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

Abstract

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.

Paper-Based Biosensors: Frontiers in Point-of-Care Detection of COVID-19 Disease

“…The sample solution is added to a "sample pad" at one end of the strip and flows by capillarity through a polymeric membrane strip, on which biomolecules, which are able to interact with the analyte, are immobilized. Finally, it reaches the "conjugate pad", which contains the specific antibodies to the target analyte, usually conjugated with colored or fluorescent NPs [62][63][64][65][66][67][68][69]. The target analyte/conjugated antibody complex then flows along the strip through the nitrocellulose membrane, where specific biological components (antibodies or antigens) are fixed in particular zones, called "test lines".…”

“…There has been a continuous improvement in LFA techniques, leading to increased sensitivity and specificity. New approaches are in development, such as signal amplification by the introduction of nanomaterials with novel physicochemical properties [45,67], or specific enzymes [128] in the assay platform, sample concentration [60,129] and fluidic control strategies [130][131][132].…”

The Microbiome Meets Nanotechnology: Opportunities and Challenges in Developing New Diagnostic Devices

“…These assays employ signal amplifiers conjugated to bioreceptors (e.g., antibodies, nucleic acids or enzymes), which enable recognition of the target analyte(s) ( Figure A). [ 60 ]…”

Electrochemical diagnostics of infectious viral diseases: Trends and challenges

“…Other review articles have summarized the sensor systems constructed for the detection of different viruses using simple device-based approaches ( Cheng et al, 2009 ), nano-electronic devices ( Yeom, 2011 ), bioanalytical microsystems ( Yadav et al, 2010 ), integrated sensor systems ( Dincau et al, 2017 ), microfluidic system ( Sin et al, 2014 ), paper-based microfluidic system ( Deka et al, 2020 ; Gong and Sinton, 2017 ), POC devices ( Tram et al, 2016 ), lab-on-a-chip technologies ( Zhu et al, 2020 ), piezoelectric, magnetostrictive ( Narita et al, 2020 ), DNA microarray ( Fesseha and Tilahun, 2020 ), and clustered regulatory interspaced short palindromic repeats (CRISPR) systems ( Hass et al, 2020 ; Kostyusheva et al, 2020 ; Strich and Chertow, 2018 ). On the other hand, some review articles have focused on the recognition matrix comprising Au nanoparticles ( Draz and Shafiee, 2018 ; Franco et al, 2015 ; Halfpenny and Wright, 2010 ), Quantum dots (QD) ( Halfpenny and Wright, 2010 ; Yeom, 2011 ), carbon nanotubes/nanowires ( Yeom, 2011 ), Aptamers ( Acquah et al, 2016 ; Hong et al, 2012 ; Labib and Berezovski, 2013 ), label-free and labeled immuno assays ( Parolo et al, 2020b ; Sin et al, 2014 ), molecularly imprinted polymers (MIP) ( Cui et al, 2020 ; Yang et al, 2020 ), and other nanomaterials ( Kizek et al, 2015 ; Mokhtarzadeh et al, 2017 ; Nasrollahzadeh et al, 2020 ). Some of the review articles have focused on the transduction methods in virus diagnosis based on optical and/or electrochemical techniques ( Cheng and Toh, 2013 ; Cui et al, 2020 ; Khristunova et al, 2020 ; Krejcova et al, 2014 ; Ozer et al, 2020 ; Xu et al, 2019 ; Yang et al, 2020 ).…”