Nanoparticles as structural and functional units in surface-confined architectures

The nanoscale engineering of functional chemical assemblies has attracted r ecent research effort to provide dense information storage, miniaturized se nsors, efficient energy conversion, light-harvesting, and mechanical motion . Functional nanoparticles exhibiting unique photonic, electronic and catal ytic properties provide invaluable building blocks for such nanoengineered architectures. Metal nanoparticle arrays crosslinked by molecular receptor units on electrodes act as selective sensing interfaces with controlled por osity and tunable sensitivity. Photosensitizer/electron-acceptor bridged ar rays of Au-nanoparticles on conductive supports act as photoelectrochemical ly active electrodes. Semiconductor nanoparticle composites on surfaces act as efficient light collecting systems, and nanoengineered semiconductor 'c ore-shell' nanocrystal assemblies reveal enhanced photoelectrochemical perf ormance due to effective charge separation. Layered metal and semiconductor nanoparticle arrays crosslinked by nucleic acids find applications in the optical, electronic and photoelectrochemical detection of DNA. Metal and se miconductor nanoparticles assembled on DNA templates may be used to generat e complex electronic circuitry. Nanoparticles incorporated in hydrogel matr ices yield new composite materials with novel magnetic, optical and electro nic properties.