Two-photon induced photoluminescence and singlet oxygen generation from aggregated gold nanoparticles.

Metal nanoparticles have potential applications as bioimaging and photosensitizing agents. Aggregation effects are generally believed to be adverse to their biomedical applications. Here we have studied the aggregation effects on two-photon induced photoluminescence and singlet oxygen generation of Au nanospheres and Au nanorods of two different aspect ratios. Aggregated Au nanospheres and short Au nanorods were found to display enhanced two-photon induced photoluminescence and singlet oxygen generation capabilities compared to the unaggregated ones. The two-photon photoluminescence of Au nanospheres and short Au nanorods were enhanced by up to 15.0- and 2.0-fold upon aggregation, and the corresponding two-photon induced singlet oxygen generation capabilities were enhanced by 8.3 and 1.8-fold, respectively. The two-photon induced photoluminescence and singlet oxygen generation of the aggregated long Au nanorods were found to be lower than the unaggregated ones. These results support that the change in their two-photon induced photoluminescence and singlet oxygen generation originate from aggregation modulated two-photon excitation efficiency. This finding is expected to foster more biomedical applications of metal nanoparticles as Au nanoparticles normally exist in an aggregated form in the biological environments. Considering their excellent biocompatibility, high inertness, ready conjugation, and easy preparation, Au nanoparticles are expected to find more applications in two-photon imaging and two-photon photodynamic therapy.

[1]  Tarasankar Pal,et al.  Interparticle coupling effect on the surface plasmon resonance of gold nanoparticles: from theory to applications. , 2007, Chemical reviews.

[2]  K. Hwang,et al.  Metal nanoparticles sensitize the formation of singlet oxygen. , 2011, Angewandte Chemie.

[3]  G. P. Kumar,et al.  Plasmonic nano-architectures for surface enhanced Raman scattering: a review , 2012 .

[4]  Qing-Hua Xu,et al.  Separation distance dependent fluorescence enhancement of fluorescein isothiocyanate by silver nanoparticles. , 2007, Chemical communications.

[5]  Mostafa A. El-Sayed,et al.  Preparation and Growth Mechanism of Gold Nanorods (NRs) Using Seed-Mediated Growth Method , 2003 .

[6]  Qing-Hua Xu,et al.  Huge enhancement in two-photon photoluminescence of Au nanoparticle clusters revealed by single-particle spectroscopy. , 2013, Journal of the American Chemical Society.

[7]  E. Coronado,et al.  The Optical Properties of Metal Nanoparticles: The Influence of Size, Shape, and Dielectric Environment , 2003 .

[8]  Shuangxi Xing,et al.  Mechanistic investigation into the spontaneous linear assembly of gold nanospheres. , 2010, Physical chemistry chemical physics : PCCP.

[9]  Lisa B. Israel,et al.  Colorimetric detection of thiol-containing amino acids using gold nanoparticles. , 2002, The Analyst.

[10]  N. Zheng,et al.  Photo‐ and pH‐Triggered Release of Anticancer Drugs from Mesoporous Silica‐Coated Pd@Ag Nanoparticles , 2012 .

[11]  Younan Xia,et al.  Gold nanostructures: a class of multifunctional materials for biomedical applications. , 2011, Chemical Society reviews.

[12]  Yi Xiao,et al.  Colorimetric detection of DNA, small molecules, proteins, and ions using unmodified gold nanoparticles and conjugated polyelectrolytes , 2010, Proceedings of the National Academy of Sciences.

[13]  Catherine J. Murphy,et al.  Fine-tuning the shape of gold nanorods , 2005 .

[14]  Xiaohua Huang,et al.  Cancer cell imaging and photothermal therapy in the near-infrared region by using gold nanorods. , 2006, Journal of the American Chemical Society.

[15]  Logan K. Ausman,et al.  Methods for describing the electromagnetic properties of silver and gold nanoparticles. , 2008, Accounts of chemical research.

[16]  M. El-Sayed,et al.  The `lightning' gold nanorods: fluorescence enhancement of over a million compared to the gold metal , 2000 .

[17]  Yun-Ling Luo,et al.  Release of photoactivatable drugs from plasmonic nanoparticles for targeted cancer therapy. , 2011, ACS nano.

[18]  P. Jain,et al.  Au nanoparticles target cancer , 2007 .

[19]  Jianfang Wang,et al.  Glutathione- and cysteine-induced transverse overgrowth on gold nanorods. , 2007, Journal of the American Chemical Society.

[20]  Tian Ming,et al.  Plasmon-Controlled Fluorescence: Beyond the Intensity Enhancement , 2012 .

[21]  Yongdoo Choi,et al.  Gold nanorod-photosensitizer complex for near-infrared fluorescence imaging and photodynamic/photothermal therapy in vivo. , 2011, ACS nano.

[22]  Hongwei Tang,et al.  Conjugated polymer/porphyrin complexes for efficient energy transfer and improving light-activated antibacterial activity. , 2009, Journal of the American Chemical Society.

[23]  Stephen Mann,et al.  One‐Dimensional Plasmon Coupling by Facile Self‐Assembly of Gold Nanoparticles into Branched Chain Networks , 2005 .

[24]  B. Nikoobakht,et al.  種結晶を媒介とした成長法を用いた金ナノロッド(NR)の調製と成長メカニズム , 2003 .

[25]  G. Xu,et al.  Gold nanorods as dual photo-sensitizing and imaging agents for two-photon photodynamic therapy. , 2012, Nanoscale.

[26]  Jianfang Wang,et al.  Extraordinary Surface Plasmon Coupled Emission Using Core/Shell Gold Nanorods , 2012 .

[27]  Yuqiang Jiang,et al.  Bioimaging with Two‐Photon‐Induced Luminescence from Triangular Nanoplates and Nanoparticle Aggregates of Gold , 2009 .

[28]  Qing-Hua Xu,et al.  Excitation Nature of Two-Photon Photoluminescence of Gold Nanorods and Coupled Gold Nanoparticles Studied by Two-Pulse Emission Modulation Spectroscopy. , 2013, The journal of physical chemistry letters.

[29]  Qing-Hua Xu,et al.  Size-dependent two-photon excitation photoluminescence enhancement in coupled noble-metal nanoparticles. , 2012, ACS applied materials & interfaces.

[30]  Catherine J. Murphy,et al.  Wet Chemical Synthesis of High Aspect Ratio Cylindrical Gold Nanorods , 2001 .

[31]  A. Borisov,et al.  Quantum plasmonics: nonlinear effects in the field enhancement of a plasmonic nanoparticle dimer. , 2012, Nano letters.

[32]  Anant Kumar Singh,et al.  Selective detection of mercury (II) ion using nonlinear optical properties of gold nanoparticles. , 2008, Journal of the American Chemical Society.

[33]  Younan Xia,et al.  Thiol-induced assembly of Au nanoparticles into chainlike structures and their fixing by encapsulation in silica shells or gelatin microspheres. , 2010, Langmuir : the ACS journal of surfaces and colloids.

[34]  P. Pramod,et al.  Plasmon Coupling in Dimers of Au Nanorods , 2008 .

[35]  C. Noguez.  Surface Plasmons on Metal Nanoparticles: The Influence of Shape and Physical Environment , 2007 .

[36]  J. Zhao,et al.  Controlled plasmonic nanostructures for surface-enhanced spectroscopy and sensing. , 2008, Accounts of chemical research.

[37]  Qing-Hua Xu,et al.  Enhanced two-photon emission in coupled metal nanoparticles induced by conjugated polymers. , 2010, Langmuir : the ACS journal of surfaces and colloids.

[38]  Chen-Sheng Yeh,et al.  Gold nanorods in photodynamic therapy, as hyperthermia agents, and in near-infrared optical imaging. , 2010, Angewandte Chemie.

[39]  Young Ha Kim,et al.  Photothermal Cancer Therapy and Imaging Based on Gold Nanorods , 2011, Annals of Biomedical Engineering.

[40]  Yihui Wu,et al.  Investigation of the NaBH4-induced aggregation of Au nanoparticles. , 2010, Langmuir : the ACS journal of surfaces and colloids.

[41]  P. Nordlander,et al.  Plasmons in strongly coupled metallic nanostructures. , 2011, Chemical reviews.

[42]  Weihai Ni,et al.  pH-Controlled reversible assembly and disassembly of gold nanorods. , 2008, Small.

[43]  Xiaohua Huang,et al.  Gold Nanorods: From Synthesis and Properties to Biological and Biomedical Applications , 2009, Advanced materials.

[44]  Shen,et al.  Photoinduced luminescence from the noble metals and its enhancement on roughened surfaces. , 1986, Physical review. B, Condensed matter.

[45]  Min Gu,et al.  Five-dimensional optical recording mediated by surface plasmons in gold nanorods , 2009, Nature.

[46]  H. Ehrenreich,et al.  Optical Properties of Ag and Cu , 1962 .

[47]  M. El-Sayed,et al.  Spectral Properties and Relaxation Dynamics of Surface Plasmon Electronic Oscillations in Gold and Silver Nanodots and Nanorods , 1999 .

[48]  Jian Zhang,et al.  Metal-enhanced fluorescence of an organic fluorophore using gold particles. , 2007, Optics express.

[49]  Prashant V. Kamat,et al.  Uniaxial Plasmon Coupling through Longitudinal Self-Assembly of Gold Nanorods , 2004 .

[50]  Qinghua Xu,et al.  Water-soluble conjugated polymer-induced self-assembly of gold nanoparticles and its application to SERS. , 2008, Langmuir : the ACS journal of surfaces and colloids.

[51]  Savka I. Stoeva,et al.  Digestive Ripening of Thiolated Gold Nanoparticles: The Effect of Alkyl Chain Length , 2002 .

[52]  X. Qu,et al.  Near‐Infrared Light‐Triggered, Targeted Drug Delivery to Cancer Cells by Aptamer Gated Nanovehicles , 2012, Advanced materials.

[53]  Muthu Kumara Gnanasammandhan,et al.  Plasmon enhanced upconversion luminescence of NaYF4:Yb,Er@SiO2@Ag core-shell nanocomposites for cell imaging. , 2012, Nanoscale.

[54]  Qing-Hua Xu,et al.  Two-photon ratiometric sensing of Hg2+ by using cysteine functionalized Ag nanoparticles. , 2011, Nanoscale.

[55]  Dayang Wang,et al.  Controlling the growth of charged-nanoparticle chains through interparticle electrostatic repulsion. , 2008, Angewandte Chemie.

[56]  Philip S Low,et al.  In vitro and in vivo two-photon luminescence imaging of single gold nanorods. , 2005, Proceedings of the National Academy of Sciences of the United States of America.

[57]  G. Frens.  Controlled nucleation for the regulation of the particle size in monodisperse gold solutions , 1973 .

[58]  Jianfang Wang,et al.  Nanonecklaces assembled from gold rods, spheres, and bipyramids. , 2007, Chemical communications.

[59]  Weihong Tan,et al.  Aptamer-assembled nanomaterials for biosensing and biomedical applications. , 2011, Small.

[60]  K. Sokolov,et al.  Two-photon luminescence imaging of cancer cells using molecularly targeted gold nanorods. , 2007, Nano letters.

[61]  Jian Wang,et al.  Optical investigations on ATP-induced aggregation of positive-charged gold nanoparticles. , 2010, Talanta.

[62]  A. Mooradian,et al.  Photoluminescence of Metals , 1969 .

[63]  Na Zhou,et al.  Band-selective coupling-induced enhancement of two-photon photoluminescence in gold nanocubes and its application as turn-on fluorescent probes for cysteine and glutathione. , 2012, ACS applied materials & interfaces.

[64]  G. Frens.  Controlled Nucleation for the Regulation of the Particle Size in Monodisperse Gold Suspensions , 1973 .

[65]  Limei Tian,et al.  Freezing the self-assembly process of gold nanocrystals. , 2012, Chemical communications.