This paper reports the results obtained by development of novel approaches for inter-matrix synthesis and characterization of polymer stabilized metal nanoparticle (PSMNP), which can be applied in molecular recognition devices (MRD) such as, sensors and biosensors. The proposed approaches are based on the use of functionalized polymeric membranes as a nanoreactor for both synthesis and characterization of PSMNP. The desired functionalization is achieved by either chemical grafting of functional groups to the polymeric matrix or by using physical immobilization of the metal-selective extractants inside the polymer by using solid-phase-incorporated-reagents (SPHINER) technique. In both cases the functional groups of either extractant or functional polymer are able to chemically fix metal ions or complexes inside the parent polymeric matrix prior to their reduction and formation of PSMNP. The results obtained by the inter-matrix synthesis and characterization of Pt- and Cu-PSMNP in polymeric membranes and on the use of these polymer-metal nanocomposite membranes as sensing elements in modified graphite-epoxy composite electrodes are reported and discussed.