Research Information System
19th International Nanoscience and Nanotechnology Conference (NanoTR-19), Ankara, Turkey, 27 - 29 August 2025, pp.395, (Summary Text)
Ferrofluids, combining magnetic and fluidic properties, find applications in sealing, lubrication, heavy metal adsorption, magnetic resonance imaging
(MRI), targeted drug delivery, hyperthermia, and biosensing. Stabilization of iron oxide nanoparticles (Fe₃O₄) within magnetic colloidal ferrofluids is
critical for long-term functionality and biomedical safety.
In this study, Fe₃O₄ nanoparticles were synthesized via co-precipitation and surface-modified with (3-aminopropyl)triethoxysilane (APTES), stearic acid
(C18:0), oleic acid (C18:1), and undecanoic acid (C11:0). Ferrofluids (0.5–5.0% w/v) were prepared in olive and sunflower oils, stored at +4°C, 25°C, and
40°C, and monitored over one month for stability through color changes and sedimentation. Nanoparticles were characterized pre- and post-modification
using vibrating sample magnetometry (VSM), Fourier-transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). The
displacement of the oil-based ferrofluid layer on a water phase in a two-phase system under a magnetic field (10–35 V, 1 Hz) was investigated at
concentrations of 1%, 2%, and 5% (w/v), using sample volumes of 0.25, 0.5, and 1 mL placed 8 mm from the source.
Results revealed that pure Fe₃O₄ and fatty acid-coated nanoparticles sedimented in both oils from day one, while APTES-coated nanoparticles sedimented
only in olive oil but remained stable in sunflower oil for 28 days. At 0.5–5.0% concentrations, APTES-coated nanoparticles showed no sedimentation for
at least 7 days at 25°C and 37°C, and up to 28 days at +4°C. VSM analysis revealed that Fe₃O₄ nanoparticles possess a saturation magnetization of ≥60
emu/g. FTIR spectra verified fatty acid coatings via characteristic peaks at 2920 and 2850 cm⁻¹. TEM images showed average particle sizes of 10–13 nm.
Ferrofluid displacement exhibited a linear relationship with voltage at 1% (R² = 0.95), near-linear at 2% (R² = 0.90), and strong linearity at 5%
concentration (R² = 0.99). At 5% (w/v), displacement ranged between 0.41–2.35 mm for 0.25 mL (5–17.5 V), 0.44–3.17 mm for 0.5 mL (5–12.5 V), and
0.41–2.30 mm for 1.0 mL (5–20 V). Additionally, ferromagnetic ball formation exhibiting sink-and-rise behavior was observed at 5% (w/v) for 1 mL and
0.25 mL volumes at 22.5 V.
Ferromagnetic ball formation enables controlled and reversible motion under magnetic fields, which is essential for advanced biomedical applications. It
allows precise actuation in guided drug delivery and injectable microactuators, offering improved targeting, reduced side effects, and minimally invasive
treatment options. These features represent key advantages for next-generation medical technologies.
This study was supported by the Scientific and Technological Research Council of Türkiye (TÜBİTAK, Grant No: 222M057) and the Scientific Research
Projects Coordination Unit of Hacettepe University (BAP, Project No: FHD-2024-21597). The authors gratefully acknowledge both institutions for their
support.