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1.
Biosensors (Basel) ; 12(3)2022 Feb 25.
Article in English | MEDLINE | ID: covidwho-1725509

ABSTRACT

Worldwide, human health is affected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Hence, the fabrication of the biosensors to diagnose SARS-CoV-2 is critical. In this paper, we report an electrochemical impedance spectroscopy (EIS)-based aptasensor for the determination of the SARS-CoV-2 receptor-binding domain (SARS-CoV-2-RBD). For this purpose, the carbon nanofibers (CNFs) were first decorated with gold nanoparticles (AuNPs). Then, the surface of the carbon-based screen-printed electrode (CSPE) was modified with the CNF-AuNP nanocomposite (CSPE/CNF-AuNP). After that, the thiol-terminal aptamer probe was immobilized on the surface of the CSPE/CNF-AuNP. The surface coverage of the aptamer was calculated to be 52.8 pmol·cm-2. The CSPE/CNF-AuNP/Aptamer was then used for the measurement of SARS-CoV-2-RBD by using the EIS method. The obtained results indicate that the signal had a linear-logarithmic relationship in the range of 0.01-64 nM with a limit of detection of 7.0 pM. The proposed aptasensor had a good selectivity to SARS-CoV-2-RBD in the presence of human serum albumin; human immunoglobulins G, A, and M, hemagglutinin, and neuraminidase. The analytical performance of the aptasensor was studied in human saliva samples. The present study indicates a practical application of the CSPE/CNF-AuNP/Aptamer for the determination of SARS-CoV-2-RBD in human saliva samples with high sensitivity and accuracy.


Subject(s)
Aptamers, Nucleotide , Biosensing Techniques , COVID-19 , Metal Nanoparticles , Nanocomposites , Nanofibers , Aptamers, Nucleotide/chemistry , Biosensing Techniques/methods , COVID-19/diagnosis , Carbon/chemistry , Dielectric Spectroscopy , Electrochemical Techniques/methods , Electrodes , Gold/chemistry , Humans , Limit of Detection , Metal Nanoparticles/chemistry , Nanofibers/chemistry , SARS-CoV-2
2.
Int J Biol Macromol ; 206: 115-147, 2022 May 01.
Article in English | MEDLINE | ID: covidwho-1697104

ABSTRACT

Thanks to their unique attributes, such as good sensitivity, selectivity, high surface-to-volume ratio, and versatile optical and electronic properties, fluorescent-based bioprobes have been used to create highly sensitive nanobiosensors to detect various biological and chemical agents. These sensors are superior to other analytical instrumentation techniques like gas chromatography, high-performance liquid chromatography, and capillary electrophoresis for being biodegradable, eco-friendly, and more economical, operational, and cost-effective. Moreover, several reports have also highlighted their application in the early detection of biomarkers associated with drug-induced organ damage such as liver, kidney, or lungs. In the present work, we comprehensively overviewed the electrochemical sensors that employ nanomaterials (nanoparticles/colloids or quantum dots, carbon dots, or nanoscaled metal-organic frameworks, etc.) to detect a variety of biological macromolecules based on fluorescent emission spectra. In addition, the most important mechanisms and methods to sense amino acids, protein, peptides, enzymes, carbohydrates, neurotransmitters, nucleic acids, vitamins, ions, metals, and electrolytes, blood gases, drugs (i.e., anti-inflammatory agents and antibiotics), toxins, alkaloids, antioxidants, cancer biomarkers, urinary metabolites (i.e., urea, uric acid, and creatinine), and pathogenic microorganisms were outlined and compared in terms of their selectivity and sensitivity. Altogether, the small dimensions and capability of these nanosensors for sensitive, label-free, real-time sensing of chemical, biological, and pharmaceutical agents could be used in array-based screening and in-vitro or in-vivo diagnostics. Although fluorescent nanoprobes are widely applied in determining biological macromolecules, unfortunately, they present many challenges and limitations. Efforts must be made to minimize such limitations in utilizing such nanobiosensors with an emphasis on their commercial developments. We believe that the current review can foster the wider incorporation of nanomedicine and will be of particular interest to researchers working on fluorescence technology, material chemistry, coordination polymers, and related research areas.


Subject(s)
Biosensing Techniques , Nanoparticles , Nanostructures , Quantum Dots , Biosensing Techniques/methods , Carbon/chemistry , Coloring Agents
3.
Molecules ; 27(2)2022 Jan 17.
Article in English | MEDLINE | ID: covidwho-1635108

ABSTRACT

The design of novel nucleoside triphosphate (NTP) analogues bearing an all-carbon quaternary center at C2' or C3' is described. The construction of this all-carbon stereogenic center involves the use of an intramoleculer photoredox-catalyzed reaction. The nucleoside analogues (NA) hydroxyl functional group at C2' was generated by diastereoselective epoxidation. In addition, highly enantioselective and diastereoselective Mukaiyama aldol reactions, diastereoselective N-glycosylations and regioselective triphosphorylation reactions were employed to synthesize the novel NTPs. Two of these compounds are inhibitors of the RNA-dependent RNA polymerase (RdRp) of SARS-CoV-2, the causal virus of COVID-19.


Subject(s)
Antiviral Agents/pharmacology , Carbon/chemistry , Heterocyclic Compounds, 4 or More Rings/pharmacology , Nucleotides/pharmacology , RNA-Dependent RNA Polymerase/antagonists & inhibitors , SARS-CoV-2/enzymology , Antiviral Agents/chemical synthesis , Antiviral Agents/chemistry , Heterocyclic Compounds, 4 or More Rings/chemical synthesis , Heterocyclic Compounds, 4 or More Rings/chemistry , Nucleotides/chemical synthesis , Nucleotides/chemistry , SARS-CoV-2/drug effects , Stereoisomerism
4.
Sci Total Environ ; 817: 152995, 2022 Apr 15.
Article in English | MEDLINE | ID: covidwho-1616761

ABSTRACT

With the spread of COVID-19, disposable medical masks (DMMs) have become a significant source of new hazardous solid waste. Their proper disposal is not only beneficial to the safety of biological systems but also useful to achieve considerable economic value. The first step of this study was to investigate the chemical composition of DMMs. It is primarily composed of polypropylene, polyethylene terephthalate and iron, with fibrous polypropylene accounting for approximately 80% of the total weight. Then, DMMs were sulfonated and oxidised by the microwave-driven concentrated sulfuric acid within 8 min based on the fact that the concentrated sulfuric acid exhibits a good microwave absorption capacity. The co-doping of sulfur and oxygen was achieved while improving the thermal stability of DMMs. Subsequently, the self-activation pyrolysis of sulfonated and oxidised DMMs (P-SO@DMMs) was further realized in low-flow-rate argon. The specific surface area of P-SO@DMMs increased from 2.0 to 830.9 m2·g-1. P-SO@DMMs sulfur cathodes have promising electrochemical properties because of their porous structures and the synergistic effect of sulfur and oxygen co-doping. The capacity of the samples irradiated by microwave for 10 min at 0.1, 0.2, 0.5, 1, 2 and 5 C were 1313.6, 1010.9, 816.5, 634.4, 513.4 and 453.1 mAh·g-1, respectively, and after returning to 0.2 C and continuing the cycle for 50 revolutions, maintained 50.5% of the initial capacity. After 400 cycles, its capacity is 38.1% of the initial capacity at 0.5 C. It is slightly higher than the electrochemical performance of the sample treated by microwave for 8 min and significantly higher than the sample treated by 6 min. This work converts structurally complex, biohazardous DMMs into porous carbon with high specific surface area by clean and efficient microwave solvothermal and self-activating pyrolysis, which facilitates the development of carbon based materials at low cost and large scale.


Subject(s)
COVID-19 , Lithium , Carbon/chemistry , Humans , Lithium/chemistry , Masks , Microwaves , Porosity , SARS-CoV-2 , Sulfur/chemistry
5.
Mikrochim Acta ; 188(12): 430, 2021 11 25.
Article in English | MEDLINE | ID: covidwho-1530326

ABSTRACT

Recent experience with the COVID-19 pandemic should be a lesson learnt with respect to the effort we have to invest in the development of new strategies for the treatment of viral diseases, along with their cheap, easy, sensitive, and selective detection. Since we live in a globalized world where just hours can play a crucial role in the spread of a virus, its detection must be as quick as possible. Thanks to their chemical stability, photostability, and superior biocompatibility, carbon dots are a kind of nanomaterial showing great potential in both the detection of various virus strains and a broad-spectrum antiviral therapy. The biosensing and antiviral properties of carbon dots can be tuned by the selection of synthesis precursors as well as by easy post-synthetic functionalization. In this review, we will first summarize current options of virus detection utilizing carbon dots by either electrochemical or optical biosensing approaches. Secondly, we will cover and share the up-to-date knowledge of carbon dots' antiviral properties, which showed promising activity against various types of viruses including SARS-CoV-2. The mechanisms of their antiviral actions will be further adressed as well. Finally, we will discuss the advantages and distadvantages of the use of carbon dots in the tangled battle against viral infections in order to provide valuable informations for further research and development of new virus biosensors and antiviral therapeutics.


Subject(s)
COVID-19 Testing/methods , COVID-19/diagnosis , COVID-19/drug therapy , COVID-19/therapy , Carbon/chemistry , Quantum Dots , Antiviral Agents/pharmacology , Biocompatible Materials , Biosensing Techniques , Electrochemistry , Humans , Molecular Targeted Therapy , Nanostructures , Phototherapy , Polymers , SARS-CoV-2 , Virus Diseases
6.
Int J Mol Sci ; 22(14)2021 Jul 14.
Article in English | MEDLINE | ID: covidwho-1323261

ABSTRACT

Good health, of vital importance in order to carry out our daily routine, consists of both physical and mental health. Tyrosine (Tyr) deficiency as well as its excess are issues that can affect mental health and can generate disorders such as depression, anxiety, or stress. Tyr is the amino acid (AA) responsible for maintaining good mental health, and for this reason, the present research presents the development of new electrochemical sensors modified with polypyrrole (PPy) doped with different doping agents such as potassium hexacyanoferrate (II) (FeCN), sodium nitroprusside (NP), and sodium dodecyl sulfate (SDS) for a selective and sensitive detection of Tyr. The development of the sensors was carried out by chronoamperometry (CA) and the electrochemical characterization was carried out by cyclic voltammetry (CV). The detection limits (LOD) obtained with each modified sensor were 8.2 × 10-8 M in the case of PPy /FeCN-SPCE, 4.3 × 10-7 M in the case of PPy/NP-SPCE, and of 3.51 × 10-7 M in the case of PPy/SDS-SPCE, thus demonstrating a good sensitivity of these sensors detecting L-Tyr. The validation of sensors was carried out through quantification of L-Tyr from three pharmaceutical products by the standard addition method with recoveries in the range 99.92-103.97%. Thus, the sensors present adequate selectivity and can be used in the pharmaceutical and medical fields.


Subject(s)
Carbon/chemistry , Electrodes , Pharmaceutical Preparations/analysis , Pharmaceutical Preparations/chemistry , Polymers/chemistry , Pyrroles/chemistry , Tyrosine/analysis , Electrochemical Techniques
7.
Faraday Discuss ; 226: 112-137, 2021 03 01.
Article in English | MEDLINE | ID: covidwho-1253998

ABSTRACT

Air quality in megacities is significantly impacted by emissions from vehicles and other urban-scale human activities. Amid the outbreak of Coronavirus (COVID-19) in January 2020, strict policies were in place to restrict people's movement, bringing about steep reductions in pollution activities and notably lower ambient concentrations of primary pollutants. In this study, we report hourly measurements of fine particulate matter (i.e., PM2.5) and its comprehensive chemical speciation, including elemental and molecular source tracers, at an urban site in Shanghai spanning a period before the lockdown restriction (BR) (1 to 23 Jan. 2020) and during the restriction (DR) (24 Jan. to 9 Feb. 2020). The overall PM2.5 was reduced by 27% from 56.2 ± 40.9 (BR) to 41.1 ± 25.3 µg m-3 (DR) and the organic carbon (OC) in PM2.5 was similar, averaged at 5.45 ± 2.37 (BR) and 5.42 ± 1.75 µgC m-3 (DR). Reduction in nitrate was prominent, from 18.1 (BR) to 9.2 µg m-3 (DR), accounting for most of the PM2.5 decrease. Source analysis of PM2.5 using positive matrix factorization modeling of comprehensive chemical composition, resolved nine primary source factors and five secondary source factors. The quantitative source analysis confirms reduced contributions from primary sources affected by COVID-19, with vehicular emissions showing the largest drop, from 4.6 (BR) to 0.61 µg m-3 (DR) and the percentage change (-87%) in par with vehicle traffic volume and fuel sale statistics (-60% to -90%). In the same time period, secondary sources are revealed to vary in response to precursor reductions from the lockdown, with two sources showing consistent enhancement while the other three showing reductions, highlighting the complexity in secondary organic aerosol formation and the nonlinear response to broad primary precursor pollutants. The combined contribution from the two secondary sources to PM2.5 increased from 7.3 ± 6.6 (BR) to 14.8 ± 9.3 µg m-3 (DR), partially offsetting the reductions from primary sources and nitrate while their increased contribution to OC, from 1.6 ± 1.4 (BR) to 3.2 ± 2.0 µgC m-3 (DR), almost offset the decrease coming from the primary sources. Results from this work underscore challenges in predicting the benefits to PM2.5 improvement from emission reductions of common urban primary sources.


Subject(s)
COVID-19/pathology , Carbon/analysis , Particulate Matter/analysis , Biomass , COVID-19/virology , Carbon/chemistry , China , Cluster Analysis , Environmental Monitoring/methods , Humans , Nitrates/analysis , Quarantine , SARS-CoV-2/isolation & purification
8.
Ecotoxicol Environ Saf ; 219: 112357, 2021 Aug.
Article in English | MEDLINE | ID: covidwho-1233412

ABSTRACT

The coronavirus disease-19 (COVID-19) pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is rampant in the world and is a serious threat to global health. The SARS-CoV-2 RNA has been detected in various environmental media, which speeds up the pace of the virus becoming a global biological pollutant. Because many engineered nanomaterials (ENMs) are capable of inducing anti-microbial activity, ENMs provide excellent solutions to overcome the virus pandemic, for instance by application as protective coatings, biosensors, or nano-agents. To tackle some mechanistic issues related to the impact of ENMs on SARS-CoV-2, we investigated the molecular interactions between carbon nanoparticles (CNPs) and a SARS-CoV-2 RNA fragment (i.e., a model molecule of frameshift stimulation element from the SARS-CoV-2 RNA genome) using molecular mechanics simulations. The interaction affinity between the CNPs and the SARS-CoV-2 RNA fragment increased in the order of fullerenes < graphenes < carbon nanotubes. Furthermore, we developed quantitative structure-activity relationship (QSAR) models to describe the interactions of 17 different types of CNPs from three dimensions with the SARS-CoV-2 RNA fragment. The QSAR models on the interaction energies of CNPs with the SARS-CoV-2 RNA fragment show high goodness-of-fit and robustness. Molecular weight, surface area, and the sum of degrees of every carbon atom were found to be the primary structural descriptors of CNPs determining the interactions. Our research not only offers a theoretical insight into the adsorption/separation and inactivation of SARS-CoV-2, but also allows to design novel ENMs which act efficiently on the genetic material RNA of SARS-CoV-2. This contributes to minimizing the challenge of time-consuming and labor-intensive virus experiments under high risk of infection, whilst meeting our precautionary demand for options to handle any new versions of the coronavirus that might emerge in the future.


Subject(s)
Carbon/chemistry , Nanoparticles/chemistry , RNA, Viral/chemistry , SARS-CoV-2 , Models, Chemical , Nucleic Acid Conformation , Quantitative Structure-Activity Relationship
9.
Inorg Chem ; 60(9): 6585-6599, 2021 May 03.
Article in English | MEDLINE | ID: covidwho-1195597

ABSTRACT

Silver vanadate nanorods (ß-AgVO3) with silver nanoparticles (Ag-NPs) decorated on the surface of the rods were synthesized by using simple hydrothermal technique and later anchored onto nitrogen-doped reduced graphene oxide (N-rGO) to make a novel nanocomposite. Experimental analyses were carried out to identify the electronic configuration by X-ray diffraction analysis, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy analysis, which revealed monoclinic patterns of the C12/m1 space group with Wulff construction forming beta silver vanadate (ß-AgVO3) crystals with optical density and phase transformations. Ag nucleation showed consistent results with metallic formation and electronic changes occurring in [AgO5] and [AgO3] clusters. Transmission electron microscopy and field-emission scanning electron microscopy with elemental mapping and EDX analysis of the morphology reveals the nanorod structure for ß-AgVO3 with AgNPs on the surface and sheets for N-rGO. Additionally, a novel electrochemical sensor is constructed by using Ag/AgVO3/N-rGO on screen-printed carbon paste electrodes for the detection of antiviral drug levofloxacin (LEV) which is used as a primary antibiotic in controlling COVID-19. Using differential pulse voltammetry, LEV is determined with a low detection limit of 0.00792 nm for a linear range of 0.09-671 µM with an ultrahigh sensitivity of 152.19 µA µM-1 cm-2. Furthermore, modified electrode performance is tested by real-time monitoring using biological and river samples.


Subject(s)
Dielectric Spectroscopy/instrumentation , Dielectric Spectroscopy/methods , Levofloxacin/analysis , Nanocomposites/chemistry , Antiviral Agents/analysis , Antiviral Agents/blood , Antiviral Agents/urine , Carbon/chemistry , Electrodes , Graphite/chemistry , Humans , Levofloxacin/blood , Levofloxacin/urine , Limit of Detection , Metal Nanoparticles/chemistry , Microscopy, Electron, Transmission , Nanotubes/chemistry , Photoelectron Spectroscopy , Silver/chemistry , Silver Compounds/chemistry , Spectroscopy, Fourier Transform Infrared , Spectrum Analysis, Raman , Tablets , Vanadates/chemistry , X-Ray Diffraction
10.
J Colloid Interface Sci ; 592: 342-348, 2021 Jun 15.
Article in English | MEDLINE | ID: covidwho-1107283

ABSTRACT

Facemasks are considered the most effective means for preventing infection and spread of viral particles. In particular, the coronavirus (COVID-19) pandemic underscores the urgent need for developing recyclable facemasks due to the considerable environmental damage and health risks imposed by disposable masks and respirators. We demonstrate synthesis of nanoporous membranes comprising carbon dots (C-dots) and poly(vinylidene fluoride) (PVDF), and demonstrate their potential use for recyclable, self-sterilized facemasks. Notably, the composite C-dot-PVDF films exhibit hydrophobic surface which prevents moisture accumulation and a compact nanopore network which allows both breathability as well as effective filtration of particles above 100 nm in diameter. Particularly important, self-sterilization occurs upon short solar irradiation of the membrane, as the embedded C-dots efficiently absorb visible light, concurrently giving rise to elevated temperatures through heat dissipation.


Subject(s)
COVID-19/prevention & control , Carbon/chemistry , Masks/virology , Nanopores , SARS-CoV-2 , Sterilization , Sunlight , COVID-19/transmission , Humans
11.
Photochem Photobiol Sci ; 20(1): 183-188, 2021 Jan.
Article in English | MEDLINE | ID: covidwho-1103608

ABSTRACT

A hypothesis is proposed to explain the increased detrimental effect of COVID-19 for Black, Asian and Minority Ethnic (BAME) men and women compared to Caucasian individuals. This is based on the differing photochemistry of phaeomelanin in fair skin and eumelanin in dark/black skin. It is suggested that a range of reactive oxygen species, including, singlet oxygen and the superoxide radical anion, derived via direct photolysis of phaeomelanin, may escape the melanocyte and cause subsequent damage to the SARS-CoV-2 virus. It is further suggested that (large) carbon and sulphur peroxy radicals, from oxygen addition to radicals formed by carbon-sulphur bond cleavage, may assist via damage to the cell membranes. It is also speculated that light absorption by phaeomelanin and the subsequent C-S bond cleavage, leads to release of pre-absorbed reactive oxygen species, such as singlet oxygen and free radicals, which may also contribute to an enhanced protective effect for fair-skinned people.


Subject(s)
COVID-19/pathology , Photochemical Processes , COVID-19/ethnology , COVID-19/virology , Carbon/chemistry , Female , Free Radicals/chemistry , Humans , Light , Male , Melanins/chemistry , Photolysis , SARS-CoV-2/isolation & purification , Singlet Oxygen/chemistry , Singlet Oxygen/metabolism , Skin/metabolism , Sulfur/chemistry , Superoxides/chemistry , Superoxides/metabolism
12.
ACS Appl Bio Mater ; 4(2): 1307-1318, 2021 02 15.
Article in English | MEDLINE | ID: covidwho-1069089

ABSTRACT

Recent evidence suggests that proinflammatory cytokines, such as tumor necrosis factor α (TNF-α), play a pivotal role in the development of inflammatory-related pathologies (covid-19, depressive disorders, sepsis, cancer, etc.,). More importantly, the development of TNF-α biosensors applied to biological fluids (e.g. sweat) could offer non-invasive solutions for the continuous monitoring of these disorders, in particular, polydimethylsiloxane (PDMS)-based biosensors. We have therefore investigated the biofunctionalization of PDMS surfaces using a silanization reaction with 3-aminopropyltriethoxysilane, for the development of a human TNF-α biosensor. The silanization conditions for 50 µm PDMS surfaces were extensively studied by using water contact angle measurements, electron dispersive X-ray and Fourier transform infrared spectroscopies, and fluorescamine detection. Evaluation of the wettability of the silanized surfaces and the Si/C ratio pointed out to the optimal silanization conditions supporting the formation of a stable and reproducible aminosilane layer, necessary for further bioconjugation. An ELISA-type immunoassay was then successfully performed for the detection and quantification of human TNF-α through fluorescent microscopy, reaching a limit of detection of 0.55 µg/mL (31.6 nM). Finally, this study reports for the first time a promising method for the development of PDMS-based biosensors for the detection of TNF-α, using a quick, stable, and simple biofunctionalization process.


Subject(s)
Dimethylpolysiloxanes/chemistry , Immunoassay/methods , Tumor Necrosis Factor-alpha/analysis , Antibodies, Immobilized/chemistry , Antibodies, Immobilized/immunology , COVID-19/metabolism , COVID-19/pathology , COVID-19/virology , Carbon/chemistry , Humans , Immunoassay/instrumentation , Limit of Detection , Microfluidics , Microscopy, Fluorescence , SARS-CoV-2/isolation & purification , Silicon/chemistry , Tumor Necrosis Factor-alpha/immunology , Wettability
13.
J Colloid Interface Sci ; 586: 673-682, 2021 Mar 15.
Article in English | MEDLINE | ID: covidwho-1065294

ABSTRACT

Paracetamol is the most commonly used antipyretic and analgesic drug in the world. The key challenge in paracetamol therapy is associated with the frequency of the dosing. Depending on the gastric filling within 10-20 min paracetamol is released and rapidly absorbed from the gastrointestinal tract. Therefore, it must be taken three or four times a day. To address the dose challenge it is desirable that the paracetamol release profile follows the zero-order kinetic model (constant rate of drug release per unit time). This goal can be achieved by using a suitable porous carrier system. Herein, non-toxic wrinkled mesoporous carbons with unique morphology were synthesized via the hard template method as new carriers for paracetamol. These particles can precisely modulate the release of paracetamol over 24 h in a simulated gastric fluid according to the zero-order kinetic model completely eliminating the initial burst release. Overall, these systems could significantly enhance the bioavailability of paracetamol and prolong its therapeutic effect in numerous diseases such as cold, flu, COVID-19, and severe pain.


Subject(s)
Acetaminophen , COVID-19/drug therapy , Carbon/chemistry , Drug Carriers , Pain/drug therapy , SARS-CoV-2 , Acetaminophen/chemistry , Acetaminophen/pharmacokinetics , Delayed-Action Preparations/chemistry , Delayed-Action Preparations/pharmacokinetics , Drug Carriers/chemistry , Drug Carriers/pharmacokinetics , Humans
14.
Anal Chem ; 93(3): 1826-1833, 2021 01 26.
Article in English | MEDLINE | ID: covidwho-997756

ABSTRACT

Collection of nasopharyngeal samples using swabs followed by the transfer of the virus into a solution and an RNA extraction step to perform reverse transcription polymerase chain reaction (PCR) is the primary method currently used for the diagnosis of COVID-19. However, the need for several reagents and steps and the high cost of PCR hinder its worldwide implementation to contain the outbreak. Here, we report a cotton-tipped electrochemical immunosensor for the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus antigen. Unlike the reported approaches, we integrated the sample collection and detection tools into a single platform by coating screen-printed electrodes with absorbing cotton padding. The immunosensor was fabricated by immobilizing the virus nucleocapsid (N) protein on carbon nanofiber-modified screen-printed electrodes which were functionalized by diazonium electrografting. The detection of the virus antigen was achieved via swabbing followed by competitive assay using a fixed amount of N protein antibody in the solution. A square wave voltammetric technique was used for the detection. The limit of detection for our electrochemical biosensor was 0.8 pg/mL for SARS-CoV-2, indicating very good sensitivity for the sensor. The biosensor did not show significant cross-reactivity with other virus antigens such as influenza A and HCoV, indicating high selectivity of the method. Moreover, the biosensor was successfully applied for the detection of the virus antigen in spiked nasal samples showing excellent recovery percentages. Thus, our electrochemical immunosensor is a promising diagnostic tool for the direct rapid detection of the COVID-19 virus that requires no sample transfer or pretreatment.


Subject(s)
COVID-19/diagnosis , Cotton Fiber , Electrochemical Techniques/methods , Immunoassay/methods , SARS-CoV-2/isolation & purification , Antibodies, Viral/immunology , Biosensing Techniques/instrumentation , Biosensing Techniques/methods , Carbon/chemistry , Coronavirus Nucleocapsid Proteins/chemistry , Coronavirus Nucleocapsid Proteins/immunology , Electrochemical Techniques/instrumentation , Electrodes , Gossypium/chemistry , Humans , Immobilized Proteins/chemistry , Immobilized Proteins/immunology , Immunoassay/instrumentation , Limit of Detection , Nanofibers/chemistry , Phosphoproteins/chemistry , Phosphoproteins/immunology , SARS-CoV-2/immunology
15.
Faraday Discuss ; 226: 112-137, 2021 03 01.
Article in English | MEDLINE | ID: covidwho-989971

ABSTRACT

Air quality in megacities is significantly impacted by emissions from vehicles and other urban-scale human activities. Amid the outbreak of Coronavirus (COVID-19) in January 2020, strict policies were in place to restrict people's movement, bringing about steep reductions in pollution activities and notably lower ambient concentrations of primary pollutants. In this study, we report hourly measurements of fine particulate matter (i.e., PM2.5) and its comprehensive chemical speciation, including elemental and molecular source tracers, at an urban site in Shanghai spanning a period before the lockdown restriction (BR) (1 to 23 Jan. 2020) and during the restriction (DR) (24 Jan. to 9 Feb. 2020). The overall PM2.5 was reduced by 27% from 56.2 ± 40.9 (BR) to 41.1 ± 25.3 µg m-3 (DR) and the organic carbon (OC) in PM2.5 was similar, averaged at 5.45 ± 2.37 (BR) and 5.42 ± 1.75 µgC m-3 (DR). Reduction in nitrate was prominent, from 18.1 (BR) to 9.2 µg m-3 (DR), accounting for most of the PM2.5 decrease. Source analysis of PM2.5 using positive matrix factorization modeling of comprehensive chemical composition, resolved nine primary source factors and five secondary source factors. The quantitative source analysis confirms reduced contributions from primary sources affected by COVID-19, with vehicular emissions showing the largest drop, from 4.6 (BR) to 0.61 µg m-3 (DR) and the percentage change (-87%) in par with vehicle traffic volume and fuel sale statistics (-60% to -90%). In the same time period, secondary sources are revealed to vary in response to precursor reductions from the lockdown, with two sources showing consistent enhancement while the other three showing reductions, highlighting the complexity in secondary organic aerosol formation and the nonlinear response to broad primary precursor pollutants. The combined contribution from the two secondary sources to PM2.5 increased from 7.3 ± 6.6 (BR) to 14.8 ± 9.3 µg m-3 (DR), partially offsetting the reductions from primary sources and nitrate while their increased contribution to OC, from 1.6 ± 1.4 (BR) to 3.2 ± 2.0 µgC m-3 (DR), almost offset the decrease coming from the primary sources. Results from this work underscore challenges in predicting the benefits to PM2.5 improvement from emission reductions of common urban primary sources.


Subject(s)
COVID-19/pathology , Carbon/analysis , Particulate Matter/analysis , Biomass , COVID-19/virology , Carbon/chemistry , China , Cluster Analysis , Environmental Monitoring/methods , Humans , Nitrates/analysis , Quarantine , SARS-CoV-2/isolation & purification
16.
Molecules ; 25(24)2020 Dec 08.
Article in English | MEDLINE | ID: covidwho-967219

ABSTRACT

With the rise in public health awareness, research on point-of-care testing (POCT) has significantly advanced. Electrochemical biosensors (ECBs) are one of the most promising candidates for the future of POCT due to their quick and accurate response, ease of operation, and cost effectiveness. This review focuses on the use of metal nanoparticles (MNPs) for fabricating ECBs that has a potential to be used for POCT. The field has expanded remarkably from its initial enzymatic and immunosensor-based setups. This review provides a concise categorization of the ECBs to allow for a better understanding of the development process. The influence of structural aspects of MNPs in biocompatibility and effective sensor design has been explored. The advances in MNP-based ECBs for the detection of some of the most prominent cancer biomarkers (carcinoembryonic antigen (CEA), cancer antigen 125 (CA125), Herceptin-2 (HER2), etc.) and small biomolecules (glucose, dopamine, hydrogen peroxide, etc.) have been discussed in detail. Additionally, the novel coronavirus (2019-nCoV) ECBs have been briefly discussed. Beyond that, the limitations and challenges that ECBs face in clinical applications are examined and possible pathways for overcoming these limitations are discussed.


Subject(s)
Electrochemical Techniques/methods , Metal Nanoparticles/chemistry , Point-of-Care Testing , Biomarkers, Tumor/analysis , Biosensing Techniques/instrumentation , Biosensing Techniques/methods , COVID-19 Testing/methods , Carbon/chemistry , Electrochemical Techniques/instrumentation , Equipment Design , Female , Humans , Male , Nanostructures/chemistry
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