The synthesis of high performance functional nanomaterials and devices with protein-based bottom-up approach is one of the most promising areas in nanobiotechnology. Structural proteins of viruses self-assemble into highly organized symmetrical and well-defined homogeneous nanostructures that can be used as scaffolds for nanomaterials synthesis. These building blocks have specific functional motifs and amino acid residues oriented in defined arrangements and through functionalization is possible to attach different technologically useful nanomaterials to the protein template (semiconductors, metals and ferromagnetic materials) obtaining hybrid nanobiomaterials. Rotavirus structural proteins have interesting applications due to their capacity for in vivo and in vitro self-assembly into structures with different properties. VP6 is a polymorphic protein that can adopt different dynamic states that result in trimers, spheres or nanotubes of several micrometers in length, with 75 or 45 nm in diameter depending of pH and ionic strength. Expressed in a recombinant system (insect cell-baculovirus) and purified by ion exchange and gel filtration chromatography, VP6 nanotubes of 75 nm diameter with a length above 2500 nm are produced. In this work VP6 nanotubes were functionalized through chemical reduction in aqueous media. The nanobiomaterials synthesized were characterized through UV/VIS spectra, dynamic light scattering and transmission electron microscopy. Results of the functionalization of VP6 nanotubes obtained can be summarized: (1) A very fine continuous coating of the outer surface was formed when sodium citrate was used as reducing agent with silver, gold, platinum and palladium precursors. (2) Discrete spherical metal nanoparticles of silver, gold, platinum and palladium ranging from 2 to 9 nm average diameters attached over the outer surface or a complete functionalization of VP6 nanotubes with silver aggregates are obtained using sodium borohydride as reducer. (3) UV/VIS absorbance spectra showed the resonance plasmon at 430 nm and 530 nm for Ag0 and Au0 nanoparticles, respectively. (4) The size distribution of functionalized VP6 nanotubes was not altered. Chemical deposition and functionalization did not cause disassembly, but under reaction conditions a diameter change from 75 to 45 nm was observed by increment in ionic strength or pH reduction in the reaction environment. (5) VP6 nanotubes in comparison with others viral scaffolds used in nanotechnological applications have superior dimensions (length), self-assembly capacity, and a dynamic flexible structure with high affinity metal deposition and in situ synthesis of nanoparticles. VP6 posses a metal binding site formed by two polar charged amino acids: glutamic acid (E315) and histidine (H316). This site is located in the outer surface of VP6 nanotubes and is correctly oriented to the solvent and could bind metallic ions under the reaction conditions tested. An additional advantage of VP6 nanotubes is that was recombinant and resulted in homogeneous materials with high quality. These hybrid nanobiomaterials could be useful in catalytic, electronic, optical and magnetic applications.

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