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Green chemistry is an innovative way to approach the synthesis of metallic nanostructures employing eco-friendly substances (natural compounds) acting as reducing agents. Usually, slow kinetics are expected due to, use of microbiological materials. In this report we study composites of natural rubber (NR) membranes fabricated using latex fromHevea brasiliensistrees (RRIM 600) that works as reducing agent for the synthesis of gold nanoparticles. A straight and clean method is presented, to produce gold nanoparticles (AuNP) in a flexible substrate or in solution, without the use of chemical reducing reagents, and at the same time providing good size’s homogeneity, reproducibility, and stability of the composites.

Abstract:The ability to control the assembly of nanoparticles on substrates used in plasmon-enhanced spectroscopy continues to drive research in the field of nanofabrication. Here we describe the use of fungi as soft biotemplates to fabricate nanostructured microtubules with gold and gold-silver nanoparticles with potential applications as sensors and biosensors. In the first step, spores of the filamentous fungus Cladosporium sphaerospermum were inoculated in a suspension of gold nanoparticles, forming stable microtubules of gold nanoparticles during fungus growth. These materials were exposed to a second suspension of silver nanoparticles, resulting in complexes multilayers structures of gold and silver nanoparticles, which were evaluated as substrates for surface-enhanced Raman scattering (SERS) using small amounts of thiophenol as probe molecules directly on the microtubules. Both gold and the gold-silver substrates provide the SERS effect.