Abstract
Gold nanorods (GNRs) have recently been developed for medical applications, and their silanization has been proposed for improving their photostability. In this paper, we show that self-assembled polyethylene glycol (PEG)ylated and silanized GNRs enjoy another benefit of silanization, i.e. its success in reshaping the plasmonic couplings typical of particle aggregation, for increasing shell widths. We investigated clusters of silanized gold nanorods that were capped with silica shells of different thickness. For a shell width of 12 nm, we obtained an optical extinction peak in the near infrared about two times greater than that in the green. In order to discuss the main features of the experimental spectra, we found it useful to model the aggregates with elementary clusters containing a small number of coupled GNRs. We availed of the discrete dipole approximation (DDA) for simulating the extinction coefficients of different basis sets. We reproduced the experimental spectrum for a shell width of 12 nm by modelling its reshaping with pairs of coupled particles in an end-to-end or side-by-side configuration and different aspect ratios.
Similar content being viewed by others
References
Huang XH, Neretina S, El-Sayed MA (2009) Gold nanorods: from synthesis and properties to biological and biomedical applications. Adv Mater 48:4880–4910
Cobley CM, Chen JY, Cho EC, Wang LV, Xia YN (2011) Gold nanostructures: a class of multifunctional materials for biomedical applications. Chem Soc Rev 40:44–56
Ratto F, Matteini P, Centi S, Rossi F, Pini R (2011) Gold nanorods as new nanochromophores for photothermal therapies. J Biophotonics 4:64–73
Dreaden EC, Alkilany AM, Huang XH, Murphy CJ, El-Sayed MA (2012) The golden age: gold nanoparticles for biomedicine. Chem Soc Rev 41:2740–2779
Mallidi S, Larson T, Tam J, Joshi PP, Karpiouk A, Sokolov K, Emelianov S (2009) Multiwavelength photoacoustic imaging and plasmon resonance coupling of gold nanoparticles for selective detection of cancer. Nano Lett 9:2825–2831
Eck W, Craig G, Sigdel A, Ritter G, Old LJ, Tang L, Brennan MF, Allen PJ, Mason MD (2008) PEGylated gold nanoparticles conjugated to monoclonal F19 antibodies as targeted labeling agents for human pancreatic carcinoma tissue. ACS Nano 2:2263–2272
Alkilany AM, Nagaria PK, Hexel CR, Shaw TJ, Murphy CJ, Wyatt MD (2009) Cellular uptake and cytotoxicity of gold nanorods: molecular origin of cytotoxicity and surface effects. Small 5:701–708
Chen YS, Frey W, Kim S, Kruizinga P, Homan K, Emelianov S (2011) Silica-coated gold nanorods as photoacoustic signal nanoamplifiers. Nano Lett 11:348–354
Jokerst JV, Thangaraj M, Kempen PJ, Sinclair R, Gambhir SS (2012) Photoacoustic imaging of mesenchymal stem cells in living mice via silica-coated gold nanorods. ACS Nano 6:5920–5930
Matteini P, Ratto F, Rossi F, Centi S, Dei L, Pini R (2010) Chitosan films doped with gold nanorods as laser-activatable hybrid bioadhesives. Adv Mater 22:4313–4316
Fernandez-Lopez C, Mateo-Mateo C, Alvarez-Puebla RA, Perez-Juste J, Pastoriza-Santos I, Liz-Marzan LM (2009) Highly controlled silica coating of PEG-capped metal nanoparticles and preparation of SERS-encoded particles. Langmuir 25:13894–13899
Joshi PP, Yoon SJ, Chen YS, Emelianov S, Sokolov KV (2013) Development and optimization of near-IR contrast agents for immune cell tracking. Biomed Opt Express 4:2609–2618
Akiyama Y, Niidome Y, Mori T, Katayama Y, Niidome TJ, Biomater (2013) PEG-silica-modified gold nanorods that retain their optical properties in tumor tissues. Sci Polym Educ 24:2071–2080
Prodan E, Radloff C, Halas NJ, Nordlander P (2003) A hybridization model for the plasmon response of complex nanostructures. Science 302:419–422
Funston AM, Novo C, Davis TJ, Mulvaney P (2009) Plasmon coupling of gold nanorods at short distances and in different geometries. Nano Lett 9:1651–1658
Barrow SJ, Wei X, Baldauf JS, Funston AM, Mulvaney P (2012) The surface plasmon modes of self-assembled gold nanocrystals. Nat Commun 3(1275):1–9
Grzelczak M, Mezzasalma SA, Herasimenka Y, Feruglio L, Montini T, Perez-Juste J, Fornasiero P, Prato M, Liz-Marzan LM (2012) Antibonding plasmon modes in colloidal gold nanorod clusters. Langmuir 28:8826–8833
Kumar J, Wei X, Barrow S, Funston AM, Thomas KG, Mulvaney P (2013) Surface plasmon coupling in end-to-end linked gold nanorod dimers and trimers. Phys Chem Chem Pys 15:4258–4264
Draine BT, Flatau PJ (2010) User guide for the discreet dipole approximation code DDSCAT 7.1. http://arxiv.org/abs/1002.1505
Johnson PB, Christy RW (1972) Optical constants of the noble metals. Phys Rev B 6:4370–4379
Stokes NL, Edgar JA, McDonagh AM, Cortie MB (2010) Spectrally selective coatings of gold nanorods on architectural glass. J Nanoparticle Res 12:2821–2830
Cristea D, Obreja P, Kusko M, Manea E, Rebigan R (2006) Polymer micromachining for micro- and nanophotonics. Mater Sci Eng C Mater Biol Appl 26:1049–1055
Jain PK, Lee KS, El-Sayed IH, El-Sayed MA (2006) Calculated absorption and scattering properties of gold nanoparticles of different size, shape, and composition: applications in biological imaging and biomedicine. J Phys Chem B 110:7238–7248
Aizpurua J, Bryant GW, Richter LJ, Garcia de Abajo FJ, Kelley BK, Mallouk T (2005) Optical properties of coupled metallic nanorods for field-enhanced spectroscopy. Phys Rev B 71(235420):1–13
Jain PK, Eustis S, El-Sayed MJ (2006) Plasmon coupling in nanorod assemblies: optical absorption, discrete dipole approximation simulation, and exciton-coupling model. J Phys Chem B 110:18243–18253
Sharma V, Park K, Srinivasarao M (2009) Colloidal dispersion of gold nanorods: historical background, optical properties, seed-mediated synthesis, shape separation and self-assembly. Mater Sci Eng R Rep 65:1–38
Weitz DA, Oliveria M (1984) Fractal structures formed by kinetic aggregation of aqueous gold colloids. Phys Rev Lett 52:1433–1436
Ratto F, Matteini P, Rossi F, Pini R (2010) Size and shape control in the overgrowth of gold nanorods. J Nanoparticle Res 12:2029–2036
Mazzoni M, Ratto F, Fortunato C, Pini R, Centi S (2014) Basic sets for aggregates of uncapped and capped gold nanorods representative alignments and couplings. IEEE conference publications on photonics technologies, 2014 Fotonica AEIT Italian Conference: 1–4 doi: 10.1109/Fotonica.2014.6843886
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Mazzoni, M., Ratto, F., Fortunato, C. et al. Basic Sets for Plasmonic Diagnostics in Aggregates of Capped and Uncapped Gold Nanorods. Plasmonics 10, 9–15 (2015). https://doi.org/10.1007/s11468-014-9770-8
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11468-014-9770-8