Final Activity Report Summary - NANBIOPTIC (Applications for semiconductor nanoparticles: from biomedicine to optics.) During her Marie Curie fellowship, Dr B.H Juarez et al. reported a novel way of nanoparticle attachment to carbon nanotubes. Carbon nanotubes are tubular carbon structures with diameters in the nanometer and lengths in the micrometer range. They are ballistic conductors which can carry extremely high current densities. Semiconductor nanoparticles are systems in which size, shape, surface and composition control their optical properties. The emission properties of semiconductor nanoparticles can be mainly controlled by their size. For instance, it is possible to tune the emission colour of nanoparticles from blue to red with increasing their size from 3 to 6 nanometers. Because of their optical properties, semiconductor nanoparticles in close contact to carbon nanotubes could improve current transport properties. Semiconductor nanoparticles absorb light and may transform this energy into electrons that are injected into the carbon nanotubes. Thus, one of the potential applications of these combined systems is their use as photo-active material in future highly efficient solar cells. This requires an efficient transformation of light absorbed by nanoparticles into electrons driven by carbon nanotubes. The novel methodology that was described during the fellowship period had some advantages in comparison to previous work reporting similar hybrid systems. The first one was the fact that the crystalline lattice of carbon nanotubes was not damaged upon nanoparticles connection. Another one was the high degree of coverage. These combined systems were studied using several means such as transmission electron microscopy, electrical and optical characterisation. It was also possible to obtain three-dimensional images of the systems. Thanks to intensive synthetic activities during almost two years it was possible to optimise the degree of coverage and understand the formation mechanism of these hybrid systems. The proposed methodology opened a large area of scientific activities in other fields, such as nanomechanics, photovoltaics, optoelectronics as well as electrochemistry and catalysis.