The present work is to study in detail the electrochemical properties of model systems of biosensor based on the controlled assembly of polymer-grafted-platinum nanoparticles and enzyme. To optimize the performance of these systems, we will focus on the detailed study of nanometer scale-transport phenomena coupled to complex charge transfer processes. This work will be performed in close collaboration with Renaud Cornut,electrochemist at LCSI. Various substrates will be studied, with various numbers of hybrid layers and compositions. New methods of immobilization of the structures to the electrode will also be tested using other grafting techniques (diazonium salts, nitrene chemistry, etc?). The resulting structures are then characterized by various methods of spectroscopy and microscopy coupled to electrochemical studies. Experiments electrochemical microscopy (SECM) allow for local information. Finally a modeling activity, in parallel with these measures, will establish a model that will be validated quantitatively. The effect of the initial structural parameters will be particularly studied. Therefore this work requires strong interaction between synthesis, electrochemistry and modeling. It will be possible to use the model to rapidly explore and optimize the synthesis conditions to obtain materials more sensitive, cheaper and more stable.