Resumen:
n this chapter firstly we give a brief overview of the main factors that control the optical properties of noble metal nanoparticles and the most commonly used approaches currently applied for the synthesis of stable colloidal dispersions of these kinds of nanostructures. Secondly, we describe the most relevant strategies for their functionalization with biomolecules and how the combination of the biorecognition properties of biomolecules with the plasmonic properties of noble metal nanoparticles can be used for sensitive and specific detection of target molecules and for the development of promising nanomedicine tools, especially for biospectroscopy and cancer therapy.