Au nanoshells

Figure 10.3 Comparison of optical spectra (Cabs, Csca, and Cext) calculated using DDA for (a) Au nanorods, (b) Au nanoshells, and (c) Au nanocages.23 (Reprinted with permission from M. Hu et al., Chem. Soc. Rev. 2006, 35, 1084-1094. Copyright the Royal Society of Chemistry.)...

Lux F, Lerouge F, Bosson J, Lemercier G, Andraud C, Vitrant G, Baldeck PL, Chassagneux F, Parola S (2009) Gold hollow spheres obtained using an innovative emulsion process towards multifunctional Au nanoshells. Nanotechnology 20 355603-355609... 

Photoacoustic imaging (PAI) Ultrasound ICG-embedded ormosil nanoparticles, Au-nanoshells Skin and other epithelia, breast cancer detection ... 

Gomez et al. [9] prepared Si02-Au nanoshells in a three-stage microfluidic system. 

Gomez L, Arruebo M, Sebastian V, Gutierrez L, Santamaria J (2012) Facile synthesis of Si02-Au nanoshells in a three-stage microfluidic system. J Mater Chem 22(40) 21420-21425... 

Au nanomaterials are the most typical metal photothermal agents, and their LSPR is closely related to their shapes and structures. Currently, several Au nanomaterials with different shapes have been well developed as excellent photothermal agents, including Au nanoparticles (AuNPs), Au nanorods (AuNRs), Au nanoshells (AuNSs), and Au nanocages (AuNCs). 

Bikram, M. Gobin, A. M. Whitmire, R. E. West, J. L. Temperature-sensitive hydrogels with Si02-Au nanoshells for controlled drug delivery. J. Controlled Release 2007,123, 219-227. 

NCs could be employed for in vivo applications. The UV-Vis absorption of the Cu2-xSe NCs showed a broad absorption peak at 970 mn which was attributed to the surface plasmon resonance. When these NCs were irradiated with a 800 nm laser for 5 min, they exhibited a photothermal transduction efficiency of 22% which is equivalent to Au nanorods (21%) and relatively higher than Au nanoshells (13%). Cu2.xSe NCs were effective in the destruction of cancer cells, and hence are promising candidate for photo-thermal applications. 

Fig. 5.3 NRS (a) and SERS (b) spectra of two different (i, ii) ds thiolated DNA oligomers (70 bases). SERS spectra were measured using Au nanoshells covered silicon NPs (adapted with permission from Barhoumi et al. 2008. Copyright 2008 American Chemical Society)...

On the other hand, intrinsic (label-free) SERS detection of DNA hybridization is obstructed by poor spectral reproducibility plus the fact that the spectral signatures of hybridized and unhybridized sequences are highly similar. To overcome these issues, two approaches were applied. First, the idea was to remove adenine from the captured strand by replacing it with isomer (2-aminopurine— 2-AP) which had different spectrum but preserved the same hybridization efficiency (Baihoumi and Halas 2010). This concept is depicted in Fig. 5.4. Spectrum a shows the SERS spectmm of thermally pretreated DNA on Au nanoshells dominated by the adenine peak at 736 cm . Spectrum b represents the SERS spectmm of DNA having 2-AP substitution attached to the Au nanoshells through a thiol moiety on its 5 -end. In this spectmm, a peak at 807 cm of the 2-AP instead of an adenine peak at 736 cm was observed. The 736 cm peak was a marker for hybridization between the native/unlabelled DNA target strand (left in the inset with A—adenine) and the... 

In intrinsic peptide/protein SERS spectra, the most intensive Raman bands belong to amino acids containing aromatic or S-S groups. Halas and co-workers prepared Au nanoshells to compare SERS spectra of three dipeptides containing Cys and one aromatic amino acid Phe, tyrosine (Tyr) or Trp (Wei et al. 2008). They... 

J. Kundu, C.S. Levin, N.J. Halas, Real-time monitoring of lipid transfer between vesicles and hybrid bilayers on Au nanoshells using surface-enhanced Raman scattering (SERS). Nanoscale 1, 114 (2009b)... 

SERS on nanoshell substrates is relatively new but large enhancements are also observed [161]. Plasmon resonance dependence of the SERS signal is also evident with nanoshells [161,162]. A single Au nanoshell, with a rough surface, has a calculated SERS enhancement of 4 x 10 whereas a Au nanoshell dimer gives a polarization-dependent enhancement of 5 x 10 [163]. Arrays of Au or Ag semishells seem to offer considerable potential as a reproducible SERS substrate [164]. 

Temperature-sensitive hydrogels with SiOj-Au nanoshells for controUed drug dehvery, M. Bikram, A. Gohin, R. E. Whitmire, and J. L. Wesfi J. Control. Release, 2007,123, 219. 

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