title: High conversion of HAuCl4 into gold nanorods: A re-seeding approach.
abstract: Gold nanorods with varying aspect ratios have been utilized in recent years for a wide range of applications including vaccines, surface enhanced Raman spectroscopy (SERS) substrates, and as medicinal therapeutic agents. The surfactant-directed seed mediated approach is an aqueous based protocol that produces monodisperse nanorods with controlled aspect ratios. However, an inherent problem with this approach is poor efficiency of gold conversion from HAuCl4 into nanorods. In fact only ∼15% of gold is converted, motivating the need for alternate synthetic protocols in order to make the process more scalable and efficient as gold nanorods progress toward commercial applications. In the current study, we have significantly improved this conversion by growing rods in several iterations of supernatant solutions that were previously discarded as waste. Inductively coupled plasma mass spectrometry (ICP-MS) data indicates ∼14% gold conversion per nanorod solution with a total recovery of ∼75%. Gold nanorods prepared in consecutive supernatant solutions generally have slightly increased aspect ratios and maintain stability and monodispersity as measured by UV-vis and TEM. The increased nanorod yield minimizes gold waste and results in a greener synthetic approach.
authors.affiliation: Department of Chemistry, Georgia Southern University, Statesboro, GA 30458, United States. Electronic address: sc06057@georgiasouthern.edu.
authors.forename: Stephanie Ann
authors.initials: SA
authors.lastname: Canonico-May
authors.affiliation: Department of Materials Science, Vanderbilt University, Nashville, TN 37235, United States. Electronic address: Kelsey.r.beavers@vanderbilt.edu.
authors.forename: Kelsey Ross
authors.initials: KR
authors.lastname: Beavers
authors.affiliation: Department of Chemistry, Georgia Southern University, Statesboro, GA 30458, United States. Electronic address: mm09468@georgiasouthern.edu.
authors.forename: Michael James
authors.initials: MJ
authors.lastname: Melvin
authors.affiliation: Department of Pharmaceutics & Pharmaceutical Technology, University of Jordan, Amman 11942, Jordan. Electronic address: alkilany77@gmail.com.
authors.forename: Alaaldin M
authors.initials: AM
authors.lastname: Alkilany
authors.affiliation: Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37235, United States. Electronic address: craig.duvall@vanderbilt.edu.
authors.forename: Craig L
authors.initials: CL
authors.lastname: Duvall
authors.affiliation: Department of Chemistry, Georgia Southern University, Statesboro, GA 30458, United States. Electronic address: jstone@georgiasouthern.edu.
authors.forename: John William
authors.initials: JW
authors.lastname: Stone
mesh_terms: D002712:Chlorides / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D017612:Gold Compounds / Q000737:chemistry*; D043942:Nanotubes / Q000737:chemistry*; D010316:Particle Size; D013059:Spectrum Analysis, Raman; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry
chemical_list: D002712:Chlorides; D017612:Gold Compounds; D013501:Surface-Active Agents; D006046:Gold; C024568:gold tetrachloride, acid
keywords: Conversion efficiency; Gold nanorods; Gold quantitation; Green synthesis; ICP-MS