Fabrication and spectroscopic studies of folic acid-conjugated Fe3O4@Au core-shell for targeted drug delivery application.

Gold coated magnetite core shell is a kind of nanoparticle that include magnetic iron oxide core with a thin layer nanogold. Fe3O4-gold core-shell nanostructure can be used in biomedical applications such as magnetic bioseparation, bioimaging, targeting drug delivery and cancer treatment. In this study, the synthesis and characterization of gold coated magnetite nanoparticles were discussed. Magnetite nanoparticles with an average size of 6 nm in diameter were synthesized by the chemical co-precipitation method and gold-coated Fe3O4 core-shell nanostructures were produced with an average size of 11.5 nm in diameter by reduction of Au(3+) with citrate ion in the presence of Fe3O4. Folate-conjugated gold coated magnetite nanoparticles were synthesized to targeting folate receptor that is overexpressed on the surface of cancerous cells. For this purpose, we used l-cysteine, as a bi-functional linker for attachment to gold surface and it was linked to the gold nanoparticles surface through its thiol group. Then, we conjugated amino-terminated nanoparticles to folic acid with an amide-linkage formation. These gold magnetic nanoparticles were characterized by various techniques such as X-ray powder diffraction (XRD) analysis, Fourier transform infrared spectrometer (FT-IR), UV-visible spectroscopy, transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), dispersive analysis of X-ray (EDAX) and vibrating sample magnetometer (VSM) analysis. The magnetic and optical properties of Fe3O4 nanostructure were changed by gold coating and attachment of l-cysteine and folic acid to Fe3O4@Au nanoparticles.

Fabrication and characterization of gold-TiO2 core-shell nanowire for immobilization of alkaline protease.

In this work, we report enhancement of the stability and biocatalytic activities of the alkaline protease enzyme immobilized on a gold/TiO2 core-shell nanowires. Gold/TiO2 core-shell nanowires were firstly prepared by the sol-gel method using a mixture of aqueous solution of titanate and chloroauric acid (HAuCI4) under ambient temperature and atmospheric condition and calcined then. As prepared nanowire was found to have a good surface biocompatibility for immobilization of the alkaline protease enzyme. The results obtained in this work showed that alkaline protease immobilized on gold-TiO2 core shell is stable and bioactive at the alkaline pH and ambient temperature. The stability and the biocatalytic activity of the immobilized gold-TiO2 core shell nano composites were monitored by UV-visible spectroscopy. Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and dispersive analysis of X-ray (EDAX) were used to characterize the size and morphology of the prepared materials.

Preparation of core-shell ZnO-SiO2 nanowires-nanotubes for immobilization of the alkaline protease enzyme.

The main goal of enzyme immobilization is industrial re-use of enzymes for many reaction cycles. In this purpose, simplicity and improvement of the enzyme properties have to be strongly associated with the design of protocols of enzyme immobilization. In the last decade, nanosized materials have been widely used as a support for enzyme immobilization, for instance, silica nanotubes, phospholipid bilayers, self-assembled monolayers Langmuir_Blodgett films, polymer matrices, galleries of alpha-zirconium, phosphate, mesoporous silicates such as MCM-41, silica nanoparticles. In this work, we report synthesis of core shell ZnO/SiO2 nanowires and used them as a support for immobilization of the alkaline protease. Characterization of this assembled systems was carried out by, Energy-dispersive X-ray spectroscopy (EDAX), Transmission electron microscopy (TEM) and Scanning electron microscopy (SEM). Biocatalytic activity of the alkaline protease in this bioconjugate system was examined and the results showed an increase of biocatalytic activity, in comparison with the free enzyme in solution.

Preparation and characterization of the hydrophilic nanocomposite coating based on epoxy resin and titanate on the glass substrate.

The hydrophilic organic-inorganic nanocomposite hybrid coatings were prepared using Tetrabutyl titanate. A simple sol-gel method has been developed for the preparation of nanocomposite coatings, at a molecular level and providing suitable conditions to obtain a complete conversion. The films were prepared on the glass substrates by dip-coating from a sol containing alcoholic tetrabutyl titanate which after the curing treatment, the gel forms a stable thin homogeneous nanocomposite coating. The obtained films were transparent to visible light and their surface hydrophilicity values were increased by increasing titania content in the water damp permeable self leveling flooring system. Characterization of the nanocomposite coating were performed by Transmission electron microscopy (TEM), Atomic force microscopy (AFM) analysis and contact angle test for water on TiO2 films that gave evidence of a strong interaction between the organic and inorganic phase with the formation of titania domains in the nanoscale range.

Biocatalytic activity of fungal protease on silver nanoparticle-loaded zeolite X microspheres.

Silver nanoparticles are excellent biocompatible surfaces for the immobilization of enzymes. However, separation of the silver nanoparticle-enzyme bioconjugate material from the reaction medium is often difficult. In this study, we investigate the assembly of the silver nanoparticles on the surface of the amine-functionalized zeolite microspheres or formation of zeolite-silver nanoparticle "core-shell" structure and thereafter, using obtained structure in immobilization of fungal protease. The assembly of silver nanoparticles on zeolite surface occurs through the amine groups present in 3-aminopropyltrimethoxysilane (3-APTS). The fungal proteases bound to the massive "core-shell" structures can be easily separated from the reaction medium by mild centrifugation and exhibited excellent reuse characteristics. The biocatalytic activity of fungal protease in the bioconjugate was marginally enhanced relative to the free enzyme in solution.