Abstract
Paper-based lateral-flow immunoassays (LFIAs) have achieved considerable commercial success and their impact in diagnostics is continuously growing. LFIA results are often obtained by visualizing by the naked eye color changes in given areas, providing a qualitative information about the presence/absence of the target analyte in the sample. However, this platform has the potential to provide ultrasensitive quantitative analysis for several applications. Indeed, LFIA is based on well-established immunological techniques, which have known in the last year great advances due to the combination of highly sensitive tracers, innovative signal amplification strategies and last-generation instrumental detectors. All these available progresses can be applied also to the LFIA platform by adapting them to a portable and miniaturized format. This possibility opens countless strategies for definitively turning the LFIA technique into an ultrasensitive quantitative method. Among the different proposals for achieving this goal, the use of enzyme-based immunoassay is very well known and widespread for routine analysis and it can represent a valid approach for improving LFIA performances. Several examples have been recently reported in literature exploiting enzymes properties and features for obtaining significative advances in this field. In this review, we aim to provide a critical overview of the recent progresses in highly sensitive LFIA detection technologies, involving the exploitation of enzyme-based amplification strategies. The features and applications of the technologies, along with future developments and challenges, are also discussed.
Highlights
Since their invention in the 1980s [1] and the launch on the market in 1984 with the pregnancy test by Unipath, a Unilever spin out at Colworth (UK), Lateral Flow Immunoassys (LFIAs) have become very popular for low-cost, easy-to-use, rapid testing in point-of-care (POC) applications [2,3]
This review aims to present the major recent achievements in the field of enzymebased LFIAs showing their advantages and weaknesses as well as the possibilities for future development
A still open issue is the delivery of the enzyme substrate, which requires an additional step in comparison to conventional visual LFIA systems
Summary
Since their invention in the 1980s [1] and the launch on the market in 1984 with the pregnancy test by Unipath, a Unilever spin out at Colworth (UK), Lateral Flow Immunoassys (LFIAs) have become very popular for low-cost, easy-to-use, rapid testing in point-of-care (POC) applications [2,3]. By measuring the signals in correspondence of the T- and C-lines and signal correction with respect to background signals, the concentration of the target analyte can be obtained by interpolation on a pre-stored calibration curve [15] In this context, numerous optical LFIA devices were commercially proposed, along with their dedicated portable readers, for different applications, such as medical diagnostics [16], food safety [17], environmental monitoring [18], and veterinary diagnostics [19]. LFIAs based on the magnetic response of magnetic-NPs offer several attractive features over other sensing modalities [32,33] They show very low detection limits and no background signals, since biological specimens (e.g., urine, serum and blood) are free from magnetic interferents. This review aims to present the major recent achievements in the field of enzymebased LFIAs showing their advantages and weaknesses as well as the possibilities for future development
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