Ratiometric Fluorescent Lateral Flow Immunoassay for Point-of-Care Testing of Acute Myocardial Infarction.

Early and rapid diagnosis of acute myocardial infarction (AMI) is of exceptional significance in the control of cardiovascular diseases. Herein we report the development of a highly sensitive ratiometric fluorescent lateral flow immunoassay (RFLFIA) strip for rapid and accurate detection of AMI biomarker, namely heart-type fatty acid binding protein (H-FABP). The RFLFIA strip works in terms of ratiometric change of fluorescence signal, arising from blending of fluorescence emitted by two composite nanostructures conjugated to capture and probe antibodies and inner filter effect of gold nanoparticles. In conjunction with using custom smartphone-based analytical device and tonality analysis, quantitative detection of H-FABP was achieved with a low limit of detection at 0.21 ng mL -1 . In addition, the RFLFIA strip can generate a visually distinguishable green-to-red color change around the threshold concentration of H-FABP (6.2 ng mL -1 ), thus allowing the semi-quantitative diagnosis by the naked eye with a high accuracy and reproducibility. Thanks to unique advantages of the ratiometric fluorescence strategy, the RFLFIA strip shows analytical performance superior to conventional fluorescence strip and comparable to clinical latex agglutination test, thus holding the potentiality in point-of-care testing and at-home self-testing diagnosis.