A1 Refereed original research article in a scientific journal
Improved sensitivity and automation of a multi-step upconversion lateral flow immunoassay using a 3D-printed actuation mechanism
Authors: Raiko Kirsti, Nääjärvi Oskari, Ekman Miikka, Koskela Sonja, Soukka Tero, Martiskainen Iida, Salminen Teppo
Publisher: Springer Science and Business Media Deutschland GmbH
Publication year: 2024
Journal: Analytical and Bioanalytical Chemistry
Journal name in source: Analytical and Bioanalytical Chemistry
Volume: 416
Issue: 6
First page : 1517
Last page: 1525
eISSN: 1618-2650
DOI: https://doi.org/10.1007/s00216-024-05156-5
Web address : https://link.springer.com/article/10.1007/s00216-024-05156-5
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/386827691
The development of sensitive point-of-care (POC) assay platforms is of interest for reducing the cost and time of diagnostics. Lateral flow assays (LFAs) are the gold standard for POC systems, but their sensitivity as such is inadequate, for example, in the case of cardiac diagnostics. The performance can be improved by incorporating different steps, such as pre-incubation to prolong the interaction time between sample and reporter for immunocomplex formation, and washing steps for background reduction. However, for POC assays, manual steps by the assay conductor are not desired. In this research, upconverting nanoparticles (UCNPs) were coated with poly(acrylic acid) (PAA) and conjugated to anti-cTnI antibodies, yielding non-clustering particles with low non-specific binding. The performance of cTnI-LFA in the PAA-anti-cTnI-UCNPs was compared to the same UCNPs with a commercial carboxyl surface. A kitchen-timer mechanism was embedded in a 3D-printed housing to produce a low-cost actuator facilitating a timed pre-incubation step for reporter and sample, and a washing step, to enable a multi-step cTnI-LFA with minimized manual labour. PAA-UCNPs showed improved mobility on nitrocellulose compared to those with a commercial surface. The mechanical actuator system was shown to improve sensitivity compared to a labour-intensive multi-step dipstick method, despite pre-incubation occurring during shaking and heating in the dipstick method. The limit of detection decreased from 7.6 to 1.5 ng/L cTnI in human plasma. The presented actuator can be easily modified for sensitivity improvement in the LFA for different analytes via pre-incubation and washing steps. Graphical abstract: [Figure not available: see fulltext.] © 2024, The Author(s).
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