Ganesha Antarnusa, Ajinkya Nene, Pinaka Elda Swastika, Yus Rama Denny, Rofiqul Umam, Vishal R. Panse, Heriyanto Syafutra, Irzaman
The sensitivity of giant magnetoresistance (GMR) biosensors can be significantly enhanced by optimizing the properties of superparamagnetic nanoparticles used as magnetic labels. In this study, Fe3O4-based superparamagnetic nanoparticles coated with tetraethyl orthosilicate (TEOS) with varying TEOS volumes (1, 2, and 3 mL) were synthesized via a co-precipitation method. Structural and morphological analyses using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and selected area electron diffraction (SAED) confirmed the successful formation of Fe3O4@TEOS with a core–shell structure, while vibrating sample magnetometer (VSM) characterization revealed a decrease in saturation magnetization as the volume of the TEOS coating increased. The stability of Fe3O4@TEOS dispersions was evaluated using zeta potential measurements, indicating an increase in electrostatic repulsion, which prevents particle agglomeration. To investigate its impact on biosensor performance, superparamagnetic nanoparticle samples were tested on a GMR sensor setup. The results showed that the optimal operating point of the GMR sensor was at a bias magnetic field of 1.7 Oe, with a limit of detection (LOD) of 1μg/mL for all samples. Higher TEOS volumes reduced magnetization but enhanced dispersibility, thus balancing sensitivity and stability of the sensor. These findings suggest that TEOS-coated Fe3O4 nanoparticles offer a promising approach to enhance the stability and sensitivity of GMR biosensors, making them suitable for highly sensitive bio-detection applications. © 2025 Elsevier Ltd
Department of Physics Education, Universitas Sultan Ageng Tirtayasa, Jalan Ciwaru Raya, Cipare, Banten, Serang, 42117, Indonesia; Nanomaterials laboratory, Universitas Sultan Ageng Tirtayasa, Jalan Raya Palka KM 3 Sindangsari, Banten, Serang, 42163, Indonesia; Department of Mechanics and Aerospace Engineering, Southern University of Science and Technology, Shenzhen, 518055, China; Department of Physics Education, Faculty of Mathematics and Natural Sciences, Universitas Negeri Yogyakarta, Jalan Colombo No 1, Karangmalang, Yogyakarta, 55281, Indonesia; Photovoltaics, Functional Device, and Artificial Intelligent Laboratory, Universitas Sultan Ageng Tirtayasa, Jalan Jenderal Sudirman, KM 3, Kotabumi, Banten, Cilegon, 42435, Indonesia; Faculty of Life and Environmental Sciences, University of Tsukuba, Ibaraki, 305-8577, Japan; Late B. S. Arts, Prof. N. G. Sci and A. G. Commerce College, Maharashtra, Sakharkherda, 443202, India; Applied Physics Division, Department of Physics, Faculty of Mathematics and Natural Science, IPB University, Bogor, 16680, Indonesia
