ABSTRACT
The diverse applications of nanomaterials, and their rapidly increasing demand, have spurred the development of novel multifunctional materials. As such, this study aimed to synthesize and characterize a magneto-luminescent nanocomposite, composed of magnetite and fluorescent quantum dots (NaGdF4:Nd3+@Fe3O4). Nanomaterial synthesis was accomplished through solvothermal and co-precipitation methods. Stable nanoparticles (NPs) with a zeta potential of -19.57 ± 0.42 mV, and a size of 4.55 ± 1.44 nm were obtained. The crystalline structure of the NPs, verified via x-ray diffraction, affirmed the hexagonal pattern of the NaGdF4:Nd3+NPs and the inverse spinel pattern of Fe3O4NPs. In the diffraction pattern of the NaGdF4:Nd3+@Fe3O4NPs, only the phase pertaining to the Fe3O4NPs was identified, indicating their influence on the nanocomposite. Magnetic measurements revealed the superparamagnetic behavior of the material. Photoluminescence spectra of NaGdF4:Nd3+and NaGdF4:Nd3+@Fe3O4NPs verified the luminescent emission around 1060 nm; a feature of the radiative transitions of Nd3+ions. Based on the assessed characteristics, the nanocomposite's multifunctionality was confirmed, positioning the material for potential use in various fields, such as biomedicine.
ABSTRACT
Nanoparticles of magnetite passivated with gelatin and starch were synthesised using a co-precipitation technique. The nanoparticles were characterised using ultraviolet-visible (UV-vis), dynamic light scattering (DLS), Zeta potential, transmission electron microscope (TEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The UV-vis spectra showed characteristic surface plasmon resonance of magnetite nanoparticles. The DLS results showed the nanoparticles to have average hydrodynamic diameters of 138 ± 2 and 283 ± 21â nm for particles passivated with gelatin and starch, respectively. The stability in a colloidal solution was greater in nanoparticles passivated with gelatin than nanoparticles obtained with starch, as can be seen by their Zeta potential value (-31 ± 2 and -16 ± 0.5â mV, respectively). According to the TEM evaluation, the use of gelatin allowed to obtain nanoparticles with a spherical morphology and an average size of 10 ± 2â nm. However, when using starch the nanoparticles exhibited diverse morphologies with an average size of 25 ± 7â nm. The XRD results confirmed the crystalline structure of the samples, which showed crystallite sizes of 14.90 and 24.43â nm for nanoparticles passivated with gelatin and starch, respectively. FTIR analysis proved the establishment of interactions between functional groups of biopolymers and magnetite nanoparticles.