It’s time for more targeted use of lateral flow tests for covid-19

For the control of immunity in COVID-19 survivors and vaccinated subjects there is an urgent need for reliable and rapid serological assays. Based on samples from 63 COVID-19 survivors up to seven months after symptom onset, and on 50 serum samples taken before the beginning of the pandemic, we compared the performance of three commercial immunoassays for the detection of SARS-CoV-2 IgA and IgG antibodies (Euroimmun SARS-COV-2 IgA/IgG, Mikrogen recomWell SARS-CoV-2 IgA/IgG, and SERION ELISA agile SARS-CoV-2 IgA/IgG) and three rapid lateral flow (immunochromatographic) tests (Abbott Panbio COVID-19 IgG/IgM, NADAL COVID-19 IgG/IgM, and Cleartest Corona 2019-nCOV IgG/IgM) with a plaque-reduction neutralization test (PRNT50) representing the gold standard. Fifty-seven out of 63 PCR-confirmed COVID-19 patients (90%) showed neutralizing antibodies. The sensitivity of the seven assays ranged from 7.0% to 98.3%, the specificity from 86.0% to 100.0%. Only one commercial immunoassay showed a sensitivity and specificity of greater than 98%.

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Gold nanoparticle-streptavidin conjugates for rapid and efficient screening of aptamer function in lateral flow sensors using novel CD4-binding aptamers identified through Crossover-SELEX

The Analyst ◽

10.1039/d0an00634c ◽

2020 ◽

Vol 145 (15) ◽

pp. 5180-5193 ◽

Cited By ~ 2

Author(s):

Tamika Fellows ◽

Lance Ho ◽

Shane Flanagan ◽

Ronen Fogel ◽

Dupe Ojo ◽

...

Keyword(s):

Gold Nanoparticle ◽

Reporting System ◽

Lateral Flow ◽

Lateral Flow Assay ◽

Flow Sensors ◽

Target Proteins ◽

Lateral Flow Tests ◽

Efficient Screening

Adaptation of conventional lateral flow tests: demonstration of a lateral flow assay in which gold nanoparticle conjugates, when bound to aptamers, serve as a reporting system to screen novel aptamers for the ability to bind to target proteins.

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Eliminating viscosity bias in lateral flow tests

Microsystems & Nanoengineering ◽

10.1038/s41378-021-00296-5 ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Daniel M. Kainz ◽

Bastian J. Breiner ◽

Susanna M. Früh ◽

Tobias Hutzenlaub ◽

Roland Zengerle ◽

...

Keyword(s):

Point Of Care ◽

Lateral Flow ◽

Nitrocellulose Membrane ◽

Widespread Application ◽

Significant Challenge ◽

Microfluidic Flow ◽

Flow Test ◽

Lateral Flow Test ◽

Lateral Flow Tests ◽

Viscosity Dependence

AbstractDespite the widespread application of point-of-care lateral flow tests, the viscosity dependence of these assay results remains a significant challenge. Here, we employ centrifugal microfluidic flow control through the nitrocellulose membrane of the strip to eliminate the viscosity bias. The key feature is the balancing of the sample flow into the cassette of the lateral flow test with the air flow out of the cassette. A viscosity-independent flow rate of 3.01 ± 0.18 µl/min (±6%) is demonstrated for samples with viscosities ranging from 1.1 mPas to 24 mPas, a factor greater than 20. In a model human IgG lateral flow assay, signal-intensity shifts caused by varying the sample viscosity from 1.1 mPas to 2.3 mPas could be reduced by more than 84%.

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Analysis of free chlorine in aqueous solution at very low concentration with lateral flow tests

Scientific Reports ◽

10.1038/s41598-019-53687-0 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 5

Author(s):

K. Uta Schwenke ◽

Dieter Spiehl ◽

Marcel Krauße ◽

Laura Riedler ◽

Anna Ruppenthal ◽

...

Keyword(s):

Reaction Zone ◽

Sample Volume ◽

Lateral Flow ◽

Free Chlorine ◽

Test Strips ◽

Flow Test ◽

Lateral Flow Test ◽

Lateral Flow Tests ◽

User Friendly ◽

Dip Test

AbstractTest strips are convenient tools for rapid, semi-quantitative analysis of a variety of parameters by dipping them for a few seconds in a sample solution followed by a simple colorimetric read-out. Their sensitivity is mainly determined by the reactivity of the test dyes on the reaction zone and is not sufficient for some applications. The detection limit of commercially available free chlorine test strips, for example, is at present not low enough to confirm the absence of this analyte as disinfectant in rinsing solutions after disinfection or to control required residual amounts of chlorine in drinking water. Therefore, we developed a user-friendly lateral flow test which is capable to detect very low amounts of free chlorine. The latter relies on a larger sample volume passing the reaction zone as compared to simple dip test strips. An amount of as low as 0.05 ppm chlorine can, however, only be detected if oxidation stable flow test substrates are used. The eventually developed flow test reaches a 10x higher sensitivity than a commercial dip test. The result is obtained within 4–5 min flow time, whereby no action is required by the user during this analysis time.

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