The Experts below are selected from a list of 9354 Experts worldwide ranked by ideXlab platform
Naomi J. Halas - One of the best experts on this subject based on the ideXlab platform.
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Electrical conductivity of cationized ferritin decorated gold Nanoshells
Journal of Applied Physics, 2012Co-Authors: Rebecca Cortez, Joseph M. Slocik, Naomi J. Halas, Joseph E. Van Nostrand, Rajesh R NaikAbstract:We report on a novel method of controlling the resistance of nanodimensional, gold-coated SiO2 nanoparticles by utilizing biomolecules chemisorbed to the nanoshell surface. Local electronic transport properties of gold-coated Nanoshells were measured using scanning conductance microscopy. These results were compared to transport properties of identical gold Nanoshells biofunctionalized with cationized ferritin protein both with and without an iron oxide core (apoferritin). Measured resistances were on the order of mega-ohms. White light irradiation effects on transport properties were also explored. The results suggest that the light energy influences the Nanoshells’ conductivity. A mechanism for assembly of gold Nanoshells with cationized ferritin or cationized apoferritin is proposed to explain the resistivity dependence on irradiation.
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theranostic Nanoshells from probe design to imaging and treatment of cancer
Accounts of Chemical Research, 2011Co-Authors: Rizia Bardhan, Amit Joshi, Naomi J. HalasAbstract:Recent advances in nanoscience and biomedicine have expanded our ability to design and construct multifunctional nanoparticles that combine targeting, therapeutic, and diagnostic functions within a single nanoscale complex. The theranostic capabilities of gold Nanoshells, spherical nanoparticles with silica cores and gold shells, have attracted tremendous attention over the past decade as Nanoshells have emerged as a promising tool for cancer therapy and bioimaging enhancement.This Account examines the design and synthesis of nanoshell-based theranostic agents, their plasmon-derived optical properties, and their corresponding applications. We discuss the design and preparation of nanoshell complexes and their ability to enhance the photoluminescence of fluorophores while maintaining their properties as MR contrast agents. In this Account, we discuss the underlying physical principles that contribute to the photothermal response of Nanoshells. We then elucidate the photophysical processes that induce nanos...
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Temperature measurements of optically trapped gold Nanoshells
Optics in the Life Sciences, 2011Co-Authors: Brooke C. Hester, Gretchen K. Campbell, Ryan Huschka, Kristian Helmerson, Naomi J. HalasAbstract:We measure the temperature of an optically trapped gold nanoshell by tracking its Brownian motion. Single Nanoshells are found to heat significantly, and this heating varies with trap wavelength and particle number.
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metallic Nanoshells with semiconductor cores optical characteristics modified by core medium properties
ACS Nano, 2010Co-Authors: Rizia Bardhan, Nathaniel K Grady, Naomi J. HalasAbstract:It is well-known that the geometry of a nanoshell controls the resonance frequencies of its plasmon modes; however, the properties of the core material also strongly influence its optical properties. Here we report the synthesis of Au Nanoshells with semiconductor cores of cuprous oxide and examine their optical characteristics. This material system allows us to systematically examine the role of core material on nanoshell optical properties, comparing Cu2O core Nanoshells (ec ∼ 7) to lower core dielectric constant SiO2 core Nanoshells (ec = 2) and higher dielectric constant mixed valency iron oxide Nanoshells (ec = 12). Increasing the core dielectric constant increases nanoparticle absorption efficiency, reduces plasmon line width, and modifies plasmon energies. Modifying the core medium provides an additional means of tailoring both the near- and far-field optical properties in this unique nanoparticle system.
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Self-assembled plasmonic nanoparticle clusters
CLEO QELS: 2010 Laser Science to Photonic Applications, 2010Co-Authors: Chihhui Wu, Rizia Bardhan, Vinothan N. Manoharan, Naomi J. Halas, Peter Nordlander, Gennady Shvets, Federico CapassoAbstract:Polymer-coated gold Nanoshells are assembled, using capillary forces, into packed clusters with tailored surface plasmon resonances. Separation between Nanoshells is engineered to be ~2 nm. Strongly coupled resonances in nanoshell dimers and trimers are observed.
Jennifer L. West - One of the best experts on this subject based on the ideXlab platform.
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nanoshell mediated photothermal therapy improves survival in a murine glioma model
Journal of Neuro-oncology, 2011Co-Authors: Patrick A. Thompson, Linna Zhang, Nastassja A Lewinski, Nabil Ahmed, Rebekah A. Drezek, Susan M Blaney, Jennifer L. WestAbstract:We are developing a novel treatment for high-grade gliomas using near infrared-absorbing silica–gold Nanoshells that are thermally activated upon exposure to a near infrared laser, thereby irreversibly damaging cancerous cells. The goal of this work was to determine the efficacy of nanoshell-mediated photothermal therapy in vivo in murine xenograft models. Tumors were induced in male IcrTac:ICR-PrkdcSCID mice by subcutaneous implantation of Firefly Luciferase-labeled U373 human glioma cells and biodistribution and survival studies were performed. To evaluate nanoparticle biodistribution, Nanoshells were delivered intravenously to tumor-bearing mice and after 6, 24, or 48 h the tumor, liver, spleen, brain, muscle, and blood were assessed for gold content by inductively coupled plasma-mass spectrometry (ICP-MS) and histology. Nanoshell concentrations in the tumor increased for the first 24 h and stabilized thereafter. Treatment efficacy was evaluated by delivering saline or Nanoshells intravenously and externally irradiating tumors with a near infrared laser 24 h post-injection. Success of treatment was assessed by monitoring tumor size, tumor luminescence, and survival time of the mice following laser irradiation. There was a significant improvement in survival for the nanoshell treatment group versus the control (P < 0.02) and 57% of the mice in the nanoshell treatment group remained tumor free at the end of the 90-day study period. By comparison, none of the mice in the control group survived beyond 24 days and mean survival was only 13.3 days. The results of these studies suggest that nanoshell-mediated photothermal therapy represents a promising novel treatment strategy for malignant glioma.
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Diagnostic and Therapeutic Applications of Nanotechnology.
Cancer Research, 2009Co-Authors: Jennifer L. WestAbstract:The increasing capability to manipulate matter at the nanoscale is generating new materials with unique properties that promise to address unmet medical needs for future generations. As an example, metal Nanoshells are a relatively new class of nanoparticles with highly tunable optical properties. Metal Nanoshells consist of a dielectric core nanoparticle such as silica surrounded by an ultrathin metal shell, usually composed of gold for biomedical applications. Depending on the size and composition of each layer of the nanoshell, particles can be designed to either absorb or scatter light over much of the visible and infrared regions of the electromagnetic spectrum, including the near infrared region where penetration of light through tissue is maximal. These particles are also easily conjugated to antibodies and other biomolecules for specific targeting. Further, the biocompatibility of these particles is excellent. One can envision a myriad of potential applications of such tunable particles. Several potential biomedical applications are under development, including immunoassays, modulated drug delivery, photothermal cancer therapy, and imaging contrast agents. For example, in photothermal cancer therapy, Nanoshells can be injected intravenously, accumulate at tumor sites due to the enhanced permeability and retention (EPR) effect and/or molecular targeting, then generate heat upon illumination with near infrared light, leading to destruction of the tumor. This has shown very promising results in several animal models. For example, in a mouse colon carcinoma model, we demonstrated 100% survival of nanoshell treated mice at 1 year. These materials are now in phase I human clinical trials. For use in diagnostics and imaging, Nanoshells can be designed to strongly scatter near infrared light. Molecularly targeted Nanoshells have been used as optical contrast agents for cancer imaging with sub-cellular resolution. For example, anti-HER2 conjugated Nanoshells allow near infrared imaging of HER2+ breast carcinoma cells. Furthermore, integrated imaging and therapy applications have been accomplished with Nanoshells designed to provide both absorption and scattering, potentially enabling “see-and-treat” approaches to cancer therapy. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr MS1-1.
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Near Infrared Absorbing Nanoparticles for Photothermal Cancer Therapy
ASME 2008 Summer Bioengineering Conference Parts A and B, 2008Co-Authors: Jennifer L. WestAbstract:Advances in nanotechnology are expected to lead to the development of new and improved therapeutic strategies, amenable to targeting, that may ultimately revolutionize cancer treatment. For example, we have developed a nanoparticle-based photothermal cancer therapy that has shown high efficacy with virtually no damage to normal tissues (Hirsch et al., 2003, O’Neal et al., 2004, Lowery et al., 2006). This therapeutic strategy employs nanoparticles called Nanoshells that are designed to strongly absorb near infrared (NIR) light. Metal Nanoshells are a new type of nanoparticle composed of a dielectric (for instance, silica) core coated with an ultrathin metallic (for instance, gold) layer. Gold Nanoshells possess physical properties similar to gold colloid, in particular, a strong optical absorption due to the collective electronic response of the metal to light. The optical absorption of gold colloid yields a brilliant red color that has been of considerable utility in consumer-related medical products, such as home pregnancy tests. In contrast, the optical response of gold Nanoshells depends dramatically on the relative size of the nanoparticle core and the thickness of the gold shell. By varying the relative core and shell thicknesses, the color of gold Nanoshells can be varied across a broad range of the optical spectrum that spans the visible and the near infrared spectral regions (Oldenburg et al., 1999). Gold Nanoshells can be made to either preferentially absorb or scatter light at their plasmon resonance by varying the size of the particle relative to the wavelength of the light at their optical resonance. For cancer therapy, Nanoshells are injected intravenously and allowed to accumulate in tumor sites due to the leakiness of the vasculature (EPR) and/or molecular targeting. Accumulation in the tumor sites peaks after several hours, at which time the tissue region is illuminated with NIR light for several minutes. NIR light is not absorbed to a significant extent by tissue components, but is strongly absorbed by Nanoshells within the tumor. This leads to rapid heating of the tumor tissue without damage to adjacent normal tissues. In preliminary studies, complete tumor regression and 100% survival with no regrowth has been achieved. Mice with CT26 colon carcinoma tumors (4 mm diameter) were injected intravenously with NIR absorbing Nanoshells that were coated with PEG-SH. 6 hr following nanoshell injection, the tumor sites were illuminated with light from a 820 nm diode laser (4 W/cm2) for 4 min. Animals in a sham group received a saline injection instead of Nanoshells prior to NIR treatment, while a control group was untreated. Tumor size and animal survival were then tracked. As shown in Figure 1, all tumors treated with Nanoshells had completely regressed within 10 days of treatment, while sham and control tumors had grown dramatically. Furthermore, all sham and control animals died within 20 days of treatment, while all nanoshell-treated mice continue to live (+12 months) with no tumor regrowth (Figure 2, O’Neal et al., 2004). Excellent nanoshell biocompatibility has been observed.Copyright © 2008 by ASME
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temperature sensitive hydrogels with sio2 au Nanoshells for controlled drug delivery
Journal of Controlled Release, 2007Co-Authors: Malavosklish Bikram, Andre M. Gobin, Rachel E Whitmire, Jennifer L. WestAbstract:Abstract Silica–gold (SiO2–Au) Nanoshells are a new class of nanoparticles that consist of a silica dielectric core that is surrounded by a gold shell. These Nanoshells are unique because their peak extinctions are very easily tunable over a wide range of wavelengths particularly in the near infrared (IR) region of the spectrum. Light in this region is transmitted through tissue with relatively little attenuation due to absorption. In addition, irradiation of SiO2–Au Nanoshells at their peak extinction coefficient results in the conversion of light to heat energy that produces a local rise in temperature. Thus, to develop a photothermal modulated drug delivery system, we have fabricated nanoshell-composite hydrogels in which SiO2–Au Nanoshells of varying concentrations have been embedded within temperature-sensitive hydrogels, for the purpose of initiating a temperature change with light. N-isopropylacrylamide-co-acrylamide (NIPAAm-co-AAm) hydrogels are temperature-sensitive hydrogels that were fabricated to exhibit a lower critical solution temperature (LCST) slightly above body temperature. The resulting composite hydrogels had the extinction spectrum of the SiO2–Au Nanoshells in which the hydrogels collapsed reversibly in response to temperature (50 °C) and laser irradiation. The degree of collapse of the hydrogels was controlled by the laser fluence as well as the concentration of SiO2–Au Nanoshells. Modulated drug delivery profiles for methylene blue, insulin, and lysozyme were achieved by irradiation of the drug-loaded nanoshell-composite hydrogels, which showed that drug release was dependent upon the molecular weight of the therapeutic molecule.
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Nanoshells for Integrated Cancer Imaging and Therapy
Clinical Cancer Research, 2006Co-Authors: Andre M. Gobin, Naomi J. Halas, Rebekah A. Drezek, Jennifer L. WestAbstract:A104 This purpose of this study was to investigate the use of Nanoshells for a combined imaging application and cancer therapy using commercially available optical coherence tomography (OCT). Gold Nanoshells are a new class of nanoparticles with tunable optical absorption that can be designed in the near infrared where penetration of light through tissue is maximal. Nanoshells consist of a dielectric core of silica with an ultrathin shell of gold. It has been previously shown that gold Nanoshells can sufficiently accumulate in tumors due to the enhanced permeability and retention (EPR) effect thus allowing ablation of tumors using an external NIR laser source. This led to complete tumor regression. In the current studies, we have designed Nanoshells to both provide optical contrast for OCT to enhance diagnostic capabilities and also to then to generate localized heating under the appropriate illumination conditions to allow for ablation of the tumor.Murine colon carcinoma cells, CT-26, were grown subcutaneously in BALB/c mice. Tumors were allowed to grow to ~5 mm diameter. The surfaces of the Nanoshells were modified with polyethylene glycol (PEG-SH) to enhance circulation. For the treatment group PEGylated Nanoshells were injected into the tail vein of the animals 20 hours prior to imaging and treatment. PBS injected animals and untreated controls were also used in the study. The tumors were imaged using the Niris Imaging System OCT by applying glycerol for index matching and placing the probe directly on the skin. Images were captured at several locations on each tumor. After imaging the tumors were exposed to a NIR laser. Tumor size and animal survival following treatment was monitored for 8 weeks after treatment.OCT images of the tumors prior to irradiation shows substantially higher contrast, indicative of higher scattering, in the tumors of mice that received systemic nanoshell injections compared to the mice receiving saline injections. Silver stained images show the presence of Nanoshells in the tumors of mice injected with Nanoshells compared to PBS injected mice. There was a greater than 80% survival rate of the nanoshell therapy mice after 8 weeks, compared to 14% for the Saline + laser group and zero for the control group. Kaplan-Meier statistical analysis on the survival data showed a median survival of 14 days for the PBS + laser treatment group and 10 days for the Untreated Control group. At 21 days and to the end of the 8 week study period, the nanoshell therapy group survival rate was significantly higher than either control group, p
Rebekah A. Drezek - One of the best experts on this subject based on the ideXlab platform.
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nanoshell mediated photothermal therapy improves survival in a murine glioma model
Journal of Neuro-oncology, 2011Co-Authors: Patrick A. Thompson, Linna Zhang, Nastassja A Lewinski, Nabil Ahmed, Rebekah A. Drezek, Susan M Blaney, Jennifer L. WestAbstract:We are developing a novel treatment for high-grade gliomas using near infrared-absorbing silica–gold Nanoshells that are thermally activated upon exposure to a near infrared laser, thereby irreversibly damaging cancerous cells. The goal of this work was to determine the efficacy of nanoshell-mediated photothermal therapy in vivo in murine xenograft models. Tumors were induced in male IcrTac:ICR-PrkdcSCID mice by subcutaneous implantation of Firefly Luciferase-labeled U373 human glioma cells and biodistribution and survival studies were performed. To evaluate nanoparticle biodistribution, Nanoshells were delivered intravenously to tumor-bearing mice and after 6, 24, or 48 h the tumor, liver, spleen, brain, muscle, and blood were assessed for gold content by inductively coupled plasma-mass spectrometry (ICP-MS) and histology. Nanoshell concentrations in the tumor increased for the first 24 h and stabilized thereafter. Treatment efficacy was evaluated by delivering saline or Nanoshells intravenously and externally irradiating tumors with a near infrared laser 24 h post-injection. Success of treatment was assessed by monitoring tumor size, tumor luminescence, and survival time of the mice following laser irradiation. There was a significant improvement in survival for the nanoshell treatment group versus the control (P < 0.02) and 57% of the mice in the nanoshell treatment group remained tumor free at the end of the 90-day study period. By comparison, none of the mice in the control group survived beyond 24 days and mean survival was only 13.3 days. The results of these studies suggest that nanoshell-mediated photothermal therapy represents a promising novel treatment strategy for malignant glioma.
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immunoconjugated gold nanoshell mediated photothermal ablation of trastuzumab resistant breast cancer cells
Breast Cancer Research and Treatment, 2011Co-Authors: Laura B Carpin, Lissett R Bickford, Germaine Agollah, Tsekuan Yu, Rachel Schiff, Yi Li, Rebekah A. DrezekAbstract:Trastuzumab is a FDA-approved drug that has shown clinical efficacy against HER2+ breast cancers and is commonly used in combination with other chemotherapeutics. However, many patients are innately resistant to trastuzumab, or will develop resistance during treatment. Alternative treatments are needed for trastuzumab-resistant patients. Here, we investigate gold nanoparticle-mediated photothermal therapies as a potential alternative treatment for chemotherapy-resistant cancers. Gold nanoshell photothermal therapy destroys the tumor cells using heat, a physical mechanism, which is able to overcome the cellular adaptations that bestow trastuzumab resistance. By adding anti-HER2 to the gold surface of the Nanoshells as a targeting modality, we increase the specificity of the Nanoshells for HER2+ breast cancer. Silica–gold Nanoshells conjugated with anti-HER2 were incubated with both trastuzumab-sensitive and trastuzumab-resistant breast cancer cells. Nanoshell binding was confirmed using two-photon laser scanning microscopy, and the cells were then ablated using a near-infrared laser. We demonstrate the successful targeting and ablation of trastuzumab-resistant cells using anti-HER2-conjugated silica–gold Nanoshells and a near-infrared laser. This study suggests potential for applying gold nanoshell-mediated therapy to trastuzumab-resistant breast cancers in vivo.
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Optical properties of gold-silica-gold multilayer Nanoshells
Optics Express, 2008Co-Authors: Ying Hu, Ryan C. Fleming, Rebekah A. DrezekAbstract:The spectral and angular radiation properties of gold-silica-gold multilayer Nanoshells are investigated using Mie theory for concentric multilayer spheres. The spectral tunability of multilayer Nanoshells is explained and characterized by a plasmon hybridization model and a universal scaling principle. A thinner intermediate silica layer, scaled by particle size, red shifts the plasmon resonance. This shift is relatively insensitive to the overall particle size and follows the universal scaling principle with respect to the resonant wavelength of a conventional silica-gold core-shell nanoshell. The extra tunability provided by the inner core further shifts the extinction peak to longer wavelengths, which is difficult to achieve on conventional sub-100 nm Nanoshells due to limitations in synthesizing ultrathin gold coatings. We found multilayer Nanoshells to be more absorbing with a larger gold core, a thinner silica layer, and a thinner outer gold shell. Both scattering intensity and angular radiation pattern were found to differ from conventional Nanoshells due to spectral modulation from the inner core. Multilayer Nanoshells may provide more backscattering at wavelengths where silica-gold core-shell Nanoshells predominantly forward scatter.
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Nanoshells for Integrated Cancer Imaging and Therapy
Clinical Cancer Research, 2006Co-Authors: Andre M. Gobin, Naomi J. Halas, Rebekah A. Drezek, Jennifer L. WestAbstract:A104 This purpose of this study was to investigate the use of Nanoshells for a combined imaging application and cancer therapy using commercially available optical coherence tomography (OCT). Gold Nanoshells are a new class of nanoparticles with tunable optical absorption that can be designed in the near infrared where penetration of light through tissue is maximal. Nanoshells consist of a dielectric core of silica with an ultrathin shell of gold. It has been previously shown that gold Nanoshells can sufficiently accumulate in tumors due to the enhanced permeability and retention (EPR) effect thus allowing ablation of tumors using an external NIR laser source. This led to complete tumor regression. In the current studies, we have designed Nanoshells to both provide optical contrast for OCT to enhance diagnostic capabilities and also to then to generate localized heating under the appropriate illumination conditions to allow for ablation of the tumor.Murine colon carcinoma cells, CT-26, were grown subcutaneously in BALB/c mice. Tumors were allowed to grow to ~5 mm diameter. The surfaces of the Nanoshells were modified with polyethylene glycol (PEG-SH) to enhance circulation. For the treatment group PEGylated Nanoshells were injected into the tail vein of the animals 20 hours prior to imaging and treatment. PBS injected animals and untreated controls were also used in the study. The tumors were imaged using the Niris Imaging System OCT by applying glycerol for index matching and placing the probe directly on the skin. Images were captured at several locations on each tumor. After imaging the tumors were exposed to a NIR laser. Tumor size and animal survival following treatment was monitored for 8 weeks after treatment.OCT images of the tumors prior to irradiation shows substantially higher contrast, indicative of higher scattering, in the tumors of mice that received systemic nanoshell injections compared to the mice receiving saline injections. Silver stained images show the presence of Nanoshells in the tumors of mice injected with Nanoshells compared to PBS injected mice. There was a greater than 80% survival rate of the nanoshell therapy mice after 8 weeks, compared to 14% for the Saline + laser group and zero for the control group. Kaplan-Meier statistical analysis on the survival data showed a median survival of 14 days for the PBS + laser treatment group and 10 days for the Untreated Control group. At 21 days and to the end of the 8 week study period, the nanoshell therapy group survival rate was significantly higher than either control group, p
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Reflectance spectroscopy of gold Nanoshells: computational predictions and experimental measurements
Journal of Nanoparticle Research, 2006Co-Authors: Nastassja A Lewinski, Rebekah A. DrezekAbstract:Gold Nanoshells are concentric spherical constructs that possess highly desirable optical responses in the near infrared. Gold Nanoshells consist of a thin outer gold shell and a silica core and can be used for both diagnostic and therapeutic purposes by tuning the optical response through changing the core–shell ratio as well as the overall size. Although optical properties of gold Nanoshells have already been well documented, the reflectance characteristics are not well understood and have not yet been elucidated by experimental measurements. Yet, in order to use gold Nanoshells as an optical contrast agent for scattering-based optical methods such as reflectance spectroscopy, it is critical to characterize the reflectance behavior. With this in mind, we used a fiber-optic-based spectrometer to measure diffuse reflectance of gold nanoshell suspensions from 500 nm to 900 nm. Experimental results show that gold Nanoshells cause a significant increase in the measured reflectance. Spectral features associated with scattering from large angles (~180°) were observed at low nanoshell concentrations. Monte Carlo modeling of gold Nanoshells reflectance demonstrated the efficacy of using such methods to predict diffuse reflectance. Our studies suggest that gold Nanoshells are an excellent candidate as optical contrast agents and that Monte Carlo methods are a useful tool for optimizing Nanoshells best suited for scattering-based optical methods.
J B Jackson - One of the best experts on this subject based on the ideXlab platform.
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surface enhanced raman scattering from individual au nanoparticles and nanoparticle dimer substrates
Nano Letters, 2005Co-Authors: J B Jackson, Nathaniel K Grady, Chris Oubre, Chad E Talley, Christopher W Hollars, Stephen M Lane, Thomas R HuserAbstract:Surface-enhanced Raman scattering (SERS) intensities for individual Au nanospheres, Nanoshells, and nanosphere and nanoshell dimers coated with nonresonant molecules are measured, where the precise nanoscale geometry of each monomer and dimer is identified through in situ atomic force microscopy. The observed intensities correlate with the integrated quartic local electromagnetic field calculated for each specific nanostructure geometry. In this study, we find that suitably fabricated Nanoshells can provide SERS enhancements comparable to nanosphere dimers.
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surface enhanced raman scattering on tunable plasmonic nanoparticle substrates
Proceedings of the National Academy of Sciences of the United States of America, 2004Co-Authors: J B Jackson, Naomi J. HalasAbstract:Au and Ag Nanoshells are investigated as substrates for surface-enhanced Raman scattering (SERS). We find that SERS enhancements on nanoshell films are dramatically different from those observed on colloidal aggregates, specifically that the Raman enhancement follows the plasmon resonance of the individual nanoparticles. Comparative finite difference time domain calculations of fields at the surface of smooth and roughened Nanoshells reveal that surface roughness contributes only slightly to the total enhancement. SERS enhancements as large as 2.5 × 1010 on Ag nanoshell films for the nonresonant molecule p-mercaptoaniline are measured.
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A rapid, whole blood immunoassay using metal Nanoshells
Proceedings of the 25th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (IEEE Cat. No.03CH37439), 2003Co-Authors: L.r. Hirsch, J.l. West, J B Jackson, Naomi J. HalasAbstract:Using metal Nanoshells as an immunoassay substrate, we describe an immunoassay capable of detecting blood borne analyte on the order of minutes. Near infrared resonant gold Nanoshells were labeled with antibodies specific to rabbit IgG analyte. The antibody-nanoshell conjugates were detectable via near infrared photometry in solution with saline, serum, and whole blood. Addition of analyte induced aggregation of antibody-nanoshell conjugates, causing a decrease in the original nanoshell near infrared resonance. Aggregation proceeded in a concentration dependent fasion in all three mediums (saline, serum, whole blood), permitting quantitative detection of analyte within 10-30 minutes and sensitivities
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Plasmon-plasmon interaction between gold Nanoshells and gold surfaces
Technical Digest. Summaries of papers presented at the Quantum Electronics and Laser Science Conference. Postconference Technical Digest (IEEE Cat. No, 2001Co-Authors: R.n. Taylor, Corey Radloff, Sarah L Westcott, J B Jackson, Naomi J. HalasAbstract:Summary form only given. Gold Nanoshells are colloidal particles with a dielectric core covered by a gold shell. The plasmon resonance of the Nanoshells can be tuned by varying the ratio of the core/shell radii. An enhancement in the electromagnetic energy can be found, at resonance, in the region close to the nanoshell known as the near field. It has been shown theoretically and experimentally that if the evanescent near fields of a surface plasmon polariton and a particle plasmon overlap, an efficient exchange of energy from the freely propagating electromagnetic waves into surface plasmons can be achieved. Previous experiments used particles that lacked the extraordinary tunability of Nanoshells. We give our sample geometry. After evaporating a layer of gold onto a glass slide, we deposit self-assembled monolayers (SAMs) of a polymer (PDDA) and Hectorite (a synthetic clay), to control the spacing between the gold surface and the Nanoshells.
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Enhancing the active lifetime of luminescent semiconducting polymers via doping with metal Nanoshells
Applied Physics Letters, 2001Co-Authors: G. D. Hale, O. E. Shmakova, J B Jackson, Naomi J. HalasAbstract:We report a dramatic, concentration-dependent decrease in the rate of photo-oxidation of semiconducting polymers due to the addition of small amounts of metal Nanoshells to the polymer. In each case, the nanoshell resonances are tuned to the triplet exciton-ground state energy of the polymer. The nanoshell dopants slow the oxidation rate yet do not affect the photoluminescent properties of the polymers to which they have been added.
Hui Wang - One of the best experts on this subject based on the ideXlab platform.
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cuprous oxide Nanoshells with geometrically tunable optical properties
ACS Nano, 2011Co-Authors: Li Zhang, Hui WangAbstract:We have systematically investigated the geometrically tunable optical properties of cuprous oxide (Cu2O) in a nanoshell geometry. Spherically symmetric Cu2O Nanoshells with fine-controlled shell thicknesses and overall dimensions over a broad size range have been fabricated in a highly controllable manner through an Ostwald ripening-based symmetric hollowing process at room temperature. Symmetric hollowing of Cu2O particles can be achieved by using polyvinylpyrrolidone as a structural directing agent to mediate aggregation of the nuclei into solid spheres at the initial stage of the process, whereas when using other structural directing agents, such as polyethylene glycol, an asymmetric hollowing process takes place during Ostwald ripening, which gives rise to the formation of asymmetric Cu2O nanoshell structures. We demonstrate, both experimentally and theoretically, that the optical responses of Cu2O Nanoshells can be fine-tuned in the visible spectral region by tailoring the inner and outer radii of th...
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Cuprous oxide Nanoshells with geometrically tunable optical properties
ACS Nano, 2011Co-Authors: Li Zhang, Hui WangAbstract:We have systematically investigated the geometrically tunable optical properties of cuprous oxide (Cu(2)O) in a nanoshell geometry. Spherically symmetric Cu(2)O Nanoshells with fine-controlled shell thicknesses and overall dimensions over a broad size range have been fabricated in a highly controllable manner through an Ostwald ripening-based symmetric hollowing process at room temperature. Symmetric hollowing of Cu(2)O particles can be achieved by using polyvinylpyrrolidone as a structural directing agent to mediate aggregation of the nuclei into solid spheres at the initial stage of the process, whereas when using other structural directing agents, such as polyethylene glycol, an asymmetric hollowing process takes place during Ostwald ripening, which gives rise to the formation of asymmetric Cu(2)O nanoshell structures. We demonstrate, both experimentally and theoretically, that the optical responses of Cu(2)O Nanoshells can be fine-tuned in the visible spectral region by tailoring the inner and outer radii of the spherically symmetric Nanoshells. Such optical tunability of Cu(2)O achieved in this nanoshell geometry is believed to be important to the optimization of Cu(2)O-based photonic materials and devices for photovoltaic and photocatalytic applications.
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controlled texturing modifies the surface topography and plasmonic properties of au Nanoshells
Journal of Physical Chemistry B, 2005Co-Authors: Hui Wang, Peter Nordlander, Glenn P Goodrich, Chris Oubre, Naomi J. HalasAbstract:We report a facile and controllable method for the postfabrication texturing of the surface topography of Au Nanoshells based on site-selective chemical etching of the polycrystalline Au nanoshell surface by a bifunctional alkanethiol molecule, cysteamine. This nanoscale surface texturing process systematically introduces dramatic changes to the plasmonic properties of the Au Nanoshells. The modification of the plasmon resonant properties of Nanoshells as a function of increased surface roughness was examined experimentally and modeled theoretically using three-dimensional finite difference time domain (FDTD) simulations.
