ORIGINAL PAPER Synthesis and characterization of PANI-Fe x -Al 1 - x (x = 0.8, 0.6) nanocomposite thin films for identification of pathogenic Leptospira Jamal Jurait 1 & Huda Abdullah 1 & Siti Khairani Bejo 2 & Iskandar Yahya 1 & Norshafadzila Mohammad Naim 1 Received: 28 November 2016 /Revised: 10 July 2017 /Accepted: 18 October 2017 # Springer-Verlag GmbH Germany 2017 Abstract Polyaniline Fe-Al nanocomposite thin films were fabricated on a glass substrate using a spin coating technique. The detection and identification of pathogenic Leptospira by measuring a current-voltage (I-V) and electrochemical imped- ance spectroscopy (EIS) showed a relationship of concentra- tion bacteria vs. current and vs. impedance. Structural proper- ties and morphology of nanocomposites were evaluated using energy-dispersive X-ray spectroscopy (EDX), atomic force microscope (AFM), transmission electron microscopy (TEM), and field emission scanning electron microscopy (FESEM). TEM and FESEM images showed the uniformed distribution of nanoparticles of Fe-Al alloy. The AFM images showed the roughness of the thin film surface to perform at a higher sensitivity. The EDX analysis confirms the presence of the polyaniline, Fe, and Al elements in the substrate. This bacterial biosensor has also been tested with a bacteria con- centration, ranging from 1 × 10 5 to 1 × 10 8 CFU mL -1 , in wet samples for disease preventions. Keywords Pathogenic Leptospira . Polyaniline . I-Vand EIS measurement . Structural properties Introduction Environmental pollution is the main source of health risks, which has become a global health matter, especially in devel- oping countries. Leptospirosis is known as a zoology disease that concerns many people in the world [1]. Leptospira bac- teria is transferred either via a direct contact together with rat urine and body fluids of an infected animal or via indirect contact with contaminated water and soil environments [2, 3]. Basically, leptospirosis disease is caused by rat urine which contains genus Leptospira bacteria. It will cause several health complications such as kidney failure, jaundice, vascular, and internal hemorrhage especially concerning mortality with a gradually increasing trend [4]. Rat urine may contain Leptospira bacteria that can be spread out into water and soil, reservoir, vegetation, and livestock [5]. Generally, the Leptospira bacteria is classified into two species; the first one is known as saprophytic strain of Leptospira bifexa, which poses as a non-fatal health risk, while the other one is pathogenic strain of Leptospira interrogans, which is fatal for humans and animals [1, 3, 5]. Therefore, referring to the life environment of Leptospira bac- teria, it is very important and necessary for the public and authorized members to study the presence of this bacteria and prevent all creatures from infections, especially to guar- antee public health safety. This matter has prompted re- searchers and scientists to study different approaches in the effective detection of Leptospira bacteria. The finding of this study is important for the well-being of those recognized to be at risk such as farmers, veterinarians, abattoir workers, fisher- men, and recreational hobbyists, particularly water [6]. The presence of Leptospira requires diagnoses in the labo- ratory by culturing bacteria from the blood, urine, and tissues using fluorescence markers. Microscopic agglutination test (MAT) method to determine agglutinating antibodies in the * Huda Abdullah huda.abdullah@ukm.edu.my 1 Department of Electrical, Electronic and System Engineering, Faculty of Engineering and Built Environment, University Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia 2 Department of Veterinary Pathology & Microbiology, Faculty of Veterinary Medicine, University Putra Malaysia, UPM, 43400 Serdang, Malaysia Ionics https://doi.org/10.1007/s11581-017-2308-2