Highly sensitive fluorescent immunosensor for detection of influenza virus based on Ag autocatalysis

A versatile, ultrasensitive immunosensor for detection of influenza virus was designed by combining silver nanoparticles (Ag NPs) labeled antibodies with indirect fluorescence. A new technology using Ag-S covalent binding was applied for antibody labeling. Influenza A (H1N1) virus, as a subtype of influenza A virus that was the most common cause of human influenza (flu), was acted as the target antigen using sandwich type-immunoreactions on the high binding ELISA plates. The antibody-labeled Ag NPs were then released by acid solution to produce Ag+ which can catalyze o-phenylenediamine (OPDA) oxidation to produce fluorescence for highly sensitive detection. Under the optimal conditions, it shows good linear relationship between fluorescence intensity and the logarithm of the concentration of H1N1 over the range of 1.0×10−12-1.0×10−8 g mL−1 with a detection limit (LOD, 3σ) of 1.0×10-13 g mL−1. Results indicated that the proposed method give a good sensitivity and simple operation for detecting the influenza virus. This work also provided a promising potential for antigen detection by Ag NPs labeled, and the steps were easy to handle.