November 10, 2006
Nanoprobes Demonstrates the Use of Gold Nanoparticles as Superior X-Ray Contrast Agents
Triiodobenzene derivatives have been the chemical platform of choice for X-ray contrast agents for more than 25 years for applications such as angiography. However, they have serious limitations for many applications: short imaging times, the need for catheterization in many cases, high viscosities that can cause arterial damage when injected and excludes their use in smaller vessels, occasional renal toxicity, and poor contrast in large patients. In research at Nanoprobes, the potential of gold nanoparticles as improved X-ray contrast agents has been investigated, and it is now reported that 1.9 nm gold nanoparticles may overcome many of these limitations. Gold has higher X-ray absorption than iodine with less bone and tissue interference, thus achieving better contrast with lower X-ray dose. Because nanoparticles clear the blood more slowly than iodine agents, they permit longer imaging times.
In studies in mice, a 5 mm tumor growing in one thigh was clearly evident from its increased vascularity and resultant higher gold content. The gold particles thus enable direct imaging, detection, and measurement of angiogenic and hypervascularized regions. The 1.9 nm gold nanoparticles were found to clear through the kidneys: a closer examination of the kidneys revealed a remarkably detailed anatomical and functional display, with blood vessels less than 100 m in diameter delineated, thus enabling in vivo vascular casting. Toxicity was also low: mice intravenously injected with the gold nanoparticles at 2.7 g Au kg-1 survived over one year without signs of illness. In a 30-day study using 60 mice, intravenous injection of the gold nanoparticles (at 700 mg Au kg-1) produced no evidence of toxicity in any animals. Even when concentrated, gold nanoparticle solutions were similar to water in viscosity, in sharp contrast to the high viscosity of iodine contrast media. The gold nanoparticles may be completely dried and later resuspend easily in water or aqueous buffers, such as phosphate buffered saline, pH 7.4. Solubility was found to be at least 1.5 g Au ml-1.
Nanoprobes is developing this reagent for commercial introduction, and products based on this technology are near release. Nanoprobes, Inc., founded in 1990, researches and develops novel microscopic and biomedical staining and imaging technology using metal nanoparticles. The company is a leader in immunogold technology. Other products include the 1.4 nm Nanogold® immunoprobes and labeling reagents, FluoroNanogold combined fluorescent and gold probes, and silver enhancers and gold-based autometallographic enhancers for ultrasensitive detection and visualization of biological targets. New product announcements and information about current products are available on the companys web site (www.nanoprobes.com). Nanoprobes recently announced a major expansion to its Yaphank, NY facility.
Hainfeld J. F.; Slatkin D. N.; Focella T. M., and Smilowitz H. M.: Gold nanoparticles: a new X-ray contrast agent. Br. J. Radiol., 79, 248-253 (2006).
3 nm section of mouse abdomen after Gold injection, showing branching of inferior vena cava and 25 m blood vessels.
For more information, contact:
July 20, 2006
First 3D Distribution of 45S rDNA in Metaphase Chromosomes by in situ hybridization with FluoroNanogold
In their recent paper in the journal Chromosoma, Elizabeth Schröder-Reiter et al. report the first 3D light and electron microscopic structure determination and 45S rDNA distribution of an unusual, peg-like terminal constriction on metaphase plant chromosomes. Their results identify this as a nucleolus organizing region (NOR). The authors developed an in situ hybridization procedure using a biotinylated hybridization probe visualized by light and scanning electron microscopy (SEM) using Alexa Fluor®* 488 FLUORONANOGOLDstreptavidin. Improvements in signal localization, labeling efficiency, and structural preservation allowed, for the first time, the 3D SEM analysis of the NOR structure and mapping of rDNA distribution.
Our recently introduced ALEXA FLUOR®* FLUORONANOGOLD combines the brightness and low bleaching of Alexa Fluor dyes with the high resolution and specificity of the 1.4 nm NANOGOLD®, all in one stable, covalently linked probe, enabling visualization of targets by fluorescence microscopy, then more detailed ultrastructural study by electron microscopy with direct correlation of results. Covalent attachment of both the ALEXA dye and NANOGOLD to the Fab antibody fragment ensure stability and shelf-life of this unique new dual probe.
Nanoprobes, Inc., founded in 1990, researches and develops novel microscopic and biomedical staining and imaging technology using metal nanoparticle immunoprobes. The company is a leader in immunogold technology. In addition to FLUORONANOGOLD, products include the 1.4 nm Nanogold® immunoprobes and labeling reagents, and silver enhancers and gold-based autometallographic enhancers for ultrasensitive visualization of biological targets. The Company recently announced a major expansion to its Yaphank, NY facility.
* Alexa Fluor is a trademark of Molecular Probes / Invitrogen.
Scanning electron micrograph of a peg-like terminal constriction of an Oziroë biflora (plant, Hyacinthaceae) chromosome. The image shows both chromosome topography (secondary electron signal) and hybridized enhanced gold signals (superimposed back-scattered electron signals, yellow) labeling 45S rDNA in the nucleolus organizing region with AlexaFluor 488 fluoronanogold-streptavidin (micrograph courtesy of Elizabeth Schröder-Reiter and Gerhard Wanner).
For more information, contact:
March 15, 2006
Nanoprobes, Incorporated Completes Major Expansion
Nanoprobes, Incorporated announces a major expansion in its office and laboratory facilities in Yaphank, NY. The company has almost doubled its laboratory and office space, and completed an extensive renovation to upgrade its facilities, research and manufacturing capabilities. Within the past 12 months, the Company has also increased its staff by more than 30%. This expansion will deepen the Companys commitment to developing novel products and technologies, while helping to provide improved support to current customers. The expanded facilities will support research projects which include novel technology for breast cancer diagnosis and characterization, and the application of metal nanoparticles as contrast agents for biomedical imaging.
Nanoprobes, Inc., founded in 1990, researches and develops novel biomedical and microscopic staining and imaging technology using metal nanoparticles and autometallography. The company is a leader in immunogold technology, with products which include the 1.4 nm Nanogold® immunoprobes and labeling reagents, FluoroNanogold combined fluorescent and gold probes, and autometallographic enhancers for ultrasensitive visualization of biological targets. The Company recently executed a licensing agreement with Ventana Medical Systems, Incorporated (VMSI) for the use of its Enzyme Metallography (EnzMet) technology as an ultrasensitive staining method for in situ hybridization and immunohistochemistry.
For more information, contact: