A flexible gradient lateral flow immunochromatographic assay for qualitative, semi-quantitative, and quantitative determination of serum amyloid A

J Immunol Methods. 2023 Oct 24:113574. doi: 10.1016/j.jim.2023.113574. Online ahead of print.ABSTRACTSerum amyloid A (SAA) is an acute-phase protein produced in response to inflammatory proteins during infections, inflammation, trauma, surgery, cancer, and other conditions. Early and accurate detection of SAA is necessary for diagnosis and monitoring of disease progression. To meet this need, we developed a gradient lateral flow immunoassay test strip using Au nanoparticles as signal reporters. The test strip has three test (T1, T2, and T3) lines with progressively decreasing concentrations of SAA antibody, enabling the determination of high, medium, and low concentrations of SAA in serum. The test strip results were analyzed using three distinct readout methods, each with different sensitivity, accuracy, and precision for SAA concentration measurements. Qualitative judgment is based on the color of the T1 line. Semi-quantitative assessment of SAA concentration is determined by the number of colored T-lines. Specifically, color development in T1 line alone indicates a concentration range of 10-50 μg/mL, while T1 and T2 lines together indicate a range of 50-100 μg/mL, and development in all three lines (T1, T2, and T3) indicates a concentration of >100 μg/mL. Quantitative analysis was performed using either smartphone imaging or image scanning with ImageJ software. By using a five-parameter logistic function, we found a strong correlation (R2 = 0.998) between the ratio o...
Source: Journal of Immunological Methods - Category: Allergy & Immunology Authors: Source Type: research