Preparation of water-soluble amorphous erbium borate (ErBO3.3H(2)O) nanoparticles with positive charge

Abstract

We report a simple one-step protocol for the preparation of nearly monodisperse and highly water-soluble erbium borate nanoparticles through a co-precipitation method. Erbium ions were precipitated by boric acid/sodium hydroxide buffer with a pH of 9.2 in the presence of polyethylene glycol (2000 gmol(-1)) (PEG). As a result of the X-ray diffraction analysis, it was determined that the products that were precipitated in the medium with/without PEG were amorphous and the calcined product has an appropriate pattern for the vaterite-type ErBO3 crystal structure. Infrared spectrophotometer and thermal gravimetric analysis revealed the chemical formulation of the ErBO3.3H(2)O compound. It was found that partially spherical nanoparticles have a size of 15 +/- 6 nm according to TEM images. The average particle size was also measured in the water using dynamic light scattering method. The particles size is equal to about 100 nm in water and the zeta potential of particles is + 41 mV, which indicates a highly stable colloidal solution. Besides ErBO3.3H(2)O nanoparticles showed strong paramagnetism, their Bohr magnetron number was found as 9.48. Thus, these nanoparticles have promising properties for biomedical applications, such as cell targeting, drug delivery, and bioimaging.