Preparation and characterization of polymer-stabilized metal nanoparticles for sensor applications

Nowadays, synthesis and application of Metal Nano-Clusters (MNC) attract great attention of scientists and technologists due to their unique electrical, magnetic and optical properties that differ from those of the bulk material. Nevertheless metallic nanoparticles are sometimes unstable and their stabilization is a crucial point to be solved in order to design new sensing devices which contain such particles. In this sense, one of most promising solution of MNC stability problems is in situ synthesis of MNC is stabilizing polymeric matrix [1]. Our research line is mainly focused on the development of novel routes to synthesize Polymer Stabilized MNC (PSMNC) by the use of both non-functionalized and functionalized polymers as MNC stabilizing media. Modification of polymeric matrices by Solid-PhaseIncorporated-Reagents (SPHINER) allows us to chemically fix metal ions or complexes inside the parent polymeric matrix prior to their reduction. Besides, the incorporation of functional groups into the polymeric chains by chemical grafting (e.g., sulfonic groups addition) permits the loading of metal ions that undergo a reduction reaction to form the desired nanoparticles. Both stabilization procedures are compatible with chemical or electrochemical reduction when using a soluble (non-crosslinked) polymer. The polymer solutions can be used for casting membranes either on an appropriate support or directly on the surface of the electrode to be used as a sensor. In the first case the reduction of metals proceeds ex situ, while in the second one in situ, i.e. in the first case after metal reduction the PSMNC containing membrane must be dissolved to prepare a sort of “ink” to be used for the second casting of membrane on the electrode surface while in the second case this step is not required.