Formation of noble metal nanocrystals in the presence of biomolecules

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dc.contributor.advisorYacaman, Miguel Joseen
dc.creatorBurt, Justin Lockhearten
dc.date.accessioned2008-08-28T23:21:44Zen
dc.date.accessioned2017-05-11T22:17:39Z
dc.date.available2008-08-28T23:21:44Zen
dc.date.available2017-05-11T22:17:39Z
dc.date.issued2007en
dc.descriptiontexten
dc.description.abstractOne of the most promising, yet least studied routes for producing biocompatible nanostructures involves synthesis in the presence of biomolecules. I hypothesized that globular proteins could provide a suitable framework to regulate the formation of noble metal nanocrystals. As proof of concept, I designed two novel synthesis protocols utilizing bovine serum albumin (BSA) protein to regulate the formation of gold nanocrystals. In the first case, the standard protocol for polyol reduction was modified by replacing ethylene glycol with glycerin, replacing synthetic polymers with BSA as protecting agent, and decreasing the reaction temperature. In the second case, the BrustSchiffrin two-phase reduction was modified by replacing alkylthiols with BSA as protecting agent, which facilitated a strictly aqueous phase synthesis. Due to superior product yield and rapid reduction at room temperature, the aqueous protocol became the foundation for subsequent studies. I extended this approach to produce well-dispersed ~2nm silver, gold, and platinum nanocrystals. Having demonstrated the feasibility of BSA-functionalized nanocrystals, some potential uses were explored. BSA-functionalized silver nanocrystals were employed in a broader study on the interaction of silver nanocrystals with HIV. BSA-functionalized gold nanocrystals were utilized for in vivo dosage of a contrast enhancing agent to bacteria. BSAfunctionalized platinum nanocrystals were studied as hydrogenation catalysts. Since many intriguing uses for protein-functionalized nanocrystals involve incorporation into biosystems, I sought to enhance biocompatibility by using ascorbic acid as reducing agent. Initial experiments revealed elongated and branched nanocrystals. Such structures were not observed in previous synthesis protocols with BSA, so I hypothesized ascorbic acid was driving their formation. To test my assertion, I reduced ionic gold in an aqueous solution of ascorbic acid, thereby discovering a new method for producing multiply-branched gold nanocrystals. Two conditions were necessary to achieve multiply-branched structures: rapid kinetics, and strongly acidic pH. By exploiting ascorbic acid complexation with BSA to moderate reaction kinetics, and using sodium hydroxide to provide basic pH, the two conditions for branching were negated, and well-dispersed ~2.5nm gold nanocrystals were obtained. This protocol represents a novel, environmentally benign approach to producing biocompatible nanocrystals, relying on proteins, ascorbic acid, sodium hydroxide, and water, all at ambient temperature.
dc.description.departmentChemical Engineeringen
dc.format.mediumelectronicen
dc.identifierb68663869en
dc.identifier.oclc166343672en
dc.identifier.urihttp://hdl.handle.net/2152/3005en
dc.language.isoengen
dc.rightsCopyright is held by the author. Presentation of this material on the Libraries' web site by University Libraries, The University of Texas at Austin was made possible under a limited license grant from the author who has retained all copyrights in the works.en
dc.subject.lcshPrecious metalsen
dc.subject.lcshNanocrystalsen
dc.subject.lcshBiomoleculesen
dc.titleFormation of noble metal nanocrystals in the presence of biomoleculesen
dc.type.genreThesisen

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