Nanoparticle syntheses using non-porous and porous polyelectrolyte multilayers for biological applications.

Polyelectrolyte multilayers comprised of poly(allylamine hydrochloride) and poly(acrylic acid) were assembled by layer-by-layer technique for metal nanoparticle syntheses. Using weak polyelectrolytes in LbL process, it is readily available to tune the deposited film properties by simple changing of the dipping solution pH. The PAH/PAA multilayer systems exhibit different surface morphologies and functionalities depending on the assembly conditions. We have studied two distinctive PAH/PAA multilayer films to utilize them for nanoparticle synthesis. The reactive functional groups of the polyelectrolytes within the films were remained after the film deposition or reactivated by a simple pH stimulus, and therefore they were allowed to undergo further chemical reactions to synthesize Pd and Au nanoparticles. Synthesized metal nanoparticles were easily characterized by their optical properties including surface plasmon absorption. These metal nanoparticle-embedded multilayers may have great potentials for biomolecule sensing or catalytically active coatings.