2.3 Characterization of the epoxy-functionalized magnetic colloidal particles
Before the application of the prepared magnetic colloidal particles (CSMPC) in MRI, they were characterized to determine the suitability of their use in biomedical diagnostic. The chemical composition of the prepared magnetic particles was examined by the Fourier-transform infrared (FTIR) spectroscopic technique using a Shimadzu FTIR 8400S instrument (IRPrestige-2, Japan). The spectra were recorded as the average of 40 scans in the region 400 to 4000 cm-1 at 4 cm-1 resolution. TEM (Phillips CM120) was used to investigate the morphology and microstructure of the magnetic polymer particles. Briefly, a drop of water diluted sample was deposited onto a carbon-coated copper grid and then left to dry at room temperature overnight before TEM imaging. Malvern Zetasizer 3000 HS instrument was used for measurement of average hydrodynamic size (D h) of the magnetic polymer colloidal particles in 10-3 M NaCl solution, at 25oC. The average value of three measurements was determined and taken into consideration. TGA (NETZSCH TG209) was used to determine the magnetite content of the magnetic polymer particles. The measurements were performed under a nitrogen atmosphere from ambient temperature up to 700oC with heating rate 20°C/min. The saturation magnetization (Ms) and magnetic behavior of the dried magnetic polymer latexes were investigated using a vibrating sample magnetometer (VSM). This test was carried out on the Automatic Bench of magnetic measurements, CNRS-IRC Lyon. The magnetization of all dried particles was investigated by decreasing the magnetic field (H) from +20000 to -20000 Oersted, at room temperature. Malvern Zetasizer (NanoZS2000) was used to measure the charge density or zeta potential (ζ) of the magnetic polymer colloidal particles in 10-3 M NaCl solution at different pH media, at 25oC. Each recorded value was the average of three measurements.

In-Vitro Magnetic Resonance Imaging Studies

Samples for MR-imaging studies were prepared by using variable concentrations (Fe concentration of 0.05, 0.025, 0.0125, 0.00625, 0.003125 ml/10ml of water) of CSMPC in deionized water. Testing was performed on all the samples using clinical 1.5T Toshiba Vantage Titan scanner. T1 and T2 weighted images were captured during testing to measure both T1 sequences “Longitudinal relaxation time” (typically TR: 40, 225, 425, 825 ms and TE: 12 ms) and T2 sequence “Transverse relaxation time” (typically TE: 15, 45, 75, 105, 135, 165 ms and TR: 5000 ms). Experimentation was done under ambient conditions by placing the colloids directly on the top of the multichannel coil’s body. MRI images were studied in K-Pacs-Lite and images were analyzed, visualized, and reconstructed using the statistical tool. Equal circular area (region of interest ROI) was chosen for each sample image and intensity data (Hounsfield) that is based on the intensity of the pixel contained within ROI were recorded. The mean intensity values were taken to compare relative intensity with reference (Deionized water) and each concentration.