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Magnetic and Plasmonic Nanoparticles for Brain Drug Delivery
Published in Carla Vitorino, Andreia Jorge, Alberto Pais, Nanoparticles for Brain Drug Delivery, 2021
The Turkevich method is still one of the most common synthetic approaches used for preparing Au NPs for bioapplications, including for brain drug delivery [20, 56]. In this method, trisodium citrate is used both as a reducing and as a stabilising agent and is added to boiling chloroauric acid (HAuCl4) solution under vigorous stirring. A red-wine solution is obtained at the end of the reaction because of the formation of Au NPs with an average diameter of around 20 nm, with a negatively charged surface and electrostatically stabilised by citrate ions [55]. The size of the nanoparticles can be adjusted by varying the citrate/Au(III) molar ratio. At high ratio values, the nucleation is faster and dominant and leads to the formation of smaller NPs [57], which is desirable to enhance the permeability of Au NPs through the BBB [19]. Small (<10 nm) and monodisperse Au NPs can be prepared by simply reversing the order of addition of the reactants. Thus, the addition of the HAuCl4 solution to the citrate solution favours the nucleation and stabilisation of Au NPs [58]. Despite the electrostatic stabilisation, citrate-stabilised particles obtained using the Turkevich method can aggregate during storage or subsequent functionalisation steps. Large molecules such as surfactants and mercaptoalkanoic acids can be used to functionalise the surface and prevent the aggregation of Au NPs [27].
Microfluidics-Based Metallic Nanoparticle Synthesis and Applications
Published in Tuhin S. Santra, Microfluidics and Bio-MEMS, 2020
Kavitha Illath, Ashwin Kumar Narasimahan, Moeto Nagai, Syrpailyne Wankhar, Tuhin S. Santra
Gold is a material with unique characteristics such as tunable optical properties, ease of functionalization, nontoxic behavior, and catalytic, physiochemical, and biological properties. These features enable us to use it in a variety of applications like therapeutics, analytical science, catalysis, sensing, medical diagnosis, biomedical imaging, and drug delivery [1, 9, 38, 77, 79, 80, 110]. Among the metallic NPs, gold possesses shape- and size-dependent properties, which makes it useful in chemical catalysis and in bionanotechnology applications [12]. In 1951, Turkevich produced 15 nm Au NPs by reducing tetrachloroauric (HAuCl4) acid at a high temperature using trisodium citrate [103]. For this method, the citrate acts as a reducing agent, a pH mediator, and a capping agent. The synthesized particles can be used as a seed for producing large-sized particles.
Calix-Assisted Fabrication of Metal Nanoparticles
Published in Klaus D. Sattler, st Century Nanoscience – A Handbook, 2019
Anita R. Kongor, Manthan K. Panchal, Vinod K. Jain, Mohd Athar
The first experimental approach to synthesize metal nanoparticles was in 1857 when Faraday, the father of modern nanoscience, first prepared and characterized colloidal gold nanoparticles in a controlled manner (Faraday 1857). Since then, numerous experimental methods have been developed to synthesize metal nanoparticles, for example, the classical reduction of chloroauric acid in aqueous solution by trisodium citrate. In the 1950s, this synthetic procedure was identified and studied by John Turkevich, a pioneer in the field of catalysis (Turkevich et al. 1951). Different chemical procedures using sodium borohydride, ascorbic acid, trisodium citrate, or alcohols as reducing agents were then reported (Masala and Seshadri 2004). The synthesis of metal nanoparticles was often carried out using a stabilizing agent in order to prevent aggregation and to control the morphology of nanoparticles. A stable bonding is necessary to provide access to durable applications in the field of sensing and catalysis.
Effect of heat treatment on microstructure and tribology behaviour of electroless Ni-P/BN(h) composite coating
Published in Transactions of the IMF, 2020
Shuai Li, Shuai Pu, Zongying You, Caiyuan Sun, Songxia Li, Jin Zhang
In the plating bath, nickel sulphate was used as the source of nickel, sodium hypophosphite as the reducing agent. Trisodium citrate dihydrate, sodium acetate and sulphocarbamide were used as complexing agent, buffering agent and stabiliser, respectively.