Attachment Of Magnetic Nanoparticles Research Articles

Applications of nanotechnology in the winemaking process

In recent times, nanotechnology is expanding its field of application to very diverse areas. One of the most outstanding uses of nanotechnology in oenology is the incorporation of nanoparticles to sensors of different nature (electrochemical, biological, amperometric or fluorimetric) to improve the analysis of wine components such as polyphenols, organic acids, biogenic amines or sulphur dioxide. An improvement in the performance of the electrodes, increasing their sensitivity, accuracy and selectivity, together with shorter response times and less pre-treatment of the sample are some of the main advantages of using nanoparticles in detection devices. There are many nanomaterials (e.g. carbon nanodots or nanotubes, gold, silver, zinc oxide, iron oxide nanoparticles or nanocomposites) with interesting and varied properties that allow making specific detections and measurements of compounds while developing simpler analysis methodologies. In addition, other utilities of nanotechnology such as the development of electronic tongues, the nano-liquid chromatography, the antimicrobial power of certain nanoparticles and nanocomposites, the removal of yeast lees in sparkling wines through the attachment of magnetic nanoparticles, the usefulness of mesoporous silica nanomaterials as clarifying agents and the possibility of creating molecularly imprinted templates for the selective extraction of specific compounds from wine have been studied.

Attachment of magnetic nanoparticles on carbon nanotubes using oleate as an interlinker molecule

Novel Fe 3O 4/carbon nanotubes (CNTs) nanocomposites were prepared by a polyol-medium solvothermal method using oleate as an interlinker molecule and characterized via X-ray diffractometry, X-ray photoelectron spectroscopy, transmission electron microscopy and vibration sample magnetometry. Results indicated that the Fe 3O 4 nanoparticles were successfully attached on the surface of CNTs and the nanocomposites were proved to be superparamagnetic with saturation magnetization of 50.0 emu g −1. A proposed formation mechanism of the magnetic nanocomposites was presented.

Processable Hybrids of Ferrocene-Containing Poly(phenylacetylene)s and Carbon Nanotubes: Fabrication and Properties

A group of ferrocene-containing poly(phenylacetylene)s (PPAs) with different alkyl spacers were synthesized by using organorhodium complexes [Rh(diene)Cl](2) and Rh (+)(nbd)[C(6)H(5)B (-)(C(6)H(5))(3)] as catalysts. With the aid of pi-pi interactions between the walls of carbon nanotubes (CNTs) and the PPA skeleton together with the ferrocene pendants, the polymer (P 1, P2(5) and P2(10)) chains effectively wrapped round the shells of both single-walled carbon nanotubes (SWNTs) and multiwalled carbon nanotubes (MWNTs). The "additive effect" of the PPA skeleton and the ferrocene pendants in dispersing the SWNTs and MWNTs resulted in the generation of highly soluble hybrids. The solubilities of P 1-functionalized SWNTs and MWNTs in tetrahydrofuran (THF) are up to 633 mg/L and 967 mg/L, respectively. They are much higher than the solubilities of M 1-modified SWNTs and MWNTs, which are only 167 mg/L and 133 mg/L in THF. The results indicate the existence of a powerful polymer effect on dispersing CNTs. The high solubilities of the hybrids in organic solvents allowed us to fabricate high-quality and large-area films. Meanwhile, the desirable loading of ferrocene-containing PPAs onto the CNTs offered polymer/CNTs hybrids with multiple redox centers and ferrocene-featured electrochemical properties. The P 1/MWNT hybrid exhibits evident optical-limiting properties. At high incident laser fluence, the optical-limiting power of P 1/MWNT is higher than that of C(60), a well-known optical limiter. Thermal analyses indicate that the decomposition temperatures ( T(d), the temperature at which a sample loses its 5% weight) for P1 and P1/MWNT are 342 and 346 degrees C, respectively, much higher than that for PPA (225 degrees C). Thus the attachment of a ferrocene pendant to a PPA backbone, followed by hybridization with CNTs, improved the thermal stability. Upon pyrolysis, both the polymer and the polymer/CNTs hybrid gave rise to superparamagnetic ceramics; the saturation magnetizations ( M(s)) of the ceramics derived from P1 and P1/MWNT are 29.9 and 26.9 emu/g, respectively. The latter datum is in the list of the best results reported for the magnetic nanocomposites obtained by the attachment of magnetic nanoparticles onto CNTs.

Alignment of Carbon Nanotubes under Low Magnetic Fields through Attachment of Magnetic Nanoparticles

The alignment of multiwalled carbon nanotubes (MWNTs) has been accomplished through deposition of uniform layers of magnetite/maghemite nanoparticles (diameter = 6-10 nm) and use of an external magnetic field. The coating of CNTs with magnetic nanoparticles was performed by combining the polymer wrapping and layer-by-layer (LbL) assembly techniques. The particle-coated MWNTs are superparamagnetic and can be aligned at room temperature on any substrate by deposition from an aqueous solution in an external field B = 0.2 T. The volume magnetization of the particle coated MWNTs is found to be enhanced by 17% compared to the pure particles in a powder indicating that either the adsorption process onto the CNTs changes the particle magnetization, or the MWNTs carry an intrinsic magnetization due to remaining Ni used as a catalyst for the growth process.

Attachment of Magnetic Nanoparticles on Carbon Nanotubes and Their Soluble Derivatives

The magnetic modification of carbon nanotubes is described here. Pyrene can be noncovalently attached on the carbon nanotube surface. A carboxylic derivative of pyrene is used as interlinker for the binding of capped magnetic nanoparticles on the carbon nanotubes. The increased organophilic character of the capped nanoparticles induces high solubility in organic media for the modified carbon nanotubes.