Gold nanoparticle suspension

When cells are mixed with gold nanoparticle suspension, the nanoparticles are located in the vicinity of cells in the extracellular region. Figure 20.15 shows a comparison of the protein fluorescence spectra of whole cells with and without spherical gold nanoparticles. Obviously gold nanoparticles quench the fluorescence of cells at their protein bands when excited at protein absorption wavelength of 280 nm. There are no obvious differoices between normal cells and cancer cells. 

Similarly to the codeposition procedure above, the metal can also be delivered as nanoparticles to the colloidal crystal template, but in this case after preparation of the template. This was demonstrated for gold nanoparticles, which were filled into the interstitial sites of a polymer opal by filtering a gold nanoparticle suspension through the preassembled opal with a filter small enough to hold back the nanoparticles [33]. The templating opal was prepared before in very much the same way by filtration of a PS latex suspension. 

S. Vafaei and D. Wen, Bubble formation in a quiescent pool of gold nanoparticle suspension., Adv. Colloid Interface Set, 159,72-93 (2010). 

In another investigation, Zhang et al. synthesized nanosilica by reacting polyvinylpyrrolidone (PVP) with water and Au. First, a concentrated gold nanoparticle suspension was diluted with ethanol, after which the solution was mixed with PVP in -pentanol and stirred for 20 min before the addition of aqueous ammonia [29]. The reaction led to the formation of PVP-water-malleable stmctures which acted as a surface where the hydrolysis of TEOS could take place. This gave rise to pure silica nanostructures that were symmetric along an axis, but bent in different ways under various experimental parameters including the amount of PVP, the quantity... 

Aqil A, Serwas H, Delplancke JL (2008) Preparation of stable suspensions of gold nanoparticles in water by sonoelectrochemistry. Ultrason Sonochem 15 1055-1061... 

Gold nanoparticles (or other metallic or semiconductor particles) are functionalized with azide groups by suspending a 2.8 nM concentration of particles in 20 ml of water and adding a 20 pm ole amount of a thiol-PEG-azide spacer ligand to the suspension with stirring. 

The last subject where time-resolved X-ray diffraction techniques proved their exceptional potential concerns chemical physics of gold nanoparticles in water. Belonging jointly to X-ray and nanoparticle physics, this subject is in a certain sense on the borderline of the present chapter [82-84]. Nevertheless, the possibilities offered by time-resolved X-ray techniques in this domain are fascinating. The heart of the problem is as follows. A suspension of gold... 

Yoshida et al. recently disclosed an alternative method that allowed them to produce stable suspensions of gold nanoparticles (1-2 nm in diameter) in nematic liquid crystals [315]. They used a simple sputter deposition process, which allowed them to prepare thin liquid crystal films of well-dispersed gold nanoparticles in both 5CB and E47 (available from Merck) with a nanoparticle size depending on the used nematic liquid crystal. Unfortunately, the authors did not provide any details on whether the nanoparticles were capped with a ligand or bare, non-coated particles, which makes it difficult to assess and compare the reported thermal as well as electro-optic data. However, very similar effects were found as a result of nanoparticle doping, including lower nematic-to-isotropic phase transition temperatures compared to the used pure nematics as well as 10% lower threshold voltages at nanoparticle concentrations below 1 wt% [315]. 

Kumar et al. nevertheless succeeded in creating stable suspensions of hexanethiol-capped gold nanoparticles (1.6 nm core diameter) and gold nanoparticles capped with a 10CB thiol (similar to nanoparticle 3 in Fig. 5) in a lyotropic hexagonal columnar phase (HI phase formed by a 42 58 w/w Triton X-100/water system) as well as an inverse hexagonal columnar phase (H2 phase formed by AOT). Both types of nanoparticles were shown to stabilize the HI phase... 

For a SERS experiment, the water-soluble cellular fraction from pollen can be obtained as shown in the schematic in Fig. 4.8. About 0.2 mg of freeze-dried pollen, which correspond to a few hundred pollen grains, was suspended in 100 dl water and incubated at room temperature. When water is added to intact pollen, the cellular interior bearing the allergens, but also other proteins, carbohydrates, pigments and nucleic acids is released [91] and hence should be contained in the aqueous supernatant. About 2 pi of the supernatant, which should contain the amount of soluble content of a few individual pollen grains can then be added to 20 pi of a solution of gold nanoparticles. The gold nanoparticles were prepared as described by Lee and Meisel [92]. In the control experiments, the volume of the nanoparticle suspension is replaced by pure water. 

Add to the previous suspension (50 pL of MB/BC-A conjugate) the desired amount of BC-T (target DNA). Incubate at 42°C for 15 min and 800 rpm in TS-100 Thermo Shaker in order to carry out the hybridization reaction. Wash the formed MB/BC-A/BC-T conjugate twice with 100 pL of TT buffer and resuspend in 20 pL of TTL buffer. It is ready for adding streptavidin-gold nanoparticles (Au-NPs) label. 

Bieri NR, Chung J, Poulikakos D, Grigoropoulos CP. (2004) Manufacturing of nanoscale thickness gold lines by laser curing of a discretely deposited nanoparticle suspension. Superlattices Microstruct 35 437-444. 

The mechanistic aspect of the fungal reduction of metal ions led by colloidal suspension is still an open question. However, in the fungal case, this process occurs probably either by reductase action or by electron shuttle quinines, or both. To elucidate the mechanism of nanoparticles formation, a novel fungal/enzyme-based in vitro approach was for the first time explained by Mukherjee et al. (2002). They successfully used species-specific NADH-dependent reductase, released by the F. oxysporum, to carry out the reduction of AuClJ ions to gold nanoparticles. Duran et al. (2005) later reported that the reduction of the metal ions occnrs by a nitrate-dependent reductase and a shuttle quinone extracellular process. The same... 

However, one of the most commonly used substrates for SE(R)RS is colloidal nanoparticle suspensions of the metal, and the most commonly used metals are silver and gold. This is due to the fact that silver tends to give the greatest enhancement in Raman scattering [35, 36], however gold nanoparticles are often... 

Colloidal gold suspension is left to reach room temperature and stored in dark glass bottles at 4°C until use. The diameter of gold nanoparticles is 16 2nm. 

The logical way to record an IRF in a two-photon microscope is to use second-harmonic generation (SHG). SHG in a crystal is not very useful because the SHG is emitted in the direction of the laser radiation. Returning it to the microscope lens with the right NA is difficult. The best way to record an IRF in a microscope is SHG by hyper Rayleigh scattering in a suspension of gold nanoparticles [206, 375]. 

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