Shape-dependent surface-enhanced Raman scattering in gold–Raman-probe–silica sandwiched nanoparticles for biocompatible applications

To meet the requirement of Raman probes (labels) for biocompatible applications, a synthetic approach has been developed to sandwich the Raman-probe (malachite green isothiocyanate, MGITC) molecules between the gold core and the silica shell in gold-SiO₂ composite nanoparticles. The gold-MGITC-SiO₂ sandwiched structure not only prevents the Raman probe from leaking out but also improves the solubility of the nanoparticles in organic solvents and in aqueous solutions even with high ionic strength. To amplify the Raman signal, three types of core, gold nanospheres, nanorods and nanostars, have been chosen as the substrates of the Raman probe. The effect of the core shape on the surface-enhanced Raman scattering (SERS) has been investigated. The colloidal nanostars showed the highest SERS enhancement factor while the nanospheres possessed the lowest SERS activity under excitation with 532 and 785 nm lasers. Three-dimensional finite-difference time domain (FDTD) simulation showed significant differences in the local electromagnetic field distributions surrounding the nanospheres, nanorods, and nanostars, which were induced by the localized surface plasmon resonance (LSPR). The electromagnetic field was enhanced remarkably around the two ends of the nanorods and around the sharp tips of the nanostars. This local electromagnetic enhancement made the dominant contribution to the SERS enhancement. Both the experiments and the simulation revealed the order nanostars > nanorods > nanospheres in terms of the enhancement factor. Finally, the biological application of the nanostar-MGITC-SiO₂ nanoparticles has been demonstrated in the monitoring of DNA hybridization. In short, the gold–MGITC-SiO₂ sandwiched nanoparticles can be used as a Raman probe that features high sensitivity, good water solubility and stability, low-background fluorescence, and the absence of photobleaching for future biological applications.

[1]  Ximei Qian,et al.  Surface-enhanced Raman nanoparticle beacons based on bioconjugated gold nanocrystals and long range plasmonic coupling. , 2008, Journal of the American Chemical Society.

[2]  Ulrich Wiesner,et al.  Plasmonic dye-sensitized solar cells using core-shell metal-insulator nanoparticles. , 2011, Nano letters.

[3]  Yung Doug Suh,et al.  Nanogap-engineerable Raman-active nanodumbbells for single-molecule detection. , 2010, Nature materials.

[4]  Cheng-Dah Chen,et al.  The Shape Transition of Gold Nanorods , 1999 .

[5]  Paul Mulvaney,et al.  Modelling the Optical Response of Gold Nanoparticles , 2008 .

[6]  M. Green,et al.  Surface plasmon enhanced silicon solar cells , 2007 .

[7]  Yue Tang,et al.  Free-Standing Polymer–Nanoparticle Superlattice Sheets Self-Assembled at the Air–Liquid Interface , 2011 .

[8]  Christoph Dellago,et al.  Structural and Morphological Transitions in Gold Nanorods: A Computer Simulation Study , 2003 .

[9]  Hristina Petrova,et al.  On the temperature stability of gold nanorods: comparison between thermal and ultrafast laser-induced heating. , 2006, Physical chemistry chemical physics : PCCP.

[10]  Paul Mulvaney,et al.  Gold nanorods: Synthesis, characterization and applications , 2005 .

[11]  Martin Moskovits,et al.  Visualizing chromatographic separation of metal ions on a surface-enhanced Raman active medium. , 2011, Nano letters.

[12]  M. El-Sayed,et al.  How Does a Gold Nanorod Melt , 2000 .

[13]  N. Fang,et al.  Ultradense gold nanostructures fabricated using hydrogen silsesquioxane resist and applications for surface-enhanced Raman spectroscopy , 2009 .

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

[15]  Dana D. Dlott,et al.  Measurement of the Distribution of Site Enhancements in Surface-Enhanced Raman Scattering , 2008, Science.

[16]  Wenlong Cheng,et al.  Free-standing nanoparticle superlattice sheets controlled by DNA. , 2009, Nature materials.

[17]  M. El-Sayed,et al.  Dependence of the enhanced optical scattering efficiency relative to that of absorption for gold metal nanorods on aspect ratio, size, end-cap shape, and medium refractive index. , 2005, The journal of physical chemistry. B.

[18]  Prashant K. Jain,et al.  Plasmonic coupling in noble metal nanostructures , 2010 .

[19]  Yiping Zhao,et al.  Rapid and sensitive detection of respiratory virus molecular signatures using a silver nanorod array SERS substrate. , 2006, Nano letters.

[20]  Harry A. Atwater,et al.  Local detection of electromagnetic energy transport below the diffraction limit in metal nanoparticle plasmon waveguides , 2003, Nature materials.

[21]  C. Murphy,et al.  Room temperature, high-yield synthesis of multiple shapes of gold nanoparticles in aqueous solution. , 2004, Journal of the American Chemical Society.

[22]  N. Jana,et al.  Preparation of Polystyrene- and Silica-Coated Gold Nanorods and Their Use as Templates for the Synthesis of Hollow Nanotubes , 2001 .

[23]  Younan Xia,et al.  Chemical synthesis of novel plasmonic nanoparticles. , 2009, Annual review of physical chemistry.

[24]  Luis M Liz-Marzán,et al.  Design of SERS-encoded, submicron, hollow particles through confined growth of encapsulated metal nanoparticles. , 2009, Journal of the American Chemical Society.

[25]  E. Wang,et al.  Well-ordered end-to-end linkage of gold nanorods , 2005, Nanotechnology.

[26]  C. Murphy,et al.  Quantitation of metal content in the silver-assisted growth of gold nanorods. , 2006, The journal of physical chemistry. B.

[27]  K. Lance Kelly,et al.  Chain Length Dependence and Sensing Capabilities of the Localized Surface Plasmon Resonance of Silver Nanoparticles Chemically Modified with Alkanethiol Self-Assembled Monolayers , 2001 .

[28]  Jeffrey N. Anker,et al.  Biosensing with plasmonic nanosensors. , 2008, Nature materials.

[29]  Shuming Nie,et al.  Spectroscopic tags using dye-embedded nanoparticles and surface-enhanced Raman scattering. , 2003, Analytical chemistry.

[30]  Tetsu Tatsuma,et al.  Localized surface plasmon resonance sensors based on wavelength-tunable spectral dips. , 2013, Nanoscale.

[31]  M. El-Sayed,et al.  Laser-Induced Shape Changes of Colloidal Gold Nanorods Using Femtosecond and Nanosecond Laser Pulses , 2000 .

[32]  Michael J. Campolongo,et al.  Building plasmonic nanostructures with DNA. , 2011, Nature nanotechnology.

[33]  Steven G. Johnson,et al.  Meep: A flexible free-software package for electromagnetic simulations by the FDTD method , 2010, Comput. Phys. Commun..

[34]  Alexander Marx,et al.  SERS labels for red laser excitation: silica-encapsulated SAMs on tunable gold/silver nanoshells. , 2009, Angewandte Chemie.

[35]  C. Haynes,et al.  Nanosphere Lithography: A Versatile Nanofabrication Tool for Studies of Size-Dependent Nanoparticle Optics , 2001 .

[36]  Zhong Lin Wang,et al.  Shell-isolated nanoparticle-enhanced Raman spectroscopy , 2010, Nature.

[37]  Leon Hirsch,et al.  Nanoshell-Enabled Photonics-Based Imaging and Therapy of Cancer , 2004, Technology in cancer research & treatment.

[38]  May D. Wang,et al.  In vivo tumor targeting and spectroscopic detection with surface-enhanced Raman nanoparticle tags , 2008, Nature Biotechnology.

[39]  Zong-Hong Lin,et al.  Bioconjugated gold nanodots and nanoparticles for protein assays based on photoluminescence quenching. , 2008, Analytical chemistry.

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

[41]  Jochen Feldmann,et al.  Label-free biosensing based on single gold nanostars as plasmonic transducers. , 2010, ACS nano.

[42]  Paul Mulvaney,et al.  Effect of the Solution Refractive Index on the Color of Gold Colloids , 1994 .

[43]  Hongxing Xu,et al.  Ag@SiO2 core-shell nanoparticles for probing spatial distribution of electromagnetic field enhancement via surface-enhanced Raman scattering. , 2009, ACS nano.

[44]  Peidong Yang,et al.  Anisotropic etching of silver nanoparticles for plasmonic structures capable of single-particle SERS. , 2010, Journal of the American Chemical Society.

[45]  Rui Li,et al.  Electrochemical and optical biosensors based on nanomaterials and nanostructures: a review. , 2011, Frontiers in bioscience.

[46]  Tuan Vo-Dinh,et al.  Gold Nanostars For Surface-Enhanced Raman Scattering: Synthesis, Characterization and Optimization. , 2008, The journal of physical chemistry. C, Nanomaterials and interfaces.

[47]  Emil Prodan,et al.  Quantum plasmonics: optical properties and tunability of metallic nanorods. , 2010, ACS nano.

[48]  Xu,et al.  Electromagnetic contributions to single-molecule sensitivity in surface-enhanced raman scattering , 2000, Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics.

[49]  Naomi J. Halas,et al.  Label-free detection of DNA hybridization using surface enhanced Raman spectroscopy. , 2010, Journal of the American Chemical Society.

[50]  Prashant K. Jain,et al.  Plasmonic photothermal therapy (PPTT) using gold nanoparticles , 2008, Lasers in Medical Science.

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

[52]  M. El-Sayed,et al.  Thermal Reshaping of Gold Nanorods in Micelles , 1998 .

[53]  N. Halas,et al.  Nano-optics from sensing to waveguiding , 2007 .

[54]  Andreas Kornowski,et al.  Tuning size and sensing properties in colloidal gold nanostars. , 2010, Langmuir : the ACS journal of surfaces and colloids.

[55]  Steven D. Christesen,et al.  Raman Cross Sections of Chemical Agents and Simulants , 1988 .

[56]  Zhilin Yang,et al.  Correlating the Shape, Surface Plasmon Resonance, and Surface-Enhanced Raman Scattering of Gold Nanorods , 2009 .

[57]  R. Composto,et al.  Tuning optical properties of gold nanorods in polymer films through thermal reshaping , 2009 .

[58]  Teri W. Odom,et al.  Large-Area Nanoscale Patterning: Chemistry Meets Fabrication , 2006 .

[59]  Jae Hee Song,et al.  Crystal overgrowth on gold nanorods: tuning the shape, facet, aspect ratio, and composition of the nanorods. , 2005, Chemistry.

[60]  R. W. Christy,et al.  Optical Constants of the Noble Metals , 1972 .

[61]  Catherine J. Murphy,et al.  Seed-Mediated Synthesis of Gold Nanorods: Role of the Size and Nature of the Seed , 2004 .

[62]  Eric C. Le Ru,et al.  Principles of Surface-Enhanced Raman Spectroscopy: And Related Plasmonic Effects , 2008 .

[63]  E. Wang,et al.  Two- and Three-Dimensional Au Nanoparticle/CoTMPyP Self-Assembled Nanotructured Materials: Film Structure, Tunable Electrocatalytic Activity, and Plasmonic Properties , 2004 .

[64]  Jianping Xie,et al.  The synthesis of SERS-active gold nanoflower tags for in vivo applications. , 2008, ACS nano.

[65]  Pierre-Michel Adam,et al.  Role of localized surface plasmons in surface-enhanced Raman scattering of shape-controlled metallic particles in regular arrays , 2005 .

[66]  Robert M. Corn,et al.  Fabrication of silica-coated gold nanorods functionalized with DNA for enhanced surface plasmon resonance imaging biosensing applications. , 2009, Langmuir : the ACS journal of surfaces and colloids.

[67]  S. Basu,et al.  Controlled interparticle spacing for surface-modified gold nanoparticle aggregates. , 2008, Langmuir : the ACS journal of surfaces and colloids.