Preparation and characterization of double shell Fe3O4 cluster@nonporous SiO[2]@mesoporous SiO[2] nanocomposite spheres and investigation of their in vitro biocompatibility

Background: multifunctional core-shell magnetic nanocomposite particles with tunable characteristics have been paid much attention for biomedical applications in recent years. A rational design and suitable preparation method must be employed to be able to exploit attractive properties of magnetic nanocomposite particles

Objectives: herein, we report on a simple approach for the synthesis of magnetic mesoporous silica nanocomposite particles [MMSPs], consisted of a Fe[3]O[4] cluster core, a nonporous silica shell and a second shell of the mesoporous silica of suitable sizes for biomedical applications and evaluate their cytotoxicity effects on human cancer prostate cell lines

Materials and Methods: clusters of magnetite [Fe[3]O[4]] nanoparticles were coated by a layer of nonporous silica using Stober method. The coating step was completed by an outer layer of mesoporous silica via template-removing method. Structural properties of MMSPs were investigated by FTIR, HR-S[T]EM, BET, XRD techniques and magnetic properties of MMSPs by VSM instrument. MTT and LDH assays were employed to study the cytotoxicity of MMSPs

Results: obtained results revealed that decreasing the precursor concentration and the reaction time at the nonporous silica shell formation step decreases the thickness of the nonporous silica shell and consequently leads to the formation of smaller MMSPs. The as-prepared MMSPs have a desirable average size of 180 +/- 10 nm, an average pore size of 3.01 nm, a high surface area of 390.4 m[2].g[-1] and a large pore volume of 0.294 cm[3].g[-1]. In addition, the MMSPs exhibited a superparamagnetic behavior and a high magnetization saturation value of 21 +/- 0.5 emu/g. Furthermore, the viability tests of DU-145 cell lines exposed to various concentrations of these particles demonstrated negligible cytotoxicity effects of the asprepared Particles

Conclusions: these results demonstrate interesting properties of MMSPs prepared in this study for biomedical applications

Optimization of secretory expression of recombinant hGM-CSF in high cell density cultivation of recombinant Escherichia coli using Taguchi statistical method

Human granulocyte macrophage colony stimulating factor [hGM-CSF] has many therapeutic applications. In this study, in order to verify the purification process, the effect of carbon source, IPTG concentration and post-induction time on the secretion of recombinant hGM-CSF into the culture medium by recombinant Escherichia coli during high cell density cultivation were evaluated by using the Taguchi statistical method. The results indicated that glucose, 1mM IPTG and a time of 6 h post-induction, represented optimum conditions. The secreted hGM-CSF, overall volumetric productivity and purified hGM-CSF were 373 mg/l, 18 mg/l/h and 63 mg/l, respectively