Publications by Type: Book Chapter

2011
T. Y. Wang, Sapozhnikova, V., Mancuso, J. J., Willsey, B., Qiu, J. Z., Ma, L. L., Li, X. K., Johnston, K. P., Feldman, M. D., and Milner, T. E., “Fluorescence Imaging of Macrophages in Atherosclerotic Plaques Using Plasmonic Gold Nanorose,” in Photonic Therapeutics and Diagnostics Vii, vol. 7883, N. Kollias, Choi, B., Zeng, H., Kang, H. W., Knudsen, B. E., Wong, B. J. F., Ilgner, J. F. R., Gregory, K. W., Tearney, G. J., Marcu, L., Hirschberg, H., Madsen, S. J., Mandelis, A., MahadevanJansen, A., and Jansen, E. D., Ed. 2011. Publisher's VersionAbstract
Macrophages are one of the most important cell types involved in the progression of atherosclerosis which can lead to myocardial infarction. To detect macrophages in atherosclerotic plaques, plasmonic gold nanorose is introduced as a nontoxic contrast agent for fluorescence imaging. We report macrophage cell culture and ex vivo tissue studies to visualize macrophages targeted by nanorose using scanning confocal microscopy. Atherosclerotic lesions were created in the aorta of a New Zealand white rabbit model subjected to a high cholesterol diet and double balloon injury. The rabbit was injected with nanoroses coated with dextran. A HeNe laser at 633 nm was used as an excitation light source and a acousto-optical beam splitter was utilized to collect fluorescence emission in 650-760 nm spectral range. Results of scanning confocal microscopy of macrophage cell culture and ex vivo tissue showed that nanoroses produce a strong fluorescence signal. The presence of nanorose in ex vivo tissue was further confirmed by photothermal wave imaging. These results suggest that scanning confocal microscopy can identify the presence and location of nanorose-loaded macrophages in atherosclerotic plaques.
2010
M. Mehrmohammadi, Ma, L. L., Chen, Y. S., Qu, M., Joshi, P., Chen, R. M., Johnston, K. P., and Emelianov, S., “Combined photothermal therapy and magneto-motive ultrasound imaging using multifunctional nanoparticles,” in Nanoscale Imaging, Sensing, and Actuation for Biomedical Applications Vii, vol. 7574, A. N. Cartwright and Nicolau, D. V., Ed. 2010. Publisher's VersionAbstract
Photothermal therapy is a laser-based non-invasive technique for cancer treatment. Photothermal therapy can be enhanced by employing metal nanoparticles that absorb the radiant energy from the laser leading to localized thermal damages. Targeting of nanoparticles leads to more efficient uptake and localization of photoabsorbers thus increasing the effectiveness of the treatment. Moreover, efficient targeting can reduce the required dosage of photoabsorbers; thereby reducing the side effects associated with general systematic administration of nanoparticles. Magnetic nanoparticles, due to their small size and response to an external magnetic field gradient have been proposed for targeted drug delivery. In this study, we investigate the applicability of multifunctional nanoparticles (e.g., magneto-plasmonic nanoparticles) and magneto-motive ultrasound imaging for image-guided photothermal therapy. Magneto-motive ultrasound imaging is an ultrasound based imaging technique capable of detecting magnetic nanoparticles indirectly by utilizing a high strength magnetic field to induce motion within the magnetically labeled tissue. The ultrasound imaging is used to detect the internal tissue motion. Due to presence of the magnetic component, the proposed multifunctional nanoparticles along with magneto-motive ultrasound imaging can be used to detect the presence of the photo absorbers. Clearly the higher concentration of magnetic carriers leads to a monotonic increase in magneto-motive ultrasound signal. Thus, magneto-motive ultrasound can determine the presence of the hybrid agents and provide information about their location and concentration. Furthermore, the magneto-motive ultrasound signal can indicate the change in tissue elasticity - a parameter that is expected to change significantly during the photothermal therapy. Therefore, a comprehensive guidance and assessment of the photothermal therapy may be feasible through magneto-motive ultrasound imaging and magneto-plasmonic nanoparticles.
T. Y. Wang, Qiu, J. Z., Ma, L. L., Li, X. K., Sun, J. J., Ryoo, S., Johnston, K. P., Feldman, M. D., and Milner, T. E., “Nanorose and Lipid Detection in Atherosclerotic Plaque Using Dual-wavelength Photothermal Wave Imaging,” in Optical Interactions with Tissues and Cells Xxi, vol. 7562, E. D. Jansen and Thomas, R. J., Ed. 2010. Publisher's VersionAbstract
Atherosclerosis and specifically rupture of vulnerable plaques account for 23% of all deaths worldwide, far surpassing both infectious diseases and cancer. In atherosclerosis, macrophages can infiltrate plaques which are often associated with lipid deposits. Photothermal wave imaging is based on the periodic thermal modulation of a sample using intensity modulated light. Intensity modulated light enters the sample and is absorbed by targeted chromophores and generates a periodic thermal modulation. We report use of photothermal wave imaging to visualize nanoroses (taken up by macrophages via endocytosis) and lipids in atherosclerotic plaques. Two excitation wavelengths were selected to image nanoroses (800 nm) and lipids (1210 nm). Atherosclerotic plaque in a rabbit abdominal artery was irradiated (800 nm and 1210 nm separately) at a frequency of 4 Hz to generate photothermal waves. The radiometric temperature at the tissue surface was recorded by an infrared (IR) camera over a 10 second time period at the frame rate of 25.6 Hz. Extraction of images (256 x 256 pixels) at various frequencies was performed by Fourier transform at each pixel. Frequency amplitude images were obtained corresponding to 800 nm and 1210 nm laser irradiation. Computed images suggest that the distributions of both nanorose and lipid can be identified in amplitude images at a frequency of 4 Hz. Nanoroses taken up by macrophages are distributed at the edges of lipid deposits. Observation of high concentration of nanoroses in atherosclerotic plaque confirms that nanoroses are present at locations associated with lipid deposits.
D. A. Slanac, Li, L., Stevenson, K. J., and Johnston, K. P., “Stable Oxygen Reduction Electrocatalysts from Presynthesized PdPt Nanoparticles on Carbon,” in Polymer Electrolyte Fuel Cells 10, Pts 1 and 2, vol. 33, H. A. Gasteiger, Weber, A., Strasser, P., Edmundson, M., Lamy, C., Darling, R., Uchida, H., Schmidt, T. J., Shirvanian, P., Buchi, F. N., Mantz, R., Zawodzinski, T., Ramani, V., Fuller, T., Inaba, M., Jones, D., and Narayanan, S. R., Ed. 2010, pp. 161-170. Publisher's VersionAbstract
We have synthesized an oxygen reduction catalyst composed of pre-synthesized Pd3Pt2 alloy nanoparticles dispersed on Vulcan carbon. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) indicate the alloy particles are 4.0nm. The catalyst loses 20% of its activity after potential cycling from 0.5 V to 1.2 V (NHE) in HClO4 compared to 70% for commercial Pt/VC. Even after 20% loss, the final activity of the Pd3Pt2/VC catalyst is 0.095 A/mg(Pt), equal to that of the fresh commercial Pt/VC. After cycling TEM shows only a small increase in particle size to 4.5nm, and X-ray photoelectron spectroscopy reveals no change in the oxidation states of the metals, indicating the stability may result from an increased dissolution resistance of the alloy relative to the base metals. The development of well-defined, stable, and active alloy catalysts facilitates a better understanding of structure-activity relationships and is encouraging for the application of commercially viable fuel cells.
J. O. Tam, Tam, J. M., Murthy, A., Ingram, D., Ma, L. L., Travis, K., Johnston, K. P., and Sokolov, K., “Biodegradable Near-Infrared Plasmonic Nanoclusters for Biomedical Applications,” in Plasmonics in Biology and Medicine Vii, vol. 7577, T. VoDinh and Lakowicz, J. R., Ed. 2010. Publisher's VersionAbstract
Nanoparticles such as gold and silver with plasmonic resonances in the near-infrared (NIR) optical region, where soft tissue is the most transparent, are of great interest in biomedical applications. A major roadblock in translation of inorganic nanoparticles to clinical practice for systemic targeting of disease is their non-biodegradable nature. In addition, gold nanoparticles that absorb in the NIR are typically greater than 50 nm, which is above the threshold size of 5.5 nm required for effective excretion from the body. Here we describe a new class of biodegradable gold nanoparticles with plasmon resonances in the NIR region. The synthesis is based on controlled assembly of very small (less than 5 nm) primary gold particles into nanoclusters with sub-100 nm overall diameter and an intense NIR absorbance. The assembly is mediated by biodegradable polymers, polyethylene glycol (PEG) and polylactic acid (PLA) copolymer, and small capping ligands on the constituent nanoparticles. Nanoclusters deaggregate into sub-5nm primary gold particles upon biodegradation of the polymer binder in live cells over one week, as shown by dark-field reflectance and hyperspectral imaging.
J. O. Tam, Tam, J. M., Murthy, A., Ingram, D., Ma, L. L., Travis, K., Johnston, K. P., and Sokolov, K., “Biodegradable Near-Infrared Plasmonic Nanoclusters for Biomedical Applications,” in Reporters, Markers, Dyes, Nanoparticles, and Molecular Probes for Biomedical Applications Ii, vol. 7576, S. Achilefu and Raghavachari, R., Ed. 2010. Publisher's VersionAbstract
Nanoparticles such as gold and silver with plasmonic resonances in the near-infrared (NIR) optical region, where soft tissue is the most transparent, are of great interest in biomedical applications. A major roadblock in translation of inorganic nanoparticles to clinical practice for systemic targeting of disease is their non-biodegradable nature. In addition, gold nanoparticles that absorb in the NIR are typically greater than 50 nm, which is above the threshold size of 5.5 nm required for effective excretion from the body. Here we describe a new class of biodegradable gold nanoparticles with plasmon resonances in the NIR region. The synthesis is based on controlled assembly of very small (less than 5 nm) primary gold particles into nanoclusters with sub-100 nm overall diameter and an intense NIR absorbance. The assembly is mediated by biodegradable polymers, polyethylene glycol (PEG) and polylactic acid (PLA) copolymer, and small capping ligands on the constituent nanoparticles. Nanoclusters deaggregate into sub-5nm primary gold particles upon biodegradation of the polymer binder in live cells over one week, as shown by dark-field reflectance and hyperspectral imaging.
S. J. Yoon, Mallidi, S., Tam, J. M., Tam, J. O., Murthy, A., Joshi, P., Johnston, K. P., Sokolov, K. V., and Emelianov, S. Y., “Biodegradable plasmonic nanoclusters as contrast agent for photoacoustic imaging,” in Photons Plus Ultrasound: Imaging and Sensing 2010, vol. 7564, A. A. Oraevsky and Wang, L. V., Ed. 2010. Publisher's VersionAbstract
Metallic nanoparticles have been widely used in a variety of imaging and therapeutic applications due to their unique optical properties in the visible and near-infrared (NIR) regions - for example, various plasmonic nanoparticles are used for molecular photoacoustic imaging and photothermal therapy. However, there are concerns that these agents may not be safe under physiological conditions, because these nanoparticles are not biodegradable, could accumulate and, therefore, could be toxic long-term. We investigate the feasibility of using biodegradable gold nanoclusters as a contrast agent for highly sensitive photoacoustic imaging. The size of these biodegradable nanoclusters, consisting of sub-5 nm primary gold particles and a biodegradable polymer binder, is less than 100 nm. Due to plasmon coupling, these nanoclusters are characterized by a broad extinction spectrum that extends to the near infrared (NIR) spectral range. Photoacoustic imaging of tissue models containing inclusions with different concentrations of nanoparticles was performed using a tunable pulsed laser system. The results indicate that the biodegradable nanoclusters, comprised of small gold nanoparticles, can be used as contrast agents in photoacoustic imaging.
2009
M. Qu, Mallidi, S., Mehrmohammadi, M., Ma, L. L., Johnston, K. P., Sokolov, K., Emelianov, S., and Ieee,Combined Photoacoustic and Magneto-Acoustic Imaging,” in 2009 Annual International Conference of the Ieee Engineering in Medicine and Biology Society, Vols 1-20, 2009, pp. 4763-4766. Publisher's VersionAbstract
Ultrasound is a widely used modality with excellent spatial resolution, low cost, portability, reliability and safety. In clinical practice and in the biomedical field, molecular ultrasound-based imaging techniques are desired to visualize tissue pathologies, such as cancer. In this paper, we present an advanced imaging technique - combined photoacoustic and magneto-acoustic imaging - capable of visualizing the anatomical, functional and biomechanical properties of tissues or organs. The experiments to test the combined imaging technique were performed using dual, nanoparticle-based contrast agents that exhibit the desired optical and magnetic properties. The results of our study demonstrate the feasibility of the combined photoacoustic and magneto-acoustic imaging that takes the advantages of each imaging techniques and provides high sensitivity, reliable contrast and good penetrating depth. Therefore, the developed imaging technique can be used in wide range of biomedical and clinical application.
2007
M. Mehrmohammadi, Oh, J., Ma, L., Yantsen, E., Larson, T., Mallidi, S., Park, S., Johnston, K. P., Sokolov, K., Milner, T., Emelianov, S., and Ieee,Imaging of iron oxide nanoparticles using magneto-motive ultrasound,” in 2007 Ieee Ultrasonics Symposium Proceedings, Vols 1-6, 2007, pp. 652-655. Publisher's VersionAbstract
Due to its excellent spatial resolution, fast and reliable performance, cost and wide availability, ultrasound should be considered the imaging modality of choice for many applications including molecular imaging. However, ultrasound imaging cannot image molecular content of tissue due to trade-off between spatial resolution and penetration depth. Consequently, contrast agents have been developed both to enhance the contrast of ultrasound images and to make the images molecularly specific. Most ultrasound contrast agents, however, are micrometer sized and may not be applicable to wide range of pathology-specific cellular and molecular imaging. We have developed an imaging technique - magneto-motive ultrasound (NMUS) imaging, capable of imaging magnetic nanoparticles subjected to time-varying magnetic field. The result of our studies indicate that magnetically excited nanoparticles can be used as contrast agents in magneto-motive ultrasound imaging thus expanding the role of ultrasound imaging to cellular scales and molecular sensitivity.
2006
K. A. Overhoff, Johnston, K. P., and Williams, R. O., “Improvement of dissolution rate of poorly water soluble drugs using a new particle engineering process: Spray freezing into liquid,” in Polymeric Drug Delivery Ii: Polymeric Matrices and Drug Particle Engineering, vol. 924, S. Svenson, Ed. 2006, pp. 305-319. Publisher's VersionAbstract
Biopharmaceutics Classification System (BCS) Class II drugs are classified as having poor water solubility and good permeability across biological membranes. Improving the dissolution should, therefore, increase the bioavailability of this class of drugs. The Spray-Freezing into Liquid (SFL) process has been shown to increase dissolution rates of BCS class II drugs by providing amorphous particles with high surface area and small primary particle size, stabilized using hydrophilic polymers. Modifying the physicochemical properties of the particles is accomplished by selecting the optimum feed system composition. This article reviews the influence of this composition and active pharmaceutical ingredient (API) potency on surface area, surface morphology, crystallinity, and dissolution rates of model API.
2004
K. T. Lim, Hwang, H. S., Seong-Soo, H. B., Park, C., Ryoo, W., and Johnston, K. P., “Synthesis of ultrafine TiO2 particles from hydrolysis of Ti((OPr)-Pr-i)(4) with PEO-b-PFOMA reverse micelles in CO2,” in Carbon Dioxide Utilization for Global Sustainability, vol. 153, S. E. Park, Chang, J. S., and Lee, K. W., Ed. 2004, pp. 569-572. Publisher's VersionAbstract
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2003
P. S. Shah, Johnston, K. P., and Korgel, B. A., “Nanocrystal synthesis and stabilization in supercritical solvents,” in Supercritical Carbon Dioxide: Separations and Processes, vol. 860, A. S. Gopalan, Wai, C. M., and Jacobs, H. K., Ed. 2003, pp. 339-352. Publisher's VersionAbstract
Sterically stabilized nanocrystals in both sc-ethane and sc-CO2 follow lower critical solution temperature (LCST) phase behavior, with increased dispersibility at higher solvent densities. Perfluorodecanethiol ligands allow for nanocrystal dispersibility in pure CO2. A single phase arrested growth technique was developed to synthesize fluorinated ligand capped nanocrystals in sc-CO2. These particles were well passivated with the stabilizing ligand, protecting them from irreversible aggregation. It was found that the nanocrystal size depended on solvent density: at conditions of adequate steric stabilization-i.e., high solvent density and long ligands-the particles grew much smaller and more monodisperse than at poor solvent conditions.
2000
K. P. Johnston and Rossky, P. J., “Solution chemistry in supercritical water: Spectroscopy and simulation,” in Supercritical Fluids: Fundamentals and Applications, vol. 366, E. Kiran, Debenedetti, P. G., and Peters, C. J., Ed. 2000, pp. 323-343. Publisher's VersionAbstract
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J. C. Meredith and Johnston, K. P., “Theory and simulation of colloid and interface science in supercritical fluids,” in Supercritical Fluids: Fundamentals and Applications, vol. 366, E. Kiran, Debenedetti, P. G., and Peters, C. J., Ed. 2000, pp. 211-227. Publisher's VersionAbstract
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1995
K. P. Johnston, Balbuena, P. B., Xiang, T., and Rossky, P. J., “Simulation and spectroscopy of solvation in water from ambient to supercritical conditions,” in Innovations in Supercritical Fluids: Science and Technology, vol. 608, K. W. Hutchenson and Foster, N. R., Ed. 1995, pp. 77-92. Publisher's VersionAbstract
A review is presented of recent computer simulation and UV-visible spectroscopic studies of the solvation of nonelectrolytes and electrolytes in ambient and supercritical water. In addition, new simulation and fluorescence results are presented to focus on subcritical water solutions at temperatures from 298 to 573 K at densities on the coexistence curve of pure liquid water. The solvation of Cl- is examined with molecular dynamics computer simulation and that of pyrene is probed with fluorescence spectroscopy. For Cl- there is little loss in the coordination number from ambient to 523 K; this behavior continues up to the critical temperature (647.13 K) due to the strong attractive nature of the chloride-water interaction. Furthermore the negative heat and entropy of hydration are relatively constant up to about 573 K. In contrast, the solvation of pyrene decreases significantly with temperature. For nonelectrolytes such as Xe, the enthalpy of hydration changes from exothermic to endothermic as the coordination number decreases. The corresponding entropy changes from negative to positive as the hydrophobic effect dissipates, and the Gibbs free energy goes through a maximum.