Magnetic Control of Fe₃O₄ Nanomaterial for Fat Ablation in Microchannel.
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ABSTRACT:
SUBMITTER: Chang M
PROVIDER: S-EPMC5458901 | biostudies-other | 2015 Nov
REPOSITORIES: biostudies-other
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Project description:Background: Minimally invasive modalities are of great interest in the field of treating bone tumors. However, providing reliable mechanical support and fast killing of tumor cells to achieve rapid recovery of physical function is still challenging in clinical works. Methods: A material with two functions, mechanical support and magnetic thermal ablation, was developed from Fe3O4 nanoparticles (NPs) distributed in a polymethylmethacrylate (PMMA) bone cement. The mechanical properties and efficiency of magnetic field-induced thermal ablation were systematically and successfully evaluated in vitro and ex vivo. CT images and pathological examination were successfully applied to evaluate therapeutic efficacy with a rabbit bone tumor model. Biosafety evaluation was performed with a rabbit in vivo, and a cytotoxicity test was performed in vitro. Results: An NP content of 6% Fe3O4 (PMMA-6% Fe3O4, mFe: 0.01 g) gave the most suitable performance for in vivo study. At the 56-day follow-up after treatment, bone tumors were ablated without obvious side effects. The pathological examination and new bone formation in CT images clearly illustrate that the bone tumors were completely eliminated. Correspondingly, after treatment, the tendency of bone tumors toward metastasis significantly decreased. Moreover, with well-designed mechanical properties, PMMA-6%Fe3O4 implantation endowed tumor-bearing rabbit legs with excellent bio-mimic bone structure and internal support. Biosafety evaluation did not induce an increase or decrease in the immune response, and major functional parameters were all at normal levels. Conclusion: We have presented a novel, highly efficient and minimally invasive approach for complete bone tumor regression and bone defect repair by magnetic thermal ablation based on PMMA containing Fe3O4 NPs; this approach shows excellent heating ability for rabbit VX2 tibial plateau tumor ablation upon exposure to an alternating magnetic field (AMF) and provides mechanical support for bone repair. The new and powerful dual-function implant is a promising minimally invasive agent for the treatment of bone tumors and has good clinical translation potential.
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Project description:Targeting cancer cells without injuring normal cells is the prime objective in treatment of cancer. In this present study, solvothermal and wet chemical precipitation techniques were employed to synthesize iron oxide (IO), hydroxyapatite (HAp), and hydroxyapatite coated iron oxide (IO-HAp) nanoparticles for magnetic hyperthermia mediated cancer therapy. The synthesized well dispersed spherical IO-HAp nanoparticles, magnetite, and apatite phases were confirmed by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and Field emission transmission electron microscopy (FETEM) with Energy Dispersive X-ray spectroscopy (EDS). The non-toxic behavior of synthesized IO-HAp nanoparticles was confirmed by cytotoxicity assay (Trypan blue and MTT assay). The synthesized nanoparticles revealed a remarkable magnetic saturation of 83.2 emu/g for IO and 40.6 emu/g for IO-HAp nanoparticles in presence of 15,000 Oe (1.5 T) magnetic field at room temperature (300 K). The magnetic hyperthermia study that was performed with IO-HAp nanoparticles showed an excellent hyperthermia effect (SAR value 85 W/g) over MG-63 osteosarcoma cells. The in vitro hyperthermia temperature (~45 °C) was reached within 3 min, which shows a very high efficiency and kills nearly all of the experimental MG-63 osteosarcoma cells within 30 min exposure. These results could potentially open new perceptions for biomaterials that are aimed for anti-cancer therapies based on magnetic hyperthermia.
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Project description:Recent experimental observations on combined electrokinetic and shear flows of colloidal suspensions in rectangular cross-section microfluidic channels have shown unusual cross-stream colloidal particle migration and dynamic assembly. Although a new electrophoresis-induced lift force has been postulated to cause the lateral migration of colloidal particles, little is known about how fluid properties and flow conditions impact this force and therefore subsequent colloidal particle migration. Furthermore, no experimental quantification of this electrophoresis-induced lift force is available. We report several key advances by demonstrating that the kinematic viscosity of the fluid can be used to modulate the spatial distribution of particles over the entire microchannel cross-section, with suppression of the colloidal particle migration observed with increase in fluid kinematic viscosity. Colloidal particle migration of ∼10 μm from not only the top and bottom microchannel walls but also from the side walls is shown with the corresponding electrophoresis-induced lift force of up to ∼30 fN. The breadth of flow conditions tested capture the channel Reynolds number in the 0.1-1.1 range, with inertial migration of colloidal particles shown in flow regimes where the migration was previously thought to be ineffective, if not for the electrophoresis-induced lift force. The ability of the electrophoresis-induced lift force to migrate colloidal particles across the entire microchannel cross-section establishes a new paradigm for three-dimensional control of colloidal particles within confined microchannels.
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Project description:Background Previous studies showed that the quantity of the left atrial (LA) periatrial fat tissue predicts recurrence after catheter ablation of atrial fibrillation (AF). We hypothesized that the quality of the LA periatrial fat tissue, measured by the mean computed tomography attenuation, predicts recurrence after AF ablation independent of the quantity of the LA periatrial fat tissue. Methods We included 143 consecutive patients with drug-refractory AF referred for the first catheter ablation of AF (62.2±10 years, 40% nonparoxysmal AF). All participants had a preablation cardiac computed tomography. We measured the quantity of the LA periatrial fat tissue by the area (millimeter square) and the quality by the mean computed tomography attenuation (Hounsfield units) in a standard 4-chamber view. Results Patients with AF recurrence after ablation (n=57) had a significantly larger fat area (167.6 [interquartile range, 124.1-255] versus 145.4 [95.6-229.3] mm2; P=0.018) and a higher fat attenuation (-92.0±9.8 versus -96.5±9.4 Hounsfield units; P=0.006) than those without recurrence (controls). LA fat attenuation was correlated with LA fat volume and LA bipolar voltage by invasive mapping and was associated with AF recurrence after adjusting for clinical risk factors, including body mass index, AF type, LA dimension, and fat area (hazard ratio, 2.65; P=0.001). Conclusions The quality of the LA periatrial fat tissue is an independent predictor of recurrence after the first AF ablation. Assessment of LA periatrial fat attenuation can improve AF ablation outcomes by refining patient selection.
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