Highly Stable Buffer-Based Zinc Oxide/Reduced Graphene Oxide Nanosurface Chemistry for Rapid Immunosensing of SARS-CoV-2 Antigens

The widespread and long-lasting effect of the COVID-19 pandemic has called attention to the significance of technological advances in the rapid diagnosis of SARS-CoV-2 virus. This study reports the use of a highly stable buffer-based zinc oxide/reduced graphene oxide (bbZnO/rGO) nanocomposite coated on carbon screen-printed electrodes for electrochemical immuno-biosensing of SARS-CoV-2 nuelocapsid (N-) protein antigens in spiked and clinical samples. The incorporation of a salt-based (ionic) matrix for uniform dispersion of the nanomixture eliminates multistep nanomaterial synthesis on the surface of the electrode and enables a stable single-step sensor nanocoating. The immuno-biosensor provides a limit of detection of 21 fg/mL over a linear range of 1-10 000 pg/mL and exhibits a sensitivity of 32.07 ohms·mL/pg·mm2 for detection of N-protein in spiked samples. The N-protein biosensor is successful in discriminating positive and negative clinical samples within 15 min, demonstrating its proof of concept used as a Clarity COVID-19 Rapid Test accuracy rapid antigen test.

Communities and testing for COVID-19

  • The response to the COVID-19 epidemic requires people to undertake actions such as mask-wearing or vaccination that also confer benefits to the whole community, and therefore, are akin to public good contributions.
  • This is the case also for participation to the mass testing that took place between November 18th and 25th, 2020 in the South Tyrol region of Italy, where 361,781 out of 500,607 (72.3%) eligible residents volunteered to take a COVID-19 rapid antigen test.
  • We examine the community characteristics that are associated with higher testing rates. Our findings point to a number of key community determinants of people’s willingness to volunteer. Convenience and social capital were important factors.
  • Beyond that, socioeconomic status and religiosity were also both positively related to greater testing, while childhood vaccinations refusal rates show a negative relationship.
Clarity Covid 19 Antigen Test
Clarity Covid 19 Antigen Test

Ultrasensitive assay for saliva-based SARS-CoV-2 antigen detection

  1. Widespread SARS-CoV-2 testing is invaluable for identifying asymptomatic/pre-symptomatic individuals. There remains a technological gap for highly reliable, easy, and quick SARS-CoV-2 diagnostic tests suitable for frequent mass testing. Compared to nasopharyngeal (NP) swab-based tests, saliva-based methods are attractive due to easier and safer sampling. Current saliva-based SARS-CoV-2 rapid antigen tests (RATs) are hindered by limited analytical sensitivity. Here, we report one of the first ultrasensitive, saliva-based SARS-CoV-2 antigen assays with an analytical sensitivity of <0.32 pg/mL, corresponding to four viral RNA copies/µL, which is comparable to that of PCR-based tests.
  2.  Using the novel electrochemiluminescence (ECL)-based immunoassay, we measured the SARS-CoV-2 nucleocapsid (N) antigen concentration in 105 salivas, obtained from non-COVID-19 and COVID-19 patients. We then verified the results with a second, independent cohort of 689 patients (3.8% SARS-CoV-2 positivity rate). We also compared our method with a widely used point-of-care rapid test.
  3. In the first cohort, at 100% specificity, the sensitivity was 92%. Our assay correctly identified samples with viral loads up to 35 CT cycles by saliva-based PCR. Paired NP swab-based PCR results were obtained for 86 cases. Our assay showed high concordance with saliva-based and NP swab-based PCR in samples with negative (<0.32 pg/mL) and strongly positive (>2 pg/mL) N antigen concentrations. In the second cohort, at 100% specificity, sensitivity was also 92%. Our assay is about 700-fold more sensitive than the Abbott Panbio Rapid Test.
We demonstrated the ultrasensitivity and specificity assay and its concordance with PCR. This novel assay is especially valuable when compliance to frequent swabbing may be problematic.

Prevalence of Pfhrp2/3 gene deletions among false negative rapid antigen test results in central India

  • The diagnosis of Plasmodium falciparum malaria is widely dependent on the P. falciparum histidine rich protein 2 (PfHRP2) antigens based rapid diagnostic tests. There are few possible factors like Pfhrp2 polymorphism, Pfhrp2 deletion and density of malaria parasite which can affect the sensitivity of the Pf-HRP2-based RDT. The primary objective of the investigation was to check whether the Pfhrp2 gene deletion is the primary cause of RDT false negative cases.
  • Febrile patients from three districts of Chhattisgarh, India were screened for malaria during 2016-2017 by microscopy and RDT. All microscopy P. falciparum positive samples were validated by PCR. Microscopy positive and RDT negative samples were analyzed for the presence of Exon 2, across Exon 1-2, upstream and downstream of both the Pfhrp2 and Pfhrp3 genes fragment by PCR.
  • Out of 203 screened samples, 85 were detected positive for P. falciparum malaria based on microscopy and PCR. Among these 85 P. falciparum positive samples, 4 samples were observed Pf-HRP2 RDT negative. Although, it signified that the RDTs used were reliable with sensitivity of 95.3% (81/85). 3/4 PfHRP2-RDT negative samples of the P. falciparum isolates exhibited complete deletion of Pfhrp2 and Pfhrp3 genes and one sample was found RDT false negative due to high parasite density.
  • Pfhrp2 and Pfhrp3 deletions that result in false negative RDTs were uncommon in our setting. The continued monitoring of RDTS which results in false negative tests due to Pfhrp2/3 gene deletion is the need of the hour for an effective malaria elimination strategy.

OraSure InteliSwab  Rapid Antigen Test performance with the SARS-CoV-2 Variants of Concern Alpha, Beta, Gamma, Delta, and Omicron

The emergence of SARS-CoV-2 in the human population and the resulting COVID-19 pandemic has led to the development of various diagnostic tests. The OraSure InteliSwab  COVID-19 Rapid Test is a recently developed and FDA emergency use authorized rapid antigen-detecting test that functions as a lateral flow device targeting the nucleocapsid protein. Due to SARS-CoV-2 evolution, there is a need to evaluate the sensitivity of rapid antigen-detecting tests for new variants, especially variants of concern like Omicron.
In this study, the sensitivity of the OraSure InteliSwab Test was investigated using cultured strains of the known variants of concern (VOCs, Alpha, Beta, Gamma, Delta, and Omicron) and the ancestral lineage (lineage A). Based on dilution series in cell culture medium, an approximate limit of detection for each variant was determined.

Accu-Tell COVID-19 IgG/IgM Rapid Test

GEN-B352-20tests Accu test 20 tests

Accu-Tell COVID-19 IgG/IgM Rapid Test

GEN-B352-40tests Accu test 40 tests

COVID-19 IgG/IgM Rapid Test Kit

UNCOV-20 UnScience 20T/kit

Panbio™ COVID-19 Ag Rapid Test Device

41FK10 Abbott 25 Tests/Kit

Panbio™ COVID-19 IgG/IgM Rapid Test

ICO-T402 Abbott 25 Tests/Kit

Panbio™ COVID-19 Ag Rapid Test Device (Nasal)

41FK11 Abbott 25 Tests/Kit

TESTO (Testosterone) ELISA test

19 Biobase 96T/Box

SARS-CoV-2 Antigen Rapid Test Kit

CoV2Ag-1 UnScience 1T

SARS-CoV-2 Antigen Rapid Test Kit

CoV2Ag-25 UnScience 25T/kit

SARS-CoV-2 Rapid Antigen Test Nasal

9901-NCOV-03G Roche Diagnostics 25 Tests/Kit

Human Streptococcus Pneumoniae (SP) Antigen Rapid Test Kit

abx092096-20tests Abbexa 20 tests

Melamine Rapid Test Kit

abx092011-50tests Abbexa 50 tests

NDV rapid test kit

RG15-03 Bionote 1 box

IBD rapid test strip

RG15-04 Bionote 10 boxes

Rabies rapid test strip

RG18-01 Bionote 10 boxes

Avian Influenza Virus Antigen Rapid Test Kit (Colloidal gold)

abx092015-40tests Abbexa 40 tests

Newcastle Disease Virus Antigen Rapid Test Kit (Colloidal gold)

abx092016-40tests Abbexa 40 tests

Human Chlamydia Trachomatis Antigen Rapid Test Kit (Colloidal gold)

abx092049-20tests Abbexa 20 tests

Coronavirus (SARS-Cov-2) Antigen Rapid Test Device (Saliva)

IOV87952 INVBIO 20T/kit

Melamine (MEL) Rapid Test Kit

abx092057-50tests Abbexa 50 tests

Clenbuterol (CLE) Rapid Test Kit

abx092058-50tests Abbexa 50 tests

Ractopamine (RAC) Rapid Test Kit

abx092059-50tests Abbexa 50 tests

Salbutamol (SAL) Rapid Test Kit

abx092060-50tests Abbexa 50 tests

Tetracycline (TCs) Rapid Test Kit

abx092063-50tests Abbexa 50 tests

Sulfonamides (Sas) Rapid Test Kit

abx092064-40tests Abbexa 40 tests

Quinolones (QNs) Rapid Test Kit

abx092065-40tests Abbexa 40 tests

Ciprofloxacin (CPFX) Rapid Test Kit

abx092066-50tests Abbexa 50 tests

Quinolones (QNs) Rapid Test Kit

abx092067-40tests Abbexa 40 tests

Brucella Antibody Rapid Test Kit

abx092069-40tests Abbexa 40 tests

Procalcitonin rapid test (Colloidal Gold)

abx095264-80Units Abbexa 80 Units

Rapid Leishmania Ab Test Kit

RB2104 Bionote 1 box

Rapid PED Ag Test Kit

RG14-01 Bionote 1 box

Avian Influenza H5 Virus Antigen Rapid Test Kit (Colloidal gold)

abx092014-40tests Abbexa 40 tests

Avian Influenza H7 Virus Antigen Rapid Test Kit (Colloidal gold)

abx092017-40tests Abbexa 40 tests

Dynamiker Monkeypox Virus Ag Rapid Test

DNK-2114-1 Dynamiker Biotechnology 20 tests

Chlamydia Rapid Test Device (Swab/Urine)

173-8537306 Abbott 20 Tests/Kit

Clenbuterol Rapid Test Kit (Colloidal gold)

abx092040-50tests Abbexa 50 tests

Ractopamine Rapid Test Kit (Colloidal gold)

abx092042-50tests Abbexa 50 tests

Salbutamol Rapid Test Kit (Colloidal gold)

abx092043-50tests Abbexa 50 tests

Chloramphenicol Rapid Test Kit (Colloidal gold)

abx092045-50tests Abbexa 50 tests

Quinolones Rapid Test Kit (Colloidal gold)

abx092046-50tests Abbexa 50 tests

Sulfonamides Rapid Test Kit (Colloidal gold)

abx092047-50tests Abbexa 50 tests

Tetracycline Rapid Test Kit (Colloidal gold)

abx092048-50tests Abbexa 50 tests

Zearalenone Rapid Test Kit (Colloidal gold)

abx092051-50tests Abbexa 50 tests

Deoxynivalenol Rapid Test Kit (Colloidal gold)

abx092052-50tests Abbexa 50 tests

Deoxynivalenol Rapid Test Kit (Colloidal gold)

abx092053-50tests Abbexa 50 tests

Aflatoxin Rapid Test Kit (Colloidal gold)

abx092054-50tests Abbexa 50 tests

Zearalenone Rapid Test Kit (Colloidal gold)

abx092056-50tests Abbexa 50 tests

Goat Brucella Antibody Rapid Test Kit

abx092070-40tests Abbexa 40 tests

Cow Brucella Antibody Rapid Test Kit

abx092071-40tests Abbexa 40 tests

Pig Parvovirus Antibody Rapid Test Kit

abx092074-50tests Abbexa 50 tests

Fetal Fibronectin rapid test (Colloidal Gold)

abx095261-80Units Abbexa 80 Units

Anigen Rapid FIV Ab Test Kit

RB22-01-DD Bionote 10 tests/Kit

Rapid Bovine Brucella Ab Test Kit

RB23-01-DD Bionote 1 kit/10 tests

Rapid Bovine TB Ab Test Kit

RB23-02-DD Bionote 1 box

Rapid FMD NSP Ab Test Kit

RB28-02-DD Bionote 1 box

Ag rapid CDV Ag Test Kit

RG11-03 Bionote 1 box

Rapid TGE/PED Ag Test Kit

RG14-03 Bionote 1 box

Ag Rapid AIV Ag Test Kit

RG15-01 Bionote 1 box/30 tests

Ag Rapid H5AIV Ag test kit

RG15-05 Bionote 1 box

2019-nCoV IgG/IgM Rapid Test Cassette (Whole Blood/Serum/Plasma)

GEN-402-25tests All test 25 tests

TruStrip RDT Anthrax Protective antigen 83 (PA83) Rapid Test cards, 25/pk

800-100-RDT-25 Alpha Diagnostics 1 pk

GENLISA™ SARS-CoV-2 (Covid-19) Surrogate Virus Neutralization Test (sVNT) ELISA

KBVH400 Krishgen 12 × 8 wells

Furaltadone Metabolite Rapid Test Kit (Colloidal gold)

abx092035-50tests Abbexa 50 tests

Furazolidone Metabolite Rapid Test Kit (Colloidal gold)

abx092036-50tests Abbexa 50 tests

Aminohydantoin Hydrochloride Rapid Test Kit (Colloidal gold)

abx092037-50tests Abbexa 50 tests

Nitrofurazone Metabolite Rapid Test Kit (Colloidal gold)

abx092038-50tests Abbexa 50 tests

Malachite Green Rapid Test Kit (Colloidal gold)

abx092041-10tests Abbexa 10 tests

Phenylethanolamine A Rapid Test Kit (Colloidal gold)

abx092044-50tests Abbexa 50 tests

Aflatoxin B1 Rapid Test Kit (Colloidal gold)

abx092050-50tests Abbexa 50 tests

Aflatoxin B1 Rapid Test Kit (Colloidal gold)

abx092055-50tests Abbexa 50 tests

Human Echovirus (ECHO) IgM Rapid Test Kit

abx092093-20tests Abbexa 20 tests

Human Toxoplasma (TOX) IgG Rapid Test Kit

abx092098-20tests Abbexa 20 tests

Ag Rapid Bov. TB Ab Test Kit

RB23-02 Bionote 1 box

Ag Rapid FMD NSP Ab Test Kit

RB28-02 Bionote 1 box

Ag Rapid CIRD-3 Ag Test Kit

RG11-09 Bionote 1 box

Bionote Rapid AIV Ag_NDV Ag Test Kit

RG15-09 Bionote 1 box

COVID-19 IgG & IgM antibody

GEN-50001-50tests Ring Bio 50 tests

NATtrol Zika Virus Stock (Qualitative) (1 mL)

TEST Zeptometrix 1 mL

TruStrip RDT Testosterone Rapid Test cards, 10/pk

1880-RDT-10 Alpha Diagnostics 1 pk

Human Hepatitis A Virus IgG Rapid Test Kit

abx092012-25tests Abbexa 25 tests

Pseudorabies Virus Antibodies Rapid Test Kit (Colloidal gold)

abx092026-50tests Abbexa 50 tests

Canine Parvovirus Antibodies Rapid Test Kit (Colloidal gold)

abx092032-40tests Abbexa 40 tests

Rabies Virus Antibodies Rapid Test Kit (Colloidal gold)

abx092033-40tests Abbexa 40 tests

Clenbuterol-Ractopamine-Salbutamol Rapid Test Kit (Colloidal gold)

abx092039-40tests Abbexa 40 tests

Cattle and Goat Hydatid Antibody Rapid Test Kit

abx092072-40tests Abbexa 40 tests

Avian Influenza H5N1 Virus Antibody Rapid Test Kit

abx092075-40tests Abbexa 40 tests

Human Chlamydia Pneumoniae (CP) IgG Rapid Test Kit

abx092079-20tests Abbexa 20 tests

Human Chlamydia Pneumoniae (CP) IgM Rapid Test Kit

abx092080-20tests Abbexa 20 tests

Human Mycoplasma Pneumoniae (MP) IgG Rapid Test Kit

abx092081-20tests Abbexa 20 tests

Human Mycoplasma Pneumoniae (MP) IgM Rapid Test Kit

abx092082-20tests Abbexa 20 tests

Human Mycobacterium Tuberculosis (MT) IgG Rapid Test Kit

abx092084-20tests Abbexa 20 tests

Human Helicobacter Pylori (HP) IgG Rapid Test Kit

abx092090-20tests Abbexa 20 tests

Human Enterovirus 71 (EV71) IgM Rapid Test Kit

abx092091-20tests Abbexa 20 tests

Human Hantavirus (HV) IgM / IgG Rapid Test Kit

abx092094-20tests Abbexa 20 tests

Human Rubella Virus (RV) IgG Rapid Test Kit

abx092097-20tests Abbexa 20 tests

Human Rabies Virus (HRV) IgG Rapid Test Kit

abx092100-20tests Abbexa 20 tests

Human Treponema Pallidum (TP) Antibody Rapid Test Kit

abx092101-20tests Abbexa 20 tests

Anticyclic citrullinated peptide antibody rapid test (Colloidal Gold)

abx095260-80Units Abbexa 80 Units

Cardiac Troponin I (cTnI) rapid test (Colloidal Gold)

abx095265-80Units Abbexa 80 Units
The OraSure InteliSwab Test showed an overall comparable performance using recombinant nucleocapsid protein and different cultured variants with recorded limits of detection ranging between 3.77 × 10 5 and 9.13 × 10 5 RNA copies/mL. Finally, the sensitivity was evaluated using oropharyngeal swabs from Syrian golden hamsters inoculated with the 6 VOCs. Ultimately, the OraSure InteliSwab  COVID-19 Rapid Test showed no decrease in sensitivity between the ancestral SARS-CoV-2 strain and any VOCs including Omicron.

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