Bi-functional nanoparticles (NPs) that consist of silica-coated magnetic cores and luminescent lanthanide (Ln) ions anchored on the silica surface via organic linker molecules are reported. Compared to individual Ln ions, the hybrid NPs show a drastically enhanced photoluminescence due to the efficient ligand-to-metal energy transfer in the Ln-loaded NPs: the new bi-functional NPs could be used in a variety of biological applications involving magnetic separation and optical detection.
"A silica layer acts simultaneously as a protection layer with scaffold to modify organic molecules because of the hydroxyl groups on the surface. Organic molecules can be attached via covalent  or hydrogen bonding . Furthermore, the control of a silica layer thickness should be also desired technology. "
[Show abstract][Hide abstract] ABSTRACT: Facile procedures to control silica thickness and surface morphology on core–shell nanoparticles (Fe3O4@SiO2) are proposed. In this proposal based on reverse micelle method, we used water dispersed iron oxide nanoparticles. The sol–gel reaction was controlled by the change of the pH of dispersion without washing or re-dispersed procedures. When dispersion with pH 9 was used for silica coating, it takes 3 days to reach 15nm thick of the silica layer, and pH 10 dispersion needs only around 12h. The required thickness could be simply obtained by a choice of the pH and reaction time. Aggregation of the core–shell nanoparticles was well prevented by surface modification by silane coupling agent containing imidazolium cationic moiety without washing the nanoparticles before treatment. Furthermore, surface roughness of silica layer was also simply controlled by change of the reaction speed and addition of water soluble ionic molecules.
Colloids and Surfaces A Physicochemical and Engineering Aspects 03/2009; 336(1-3). DOI:10.1016/j.colsurfa.2008.11.013 · 2.75 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Fe3O4 magnetic nanoparticles (MNPs) were synthesized and silanized to form a core–shell (Fe3O4–SiO2) structure. Afterwards, surface modification with amino silane was carried out to produce amino groups on the MNPs for the biomolecule immobilization. In order to test the performance of amino functional MNPs as immobilization platform in biosensing applications, glucose oxidase was immobilized on the surface via glutaraldehyde. Obtained Bio-MNPs were then fixed onto the carbon paste electrode by the aid of magnetic force and used as the working electrode during the amperometric measurements at −0.7 V versus Ag/AgCl. After optimization of some parameters affecting the biosensor performance, analytical characterization was carried out. Linearity was found in the range of 0.25–2.0 mM glucose and defined by the equation of y = 8.366x + 1.819, (R
2 = 0.996). Proposed biosensor was then applied for the glucose analysis in various beverages. Finally, data were compared with a commercial enzyme assay kit based on spectrophotometric Trinder reaction as a reference method.
Schematic representation of the biosensing system based on core-shell modified magnetic nanoparticles
[Show abstract][Hide abstract] ABSTRACT: The tremendous developments of materials with fine tuning of the composition, shape, size and chemical functionalities at
the nanometre scale has opened a wide range of applications in medicine. An overview of hybrid nanomaterials for applications
in biological environment will be presented. The use of functional particles for medical imaging and therapy will be especially
discussed. These functional systems usually require combination of different properties such as luminescence (imaging) or
molecular recognition (targeting) and non-linear optical properties (therapy), together with size/shape control and biocompatibility
(cells diffusion, solubility, biochemical stability). For example series of hybrid metal or oxide nanoparticles can be prepared
for medical imaging. Some of them are already commercially available. The most recent work in this field will be presented
and the future developments will be discussed. For example one can expect to combine several imaging techniques (multimodal
contrast agents) or imaging and therapy in the same nanocomposite. The use of hybrid systems combining inorganic (metal or
oxide) with their organic counterparts shows the most promising routes towards such applications in biological environment.
New trends in the field of phototherapy will be discussed.
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