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Effect of Coprecipitation and Hydrothermal Parameters on the Properties of Ferrofluids Based on Magnetite Nanoparticles as MRI Contrast Agent

Ahmadi, Reza | 2011

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 41987 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Madaah Hosseini, Hamid Reza
  7. Abstract:
  8. Ferrofluids are special stable suspensions of magnetic nanoparticles dispersed in liquid phase. These materials have numerous biological applications such as drug delivery, magnetic hyperthermia and magnetic resonance imaging due to their special magnetic properties and fluidity. Particle size and magnetic properties of ferrofluids have an important role in these applications. In this work, magnetite-based ferrofluids have been synthesized via coprecipitation and hydrothermal methods. In the coprecipitation process, cysteine and dextran surfactants have been used as ferrofluid stabilizer and effect of synthesize temperature, time, pH and surfactant concentration have been investigated on ferrofluid properties. “Design of experiments” method has been performed via Qualitek 4 software in order to obtain desired properties for MRI application, especially suitable hydrodynamic size. Ferrofluids’ characterization has been used via TEM, XRD, AAS, VSM, FT-IR, DLS and PCS Techniques. Avrami model has been used in order to investigate nanoparticles formation kinetic in coprecipitation process via measurement of pH and Fe ion concentration. In hydrothermal process, oeic acid has been used in order to obtain stable ferrofluid and effect of time, temperature and medium acidity have been investigated on nanoparticles’ size and saturation magnetization. Using characterization results, Avrami model have been verified for investigation of nanoparticles’ formation kinetics via hydrothermal process. After biocompatibility tests, ferrofluids synthesized via coprecipitation and hydrothermal approaches have been injected into rats and MRI studies have been performed in order to investigate suitable drug delivery and MR images’ contrast enhancement.
    Results show that ferrofluids with average hydrodynamic size of 20-40 and 60-100 nanometers have been synthesized via coprecipitation and hydrothermal methods suitable for drug delivery and MRI from lymph nodes and spleen, respectively. Size distribution diagram in hydrothermal process was sharper than coprecipitation. Data analysis via Qualitek 4 software led to optimum conditions with hydrodynamic sizes of 64 and 27 nm for coprecipitation synthesize of ferrofluids in the present of dextran with molecular weight of 40000 and 15000 gram/mole, respectively. Coprecipitation synthesize of ferrofluid in various pHs using cysteine as surfactant led to formation of stable specimens with hydrodynamic size of 30-100 nm and saturation magnetizations above 70 emu/gram. Hydrothermally synthesized nanoparticles had mean hydrodynamic sizes around 80 nm and saturation magnetizations in the range of 30-65 emu/gram. MRI results show that ferrofluids synthesized via coprecipitation and hydrothermal processes in this work, were suitable for drug delivery and MR imaging of lymph nodes and spleen, based on their hydrodynamic size
  9. Keywords:
  10. Magnetite Nanoparticle ; Co-Precipitation ; Biocompatibility ; Hydrothermal Effect

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