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Gold Nanomaterials at Work in Biomedicine *
Published in Valerio Voliani, Nanomaterials and Neoplasms, 2021
Xuan Yang, Miaoxin Yang, Pang Bo, Madeline Vara, Younan Xia
The Brust method for the synthesis of Au nanoparticles was developed in the early 1990s by Brust and Schiffrin [91]. Whereas the Turkevich method is based on an aqueous system, the Brust method involves the use of an organic solvent. In a typical synthesis, HAuCl4 is transferred from an aqueous phase to toluene with the use of tetraoctylammonium bromide (TOAB) as a phase-transfer agent, and then reduced to Au(0) atoms by NaBH4. Dodecanethiol is typically added into the organic phase to serve as a capping agent. The resultant nanoparticles are much smaller in size (typically, 5–6 nm) than those prepared using the Turkevich method. Heath, Gelbart, and their coworkers further demonstrated that Au nanoparticles with sizes ranging from 1.5 to 20 nm could be readily obtained by varying the molar ratio of HAuCl4 to the thiol [92].
High-Performance Liquid Chromatography
Published in Adorjan Aszalos, Modern Analysis of Antibiotics, 2020
Joel J. Kirschbaum, Adorjan Aszalos
Ceftriaxone in body fluids was analyzed using an octadecylsilane column and a mobile phase of acetonitrile-1% hexadecyltrimethylammonium bromide-0.1 M phosphate buffer (pH 7), 60:30:10 for plasma and 44:35:21 for urine, flowing at 2 ml/min into a detector set to 280 nm [262]. The linear range was 2–300 yg/ml, and at least 0.5 μg/ml could be detected. A similar system but using 0.58% tetraoctylammonium bromide and 2% 1 M phosphate-acetonitrile (600:400) as mobile phase aided in quantifying drug in urine [263]. Responses were linear between 6 and 167 μg/ml.
Gold Nanoparticles as Promising Agents for Cancer Therapy
Published in Hala Gali-Muhtasib, Racha Chouaib, Nanoparticle Drug Delivery Systems for Cancer Treatment, 2020
Nadine Karaki, Hassan Hajj Ali, Assem El Kak
The Brust–Schiffrin method is one of the first reported to synthesize GNPs in organic media, and it is until now one of the most widely performed to prepare uniform small particles of narrow distributions [48]. It is a classic sulfhydryl ligand method that consists of two biphasic reduction procedures. To prepare GNPs, phase transfer agent and stabilizer of GNPs such as tetraoctylammonium bromide (TOABr) or tetraoctylammonium chloride (TOACl), are used in addition to a reducing agent such as NaBH4 and a thiol ligand (Fig. 9.2). Generally, the gold salts are transferred from a water phase into an organic phase (e.g., toluene, ethanol and ethylene glycol) by a phase transfer agent. Then, NPs are nucleated through a reduction step through thiols ligands and NaBH4. A recent study showed that the species is a better precursor in the Brust–Schiffrin method to synthesize GNPs as it is more resistant to the formation of Au(I) thiolate species than [AuCl4] [49], knowing that the formation of Au(I) thiolate must be avoided to achieve a good yield of NPs [50].
Role of gold and silver nanoparticles in cancer nano-medicine
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2018
Heerak Chugh, Damini Sood, Ishita Chandra, Vartika Tomar, Gagan Dhawan, Ramesh Chandra
Brust–Schiffrin method produces monodisperse solutions with NPs of size less than 10 nm with a greater loading capacity. Moreover, it produces NPs stabilized with organic ligands mostly thiolate. Since it was first described in 1994 by Brust et al. for synthesis of AuNPs stabilized with thiolate ligand, it has been utilized to synthesize other metal NPs with different organic ligands [39,40]. Burst et al. prepared NPs of size 1–3 nm for which they used water-toluene system as a two-phase system to reduce hydrogen tetrachloroaurate (HAuCl4) using NaBH4 in the presence of stabilizing agent, alkanethiol which adheres to the surface of the particles [40]. They also showed the synthesis of about 2 nm thiol coated AuNPs in single-phase (organic) system using p-mercaptophenol [41]. The method generally involves three sequential steps: initially, tetraoctylammonium bromide, a phase transfer agents aids in transferring tetrahydrochloroaurate from aqueous to organic phase; alkanethiol reduce Au (III) to Au (I); in the final part addition of NaBH4 produces uniform monodispersed AuNPs formulation [42]. It is also noteworthy to mention here that the mechanism that this method follows for synthesis is different from the general mechanism that the synthesis of NPs follows. Here, the process of nucleation is continuous rather than a sequential process of nucleation, then growth and so forth. This mechanism explains why Brust–Schiffrin method concludes in monodispersity; the continuous nucleation, growth and then capping by thiol limit the growth at a particular size and results in uniformity of size among the NPs [39].
Systematic determination of the relationship between nanoparticle core diameter and toxicity for a series of structurally analogous gold nanoparticles in zebrafish
Published in Nanotoxicology, 2019
Lisa Truong, Tatiana Zaikova, Brandi L. Baldock, Michele Balik-Meisner, Kimberly To, David M. Reif, Zachary C. Kennedy, James E. Hutchison, Robert L. Tanguay
AuNP synthesis and characterization. All NPs were prepared through interfacial ligand exchange reactions between triphenylphosphine- or tetraoctylammonium bromide (TOAB)-protected NPs and TMAT using published procedures (Kearns, 2007; McKenzie, Zaikova and Hutchison 2014; Woehrle, Brown and Hutchison 2005) briefly described below. The thiocholine trifluoroacetate solutions were neutralized by passing them through a poly (4-vinylpyridine) column before addition to the NP solutions for all syntheses because acidic TMAT solutions lead to NP decomposition during ligand exchange.