(638d) Gold-Nanoparticle Conjugation on Genetically Engineered Tobacco Mosaic Virus

Tobacco Mosaic Virus (TMV) virus particle has a diameter and length of 18 nm and 300 nm. TMV is used a model material to investigate the potential use of bio-templates to synthesize metal / semiconductor nano-wires. Previously, this group studied the synthesis of metal coated nano-rods by using genetically engineered TMV. Metal cations were reduced on TMV virion with DMAB. Gold, silver, palladium, and platinum coated TMV nano-rods were prepared. Palladium-coated TMV virions were tested as hydrogen sensing material and displayed a fast signal response time and extended durability over repeated test cycles. Fundamental understanding of these advantages requires controlling the size of particles deposited on the TMV surface.

Current coating methods have limitations in controlling particle-sizes on the TMV virion. Excessive salt concentrations are mostly consumed to produce random-size particles in solution and particle growth on the TMV surface is low. Even though particle synthesis techniques are well established to control the metal particle-size by using capping agents, they are rarely deposited on TMV virions due to the repulsive nature of the capping agent to the TMV surface. Therefore, a study of nanoparticle conjugation on the TMV virion was initiated.

In this study, gold-chloride is reduced with dimethylamine borane (DMAB) and two salts, sodium citrate and sodium chloride. The two different salts play different roles. An increase of the sodium citrate concentration tends to reduce the size of gold nano particles whereas an increase in sodium chloride concentration tends to enlarge the gold particles. Sodium citrate caps the growth of the gold-nanoparticles while sodium chloride enhances inter-particle aggregation. However, if the gold-chloride solution described above is reduced with TMV mutants, gold-particle aggregation is suppressed and gold-TMV binding is favored. The samples are characterized with Dynamic Light Scattering (DLS), UV-Vis Spectrometer, and Transmission Electron Microscopy (TEM). This research will help to elucidate how capped quantum-dots can be conjugated onto selective sites.