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Title: Synthesis and Properties of Room Temperature Stabilized FeO-ZrO2 Nanoceramics
Authors: Imran, Muhammad
Keywords: Physical Sciences
Solid State Physics
Issue Date: 2021
Publisher: University of the Punjab , Lahore
Abstract: Zirconia ceramics have received much attention because of good mechanical strength, good thermal properties, biocompatibility and white color. These properties make zirconia suitable for biomedical applications including orthopedic, maxillofacial implants and numerous imaging applications. Among three crystallographic phases of zirconia, i.e. monoclinic, tetragonal and cubic, tetragonal zirconia is more suitable for above-mentioned applications. However, tetragonal zirconia is stable at higher temperatures and transforms to monoclinic phase upon cooling. Such crystallographic transformation of zirconia hinders its application in biomedical fields. This research includes stabilization of tetragonal zirconia nanostructures at room temperature using iron oxide as stabilizer. Different routes of sol-gel and microwave assisted sol-gel preparation were used. Iron oxide, to be used as stabilizer was optimized by varying pH in the range of 1 to 11 using sol-gel method. Optimized samples, with superparamagnetic behavior (coercivity < 20Oe) are observed at pH 2 (hematite), 7(maghemite), 9 (magnetite) and 10 (magnetite). Iron oxide samples with pH 2 and 9 are checked for hemolysis activity. Results based on % hemolysis activity show that nanoparticles are non-toxic and biocompatible. Optimized iron oxide nanoparticles, with pH 2 and 9, are used to stabilize zirconia under as-synthesized conditions. Iron oxide content is varied in the range of 1-10 wt%. Mixed zirconia phases, i.e. monoclinic and tetragonal, are observed using iron oxide with acidic pH value. Pure tetragonal zirconia phase is observed in case of basic pH value of iron oxide with concentration of 5-6 wt%. Stabilized nanoparticles were heat treated at higher temperatures of 500oC to check and confirm their phase stability. Biocompatible dielectric constant value of ~ 80 and tangent loss ~ 0.06 (log f= 4) is observed for zirconia stabilized with 6 wt% basic iron oxide. Hemolytic response of stabilized zirconia nanoparticles is studied and non-toxic response, less than 5%, is observed. Effects of microwaves are also investigated on the stability of tetragonal zirconia phase. Microwave powers are varied (100 - 1000 W) with basic pH value of 5wt% of iron oxide. SEM and TEM reveal formation of spherical nanoparticles with diameter of ~ 10-20 nm. XRD results show phase pure tetragonal zirconia (t-ZrO2) at microwave power of 500W without any post heat treatment. Crystallite size calculated from XRD data (~23nm) matches well with the previously reported value for stabilization of t-ZrO2. Microwave energy dissipation results in stresses causing volume shrinkage leading to monoclinic to tetragonal phase transformation with higher X-ray density and hardness of ~1347HV. VSM results vi show ferromagnetic response with low coercivity (600Oe) value and saturation magnetization (~ 2emu/g). Microwave-assisted sol-gel synthesized stabilized zirconia nanoparticles are radiolabeled with technetium-99m to study bio-distribution in rabbit. Radiolabeling technique is used to dissolve iron oxide stabilized zirconia nanoparticles using Technetium-99m (99mTc) labeled radiopharmaceuticals. According to pH of rabbit, pH of solution is maintained and injected into rabbit. Results of biodistribution studies show that the 99mTc-labeled nanoparticles possess proper radiolabeling stability in their original suspension as well as in blood serum. To get gamma camera images, CT scan of rabbit is done for several times to get desirable results and to check the survival of rabbit. Results proved that the new method offers the opportunity to examine further specifically targeted and drug payload carrier variants of zirconia nanoparticles using PET/CT imaging. High uptake of radiotracer in stomach of rabbit is found to be potential candidate for its use in tumor therapies. To increase the contrast capability honey is added during synthesis of iron oxide stabilized zirconia nanoparticles. Stabilization of zirconia is optimized using conventional sol-gel and microwave assisted sol-gel methods. Stabilized zirconia nanoparticles, synthesized using microwave-assisted sol-gel method, at microwave power of 700 - 900W and 5wt% of basic iron oxide exhibit low hemolytic tendency thus, useful to check for in-vivo biodistribution activity. Antioxidant activity of optimized sample shows maximum value (85%) of reactive oxidative species (ROS) inhibition. In-vitro cancer cell viability is also checked for the stabilized sample. 99mTc-radiolabeled nanoparticles are injected in rabbits to check the biodistribution of stabilized nanoparticles. High uptake of radiotracer in bladder of rabbit is found to be potential candidate for its use in tumor therapies. Urination and physical properties of rabbit, after injection of nanoparticles, are checked periodically for many months and found normal.
Gov't Doc #: 22434
Appears in Collections:PhD Thesis of All Public / Private Sector Universities / DAIs.

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