Development of a Reliable Assay of Eco-friendly Fe 3 O 4 @Ag Nanocomposite-Based Giant Magnetoresistance Sensor

• Published in: Journal of the Electrochemical Society 2024-11, Vol.171 (11), p.117501
• Main Authors: Wibowo, Nur Aji, Hariyanto, Dani Muhammad, Zurnansyah, Darmawan, Mahardika Yoga, Ardiyanti, Harlina, Istiqomah, Nurul Imani, Nakamura, Kohji, Suharyadi, Edi
• Format: Article
• Language: English
• ISSN: 0013-4651; 1945-7111
• DOI: 10.1149/1945-7111/ad8a8f

For the development of green magnetic-based immunoassay devices, the rapid and reliable assay method of eco-friendly magnetic labels with a lower energy requirement is vital. This work proposes a green-synthesized Fe 3 O 4 @Ag magnetic label assay system using GMR chips and a simple microcontroller-based data acquisition tool. Optical analysis shows the successful synthesis of Fe 3 O 4 @Ag with the assistance of Moringa oleifera (MO) extract as a reducing and stabilizing agent. Meanwhile, according to characterization, MO-assisted green-synthesized Fe 3 O 4 @Ag nanocomposites feature cubic inverse spinel structures and ferromagnetic characteristics that possess multi-domain structures. The sensor system generates an intense signal, varying from tens to hundreds of millivolts, allowing for its detection using a simple microcontroller system. The sensor exhibits a stable and reliable response to the increase in the concentration of Fe 3 O 4 @Ag nanocomposite, even though it is subjected to weak magnetic field induction. Furthermore, the introduction of Ag on the surface of Fe 3 O 4 nanoparticles succeeded in optimizing the detection features, as evidenced by the lower limit of detection compared to detecting the bare Fe 3 O 4 . The GMR-based sensor, featuring a simple microcontroller structure and an eco-friendly Fe 3 O 4 @Ag nanocomposite as a magnetic label, exhibits significant potential as a rapid and reliable green biosensor that is power-efficient.