Plasmonic gold nanoparticles

Link S and El-Sayed M A 1999 Size and temperature dependence of the plasmon absorption of colloidal gold nanoparticles J. Phys. Chem. B 103 4212... 

The last problem of this series concerns femtosecond laser ablation from gold nanoparticles [87]. In this process, solid material transforms into a volatile phase initiated by rapid deposition of energy. This ablation is nonthermal in nature. Material ejection is induced by the enhancement of the electric field close to the curved nanoparticle surface. This ablation is achievable for laser excitation powers far below the onset of general catastrophic material deterioration, such as plasma formation or laser-induced explosive boiling. Anisotropy in the ablation pattern was observed. It coincides with a reduction of the surface barrier from water vaporization and particle melting. This effect limits any high-power manipulation of nanostructured surfaces such as surface-enhanced Raman measurements or plasmonics with femtosecond pulses. 

Pissuwan, D., Valenzuela, S. and Cortie, M.B. (2006) Therapeutic possibilities of plasmonically heated gold nanoparticles. Trends in Biotechnology, 24, 62-67. 

Cortie, M., Xu, X., Zareie, H., Chowdhury, H. and Smith, G.(12th-15th Dec 2005) Plasmonic heating of gold nanoparticles and its exploitation, presented at Smart Materials, Nano-, and Micro-Smart Systems 11, Sydney, Australia, SPIE, 5649, pp. 565-573. 

In summary, it has been demonstrated that plasmon-mode wavefunctions of gold nanoparticles resonant with the incident light can be visualized by near-field transmission imaging. 

The branched polysaccharide dextran is assembled with alkanethiol-modified gold nanoparticles and the resulting nanocomposite is then functionalized to facilitate the specific binding of target biomolecules. This biorecognition process can be easily detected by particle plasmon resonance (PPR), based on the optical properties of gold nanoparticles [163]. 

Long period gratings modified by the deposition of a self-assembled colloid monolayer of gold have been shown to enhance SRI sensitivity, which was attributed to the localized surface plasmon resonance (LSPR) of gold nanoparticles61. The system was used after functionalization of the gold nanoparticles with dini-trophenyl (DNP) antigen, for the detection of anti-(DNP) with a limit of detection as low as 9.5 x 10 10 M. 

It is difficult to predict the effect of surface functionalization on the optical properties of nanoparticles in general. Surface ligands have only minor influence on the spectroscopic properties of nanoparticles, the properties of which are primarily dominated by the crystal field of the host lattice (e.g., rare-earth doped nanocrystals) or by plasmon resonance (e.g., gold nanoparticles). In the case of QDs, the fluorescence quantum yield and decay behavior respond to surface functionalization and bioconjugation, whereas the spectral position and shape of the absorption and emission are barely affected. 

The electronic structure and hence optical properties of nanomaterials depend on the core size. For example, nanoparticles of core size >3 nm show surface plasmon resonance, which is due to the excitation of surface plasmons of nanoparticles by light. When the size of gold nanoparticles comes down to around 1 nm, which is equal to the de Broglie wavelength of the conduction electrons, the electronic bands... 

Srivastava S, Frankamp BL, Rotello VM. Controlled plasmon resonance of gold nanoparticles self-assembled with PAMAM dendrimers. Chem Mater 2005 17 487-490. 

Template core-shell particles with cores comprised mainly of poly(glycidyl methacrylate) (GMA) and shells consisting mainly of PNIPAM and amino or thiol-functionalized have been used for the synthesis of Au NPs. The obtained hybrid particles exhibited a reversible color change from red to purple, which originated from the surface plasmon resonance of gold nanoparticles and was temperature-dependent in the range 25-40 °C [96] (Scheme 3.15). 

Chitosan-stabilized Au NPs can be selectively synthesized on surfaces like poly (dimethylsiloxane) (PDMS) films using HAuC14 as precursor. The computation of surface plasmon bands (SPBs) based on Mie theory and experimental results indicates that the particles are partially coated by chitosan. The proposed mechanism implies that chitosan acts as a reducing/stabilizing agent. Furthermore, PDMS films patterned with chitosan could induce localized synthesis of gold nanoparticles in regions capped with chitosan only [110]. 

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