Chemicals colloidal gold

One-dimensional colloidal gold and silver nano-structures by Murphy et al. (2006). Recent advances in the synthesis of metallic nanorods and nanowires are reviewed. The increasing relevance of the bottom-up chemical synthesis is underlined. Physical properties and potential applications are described with emphasis on silver and gold. 

Considerable research effort was focused on systems of colloidal gold of which a broad variety of synthetic procedures were reported [140 b, fj. While native colloidal gold solutions are only stable for a restricted time, Brust et al. [141] were able to overcome this problem by developing a simple method for the in situ preparation of alkyl thiol-stabihzed gold nanoparticles. This synthetic route yields air-stable and easy to handle passivated nanoparticles of moderate polydispersity, and is now commonly employed for the preparation of inorganic-organic core-shell composites. Such composites are used as catalytic systems with principally two different functions of the protective 3D-SAM layer. Either the metal nanoparticle core can be used as the catalytically active center and the thiol layer is only used to stabihze the system [142], or the 3D-SAM is used as a Hnker system to chemically attach further catalytic functions [143]. 

Chemically prepared colloidal gold nanoparticles were immobilized as a submonolayer on Au(lll) surface modified with self-assembled monolayers (SAMs) of 4-aminothiophenol [14]. This submonolayer of Au nanoparticles was subsequently characterized using STM. 

Other manifestations of the second class of method include deposition of colloidal gold onto a support (Section 4.3.6), and photochemical or sono-chemical activation of the precursor to encourage its interaction with the support. 

B) Extinction spectrum of colloidal gold NPs with a diameter of ca. 13 nm and emission spectrum of LaP04 Ce,Tb NPs. (C) Evolution of emission intensity of biotinylated LaP04 Ce,Tb NPs with the addition of avidin coated gold NPs. Reprinted with permission from Gu et al. (2008a). Copyright 2008 American Chemical Society. 

Cheng, S. F., Chau, L. K. (2003) Colloidal Gold-Modified Optical Fiber for Chemical and Biochemical Sensing. Analytical Chemistry 75 16-21. 

A chemical may adhere to a native protein to produce an antigen and ehcit an antibody response. For example, colloidal gold and gold salts, which are used to treat rheumatoid arthritis, induce membranous nephropathy with numerous electron-dense deposits... 

Fig. 18.1 Panigrahi et al. show (a) the dependence of the catalyzed reaction rate on colloidal gold nanoparticle size from 8 to 55 nm and (b) the dependence of the reaction rate on the total available surface area of the colloidal nanoparticles. The linear dependence shows that the surfaces are the same for 8 to 55 nm colloidal particles, but does not prove if catalysis is heterogeneous (surface catalyzed) or homogeneous (solution catalyzed). The total gold atom concentration was kept constant in each experiment. Reprinted with permission from [9]. Copyright 2007, American Chemical Society...

A. Henglein, Radiolytic Preparation of Ultrafine Colloidal Gold Particles in Aqueous Solution Optical Spectrum, Controlled Growth, and Some Chemical Reactions. Langmuir 1998,... 

In a 1941 issue of the Doklady Akademii Nauk SSSR appeared a paper by Anton V. Chapek (transliteration) on colloidal gold. The paper was No. 14. In abstracting the paper, the Chemical Abstracts reference to paper 13 was wanted, but this name could not be found in the author index. Some time later a paper by Viktor A. Yankovskil No. 7 of a series, was abstracted. Again a search of the author index gave no trace of the preceding papers. 

Figure 16.9 Transient absorption spectra of 15 nm spherical gold nanoparticles after excitation at 400 nm with 100 fs laser pulses, recorded as different delay times. Also shown is the steady-state UV/Vis-absorption spectrum of the colloidal gold solution. The inset shows the decay of the transient bleach when the particles are monitored at the hleach maximum at 520 nm. Fitting of the decay curve yields electron-phonon and phonon-phonon relaxation times of 3.1 and 90 ps, respectively. (Reproduced with permission from S. Link and M. El-Sayed, 1999. J. Phys. Chem. B 103 8410 8426. Copyright 1999 American Chemical Society.)...

---