Sensitivity, specificity and difficulty of operation are the main 3 factors that are important for the development and choosing lateral flow immunoassays (LFIA) strips. It is hoped that we can get a good balance point of the factors, is get as lower limits of detection (LOD) as possible while maintaining the operation procedures easy to run.
Now we can provide a silver based method to amplify sensitivity 3-10 folds. In previous research, for the small molecule, PSA was used as model analyte, the LOD was as low as 0.1 ng/mL. And for big analytes, Ralstonia solanacearum, a kind of plant pathogen, 2×102 CFU/mL was the LOD reported. And the total time for the assay is only less than 20 min, and the steps are all very easy to operate.
Comparison of the test lines obtained in a Lateral Flow Immunoassay Dipstick for PSA (0.5 ng/mL). A) Antibody labelled with AuNP (40nm). B) Silver enhancement signal using the immersion method. C means control line and T means test line.
Another advantage of our silver enhancement method is that this kit show interesting features in colorimetric, electrical and electrochemical properties for quantitative biosensing. Thus it can be modified to link to electrochemical label for immunoassays, to explore the coupling of the strip with an electrochemical transducer in future work.
Rodríguez M O, Covián L B, García A C, et al. Silver and gold enhancement methods for lateral flow immunoassays[J]. Talanta, 2016, 148: 272-278.
Panferov V G, Safenkova I V, Varitsev Y A, et al. Development of the sensitive lateral flow immunoassay with silver enhancement for the detection of Ralstonia solanacearum in potato tubers[J]. Talanta, 2016, 152: 521-530.
Related reading: Lateral Flow Test Kits