Metal Nanoparticle Growth within Clay-Polymer Nacre-Inspired Materials for Improved Catalysis and Plasmonic Detection in Complex Biofluids.

Recent studies have shown that layered silicate clays can be used to form a nacre-like bioinspired layered structure with various polymer fillers, leading to composite films with good material strength, gas-barrier properties, and high loading capacity. We go one step further by in situ growing metal nanoparticles in nacre-like layered films based on layered silicate clays, which can be used for applications in plasmonic sensing and catalysis. The degree of anisotropy of the nanoparticles grown in the film can be controlled by adjusting the ratio of clay to polymer or gold to clay and reducing agent concentration, as well as silver overgrowth, which greatly enhances the surface enhanced Raman scattering activity of the composite. We show the performance of the films for SERS detection of bacterial quorum sensing molecules in culture medium, and catalytic properties are demonstrated through the reduction of 4-nitroaniline. These films serve as the first example of seedless, in situ nanoparticle growth within nacre-mimetic materials, and open the path to basic research on the influence of different building blocks and polymeric mortars on nanoparticle morphology and distribution, as well as applications in catalysis, sensing, and antimicrobial surfaces using such materials.