Core-shell Hollow Spheres Research Articles

Preparation of a nanocomposite of magnetic, conducting nanoporous polyaniline and hollow manganese ferrite

A nanocomposite of conducting, protonated, polyaniline and hollow MnFe2O4 was successfully synthesized by in situ self-assembly polymerization. First, core-shell hollow spheres of MnFe2O4 were fabricated by template polymerization, in which ferrite nanoparticles were coated onto the surface of functionalized core polystyrene (PS) spheres, and the core polymer was subsequently removed by calcination. Fourier transform infrared spectroscopy spectra of the ferrite-coated PS spheres and MnFe2O4 hollow spheres confirmed the elimination of the organic template after calcination. Scanning electron microscopy images revealed that the resultant composite was structurally nanoporous. The shape and holes of the MnFe2O4 spheres were investigated by transmission electron microscopy. In addition, the magnetic properties of the nanocomposite and MnFe2O4 were characterized on a vibrating sample magnetometer with maximum saturation magnetization values of 1.59 and 66.7 emu g−1, respectively. The X-ray diffraction patterns of the ferrite sample agreed well with the standard pattern of the cubic structure. Atomic force microscopy was used for surface morphology analysis. The polyaniline (PANi)/MnFe2O4 nanocomposite containing hollow ferromagnetic nanoparticles has been synthesized. This report is a helpful method to improve mixability of inorganic particles with an organic phase. The results of atomic force microscopy image indicate the even distribution of MnFe2O4 in the PANi base, and this proves the effectiveness of dodecyl benzene sulfonic acid and ultrasonic devices in mixing two non-homogenous phases.

Monodisperse core–shell structured up-conversion Yb(OH)CO 3@YbPO 4:Er 3+ hollow spheres as drug carriers

In this work, we report a facile solution–phase synthesis of monodisperse core–shell structured Yb-(OH)CO 3@YbPO 4 hollow spheres (size around 380 nm) by utilizing the colloidal sphere of Yb(OH)CO 3 as the sacrificial template via the Kirkendall effect. The Er 3+ doped Yb(OH)CO 3@YbPO 4 core–shell hollow spheres can be prepared similarly, which exhibit strong green emission under 980 nm NIR laser excitation even after loading with drug molecules. Most importantly, the sample can be used as an effective drug delivery carrier. The biocompatibility test on L929 fibroblast cells using MTT assay reveals low cytotoxicity of the system. A typical anticancer drug, doxorubicin hydrochloride (DOX), is used for drug loading, and the release properties, cytotoxicity, uptake behavior and therapeutic effects were examined. It is found that DOX is shuttled into cell by core–shell hollow spheres carrier and released inside cells after endocytosis, and the DOX-loaded spheres exhibited greater cytotoxicity than free DOX. These results indicate that the core–shell Er 3+ doped Yb(OH)CO 3@YbPO 4 hollow spheres have potential for drug loading and delivery into cancer cells to induce cell death.