Controlled synthesis and luminescent properties of uniform SrMoO4 hollow microstructures and application as drug carrier

Abstract

SrMoO₄ hollow microstructures with tailored morphologies, sizes and dimensions were synthesized with the assistance of sodium poly(4-styrenesulfonate) (PSS) under mild reaction conditions. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectrum (EDS), down-conversion photoluminescence (PL) and cathodoluminescence (CL) spectra were employed to characterize the samples. The results indicate that the phase, morphology and size of the SrMoO₄ microstructures can be rationally tuned in a controlled manner by altering the amount of PSS, the concentration of reactants and the pH value of the initial solutions. Moreover, the crystal growth process was thoroughly studied through a series of time-dependent experiments and a possible formation mechanism was proposed on the basis of Ostwald ripening. Upon ultraviolet (UV) excitation and low voltage electron beams, SrMoO₄:Ln³⁺ (Ln = Eu, Tb) hollow microstructures exhibit bright red (Eu³⁺, ⁵D₀ → ⁷F₂) and green (Tb³⁺, ⁵D₄ → ⁷F₅) luminescence. A doxorubicin hydrochloride (DOX) release test exhibited clear sustained drug release property. Notably, the PL intensity of the functional system increases with the amount of DOX released, thus allowing the carrier to be monitored and tracked by the change in PL intensity. A MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay showed the good biocompatibility of SrMoO₄:Ln³⁺ hollow spheres, indicating the potential application of this kind of material in biomedicine and other fields.