pneumonia, Viral/drug therapy , Silver/administration & dosage , Animals , Antiviral Agents/toxicity , Betacoronavirus/physiology , COVID-19 , Cell Line , Cell Survival/drug effects , Chlorocebus aethiops , Coronavirus Infections/epidemiology , Coronavirus Infections/virology , Dose-Response Relationship, Drug , Humans , Metal Nanoparticles/toxicity , Metal Nanoparticles/ultrastructure , Pandemics , Particle Size , Pneumonia, Viral/epidemiology , Pneumonia, Viral/virology , SARS-CoV-2 , Silver/toxicity , Vero Cells , Virus Internalization/drug effects
4.
Biosens Bioelectron ; 166: 112431, 2020 Oct 15.
Article in English | MEDLINE | ID: covidwho-654767

ABSTRACT

Last few decades, viruses are a real menace to human safety. Therefore, the rapid identification of viruses should be one of the best ways to prevent an outbreak and important implications for medical healthcare. The recent outbreak of coronavirus disease (COVID-19) is an infectious disease caused by a newly discovered coronavirus which belongs to the single-stranded, positive-strand RNA viruses. The pandemic dimension spread of COVID-19 poses a severe threat to the health and lives of seven billion people worldwide. There is a growing urgency worldwide to establish a point-of-care device for the rapid detection of COVID-19 to prevent subsequent secondary spread. Therefore, the need for sensitive, selective, and rapid diagnostic devices plays a vital role in selecting appropriate treatments and to prevent the epidemics. During the last decade, electrochemical biosensors have emerged as reliable analytical devices and represent a new promising tool for the detection of different pathogenic viruses. This review summarizes the state of the art of different virus detection with currently available electrochemical detection methods. Moreover, this review discusses different fabrication techniques, detection principles, and applications of various virus biosensors. Future research also looks at the use of electrochemical biosensors regarding a potential detection kit for the rapid identification of the COVID-19.


Subject(s)
Betacoronavirus , Biosensing Techniques/instrumentation , Clinical Laboratory Techniques/instrumentation , Coronavirus Infections/diagnosis , Electrochemical Techniques/instrumentation , Pneumonia, Viral/diagnosis , Viruses/isolation & purification , Animals , Betacoronavirus/isolation & purification , Betacoronavirus/pathogenicity , COVID-19 , COVID-19 Testing , Coronavirus Infections/virology , Equipment Design , Humans , Metal Nanoparticles/chemistry , Metal Nanoparticles/ultrastructure , Microscopy, Electron, Scanning , Pandemics , Pneumonia, Viral/virology , Point-of-Care Testing , SARS-CoV-2 , Viruses/pathogenicity
5.
ACS Nano ; 14(6): 7617-7627, 2020 06 23.
Article in English | MEDLINE | ID: covidwho-647565

ABSTRACT

The current outbreak of the pandemic coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) demands its rapid, convenient, and large-scale diagnosis to downregulate its spread within as well as across the communities. But the reliability, reproducibility, and selectivity of majority of such diagnostic tests fail when they are tested either to a viral load at its early representation or to a viral gene mutated during its current spread. In this regard, a selective "naked-eye" detection of SARS-CoV-2 is highly desirable, which can be tested without accessing any advanced instrumental techniques. We herein report the development of a colorimetric assay based on gold nanoparticles (AuNPs), when capped with suitably designed thiol-modified antisense oligonucleotides (ASOs) specific for N-gene (nucleocapsid phosphoprotein) of SARS-CoV-2, could be used for diagnosing positive COVID-19 cases within 10 min from the isolated RNA samples. The thiol-modified ASO-capped AuNPs agglomerate selectively in the presence of its target RNA sequence of SARS-CoV-2 and demonstrate a change in its surface plasmon resonance. Further, the addition of RNaseH cleaves the RNA strand from the RNA-DNA hybrid leading to a visually detectable precipitate from the solution mediated by the additional agglomeration among the AuNPs. The selectivity of the assay has been monitored in the presence of MERS-CoV viral RNA with a limit of detection of 0.18 ng/µL of RNA having SARS-CoV-2 viral load. Thus, the current study reports a selective and visual "naked-eye" detection of COVID-19 causative virus, SARS-CoV-2, without the requirement of any sophisticated instrumental techniques.


Subject(s)
Betacoronavirus/genetics , Biosensing Techniques/methods , Coronavirus Infections/diagnosis , Metal Nanoparticles , Nucleocapsid Proteins/genetics , Oligonucleotides, Antisense/genetics , Pneumonia, Viral/diagnosis , Base Sequence , Betacoronavirus/isolation & purification , COVID-19 , Colorimetry/methods , Coronavirus Infections/epidemiology , Coronavirus Infections/virology , Coronavirus Nucleocapsid Proteins , Genes, Viral , Gold , Humans , Metal Nanoparticles/ultrastructure , Microscopy, Electron, Transmission , Nanotechnology/methods , Pandemics , Phosphoproteins , Pneumonia, Viral/epidemiology , Pneumonia, Viral/virology , RNA Caps/genetics , RNA, Viral/genetics , SARS-CoV-2 , Surface Plasmon Resonance/methods
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