Engineered Polyethylene Glycol-Coated Zinc Ferrite Nanoparticles as a Novel Magnetic Resonance Imaging Contrast Agent.

Polyethylene glycol (PEG) was utilized to functionalize the surface of zinc ferrite nanoparticles (NPs) synthesized by the hydrothermal process in order to prevent aggregation and improve the biocompatibility of the NPs for the proposed magnetic resonance imaging (MRI) agent. Various spectroscopy techniques were used to examine the NPs' structure, size, morphology, and magnetic properties. The NPs had a cubic spinel structure with an average size of 8 nm. The formations of the spinel ferrite and the PEG coating band at the ranges of 300-600 and 800-2000 cm-1, respectively, were validated by Fourier-transform infrared spectroscopy. The NPs were spherical in shape, and energy-dispersive X-ray spectroscopy with mapping confirmed the presence of zinc, iron, and oxygen in the samples. The results of high-resolution transmission electron microscopy revealed an average size of 14 nm and increased stability after PEG coating. The decrease in zeta potential from -24.5 to -36.5 mV confirmed the PEG coating on the surface of the NPs. A high saturation magnetization of ∼50 emu/g, measured by vibration sample magnetometer, indicated the magnetic potential of NPs for biomedical applications. An MTT assay was used to examine the cytotoxicity and viability of human normal skin cells (HSF 1184) exposed to zinc ferrite and PEG@Zn ferrite NPs at various concentrations. After 24 h of treatment, negligible cytotoxicity of PEG-coated NPs was observed at high concentrations. Magnetic resonance imaging (MRI) suggested that PEG@Zn ferrite NPs are a unique and perfectly suited contrast agent for T2-weighted MRI and can successfully enhance the image contrast.

Silver-Decorated and Silica-Capped Magnetite Nanoparticles with Effective Antibacterial Activity and Reusability.

Fruits are safe, toxin-free, and biomolecule-rich raw materials that may be utilized to decrease metal ions and stabilize nanoparticles. Here, we demonstrate the green synthesis of magnetite nanoparticles which were first capped with a layer of silica, followed by the decoration of silver nanoparticles, termed Ag@SiO2@Fe3O4, by using lemon fruit extract as the reducing agent in a size range of ∼90 nm. The effect of the green stabilizer on the characteristics of nanoparticles was examined via different spectroscopy techniques, and the elemental composition of the multilayer-coated structures was verified. The saturation magnetization of bare Fe3O4 nanoparticles at room temperature was recorded as 78.5 emu/g, whereas it decreased to 56.4 and 43.8 emu/g for silica coating and subsequent decoration with silver nanoparticles. All nanoparticles displayed superparamagnetic behavior with almost zero coercivity. While magnetization decreased with further coating processes, the specific surface area increased with silica coating from 67 to 180 m2 g-1 and decreased after the addition of silver and reached 98 m2 g-1, which can be explained by the organization of silver nanoparticles in an island-like model. Zeta potential values also decreased from -18 to -34 mV with coating, indicating an enhanced stabilization effect of the addition of silica and silver. The antibacterial tests against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) revealed that the bare Fe3O4 and SiO2@Fe3O4 did not show sufficient effect, while Ag@SiO2@Fe3O4, even at low concentrations (≤ 200 µg/mL), displayed high antibacterial activity due to the existence of silver atoms on the surface of nanoparticles. Furthermore, the in vitro cytotoxicity assay revealed that Ag@SiO2@Fe3O4 nanoparticles were not toxic to HSF-1184 cells at 200 µg/mL concentration. Antibacterial activity during consecutive magnetic separation and recycling steps was also investigated, and nanoparticles offered a high antibacterial effect for more than 10 cycles of recycling, making them potentially useful in biomedical fields.

Papain grafted into the silica coated iron-based magnetic nanoparticles 'IONPs@SiO2-PPN' as a new delivery vehicle to the HeLa cells.

The present study aims at engineering, fabrication, characterization, and qualifications of papain (PPN) conjugated SiO2-coated iron oxide nanoparticles 'IONPs@SiO2-PPN'. Initially fabricated iron oxide nanoparticles (IONPs) were coated with silica (SiO2) using sol-gel method to hinder the aggregation and to enhance biocompatibility. Next, PPN was loaded as an anticancer agent into the silica coated IONPs (IONPs@SiO2) for the delivery of papain to the HeLa cancer cells. This fabricated silica-coated based magnetic nanoparticle is introduced as a new physiologically-compatible and stable drug delivery vehicle for delivering of PPN to the HeLa cancer cell line. The IONPs@SiO2-PPN were characterized using FT-IR, AAS, FESEM, XRD, DLS, and VSM equipment. Silica was amended on the surface of iron oxide nanoparticles (IONPs, γ-Fe2O3) to modify its biocompatibility and stability. The solvent evaporation method was used to activate PPN vectorization. The following tests were performed to highlight the compatibility of our proposed delivery vehicle: in vitro toxicity assay, in vivo acute systemic toxicity test, and the histology examination. The results demonstrated that IONPs@SiO2-PPN successfully reduced the IC50 values compared with the native PPN. Also, the structural alternations of HeLa cells exposed to IONPs@SiO2-PPN exhibited higher typical hallmarks of apoptosis compared to the cells treated with the native PPN. The in vivo acute toxicity test indicated no clinical signs of distress/discomfort or weight loss in Balb/C mice a week after the intravenous injection of IONPs@SiO2 (10 mg kg-1). Besides, the tissues architectures were not affected and the pathological inflammatory alternations detection failed. In conclusion, IONPs@SiO2-PPN can be chosen as a potent candidate for further medical applications in the future, for instance as a drug delivery vehicle or hyperthermia agent.

Effect of Sintering on Di-Electric Characteristics of Al-Cu Doped Cobalt Ferrite Nanoparticles.

Aluminium substituted cobalt-copper Co1-xCuxFe2-xAlxO4, (x ═ 0.8) nanoparticles are grown and sintered at different temperature in the range 600 to 900 °C. XRD analysis on nanoparticles prepared at sintered temperatures of 700 °C and 800 °C confirms the spinel structure and presence of hematite phase (alpha ferrite) in them. The dielectric behaviour of the prepared nano-particles is investigated. Although crystallinity improved with increase in sintering temperature and there was a dielectric loss at higher probe analyser frequency. The synthesized nanoparticles an average particle size of 20-24 nm while the FTIR absorption in regions of 586-595 cm-1 and 450-460 cm-1 indicated the presence of intrinsic vibrations of the tetrahedral and octahedral complexes respectively. Electrical resistivity as a function of temperature confirms the semiconducting nature of the Cu-Al substituted cobalt ferrite, and is attributed to the hopping mechanism between Fe2+ Fe3+ ions and Co2+ Cu2+, Co2+ Al3+. The lower values of dielectric constants and dielectric losses make Al-Cu doped cobalt ferrite, a potential material for microwave and radio wave absorber applications.

Synthesis, characterization and in vitro evaluation of exquisite targeting SPIONs-PEG-HER in HER2+ human breast cancer cells.

A stable, biocompatible and exquisite SPIONs-PEG-HER targeting complex was developed. Initially synthesized superparamagnetic iron oxide nanoparticles (SPIONs) were silanized using 3-aminopropyltrimethoxysilane (APS) as the coupling agent in order to allow the covalent bonding of polyethylene glycol (PEG) to the SPIONs to improve the biocompatibility of the SPIONs. SPIONs-PEG were then conjugated with herceptin (HER) to permit the SPIONs-PEG-HER to target the specific receptors expressed over the surface of the HER2+ metastatic breast cancer cells. Each preparation step was physico-chemically analyzed and characterized by a number of analytical methods including AAS, FTIR spectroscopy, XRD, FESEM, TEM, DLS and VSM. The biocompatibility of SPIONs-PEG-HER was evaluated in vitro on HSF-1184 (human skin fibroblast cells), SK-BR-3 (human breast cancer cells, HER+), MDA-MB-231 (human breast cancer cells, HER-) and MDA-MB-468 (human breast cancer cells, HER-) cell lines by performing MTT and trypan blue assays. The hemolysis analysis results of the SPIONs-PEG-HER and SPIONs-PEG did not indicate any sign of lysis while in contact with erythrocytes. Additionally, there were no morphological changes seen in RBCs after incubation with SPIONs-PEG-HER and SPIONs-PEG under a light microscope. The qualitative and quantitative in vitro targeting studies confirmed the high level of SPION-PEG-HER binding to SK-BR-3 (HER2+ metastatic breast cancer cells). Thus, the results reflected that the SPIONs-PEG-HER can be chosen as a favorable biomaterial for biomedical applications, chiefly magnetic hyperthermia, in the future.

Impact of annealing on surface morphology and photoluminescence of self-assembled Ge and Si quantum dots.

Controlled growth and characterization of germanium (Ge) and silicon (Si) nanostructure are the key issues for optoelectronic device fabrication. The role of post-annealing on the structural and optical properties of radio frequency (rf) magnetron sputtering grown of Ge and Si quantum dots (QDs) deposited on Si(100) substrate is studied. Atomic force microscopy confirmed the formation of Si and Ge QDs with estimated sizes lower than -17 nm and -14 nm respectively. The X-ray diffraction analysis revealed the formation of Si and Ge QDs accompanied by SiO2 with estimated sizes of -5 and -7 nm for post-annealed Si and pre-annealed Ge QDs respectively. The room temperature photoluminescence spectra for Ge and Si demonstrated an emission peak at 3.20 and 2.72 eV respectively, which are attributed to the electron and hole recombination within QDs. A shift in the PL peak is observed through annealing which is ascribable to the changes in size of QDs and quantum confinement effect. The thermal annealing at 600 degrees C is found to play an important role in controlling the shape, number density, root mean square (rms) roughness and the energy shift of the luminescence band for both Si and Ge QDs. The influence of annealing on growth morphology for Ge QDs is appeared to be stronger than Si.