Detection of Green-Synthesized Fe3O4/Ag Composite Nanoparticles as Magnetic Labels for GMR-Based Biosensor Applications Dani Muhammad Hariyanto (a), Zurnansyah (a), Nur Aji Wibowo (b), Mahardika Yoga Darmawan (a)(c), Harlina Ardiyanti (a)(c), Nurul Imani Istiqomah (a), and Edi Suharyadi (a*)
(a) Department of Physics, Universitas Gadjah Mada, Yogyakarta, Indonesia
(b) Department of Physics, Universitas Kristen Satya Wacana, Salatiga, Indonesia
(c) Department of Physics, Institut Teknologi Sumatera, Lampung, Indonesia
*Corresponding author: esuharyadi[at]ugm.ac.id
Abstract
In the research of giant magnetoresistance (GMR) biosensing technology, it is crucial to investigate the magnetic labels and their characteristics on the sensor signal performance. This study uses a commercial GMR chip AAL024 equipped with a basic differential amplifier circuit and an arduino microcontroller (AM) for directly detecting green synthesized Fe3O4/Ag composite nanoparticles (NPs) as a magnetic label. The Fe3O4 magnetic nanoparticles (MNPs) were synthesized by a chemical coprecipitation method utilizing Moringa Oleifera extract as a green reducing agent. Meanwhile, surface modification with Ag NPs was conducted to cover the deficiency of Fe3O4, which is easily agglomerated and oxidized. The X ray diffraction results demonstrate that Fe3O4 and Fe3O4/Ag have cubic inverse spinel structure with crystallite size of 5.7 nm and 11.2, respectively. The larger crystallite size obtained explains the successful formation of composites between Fe3O4 MNPs and Ag NPs. The scanning electron microscopy images illustrate the granular shapes with non homogeneous distribution on the surface of Fe3O4 and Fe3O4/Ag composite, while energy dispersive X ray spectrums confirm the presence of Fe element percentage of 70.9% and 61.7% for both investigated samples. The magnetic properties study shows that saturation magnetization of Fe3O4/Ag composite is 43.2 emu/gr, and it is lower than Fe3O4 MNPs. Furthermore, sensor performance is examined by sensitivity and limit of detection (LOD) obtained. The sensor sensitivity of Fe3O4 is 5.67 mV(mg/mL), and Fe3O4/Ag with different Ag concentrations are in the range of 3.99 until 4.24 mV(mg/mL). The smallest LOD value is obtained by Fe3O4/Ag 60 mM with 0.75 mg/mL. Therefore, these promising performances demonstrate the potential of green synthesized Fe3O4/Ag composite NPs as a suitable candidate for magnetic labels in GMR biosensor applications.
Keywords: Giant Magnetoresistance- Green-Synthesized- Fe3O4/Ag- Magnetic Labels- Commercial GMR
Topic: Instrumentation, Acoustics and Signal Processing
