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A synthesis method for nanocomposite microspheres containing Ni nanoparticles via chemical surface modification has been developed, by which particle size and interparticle distance for embedded Ni nanoparticles can be systematically controlled. The process relies on introduction of carboxyl acid groups via hydrolysis of matrix polymer, incorporation of Ni ions via ion exchange reaction, hydrogen-induced reduction of doped Ni ions in the sphere followed by Ni nanoparticle-catalyzed decomposition of the surrounding polymer matrix. We demonstrate the formation of Ni nanoparticles in polymer microspheres and structural change of polymer matrix upon reaction by FT-IR, SEM, and cross-sectional TEM studies, and show that initial Ni ion loading determines final nanoparticle size ranging from 3 to 8 nm, which are homogeneously distributed in the whole of the microspheres. The heat-treatment in a hydrogen atmosphere at fixed temperature causes decomposition of the polymer matrix via catalytic reaction of Ni nanoparticles, resulting in a gradual increase in the volume fraction of the Ni phase in the spheres and thus decrease of the average interparticle distance. The process reported herein allows, therefore, one to independently control size and interparticle distance of Ni nanoparticles and is an effective methodology for preparing high-quality nanocomposites with a tailored microstructure which further allows control of functions. [ABSTRACT FROM AUTHOR]

The effect of DNA loadings on the thermal stability of DNA duplex immobilized on gold nanoparticles has been investigated. The modestly loaded duplexes on the gold nanoparticles showed enhanced thermal stability, as compared to that of the free duplex (without gold nanoparticles). However, the highly loaded duplex showed stability similar to that of free duplex. The stability could be controlled over a wide temperature range simply by varying the salt concentration (over 50 °C). Additionally, the gold nanoparticles with modestly loaded oligonucleotides could be used as nanoprobes for effective and fast strand exchange reactions, based on the increased thermal stability of the immobilized duplex. These results indicate that the interaction between the duplex and the nanoparticle surface plays an important role in determining the stability of the duplex. [ABSTRACT FROM AUTHOR]

This article reports that the size-dependent optical properties of semiconductor nanocrystals have recently motivated attempts to use them as novel building blocks for optoelectronics and bioengineering applications. The article emphasises on band gap engineering of cadmium telluride (CdTe) nanocrystals. The development of facile methods for controlling the optical properties of nanocrystals in mild conditions is an important challenge and could lead to a more powerful set of band gap engineering schemes. Previous attempts using direct phase transfer of thioglicolic acid- stabilized CdTe nanocrystals from water to a dodecanethiol phase did not result in any distinct changes in solution color; rather, a slight red shift was observed in both absorption and emission spectra.