scholarly journals All-Dielectric Metasurface Fluorescence Biosensors for High-Sensitivity Antibody/Antigen Detection

ACS Nano ◽  
2020 ◽  
Vol 14 (12) ◽  
pp. 17458-17467
Author(s):  
Masanobu Iwanaga
Keyword(s):  
High Sensitivity ◽  
Antigen Detection ◽  
Dielectric Metasurface

scholarly journals All-Dielectric Metasurface for Sensing Microcystin-LR

Electronics ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1363
Author(s):  
Binze Ma ◽  
Ao Ouyang ◽  
Juechen Zhong ◽  
Pavel A. Belov ◽  
Ravindra Kumar Sinha ◽  
...  
Keyword(s):  
Quality Factor ◽  
Bound States ◽  
High Sensitivity ◽  
Concentration Limit ◽  
Specific Recognition ◽  
Low Concentrations ◽  
Freshwater Bodies ◽  
Toxic Pollutant ◽  
Small Change ◽  
Dielectric Metasurface

Sensing Microcystin-LR (MC-LR) is an important issue for environmental monitoring, as the MC-LR is a common toxic pollutant found in freshwater bodies. The demand for sensitive detection method of MC-LR at low concentrations can be addressed by metasurface-based sensors, which are feasible and highly efficient. Here, we demonstrate an all-dielectric metasurface for sensing MC-LR. Its working principle is based on quasi-bound states in the continuum mode (QBIC), and it manifests a high-quality factor and high sensitivity. The dielectric metasurface can detect a small change in the refractive index of the surrounding environment with a quality factor of ~170 and a sensitivity of ~788 nm/RIU. MC-LR can be specifically identified in mixed water with a concentration limit of as low as 0.002 μg/L by a specific recognition technique for combined antigen and antibody. Furthermore, the demonstrated detection of MC-LR can be extended to the identification and monitoring of other analytes, such as viruses, and the designed dielectric metasurface can serve as a monitor platform with high sensitivity and high specific recognition capability.

scholarly journals A new method for transfer of polyethylene glycol-embedded tissue sections to silanated slides for immunocytochemistry.

1991 ◽  
Vol 39 (4) ◽  
pp. 537-540 ◽  
Author(s):  
K X Gao ◽  
J D Godkin
Keyword(s):  
Polyethylene Glycol ◽  
Colloidal Gold ◽  
Cell Structure ◽  
High Sensitivity ◽  
Antigen Detection ◽  
New Method ◽  
Retinol Binding Protein ◽  
Tissue Sections ◽  
Glass Slides ◽  
Structural Preservation

Polyethylene glycol (PEG) is an excellent embedding medium for immunohistochemical studies. It provides structural preservation superior to frozen sections and increased sensitivity of antigen detection compared with paraffin sections. One limitation of PEG embedment is that PEG sections are difficult to handle and adhere poorly to glass slides. Here we present a simple and effective method for embedding tissues in PEG and transferring the resultant sections onto silanated glass slides. In addition, a method for silver enhanced colloidal gold immunostaining was combined with common dye staining to demonstrate the excellent structure preservation and sensitive antigen detection. Bovine chorionic membrane was fixed with Bouin's fixative, embedded in polyethylene glycol (PEG) 1500, cut into 5-microns sections, flattened over agarose blocks (10 x 10 x 2 mm3), and blotted onto Digene silanated slides. Slides were then washed in PBS, which removed the PEG and agarose blocks. Tissue sections were immunocytochemically stained with dilute antiserum raised in a rabbit against purified bovine placental retinol binding protein (bpRBP). Sections were washed and incubated with 1-nm colloidal gold-labeled goat anti-rabbit IgG. The immunogold particles were enhanced by silver staining (IGSS). Specimens were observed and photographed with an Olympus epipolarization microscope. The new method offered excellent morphological preservation of cell structure and the epipolarization microscopy provided high sensitivity for detection of specific immunogold-silver particles.

scholarly journals Algorithm of Laboratory Diagnostics Applied for Examination of Ixodic Ticks for Tularemia

2012 ◽  
pp. 79-81
Author(s):  
A. A. Zaitsev ◽  
O. A. Gnusareva ◽  
B. V. Solodovnikov ◽  
N. S. Tsareva ◽  
V. V. Ostapovich ◽  
...  
Keyword(s):  
Immunosorbent Assay ◽  
High Sensitivity ◽  
Diagnostic Value ◽  
Antigen Detection ◽  
Laboratory Analysis ◽  
Enzyme Linked Immunosorbent Assay ◽  
Laboratory Diagnostics ◽  
Primary Screening ◽  
Species Specific

Put forward is the algorithm of laboratory diagnostics applied for examination of Ixodic ticks (IT) for tularemia. It involves carrying out primary screening of tick suspensions for the presence of species-specific fragments of DNA and antigen. It is recommended that laboratory analysis starts with PCR, taking into account its high sensitivity and diagnostic value. Pools with positive PCR tests are subjected to verification by means of enzyme-linked immunosorbent assay and immune-chromatographic tests. In case of tularemia antigen detection, these pools of IT are examined with the help of biological or bacteriological techniques to isolate the agent.

scholarly journals Clinical Application of a New SARS-CoV-2 Antigen Detection Kit (Colloidal Gold) in the Detection of COVID-19

Diagnostics ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 995
Author(s):  
Evangelos Terpos ◽  
Ioannis Ntanasis-Stathopoulos ◽  
Miha Skvarč
Keyword(s):  
Sensitivity And Specificity ◽  
Colloidal Gold ◽  
False Negative ◽  
High Sensitivity ◽  
Antigen Detection ◽  
Disease Course ◽  
Ct Value ◽  
Nasal Swabs ◽  
Precise Diagnosis ◽  
Positive Cycle

The precise diagnosis of COVID-19 is of outmost importance in order to effectively treat patients and prevent SARS-CoV-2 transmission. Herein, we evaluated the sensitivity and specificity of the COVID-19 Antigen Detection Kit (Colloidal Gold—CG) compared with PCR in nasopharyngeal and nasal samples. A total of 114 positive and 244 negative nasopharyngeal specimens confirmed by PCR were used in this comparative study. When the PCR positive Cycle Threshold (Ct) value was ≤25, CG sensitivity was 100%. When the PCR positive Ct value was ≤33, CG sensitivity was 99%. When the PCR positive Ct value was ≤40, CG sensitivity was 89.47%. Regarding nasal swabs, a total of 109 positive and 250 negative specimens confirmed by PCR were used. When the PCR positive Ct value was ≤25, CG sensitivity was 100%. When the PCR positive Ct value was ≤33, CG sensitivity was 96.12%. When the PCR positive Ct value was ≤37, CG sensitivity was 91.74%. Specificity was above 99% regardless of the Ct value of PCR positivity for both nasopharyngeal and nasal specimens. Overall, the CG showed high sensitivity and specificity when the PCR Ct value was less than 33. Therefore, CG can be used for screening early in the disease course. Confirmatory PCR is essential when a false negative result is suspected.

scholarly journals Evaluation of Two Rapid Antigenic Tests for the Detection of SARS-CoV-2 in Nasopharyngeal Swabs

2021 ◽  
Vol 10 (13) ◽  
pp. 2774
Author(s):  
Ysaline Seynaeve ◽  
Justine Heylen ◽  
Corentin Fontaine ◽  
François Maclot ◽  
Cécile Meex ◽  
...  
Keyword(s):  
Real Life ◽  
Rapid Test ◽  
High Sensitivity ◽  
Antigen Detection ◽  
Ease Of Use ◽  
University Hospital ◽  
Performance Criteria ◽  
World Health ◽  
Diagnostic Tools ◽  
The University

(1) Background: In the current context of the COVID-19 crisis, there is a need for fast, easy-to-use, and sensitive diagnostic tools in addition to molecular methods. We have therefore decided to evaluate the performance of newly available antigen detection kits in “real-life” laboratory conditions. (2) Methods: The sensitivity and specificity of two rapid diagnostic tests (RDT)—the COVID-19 Ag Respi-Strip from Coris Bioconcept, Belgium (CoRDT), and the coronavirus antigen rapid test cassette from Healgen Scientific, LLC, USA (HeRDT)—were evaluated on 193 nasopharyngeal samples using RT-PCR as the gold standard. (3) Results: The sensitivity obtained for HeRDT was 88% for all collected samples and 91.1% for samples with Ct ≤ 31. For the CoRDT test, the sensitivity obtained was 62% for all collected samples and 68.9% for samples with Ct ≤ 31. (4) Conclusions: Despite the excellent specificity obtained for both kits, the poor sensitivity of the CoRDT did not allow for its use in the rapid diagnosis of COVID-19. HeRDT satisfied the World Health Organization’s performance criteria for rapid antigen detection tests. Its high sensitivity, quick response, and ease of use allowed for the implementation of HeRDT at the laboratory of the University Hospital of Liège.

scholarly journals Using the near field optical trapping effect of a dielectric metasurface to improve SERS enhancement for virus detection

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Cameron F. Kenworthy ◽  
L. Pjotr Stoevelaar ◽  
Andrew J. Alexander ◽  
Giampiero Gerini
Keyword(s):  
Raman Spectroscopy ◽  
Enhancement Factor ◽  
Optical Trapping ◽  
Near Field ◽  
Virus Detection ◽  
High Sensitivity ◽  
Surface Enhanced Raman Spectroscopy ◽  
Crystal Nucleation ◽  
Temperature Sensitive ◽  
Dielectric Metasurface

AbstractIn this paper, we report the effect of optical trapping on the enhancement factor for Raman spectroscopy, using a dielectric metasurface. It was found that a higher enhancement factor (up to 275%) can be obtained in a substrate immersed in water, where particles are freee to move, compared to a dried substrate, where the particles (radius $$r=9$$ r = 9  nm, refractive index $$n=1.58$$ n = 1.58 ) are fixed on the surface. The highest enhancement is obtained at low concentrations because, this case, the particles are trapped preferentially in the regions of highest electric field (hotspots). For high concentrations, it was observed that the hotspots become saturated with particles and that additional particles are forced to occupy regions of lower field. The dielectric metasurface offers low optical absorption compared to conventional gold substrates. This aspect can be important for temperature-sensitive applications. The method shows potential for applications in crystal nucleation, where high solute supersaturation can be achieved near the high-field regions of the metasurface. The high sensitivity for SERS (surface-enhanced Raman spectroscopy) at low analyte concentrations makes the proposed method highly promising for detection of small biological particles, such as proteins or viruses.

scholarly journals Head-to-head comparison of four antigen-based rapid detection tests for the diagnosis of SARS-CoV-2 in respiratory samples

2020 ◽  
Author(s):  
Thomas Weitzel ◽  
Paulette Legarraga ◽  
Mirentxu Iruretagoyena ◽  
Gabriel Pizarro ◽  
Valeska Vollrath ◽  
...  
Keyword(s):  
Test Performance ◽  
High Performance ◽  
High Sensitivity ◽  
Turnaround Time ◽  
Antigen Detection ◽  
Diagnostic Methods ◽  
Significant Heterogeneity ◽  
Rt Pcr ◽  
Viral Loads ◽  
Development And Validation

AbstractIn the context of the Covid-19 pandemic, the development and validation of rapid and easy-to-perform diagnostic methods are of high priority. We compared the performance of four rapid antigen detection tests for SARS-CoV-2 in respiratory samples. Immunochromatographic SARS-CoV-2 assays from RapiGEN, Liming bio, Savant, and Bioeasy were evaluated using universal transport medium containing naso-oropharyngeal swabs from suspected Covid-19 cases. The diagnostic accuracy was determined in comparison to SARS-CoV-2 RT-PCR. A total of 111 samples were included; 80 were RT-PCR positive. Median patients’ age was 40 years, 55% were female, and 88% presented within the first week after symptom onset. The evaluation of the Liming bio assay was discontinued due to insufficient performance. The overall sensitivity values of RapiGEN, Liming bio, and Bioeasy tests were 62.0% (CI95% 51.0–71.9), 16.7% (CI95% 10.0–26.5), and 85.0% (CI95% 75.6–91.2), respectively, with specificities of 100%. Sensitivity was significantly higher in samples with high viral loads (RapiGEN, 84.9%; Bioeasy, 100%). The study highlighted the significant heterogeneity of test performance among evaluated assays, which might have been influenced by the use of a non-validated sample material. The high sensitivity of some tests demonstrated that rapid antigen detection has the potential to serve as an alternative diagnostic method, especially in patients presenting with high viral loads in early phases of infection. This is particularly important in situations with limited access to RT-PCR or prolonged turnaround time. Further comparative evaluations are necessary to select products with high performance among the growing market of diagnostic tests for SARS-CoV-2.

scholarly journals Self-testing for the detection of SARS-CoV-2 infection with rapid antigen tests

2021 ◽  
Author(s):  
J. J.J.M. Stohr ◽  
V. F. Zwart ◽  
G. Goderski ◽  
A. Meijer ◽  
C. R.S. Nagel-Imming ◽  
...  
Keyword(s):  
Sensitivity And Specificity ◽  
False Negative ◽  
Positive Culture ◽  
High Sensitivity ◽  
High Specificity ◽  
Antigen Detection ◽  
Qrt Pcr ◽  
Ct Value ◽  
Viral Culture ◽  
Self Testing

AbstractIntroductionSelf-testing for COVID-19 infection with lateral flow assay SARS-CoV-2 rapid antigen detection tests (RDT), provides rapid results and could enable frequent and extensive testing in the community, thereby improving the control of SARS-CoV-2. The objective of this study is to evaluate the performance of self-testing using RDT without assistance.MethodsParticipants visiting a municipal SARS-CoV-2 testing centre, received self-testing kits containing either the BD Veritor System (BD RDT) or Roche SARS-CoV-2 antigen detection test (Roche RDT). Oro-nasopharyngeal swabs were collected from the participants for qRT-PCR testing. As a proxy for contagiousness, viral culture was performed on a selection of qRT-PCR positive samples to determine the Ct-value at which the chance of a positive culture was dropping below 0.5 (Ct-value cut-off). Sensitivity and specificity of self-testing were compared to qRT-PCR with a Ct-value below the Ct value cut-off. Determinants independently associated with a false-negative self-test result were determined.ResultsA total of 3,215 participants were included (BD RDT n=1604; Roche RDT n=1611). Sensitivity and specificity of self-testing compared to the qRT-PCR results with Ct-value below the Ct-value cut-off was 78.0% (95% CI:72.5-82.8) and 99.4% (95%CI: 99.0-99.6) respectively. Determinants independently associated with a false-negative self-testing results were: higher age, low viral load and finding self-testing difficult.DiscussionSelf-testing using currently available RDT’s has a high specificity and relatively high sensitivity to identify individuals with a high probability of contagiousness. The performance of two tests were comparable. This application has the potential for frequent and extensive testing which may be an aid to lift restrictions to society while controlling the spread of SARS-CoV-2.

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