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

2019 ◽  
Vol 9 (1) ◽  
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.

scholarly journals Quantum Dot-Based Lateral Flow Test Strips for Highly Sensitive Detection of the Tetanus Antibody

ACS Omega ◽  
2019 ◽  
Vol 4 (4) ◽  
pp. 6789-6795 ◽  
Author(s):  
Junyan Wang ◽  
Hong-Min Meng ◽  
Juan Chen ◽  
Juanzu Liu ◽  
Lin Zhang ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Lateral Flow ◽  
Sensitive Detection ◽  
Test Strips ◽  
Flow Test ◽  
Highly Sensitive ◽  
Lateral Flow Test ◽  
Highly Sensitive Detection

scholarly journals Eliminating viscosity bias in lateral flow tests

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%.

Multiplex Lateral-Flow Test Strips Fabricated by Two-Dimensional Shaping

2008 ◽  
Vol 1 (1) ◽  
pp. 124-129 ◽  
Author(s):  
Erin M. Fenton ◽  
Monica R. Mascarenas ◽  
Gabriel P. López ◽  
Scott S. Sibbett
Keyword(s):  
Lateral Flow ◽  
Two Dimensional ◽  
Test Strips ◽  
Flow Test ◽  
Lateral Flow Test

scholarly journals Modification of a nitrocellulose membrane with nanofibers for sensitivity enhancement in lateral flow test strips

RSC Advances ◽  
2021 ◽  
Vol 11 (43) ◽  
pp. 26493-26501
Author(s):  
Xue Wang ◽  
Chao-Hua Xue ◽  
Dong Yang ◽  
Shun-Tian Jia ◽  
Ya-Ru Ding ◽  
...  
Keyword(s):  
Detection Limit ◽  
Sensitivity Enhancement ◽  
Lateral Flow ◽  
Fibrous Membrane ◽  
Nitrocellulose Membrane ◽  
Test Strips ◽  
Flow Test ◽  
New Type ◽  
Lateral Flow Test

We constructed a new type of ICT strip by replacing the conventional nitrocellulose membrane with an electrospin-coated nitrocellulose (ENC) fibrous membrane, and the ICT strip could obtain an HCG detection limit of 0.22 mIU mL−1, and an LH detection limit of 0.36 mIU mL−1.

scholarly journals Controlling Capillary Flow Rate on Lateral Flow Test Substrates by Tape

Micromachines ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 562
Author(s):  
Zhiqing Xiao ◽  
Yuqian Yang ◽  
Xingwei Zhang ◽  
Weijin Guo
Keyword(s):  
Flow Rate ◽  
Rate Control ◽  
Capillary Flow ◽  
Lateral Flow ◽  
Average Flow Rate ◽  
Average Flow ◽  
Flow Test ◽  
Lateral Flow Test ◽  
Lateral Flow Tests ◽  
Flow Rate Control

Controlling capillary flow rate of sample liquid is of high interest for lateral flow tests, since the flow rate can affect the dissolution and mixing of the immunoreagents and the efficiency of immunoreactions. Here we develop a facile method to adjust the capillary flow rate on lateral flow test substrates by using tape to cover the surface of substrates. We test this method on the traditional lateral flow test substrate—nitrocellulose and a novel lateral flow test substrate—synthetic paper, which is a porous media made by interlocked off-stoichiometry thiol-ene (OSTE) micropillars. We found that after the surface was covered by tape, the average flow rate decreased to 61% of the original flow rate on nitrocellulose, while the average flow rate increased to at least 320% of the original flow rate on synthetic paper. More interesting, besides the increase of flow rate, the volume capacity of synthetic paper also increases after covered by tape. Furthermore, we investigated the influence of length and position of tape on the capillary flow rate for nitrocellulose. A longer tape will lead to a smaller flow rate. The influence of tape of same length on the flow rate is bigger when the tape is placed closer to the loading pad. These results can help in the flow rate control on lateral flow test substrates, and potentially improve the performance of lateral flow tests.

scholarly journals Enlargement of Gold Nanoparticles for Sensitive Immunochromatographic Diagnostics of Potato Brown Rot

Sensors ◽  
2019 ◽  
Vol 19 (1) ◽  
pp. 153 ◽  
Author(s):  
Shyatesa C. Razo ◽  
Natalia A. Panferova ◽  
Vasily G. Panferov ◽  
Irina V. Safenkova ◽  
Natalia V. Drenova ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Detection Limit ◽  
Brown Rot ◽  
Lateral Flow ◽  
Lateral Flow Immunoassay ◽  
Test Strips ◽  
Flow Test ◽  
Test Zone ◽  
Lateral Flow Test ◽  
Potato Brown Rot

Lateral flow immunoassay (LFIA) is a convenient tool for rapid field-based control of various bacterial targets. However, for many applications, the detection limits obtained by LFIA are not sufficient. In this paper, we propose enlarging gold nanoparticles’ (GNPs) size to develop a sensitive lateral flow immunoassay to detect Ralstonia solanacearum. This bacterium is a quarantine organism that causes potato brown rot. We fabricated lateral flow test strips using gold nanoparticles (17.4 ± 1.0 nm) as a label and their conjugates with antibodies specific to R. solanacearum. We proposed a signal enhancement in the test strips’ test zone due to the tetrachloroauric (III) anion reduction on the GNP surface, and the increase in size of the gold nanoparticles on the test strips was approximately up to 100 nm, as confirmed by scanning electron microscopy. Overall, the gold enhancement approach decreased the detection limit of R. solanacearum by 33 times, to as low as 3 × 104 cells∙mL–1 in the potato tuber extract. The achieved detection limit allows the diagnosis of latent infection in potato tubers. The developed approach based on gold enhancement does not complicate analyses and requires only 3 min. The developed assay together with the sample preparation and gold enlargement requires 15 min. Thus, the developed approach is promising for the development of lateral flow test strips and their subsequent introduction into diagnostic practice.

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