Superparamagnetic behavior of sulfonated fullerene (C60SO3H): Synthesis and characterization for biomedical applications

Abstract Fullerenes were synthesized to form sulfonated fullerenes by novel less cost-effective manner using diethyl ether as solvent. The synthesized sulfonated fullerene was extensively characterized by UV–Vis, FT-IR, FT-RAMAN, XRD, SEM HRTEM, XPS, EPR and VSM. FT-IR characterization reveals the presence of functional SO3H groups and FT-Raman characterization confirms the symmetry of the molecule. UV–Vis spectral analysis endorses red shifting of absorption peak. EPR spectrum, at room temperature with g-factor values, indicates the paramagnetic nature and magnetic ion sites of the samples. Structural changes, in sulfonated fullerene, are observed through Scanning electron microscope (SEM) and High-resolution transmission electron microscope (HRTEM). HRTEM micrographs showed that the sulfonation improves the good dispersion of fullerene in water. X-ray photoelectron spectroscopy (XPS) and energy dispersive spectroscopy (EDX) confirm the presence of carbon, sulphur and oxygen element in the molecule. Magnetization studies were measured using a vibrating sample magnetometer (VSM). The sulfonated fullerene exhibited superparamagnetic (SPM) behaviour at 5K with saturation magnetization value (ms = 0.14 emu/g). The zero-field cooled (ZFC) curve exhibited a blocking temperature Tb which is close to 5 K. Such superparamagnetic studies attempted for the first time in this work for sulfonated fullerene and the result displays potential applications in the field of magnetically guided drug delivery and can be envisaged as a good agent for various biomedical and engineering purposes in future.