Immunomagnetic Separation and Impedance Measurement for Rapid Detection of Avian Influenza Virus
A method for specific and rapid detection of H5 subtype avian influenza virus was developed based on immunomagnetic separation coupled with impedance measurement.The biotin-labeled anti-H5 monoclonal antibodies were immobilized onto the streptavidin-coated magnetic nanobeads to separate and concentrate avian influenza virus H5N1.Impedance measurement was performed by the gold interdigitated array microelectrodes.Impedance magnitude increased with the increase of the concentration of H5N1 virus in the sample solution at the frequency of 100 kHz.The effects of antibody concentration,immunoreaction time and magnetic separation time were investigated and the optimized conditions were 0.25 g/L antibody,60 min immunoreaction time and 3 min magnetic separation time.A linear relationship between the logarithmic value of concentration of H5N1 virus and the value of impedance signal was found in pure virus sample with concentration range of 21-24 HA unit per 50 μL and in swab sample with concentration of 20-24 HA unit per 50 μL.The detection limits in pure virus sample and swab sample were 0.5 HA unit per 50 μL and 2 HA unit per 50 μL,respectively.