This work describes a two-step conjugate synthesis of a porous organometallic nanostructured materials composed of ferrocenemonocarboxylic (Fc-COOH) and 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) and then a reagentless amperometric immunosensor prepared with positively charged gold nanoparticles (PGN) immobilized in this nanostructure conductive film is developed. This nanostructured material containing ferrocenyl (PTC-Fc) could easily form stable film on the electrode surface with efficient redox-activity and excellent conductivity. Furthermore, with the negatively charged surface, this film can be used as an interface to adsorbing the PGN, which was prepared in organic solvents at relatively high concentrations with improved monodispersity compared to those prepared in aqueous solution. The presence of PGN provided a congenial microenvironment for adsorbed biomolecules and decreased the electron-transfer impedance. Thus, with carcinoembryonic antibody (anti-CEA) as a model antibody, the proposed immunosensor showed rapid and highly sensitive amperometric response to carcinoembryonic antigen (CEA) with acceptable preparation reproducibility and stability.