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1.
Int J Biol Macromol ; 203: 466-480, 2022 Apr 01.
Article in English | MEDLINE | ID: covidwho-1630871

ABSTRACT

The SARS-CoV-2 nucleocapsid protein (N) is a multifunctional promiscuous nucleic acid-binding protein, which plays a major role in nucleocapsid assembly and discontinuous RNA transcription, facilitating the template switch of transcriptional regulatory sequences (TRS). Here, we dissect the structural features of the N protein N-terminal domain (N-NTD) and N-NTD plus the SR-rich motif (N-NTD-SR) upon binding to single and double-stranded TRS DNA, as well as their activities for dsTRS melting and TRS-induced liquid-liquid phase separation (LLPS). Our study gives insights on the specificity for N-NTD(-SR) interaction with TRS. We observed an approximation of the triple-thymidine (TTT) motif of the TRS to ß-sheet II, giving rise to an orientation difference of ~25° between dsTRS and non-specific sequence (dsNS). It led to a local unfavorable energetic contribution that might trigger the melting activity. The thermodynamic parameters of binding of ssTRSs and dsTRS suggested that the duplex dissociation of the dsTRS in the binding cleft is entropically favorable. We showed a preference for TRS in the formation of liquid condensates when compared to NS. Moreover, our results on DNA binding may serve as a starting point for the design of inhibitors, including aptamers, against N, a possible therapeutic target essential for the virus infectivity.


Subject(s)
COVID-19/virology , Nucleic Acids/metabolism , Nucleocapsid Proteins/metabolism , Protein Interaction Domains and Motifs , SARS-CoV-2/physiology , Binding Sites , DNA/chemistry , DNA/metabolism , Gene Expression Regulation, Viral , Host-Pathogen Interactions , Humans , Hydrogen Bonding , Models, Molecular , Nucleic Acids/chemistry , Nucleocapsid Proteins/chemistry , Protein Binding , RNA/chemistry , RNA/metabolism , Spectrum Analysis , Structure-Activity Relationship
2.
Virology ; 566: 42-55, 2022 01.
Article in English | MEDLINE | ID: covidwho-1537114

ABSTRACT

All available SARS-CoV-2 spike protein crystal and cryo-EM structures have shown missing electron densities for cytosolic C-terminal regions (CTR). Generally, the missing electron densities point towards the intrinsically disordered nature of the protein region (IDPR). This curiosity has led us to investigate the cytosolic CTR of the spike glycoprotein of SARS-CoV-2 in isolation. The spike CTR is supposed to be from 1235 to 1273 residues or 1242-1273 residues based on our used prediction. Therefore, we have demonstrated the structural conformation of cytosolic region and its dynamics through computer simulations up to microsecond timescale using OPLS and CHARMM forcefields. The simulations have revealed the unstructured conformation of cytosolic region. Further, we have validated our computational observations with circular dichroism (CD) spectroscopy-based experiments and found its signature spectra at 198 nm. We believe that our findings will surely help in understanding the structure-function relationship of the spike protein's cytosolic region.


Subject(s)
COVID-19/virology , SARS-CoV-2/chemistry , Spike Glycoprotein, Coronavirus/chemistry , Circular Dichroism/methods , Cryoelectron Microscopy , Humans , Models, Molecular , Molecular Dynamics Simulation , Protein Binding , Protein Conformation , Protein Domains , Spectrum Analysis , Structure-Activity Relationship
3.
Molecules ; 26(21)2021 Oct 20.
Article in English | MEDLINE | ID: covidwho-1512506

ABSTRACT

Three silver(I) dipeptide complexes [Ag(GlyGly)]n(NO3)n (AgGlyGly), [Ag2(GlyAla)(NO3)2]n (AgGlyAla) and [Ag2(HGlyAsp)(NO3)]n (AgGlyAsp) were prepared, investigated and characterized by vibrational spectroscopy (mid-IR), elemental and thermogravimetric analysis and mass spectrometry. For AgGlyGly, X-ray crystallography was also performed. Their stability in biological testing media was verified by time-dependent NMR measurements. Their in vitro antimicrobial activity was evaluated against selected pathogenic microorganisms. Moreover, the influence of silver(I) dipeptide complexes on microbial film formation was described. Further, the cytotoxicity of the complexes against selected cancer cells (BLM, MDA-MB-231, HeLa, HCT116, MCF-7 and Jurkat) and fibroblasts (BJ-5ta) using a colorimetric MTS assay was tested, and the selectivity index (SI) was identified. The mechanism of action of Ag(I) dipeptide complexes was elucidated and discussed by the study in terms of their binding affinity toward the CT DNA, the ability to cleave the DNA and the ability to influence numbers of cells within each cell cycle phase. The new silver(I) dipeptide complexes are able to bind into DNA by noncovalent interaction, and the topoisomerase I inhibition study showed that the studied complexes inhibit its activity at a concentration of 15 µM.


Subject(s)
Anti-Infective Agents/chemistry , Anti-Infective Agents/pharmacology , Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacology , Coordination Complexes/chemistry , Coordination Complexes/pharmacology , Dipeptides/chemistry , Silver/chemistry , Anti-Infective Agents/chemical synthesis , Antineoplastic Agents/chemical synthesis , Cell Cycle/drug effects , Cell Line, Tumor , Chemical Phenomena , Chemistry Techniques, Synthetic , Coordination Complexes/chemical synthesis , Crystallography, X-Ray , Dose-Response Relationship, Drug , Drug Stability , Humans , Molecular Conformation , Molecular Dynamics Simulation , Spectrum Analysis , Structure-Activity Relationship , Thermogravimetry
4.
Talanta ; 237: 122916, 2022 Jan 15.
Article in English | MEDLINE | ID: covidwho-1506048

ABSTRACT

Herein, we show differences in blood serum of asymptomatic and symptomatic pregnant women infected with COVID-19 and correlate them with laboratory indexes, ATR FTIR and multivariate machine learning methods. We collected the sera of COVID-19 diagnosed pregnant women, in the second trimester (n = 12), third-trimester (n = 7), and second-trimester with severe symptoms (n = 7) compared to the healthy pregnant (n = 11) women, which makes a total of 37 participants. To assign the accuracy of FTIR spectra regions where peak shifts occurred, the Random Forest algorithm, traditional C5.0 single decision tree algorithm and deep neural network approach were used. We verified the correspondence between the FTIR results and the laboratory indexes such as: the count of peripheral blood cells, biochemical parameters, and coagulation indicators of pregnant women. CH2 scissoring, amide II, amide I vibrations could be used to differentiate the groups. The accuracy calculated by machine learning methods was higher than 90%. We also developed a method based on the dynamics of the absorbance spectra allowing to determine the differences between the spectra of healthy and COVID-19 patients. Laboratory indexes of biochemical parameters associated with COVID-19 validate changes in the total amount of proteins, albumin and lipase.


Subject(s)
COVID-19 , Female , Humans , Laboratories , Machine Learning , Pregnancy , Pregnant Women , SARS-CoV-2 , Serum , Spectrum Analysis , Vibration
5.
ACS Appl Mater Interfaces ; 13(37): 44136-44146, 2021 Sep 22.
Article in English | MEDLINE | ID: covidwho-1402018

ABSTRACT

With the ongoing global pandemic of coronavirus disease 2019 (COVID-19), there is an increasing quest for more accessible, easy-to-use, rapid, inexpensive, and high-accuracy diagnostic tools. Traditional disease diagnostic methods such as qRT-PCR (quantitative reverse transcription-PCR) and ELISA (enzyme-linked immunosorbent assay) require multiple steps, trained technicians, and long turnaround time that may worsen the disease surveillance and pandemic control. In sight of this situation, a rapid, one-step, easy-to-use, and high-accuracy diagnostic platform will be valuable for future epidemic control, especially for regions with scarce medical resources. Herein, we report a magnetic particle spectroscopy (MPS) platform for the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) biomarkers: spike and nucleocapsid proteins. This technique monitors the dynamic magnetic responses of magnetic nanoparticles (MNPs) and uses their higher harmonics as a measure of the nanoparticles' binding states. By anchoring polyclonal antibodies (pAbs) onto MNP surfaces, these nanoparticles function as nanoprobes to specifically bind to target analytes (SARS-CoV-2 spike and nucleocapsid proteins in this work) and form nanoparticle clusters. This binding event causes detectable changes in higher harmonics and allows for quantitative and qualitative detection of target analytes in the liquid phase. We have achieved detection limits of 1.56 nM (equivalent to 125 fmole) and 12.5 nM (equivalent to 1 pmole) for detecting SARS-CoV-2 spike and nucleocapsid proteins, respectively. This MPS platform combined with the one-step, wash-free, nanoparticle clustering-based assay method is intrinsically versatile and allows for the detection of a variety of other disease biomarkers by simply changing the surface functional groups on MNPs.


Subject(s)
COVID-19/virology , Nanoparticles/chemistry , Nucleocapsid Proteins/chemistry , SARS-CoV-2/chemistry , Spectrum Analysis/methods , Spike Glycoprotein, Coronavirus/chemistry , Cluster Analysis , Humans
6.
Commun Biol ; 4(1): 956, 2021 08 11.
Article in English | MEDLINE | ID: covidwho-1354120

ABSTRACT

Lipid Nanoparticles (LNPs) are used to deliver siRNA and COVID-19 mRNA vaccines. The main factor known to determine their delivery efficiency is the pKa of the LNP containing an ionizable lipid. Herein, we report a method that can predict the LNP pKa from the structure of the ionizable lipid. We used theoretical, NMR, fluorescent-dye binding, and electrophoretic mobility methods to comprehensively measure protonation of both the ionizable lipid and the formulated LNP. The pKa of the ionizable lipid was 2-3 units higher than the pKa of the LNP primarily due to proton solvation energy differences between the LNP and aqueous medium. We exploited these results to explain a wide range of delivery efficiencies in vitro and in vivo for intramuscular (IM) and intravascular (IV) administration of different ionizable lipids at escalating ionizable lipid-to-mRNA ratios in the LNP. In addition, we determined that more negatively charged LNPs exhibit higher off-target systemic expression of mRNA in the liver following IM administration. This undesirable systemic off-target expression of mRNA-LNP vaccines could be minimized through appropriate design of the ionizable lipid and LNP.


Subject(s)
Gene Expression , Ions/chemistry , Lipids/chemistry , Nanoparticles/chemistry , RNA, Messenger/chemistry , RNA, Messenger/genetics , Administration, Intravenous , Animals , Drug Compounding , Humans , Hydrogen-Ion Concentration , Injections, Intramuscular , Mice , Molecular Structure , Nanoparticles/ultrastructure , RNA, Messenger/administration & dosage , RNA, Messenger/pharmacokinetics , Spectrum Analysis , Tissue Distribution , Transfection
7.
J Nat Prod ; 83(12): 3493-3501, 2020 12 24.
Article in English | MEDLINE | ID: covidwho-1351918

ABSTRACT

Svalbardines A and B (1 and 2) and annularin K (3) were isolated from cultures of Poaceicola sp. E1PB, an endophyte isolated from the petals of Papaver dahlianum from Svalbard, Norway. Svalbardine A (1) is a pyrano[3,2-c]chromen-4-one, a new analogue of citromycetin. Svalbardine B (2) displays an unprecedented carbon skeleton based on a 5'-benzyl-spiro[chroman-3,7'-isochromene]-4,8'-dione core. Annularin K (3) is a hydroxylated derivative of annularin D. The structure of these new polyketides, along with those of known compounds 4-6, was established by spectrometric analysis, including extensive ESI-CID-MSn processing in the case of svalbardine B (2).


Subject(s)
Ascomycota/chemistry , Spectrometry, Mass, Electrospray Ionization/methods , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/isolation & purification , Anti-Bacterial Agents/pharmacology , Arctic Regions , Microbial Sensitivity Tests , Molecular Structure , Spectrum Analysis
8.
Biosens Bioelectron ; 192: 113536, 2021 Nov 15.
Article in English | MEDLINE | ID: covidwho-1330665

ABSTRACT

The ongoing COVID-19 pandemic stresses the need for widely available diagnostic tests for the presence of SARS-CoV-2 in individuals. Due to the limited availability of vaccines, diagnostic assays which are cheap, easy-to-use at the point-of-need, reliable and fast, are currently the only way to control the pandemic situation. Here we present a diagnostic assay for the detection of pathogen-specific nucleic acids based on changes of the magnetic response of magnetic nanoparticles: The target-mediated hybridization of modified nanoparticles leads to an increase in the hydrodynamic radius. This resulting change in the magnetic behaviour in an ac magnetic field can be measured via magnetic particle spectroscopy (MPS), providing a viable tool for the accurate detection of target nucleic acids. In this work we show that single stranded DNA can be detected in a concentration-dependent manner by these means. In addition to detecting synthetic DNA with an arbitrary sequence in a concentration down to 500 pM, we show that RNA and SARS-CoV-2-specific DNA as well as saliva as a sample medium can be used for an accurate assay. These proof-of-principle experiments show the potential of MPS based assays for the reliable and fast diagnostics of pathogens like SARS-CoV-2 in a point-of-need fashion without the need of complex sample preparation.


Subject(s)
Biosensing Techniques , COVID-19 , Nucleic Acids , Humans , Magnetic Phenomena , Pandemics , RNA, Viral , SARS-CoV-2 , Sensitivity and Specificity , Spectrum Analysis
9.
EBioMedicine ; 69: 103480, 2021 07.
Article in English | MEDLINE | ID: covidwho-1305232

ABSTRACT

In this article of EBioMedicine, Santosh Renuse and colleagues1 show the relevance of combining immunoaffinity capture with targeted mass spectrometry measurement to detect SARS-CoV-2 nucleocapsid proteins in nasopharyngeal swab samples. The COVID-19 pandemic has confirmed the need to improve the toolbox available to diagnose respiratory infections. Rapid, reliable, and highly specific detection is essential if we are to mount immediate preventive and therapeutic responses. This report stands out from previous studies as it implements immunocapture along with robust validation for a large cohort of subjects. The results presented show that mass spectrometry is definitively at a crossroads for large-scale clinical applications.


Subject(s)
COVID-19 , SARS-CoV-2 , Humans , Mass Spectrometry , Pandemics , Spectrum Analysis
10.
Nucleic Acids Res ; 49(13): 7695-7712, 2021 07 21.
Article in English | MEDLINE | ID: covidwho-1298980

ABSTRACT

The multidomain non-structural protein 3 (Nsp3) is the largest protein encoded by coronavirus (CoV) genomes and several regions of this protein are essential for viral replication. Of note, SARS-CoV Nsp3 contains a SARS-Unique Domain (SUD), which can bind Guanine-rich non-canonical nucleic acid structures called G-quadruplexes (G4) and is essential for SARS-CoV replication. We show herein that the SARS-CoV-2 Nsp3 protein also contains a SUD domain that interacts with G4s. Indeed, interactions between SUD proteins and both DNA and RNA G4s were evidenced by G4 pull-down, Surface Plasmon Resonance and Homogenous Time Resolved Fluorescence. These interactions can be disrupted by mutations that prevent oligonucleotides from folding into G4 structures and, interestingly, by molecules known as specific ligands of these G4s. Structural models for these interactions are proposed and reveal significant differences with the crystallographic and modeled 3D structures of the SARS-CoV SUD-NM/G4 interaction. Altogether, our results pave the way for further studies on the role of SUD/G4 interactions during SARS-CoV-2 replication and the use of inhibitors of these interactions as potential antiviral compounds.


Subject(s)
COVID-19/virology , Coronavirus Papain-Like Proteases/metabolism , G-Quadruplexes , Protein Interaction Domains and Motifs , SARS-CoV-2 , Amino Acid Sequence , Coronavirus Papain-Like Proteases/chemistry , Humans , Ligands , Models, Molecular , Protein Binding , Protein Conformation , Recombinant Proteins/chemistry , Recombinant Proteins/metabolism , Spectrum Analysis , Structure-Activity Relationship , Virus Replication
11.
Front Public Health ; 9: 604093, 2021.
Article in English | MEDLINE | ID: covidwho-1291712

ABSTRACT

Novel coronavirus (COVID-19) was discovered in Wuhan, China in December 2019, and has affected millions of lives worldwide. On 29th April 2020, Malaysia reported more than 5,000 COVID-19 cases; the second highest in the Southeast Asian region after Singapore. Recently, a forecasting model was developed to measure and predict COVID-19 cases in Malaysia on daily basis for the next 10 days using previously-confirmed cases. A Recurrent Forecasting-Singular Spectrum Analysis (RF-SSA) is proposed by establishing L and ET parameters via several tests. The advantage of using this forecasting model is it would discriminate noise in a time series trend and produce significant forecasting results. The RF-SSA model assessment was based on the official COVID-19 data released by the World Health Organization (WHO) to predict daily confirmed cases between 30th April and 31st May, 2020. These results revealed that parameter L = 5 (T/20) for the RF-SSA model was indeed suitable for short-time series outbreak data, while the appropriate number of eigentriples was integral as it influenced the forecasting results. Evidently, the RF-SSA had over-forecasted the cases by 0.36%. This signifies the competence of RF-SSA in predicting the impending number of COVID-19 cases. Nonetheless, an enhanced RF-SSA algorithm should be developed for higher effectivity of capturing any extreme data changes.


Subject(s)
COVID-19 , China , Humans , Malaysia , SARS-CoV-2 , Singapore , Spectrum Analysis
12.
Int J Mol Sci ; 22(12)2021 Jun 17.
Article in English | MEDLINE | ID: covidwho-1282513

ABSTRACT

Novel antiviral nanotherapeutics, which may inactivate the virus and block it from entering host cells, represent an important challenge to face viral global health emergencies around the world. Using a combination of bioorthogonal copper-catalyzed 1,3-dipolar alkyne/azide cycloaddition (CuAAC) and photoinitiated thiol-ene coupling, monofunctional and bifunctional peptidodendrimer conjugates were obtained. The conjugates are biocompatible and demonstrate no toxicity to cells at biologically relevant concentrations. Furthermore, the orthogonal addition of multiple copies of two different antiviral peptides on the surface of a single dendrimer allowed the resulting bioconjugates to inhibit Herpes simplex virus type 1 at both the early and the late stages of the infection process. The presented work builds on further improving this attractive design to obtain a new class of therapeutics.


Subject(s)
Antiviral Agents/pharmacology , Dendrimers/pharmacology , Glycoproteins , Herpesvirus 1, Human , Peptides/pharmacology , Viral Proteins , Amino Acid Sequence , Animals , Antiviral Agents/chemistry , CHO Cells , Cell Line , Cell Survival/drug effects , Chemical Phenomena , Chemistry Techniques, Synthetic , Chromatography, High Pressure Liquid , Cricetulus , Dendrimers/chemistry , Glycoproteins/chemistry , Herpesvirus 1, Human/metabolism , Microbial Sensitivity Tests , Molecular Structure , Peptides/chemistry , Spectrum Analysis , Viral Proteins/chemistry
13.
Nanoscale ; 13(22): 10133-10142, 2021 Jun 14.
Article in English | MEDLINE | ID: covidwho-1249216

ABSTRACT

Efficient point-of-care diagnosis of severe acute respiratory syndrome-corovavirus-2 (SARS-CoV-2) is crucial for the early control of novel coronavirus infections. At present, polymerase chain reaction (PCR) is primarily used to detect SARS-CoV-2. Despite the high sensitivity, the PCR process is time-consuming and complex which limits its applicability for rapid testing of large-scale outbreaks. Here, we propose a rapid and easy-to-implement approach for SARS-CoV-2 detection based on surface enhanced infrared absorption (SEIRA) spectroscopy. The evaporated gold nano-island films are used as SEIRA substrates which are functionalized with the single-stranded DNA probes for specific binding to selected SARS-CoV-2 genomic sequences. The infrared absorption spectra are analyzed using the principal component analysis method to identify the key characteristic differences between infected and control samples. The SEIRA-based biosensor demonstrates rapid detection of SARS-CoV-2, completing the detection of 1 µM viral nucleic acids within less than 5 min without any amplification. When combined with the recombinase polymerase amplification treatment, the detection capability of 2.98 copies per µL (5 aM) can be completed within 30 min. This approach provides a simple and economical alternative for COVID-19 diagnosis, which can be potentially useful in monitoring and controlling future pandemics in a timely manner.


Subject(s)
COVID-19 , Nucleic Acids , COVID-19 Testing , Humans , Nucleic Acid Amplification Techniques , RNA, Viral , SARS-CoV-2 , Sensitivity and Specificity , Spectrum Analysis
14.
Talanta ; 228: 122211, 2021 Jun 01.
Article in English | MEDLINE | ID: covidwho-1078202

ABSTRACT

The characterisation of individual nanoparticles by single particle ICP-MS (SP-ICP-MS) has paved the way for the analysis of smallest biological systems. This study suggests to adapting this method for single viruses (SV) identification and counting. With high resolution multi-channel sector field (MC SF) ICP-MS records in SV detection mode, the counting of master and key ions can allow analysis and identification of single viruses. The counting of 2-500 virial units can be performed in 20 s. Analyses are proposed to be carried out in Ar torch for master ions: 12C+, 13C+, 14N+, 15N+, and key ions 31P+, 32S+, 33S+ and 34S+. All interferences are discussed in detail. The use of high resolution SF ICP-MS is recommended while options with anaerobic/aerobic atmospheres are explored to upgrade the analysis when using quadrupole ICP-MS. Application for two virus types (SARS-COV2 and bacteriophage T5) is investigated using time scan and fixed mass analysis for the selected virus ions allowing characterisation of the species using the N/C, P/C and S/C molar ratio's and quantification of their number concentration.


Subject(s)
COVID-19 , RNA, Viral , Humans , Mass Spectrometry , SARS-CoV-2 , Spectrum Analysis
15.
Sci Total Environ ; 770: 144725, 2021 May 20.
Article in English | MEDLINE | ID: covidwho-1046138

ABSTRACT

In March 2020, COVID-19 was officially classified as a pandemic and as a consequence people have adopted strenuous measures to prevent infection, such as the wearing of PPE and self-quarantining, with no knowledge of when the measures will no longer be necessary. Coronavirus has long been known to be non-infectious when airborne; however, studies are starting to show that the virus can infect through airborne transmission and can remain airborne for a significant period of time. In the present study, a spark-induced plasma spectroscopy was devised to characterize the air propagation of the virus in real-time. The risk of air propagation was evaluated in terms of changes in virus concentration with respect to distance traveled and measurement time. Thus, our study provides a benchmark for performing real-time detection of virus propagation and instantaneous monitoring of coronavirus in the air.


Subject(s)
COVID-19 , Humans , Pandemics , Plasma , SARS-CoV-2 , Spectrum Analysis
16.
Molecules ; 25(23)2020 Nov 26.
Article in English | MEDLINE | ID: covidwho-954930

ABSTRACT

Filtration systems used in technical and medical applications require components for fine particle deep filtration to be highly efficient and at the same time air permeable. In high efficiency filters, nonwoven meshes, which show increased performance based on small fiber diameters (e.g., using nanofibers), can be used as fine particle filter layers. Nanofiber nonwoven meshes made by electrospinning of spider silk proteins have been recently shown to exhibit required filter properties. Needle-based electrospinning, however, is limited regarding its productivity and scalability. Centrifugal electrospinning, in contrast, has been shown to allow manufacturing of ultrathin polymer nonwoven meshes in an efficient and scalable manner. Here, continuous roll-to-roll production of nonwoven meshes made of recombinant spider silk proteins is established using centrifugal electrospinning. The produced spider silk nanofiber meshes show high filter efficiency in the case of fine particulate matter below 2.5 µm (PM2.5) and a low pressure drop, resulting in excellent filter quality.


Subject(s)
Arthropod Proteins , Filtration , Membranes, Artificial , Nanofibers , Silk , Air Filters , Arthropod Proteins/chemistry , Filtration/methods , Nanofibers/ultrastructure , Spectrum Analysis
17.
Am J Infect Control ; 49(1): 1-7, 2021 01.
Article in English | MEDLINE | ID: covidwho-917194

ABSTRACT

BACKGROUND: Due to COVID-19 and high demand for respirators, some healthcare professionals have been using the Halyard H600 fabric as an alternative to N95 respirators without testing the filtration efficiency of the fabric with established scientific methods. The purpose of this study was to assess the efficiency of the Halyard H600 as a respirator filtering material as compared to the NIOSH-certified N95 and P100 filters, and determine if H600 is a good alternative for respiratory protection for healthcare professionals during the COVID-19 pandemic. METHODS: Three filter types (Halyard H600, N95, and P100) were challenged with salt particles inside an exposure chamber at a flow rate of 43 LPM and relative humidity of 40 ± 2%. N95 and P100 respirator filters were tested initially to establish the validity of the chamber, followed by the Halyard H600 fabric. Particle penetration was measured using an aerosol spectrometer. The filtration efficiency was calculated for different particle sizes by measuring the particle number concentration upstream and downstream of the filter. The pressure drop across the filter materials was measured using a manometer. RESULTS: The efficiency of the P100 for particles ≥250 nm was 100%. The N95 efficiency was 97 ± 1% at 275 nm, 99 ± 0% at 324 nm, and 100% for larger particles. The Halyard H600 fabric had a variable efficiency with an average of 62 ± 28% at 275 nm, 89 ± 8% at 324 nm, and 100% efficiency for particles >450 nm. The pressure drop values for P100 and N95 were 32 and 8 mmH2O, respectively. The Halyard H600 fabric resistance increased dramatically from 30 mmH2O at the start of the exposure to 65 mmH2O after 16-minutes of exposure. CONCLUSION: The high variability in filter efficiency for particles ≤324 nm and the increased fabric breathing resistance demonstrate that the Halyard H600 has an inferior performance and is not a good substitute for N95 and P100. Thus, the use of the Halyard H600 fabric for respiratory protection is not recommended.


Subject(s)
Air Filters , COVID-19/prevention & control , Materials Testing , Respiratory Protective Devices , Textiles , COVID-19/transmission , Humans , N95 Respirators , Particle Size , Pressure , SARS-CoV-2 , Spectrum Analysis , Sterilization
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