Sensitivity and colour intensity enhancement in lateral flow immunoassay tests by adjustment of test line position

Asiaei, Sasan; Bidgoli, Mostafa Rabbani; Zadehkafi, Ali; Saderi, Narges; Siavashi, Majid

doi:10.1016/j.cca.2018.10.001

Cited by 12 publications

(6 citation statements)

References 27 publications

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“…The further it is placed from the conjugate pad, the more time is allowed for the labelled detection bioreceptors and the target to interact, thus increasing the number of possible immunecomplexes to be captured onto the test line. 164 The only requirement for the control line is that it must be positioned after the test line, since it should confirm successful flow of the sample front until the end of the strip. Usually, the test line is dispensed 12-13 mm from the origin of a 60 mm strip, while the control line is 4 mm behind the test line.…”

Section: Membranementioning

confidence: 99%

Tutorial: design and fabrication of nanoparticle-based lateral-flow immunoassays

et al. 2020

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Lateral flow assays (LFA) are quick, simple and cheap assays to analyse a variety of samples at the point of care or in the field, making them one of the most widespread biosensors currently available. They have been successfully employed for the detection of a myriad of different targets (ranging from atoms up to whole cells) in all type of samples (including water, blood, foodstuff and environmental samples). Their operation relies on the capillary flow of the sample within a series of sequential pads with different functionalities aiming to generate a signal indicating the absence/presence (and, in some cases, the concentration) of the analyte of interest. In order to have a user-friendly operation, their development requires the optimization of multiple, interconnected parameters that may overwhelm new developers. In this Tutorial we provide the readers with: 1) the basic knowledge to understand the principles governing an LFA and to take informed decisions during lateral flow strip design and fabrication, 2) a roadmap for optimal LFA development independent of the specific application, 3) a step by step example protocol for the assembly and operation of an LF strip for the detection of Human Immunoglobulin G and 4) an extensive troubleshooting section addressing the most frequent issues in designing, assembling and using LFAs.

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Section: Membranementioning

confidence: 99%

Tutorial: design and fabrication of nanoparticle-based lateral-flow immunoassays

et al. 2020

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“…10 μL of sample was dispensed and the movement of fluid through the porous medium was recorded in real time. At each runway direction, the average flow velocity was measured on the pad for at-least four consecutive equally spaced distances, (Asiaei et al 2018 ), and the result was used as a normal inflow velocity of 5 mm/sec as a boundary condition. The boundary conditions applied to each part of the μPADs are illustrated in (Table 1 ).…”

Section: Methodsmentioning

confidence: 99%

“…For quantifying the amount of nitrite, an image was taken from the device after the test, and the analyses of the presence of nitrite were performed by image processing algorithms developed using MATLAB (Choobbari et al 2020 ). The color intensity was measured according to the scanned images' RGB color codes (Rhouma et al 2009 ; Asiaei et al 2018 ). The performance of the five geometries, as mentioned above, is assessed by image colorimetry processing.…”

Section: Methodsmentioning

confidence: 99%

Nitrite enhanced detection from saliva by simple geometrical modifications of paper-based micromixers

Mollaie

Asiaei

Aryan

2022

Microfluid Nanofluid

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Dysregulation of nitric oxide (NO) and it’s two relatively stable metabolites, nitrite, and nitrate, in SARS-CoV-2, are reported in infected populations, especially for nitrates levels > 68.4 μmol/L. In this paper, we measure the abnormal presence of nitrite in the saliva by developing a cheap μPAD for colorimetric detection through the modified Griess reaction. This includes a diazotization reaction between nitrite and Griess reagent, including Sulfanilamide and N-Naphthyl-ethylenediamine in an acidic medium, causing a pink Azo compound. The modifications are suggested by a numerical method model that couples the mass flux with the porosity medium equations (convection, diffusion and, dispersion) that improves the mixing process. The mixing index was quantified from the concentration deviation method via simulation of a homogeneous two-phase flow in a porous environment. Five μPAD designs were fabricated to verify the simulation results of mixing enhancement on the Griess reactants in saliva samples. The investigated geometries include straight, helical, zig–zag, square wave, and inclined jagged shapes fabricated by direct laser writing, suitable for low cost, mass fabrication. Inclined jagged micromixer exhibited the best performance with up to 40% improvement compared with the simple straight geometry. Deliberate geometrical modifications, exemplified here in a jagged micromixer on paper, cut the limit of detection (LOD) by at least half without impacting the linear detection range.

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“…Development methods based on silver staining or silver deposition on AuNPs LFTS for increasing the sensitivity of analysis were also reported. − Several other similar methods are also being implemented to enhance the sensitivity of the LFTS by using cotton thread-embedded papers or alkaline phosphatase or by varying the test line position on the LFTS …”

Section: Nanoparticle-based Lateral Flow Test Stripsmentioning

confidence: 99%

“…70−72 Several other similar methods are also being implemented to enhance the sensitivity of the LFTS by using cotton thread-embedded papers 73 or alkaline phosphatase 74 or by varying the test line position on the LFTS. 75…”

Section: Nanoparticle-based Lateral Flow Test Stripsmentioning

confidence: 99%

Nanopaper Biosensors at Point of Care

et al. 2022

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In this review, we provide an overview of the nanopaper biosensors used for point of care (POC) diagnostics in various fields such as biomedical, environmental, food safety, and agriculture. The lateral flow assays (LFAs) comprising nanoparticles have drawn the interest of researchers due to their high sensitivity, low cost, lower time consumption, lack of equipment, and easy handling characteristics. These assays have become an integral part of the health sector all over the world over a short time period and are extensively being engaged in diagnosis of viral infections in regions low on resources. A large number of innovative approaches have been introduced in making these test-strips or nanopaper biosensors as quickly as possible, because of their ease of operation, cheaper cost, and quick results, even with the simplest setups or in pathological laboratories, etc. Keeping all this in mind, we have reviewed the nanoparticles based lateral flow test strips (LFTS), their composition, working methods, reaction mechanisms, detection methods, and applications in different fields. We also provide an overview of paper-based microfluidic analytical devices (μPADs) and our perspective about the future trends which may facilitate understanding their applications.

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Sensitivity and colour intensity enhancement in lateral flow immunoassay tests by adjustment of test line position

Cited by 12 publications

References 27 publications

Tutorial: design and fabrication of nanoparticle-based lateral-flow immunoassays

Tutorial: design and fabrication of nanoparticle-based lateral-flow immunoassays

Nitrite enhanced detection from saliva by simple geometrical modifications of paper-based micromixers

Nanopaper Biosensors at Point of Care

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