This thesis, divided in three sections, is dedicated to the synthesis, characterization and application of different semiconductor nanomaterials.

The first one is dedicated to quantum dots (QDs), fluorescent nanoparticles with physical properties dominated by the quantum confinement of the excitons. The interaction with gold increasing the fluorescence intensity was studied. They were encapsulated with polymers to be used for multiplex analysis in flow cytometry, decreasing the price of the equipment used. Or by silica to use them as sensors for trypsin activity in cystic fibrosis, taking advantage of the Förster Resonance Energy Transfer effect. Finally, in this thesis, they have been also used to track the movement of Fcg receptors in human platelets.

The second block is dedicated to Up Conversion Nanoparticles, that they are excited by two or more infrared photons and emit one of higher energy. We have used these materials to specifically recognize Toll like receptors in human neutrophils as well as to be incorporated to hydrotalcite to be released in the organism and to act as a cobalt sensor for in vivo applications.

Finally, in the third block we have synthesized Bismuth Sulfide as photocatalyst in the a-alkylation of aldehydes and different charged titanium oxide nanoparticles as scaffold for perovskite solar cells.