Affinity biosensors, due to their selectivity, sensitivity and the fact they can be developed in a reagent-less and reusable format, find large application in environmental and clinical analysis. Key elements in biosensor development are: (i) the electrode surface (transducer) chemistry/properties, (ii) the recognition element and (iii) the signal generation element. In this proposal electrodeposition of nano-particles will be investigated as a way of modifying the transducer (electrode) chemistry/properties in order to improve/optimise the performances/layout of electrochemical molecular beacon biosensor. Several applications of RnEs will be investigated. · RnEs as a possible route to improve biosensors sensitivity (due the intrinsic catalytic properties of the nano-particles) · RnEs as a way generating specific attachment sites suitable for the recognition element. · Nano-particles as physical masks (template) for patterning, at nano size level, self assembled monolayer (SAM) of thiolated molecules onto Au surface (definition free sites, suitable for the recognition element attachment, in an antifouling matrix). Furthermore the influences of nature of the redox centre over the performances of electrochemical molecular beacon will be investigated in this proposal. The knowledge generated will be applied to the realisation of electrochemical molecular beacon DNA sensors for the prenatal diagnosis of Cystic Fibrosis and Thalassemia two of the most common genetic diseases. These areas of application have been chosen because of the relevance of the two diseases and because of the necessity to simplify the pre natal diagnosis of them that currently is performed with invasive, costly and risky procedures such as amniocentesis and “chorionic villa sampling”.