Magnetic nanoparticle-based immunoassay for rapid detection of influenza infections by using an integrated microfluidic system

Magnetic manganese ferrite (MnFe2O4) nanoparticles with approximately 100 nm in diameter were used to improve the performance of an immunoassay for detecting influenza infections. The synthesized nanoparticles were tested for long-term storage to confirm the stability of their thermal decomposition process. Then, an integrated microfluidic system was developed to perform the diagnosis process automatically, including virus purification and detection. To apply these nanoparticles for influenza diagnosis, a micromixer was optimized to reduce the dead volume within the microfluidic chip. Furthermore, the mixing index of the micromixer could achieve as high as 97% in 2 seconds. The optical signals showed that this nanoparticle-based immunoassay with dynamic mixing could successfully achieve a detection limit of influenza as low as 0.007 HAU. When compared with the 4.5-mu m magnetic beads, the optical signals of the MnFe2O4 nanoparticles were twice as sensitive. Furthermore, five clinical specimens were tested to verify the usability of the developed system. From the Clinical Editor: In this study, magnetic manganese ferrite nanoparticles were used to improve the performance of a novel immunoassay for the rapid and efficient detection of influenza infections. (C) 2014 Elsevier Inc. All rights reserved.