Synthesis and Characterization of Tea Polyphenol–Coated Magnetite Nanoparticles for Hyperthermia Application

Abstract

Tea polyphenol–coated magnetite nanoparticles were evaluated for hyperthermia application. Polyphenol extracted from the tea leaves was used as a reducing and capping agent for the synthesis of good-quality mono-dispersed magnetite nanoparticles from an iron hydroxide solution. The as-synthesized samples were found to be mostly single-phase magnetite (Fe3O4) with a small amount of hematite (α-Fe2O3) as a secondary phase. Tea polyphenol suppresses the amount of the secondary phase present in the samples. X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transmission infrared spectrometry (FTIR), and vibration sample magnetometry (VSM) were used to investigate the properties of the samples. The Rietveld refinement technique was employed for the quantitative estimation of the secondary α-Fe2O3 phase along with the primary Fe3O4 phase from the XRD patterns. Absorption peaks at 1635/1615 cm−1 and 2950/2862 cm−1 due to the C=C bond and the C–H stretching vibration, respectively, bear the signature of polyphenol present in the samples. The average particle size of the particles was measured by TEM as 10 nm. Polyphenol coating enhances the value of the saturation magnetization (MS) of the iron oxide nanoparticles from 39 to 44 emu/g. The blocking temperature for coated and uncoated samples was estimated as 167 K and 195 K, respectively, which also confirms that samples are superparamagnetic at room temperature. Cytotoxicity of the nanoparticles was investigated using MTT assay on the L929 fibroblast cell line, and cell viability was found to increase for the coated sample. The specific absorption rate of polyphenol-coated nanoparticles in water was measured as 105 W/g for a sample concentration of 5 mg/ml in the AC magnetic field of 7.74 kA/m and frequency 337 kHz as compared to 66 W/g for the uncoated sample under the same conditions. The results demonstrate that the polyphenol coating enhances MS and biocompatibility of these nanoparticles which can be considered as a potential candidate for use as thermo seeds in hyperthermia application.