Pandemic Influenza Detection by Electrically Active Magnetic Nanoparticles and Surface Plasmon Resonance.

Influenza A virus (FLUAV), the causative agent of influenza infection, has received extensive attention due to the recent swine-origin H1N1 pandemic. FLUAV has long been the cause of annual epidemics as well as less frequent but more severe global pandemics. Here, we describe a biosensor utilizing electrically active magnetic (EAM) polyaniline-coated nanoparticles as the transducer in an electrochemical biosensor for rapidly identifying FLUAV strains based on receptor specificity, which will be useful to monitor animal influenza infections and to characterize pandemic potential of strains that have transmitted from animals to humans. Pandemic potential requires human-to-human transmissibility, which is dependent upon FLUAV hemagglutinin (HA) specificity for host glycan receptors. Avian FLUAV preferentially bind to α2,3-linked receptors, while human FLUAV bind to α2,6-linked receptors. EAM nanoparticles were prepared by synthesizing aniline monomer around gamma iron (III) oxide (γ-Fe2O3) cores, yielding 25-100-nm diameter nanoparticles that were structurally characterized by transmission electron microscopy and electron diffraction. The EAM nanoparticles were coated with monoclonal antibodies specific to H5N1 (A/Vietnam/1203/04). Specificity of binding between glycans and H5 was demonstrated. The biosensor results were correlative to supporting data from a surface plasmon resonance assay that characterized HA/glycan binding and α-H5 antibody activity. This novel study applies EAM nanoparticles as the transducer in a specific, portable, easy-to-use biosensor with great potential for disease monitoring and biosecurity applications.

Nanoparticle-based biosensor for the detection of emerging pandemic influenza strains.

Electrically active magnetic (EAM) nanoparticles, consisting of aniline monomer polymerized around gamma iron(III) oxide (γ-Fe(2)O(3)) cores, serve as the basis of a direct-charge transfer biosensor developed for detection of surface glycoprotein hemagglutinin (HA) from the Influenza A virus (FLUAV) H5N1 (A/Vietnam/1203/04). H5N1 preferentially binds α2,3-linked host glycan receptors. EAM nanoparticles were immunofunctionalized with antibodies against target HA. Glycans preincubated with HA in 10% mouse serum were incubated with anti-HA-EAM complexes. The anti-HA-EAM complexes effectively acted as immunomagnetic separator of HA from mouse serum matrix. EAM nanoparticles served as the biosensor transducer for cyclic voltammetry measurements. The polyaniline was made electrically active by hydrochloric acid doping. Experimental results indicate that the biosensor is able to detect recombinant H5 HA at 1.4 µM in 10% mouse serum, with high specificity for H5 as compared to H1 (H1N1 A/South Carolina/1/18). This novel design applies EAM nanoparticles in a sensitive, specific, affordable, and easy-to-use biosensor with applications in disease monitoring and biosecurity.