Superparamagnetic core-shell nanoparticles as solid supports for peptide synthesis.

Functional superparamagnetic core-shell nanoparticles are synthesized by a microwave assisted route and can be used as colloidal supports for peptide synthesis in "quasi solution".

Formation mechanism of LiFePO4 sticks grown by a microwave-assisted liquid-phase process.

A time-dependent study on the formation of LiFePO4 with olivine-type structure is presented. The material is synthesized through a non-aqueous route in benzyl alcohol assisted by microwave radiation. The LiFePO4 forms with an anisotropic morphology of microscale stick-like particles. The detailed structure of these particles and their evolution with reaction time is revealed by transmission electron microscopy; a 3D reconstruction of a particle by electron tomography provides insight into the formation mechanism of these sticks. Without applying a thermal post-annealing treatment or a carbon coating, the electrochemical behavior of the LiFePO4 microsticks is assessed for the preparation of cathodes in lithium-ion batteries.

Microwave-assisted nonaqueous sol-gel deposition of different spinel ferrites and barium titanate perovskite thin films.

Rapid and selective heating of solvents by microwave irradiation coupled to nonaqueous sol-gel chemistry makes it possible to simultaneously synthesize metal oxide nanoparticles within minutes and deposit them on substrates. The simple immersion of substrates, such as glass slides, in the reaction solution results after microwave heating in the deposition of homogeneous porous thin films whose thickness can be adjusted through the precursor concentration. Here we use such a microwave-assisted nonaqueous sol-gel process for the formation of various spinel ferrite MFe2O4 (M = Fe, Co, Mn, Ni) and BaTiO3 nanoparticles and their deposition as thin films. The approach offers high flexibility with respect to controlling the crystal size by adjusting the reaction time and/or temperature. Based on the example of CoFe2O4 nanoparticles, we show how the crystal size can carefully be tuned from 4 to 8 nm, resulting in a continuous change of the magnetic properties.

Microwave chemistry for inorganic nanomaterials synthesis.

This Feature Article gives an overview of microwave-assisted liquid phase routes to inorganic nanomaterials. Whereas microwave chemistry is a well-established technique in organic synthesis, its use in inorganic nanomaterials' synthesis is still at the beginning and far away from having reached its full potential. However, the rapidly growing number of publications in this field suggests that microwave chemistry will play an outstanding role in the broad field of Nanoscience and Nanotechnology. This article is not meant to give an exhaustive overview of all nanomaterials synthesized by the microwave technique, but to discuss the new opportunities that arise as a result of the unique features of microwave chemistry. Principles, advantages and limitations of microwave chemistry are introduced, its application in the synthesis of different classes of functional nanomaterials is discussed, and finally expected benefits for nanomaterials' synthesis are elaborated.

Ultrastable iron oxide nanoparticle colloidal suspensions using dispersants with catechol-derived anchor groups.

We have found catechol-derivative anchor groups which possess irreversible binding affinity to iron oxide and thus can optimally disperse superparamagnetic nanoparticles under physiologic conditions. This not only leads to ultrastable iron oxide nanoparticles but also allows close control over the hydrodynamic diameter and interfacial chemistry. The latter is a crucial breakthrough to assemble functionalized magnetic nanoparticles, e.g., as targeted magnetic resonance contrast agents.

Kinetic and thermodynamic aspects in the microwave-assisted synthesis of ZnO nanoparticles in benzyl alcohol.

A detailed study of kinetic and thermodynamic aspects in the microwave-assisted synthesis of ZnO nanoparticles from zinc acetate and benzyl alcohol is presented. The use of a nonaqueous sol-gel approach provides the unique opportunity to investigate simultaneously the organic reaction, that is, the esterification between acetate and benzyl alcohol, and the inorganic process, represented by the growth of the ZnO nanoparticles. Monitoring both the formation of the organic species as well as ZnO crystal size with time makes it possible to directly correlate the kinetics of the organic side reaction with the growth kinetics of the ZnO nanoparticles. The esterification reaction, which is the chemical basis for producing the monomers for ZnO formation, was found to be first order. The growth of the ZnO nanoparticles followed the Lifshitz-Slyozov-Wagner model for coarsening, pointing to a diffusion-limited process. Comparison of the microwave-mediated route with conventional heating showed that microwave irradiation greatly accelerates nanoparticle formation by (a) facilitating the dissolution of the precursor in the solvent, (b) increasing the rate constants for the esterification reaction by 1 order of magnitude, resulting in faster production of monomer and consequently in an earlier nucleation event, and (c) increasing the rate constants k(growth) for the crystal growth from 3.9 nm(3)/min (conventional heating) to 15.4 nm(3)/min (microwave heating).

One-minute synthesis of crystalline binary and ternary metal oxide nanoparticles.

Highly crystalline metal oxide nanoparticles such as CoO, ZnO, Fe(3)O(4), MnO, Mn(3)O(4), and BaTiO(3) were synthesized in just a few minutes by reacting metal alkoxides, acetates or acetylacetonates with benzyl alcohol under microwave heating.