Dual-layered and double-targeted nanogold based lateral flow immunoassay for influenza virus

We report on a highly sensitive lateral flow immunoassay (LFIA) for influenza A which serves as a model antigen. Gold nanoparticles conjugated to monoclonal antibodies specific to the two most abundant influenza A proteins, nucleoprotein and matrix protein, were used as detector probes. Using this approach, the nucleoprotein and matrix protein in the virion were detected simultaneously. The signal was further amplified via a signal amplification strategy that is making use of two-layered nanogold in combination with a double-targeted detection format. Under optimized conditions, the system is capable of detecting influenza A antigens in infected cells at levels as low as 47 TCID50 center dot mL(-1) (50 % tissue culture infectious dose) within 15 min. Compared to the conventional LFIA based on single-targeted detection, the detection capability of this system is better by a factor of 8 without requiring additional steps or instruments. In addition to its simplicity and rapidity, this LFIA also can detect the target analyte in even complex biological matrix. This proof-of-principle of a dual-layered and double-targeted nanogold-based LFIA is deemed to be useful for developing single-step, rapid, and sensitive tests for screening and diagnosis.