Nanomaterial based biosensors are emerging as sensitive, specific, efficient and rapid diagnostic tools for the detection of pathogenic microorganisms in biodefense and diagnostics. This research demonstrates the novel application of a nanostructured material in the dual function of a magnetic concentrator and a transducer in biosensor devices. The nanostructured materials are synthesized from aniline monomer made electrically active by acid doping coating the surface of gamma iron oxide cores. The synthesized electrically active polyaniline coated magnetic (EAPM) nanoparticles are adapted in antibody based and DNA based biosensors for the detection of Bacillus anthracis as a model pathogen. The antibody based detection involves immunomagnetic concentration of targets using biologically modified EAPM nanoparticles followed by their direct application to a charge transfer biosensor. Experimental results indicate that the biosensor is able to detect B. anthracis spores at concentrations as low as 4.2 × 10² spores per ml in 16 min. The DNA based detection mechanism encompasses sandwiched hybridization of DNA targets onto probe labeled EAPM nanoparticles which is succeeded by electrochemical detection of the EAPM DNA hybrids on screen printed carbon electrodes. The sensitivity of the DNA biosensor is assessed to be 0.01ng/μl of PCR amplified B. anthracis pag A gene fragment in a total detection time of 60 min.