An integrated approach to the fabrication of multilayered nanocomposite membranes from layer-by-layer assembled polymers and single-wall carbon nanotubes is presented. The integrated bottom-up and top-down approach provides multifunctional molecular assemblies of tailored architectures and material properties for various versatile reaction/sensing materials of nanometer thickness, and will enable large-scale, reproducible production of membrane-based, highly integrated microsensors.