Lateral flow assays (LFAs) are the technology behind low-cost, simple, rapid and portable detection devices popular in biomedicine, agriculture, food and environmental sciences. This review presents an overview of the principle of the method and the critical components of the assay, focusing on lateral flow immunoassays. This type of assay has recently attracted considerable interest because of its potential to provide instantaneous diagnosis directly to patients. The range and interpretation of results and parameters used for evaluation of the assay will also be discussed. The main advantages and disadvantages of LFAs will be summarized and relevant future improvements to testing devices and strategies will be proposed. Finally, the major recent advances and future diagnostic applications in the LFA field will be explored.

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Lateral flow assays (LFAs) enable the simple and rapid detection and quantification of analytes and is popular for point-of-care (PoC), point-of-use and outdoor testing applications. LFAs typically depend on antibody or nucleic acid based recognition. We present the innovative concept of a LFA using lectins in the role of the biorecognition element. Lectins are a special kind of glycan-binding protein and the lectin-based LFA herein described was developed for the determination of the glycosylation of free prostate specific antigen (PSA). PSA is routinely used as a biomarker of prostate cancer (PCa) and the glycosylation status of PSA is a more specific marker of disease progress than only the PSA level. Using the lectin-based LFA we were able to detect α-2,6 sialic acid present in fPSA using Sambucus nigra (SNA) lectin. As a negative control, we employed Maackia amurensis lectin II (MAA II) which specifically binds α-2,3 sialic acid. The novel approach presented here can be applied to a wide range of biomarkers that have a significant impact on clinical diagnosis and prognosis, providing an alternative to standard lectin-based assays. The assay uses commercial components and is easily performed by applying a sample to the sampling pad on the lectin-based LFA strip, with results obtained within 10 minutes.

Aberrant Squamous Cell Carcinoma Antigen (SCCA) expression is an early hepatocarcinogenetic event and circulating SCCA-IgM complexes are elevated in most HCC patients. We evaluated whether serum SCCA-IgM levels can identify HCV +ve cirrhotic patients at low HCC risk. In this retrospective study we enrolled 29 cirrhotic patients in whom serum SCCA-IgM was measured 8 - 69 months (median 31) before HCC diagnosis, and 28 cirrhotic patients who remained HCC- free, with SCCA-IgM measured 15 - 68 months (median 48) before the study end. The best discriminating value of SCCA-IgM was calculated and tested in predicting HCC diagnosis within 12, 24 and 36 months. Sensitivity analysis, considering different HCC incidence, was conducted to identify the patient subgroup with an annual cancer risk below the threshold of a cost-effective semiannual surveillance with ultrasound. Cumulative HCC incidence at 12, 24 and 36 months was 7.0%, 15.7% and 26.3%, respectively. SCCA-IgM levels were higher in HCC than in cirrhotic patients [median: 381 (95% C.I.: 50 - 5289) vs. 100 (70 - 493) AU/mL, P = 0.005]. The SCCA-IgM value ≤ 200 AU/mL accurately identified patients at low risk of HCC development in the subsequent year (sensitivity 75%, specificity 62%, positive predictive value 13% and negative predictive value 97%). Considering an annual HCC incidence ≤ 3%, patients with SCCA-IgM ≤ 200 AU/mL (60% of the whole patients) had an HCC risk below the accepted threshold of a cost-effective surveillance (1.5%). In conclusion, provided that our provocative results are confirmed in larger studies, SCCA-IgM serum measurement could permit implementation of a two step (with different costs) surveillance: an initial serological surveillance, based on the annual monitoring of this biomarker, and the conventional surveillance by semiannual US when SCCA-IgM becomes >200 AU/mL. This could improve the cost/effectiveness of surveillance of HCV infected patients at risk of HCC