A larva's brain in (a) bright field and (b) NIR fluorescence images, plus (c) the spectra of emission spots 1 and 2 in frame (b).
Rice University scientists have captured the first optical images of carbon nanotubes inside a living organism. Using fruit flies, the researchers confirmed that a technique developed at Rice—near-infrared (NIR) fluorescent imaging—was capable of detecting DNA-sized nanotubes inside living fruit flies. “Carbon nanotubes are much smaller than living cells, and they give off fluorescent light in a way that researchers hope to harness to detect diseases earlier than currently possible,” said research coauthor Bruce Weisman, professor of chemistry. “In order to do that, we need to learn how to detect and monitor nanotubes inside living tissues, and we must also determine whether they pose any hazards to organisms.” Researchers have studied how carbon nanotubes interact with tissues of rabbits, mice, and other animals, but Weisman and coauthor Kathleen Beckingham, professor of biochemistry and cell biology, chose something smaller—the fruit fly Drosophila melanogaster—to attempt the first-ever detection of nanotubes inside a living animal. In the study, fruit fly larvae were raised on a yeast paste that contained carbon nanotubes. The flies were fed this food from the time they hatched throughout their initial feeding phase of 4-5 days. Fruit flies are ravenous eaters during this period and gain weight continuously until they are about 200 times heavier than hatchlings. Then they become pupae. As pupae, they do not eat or grow. They mature inside pupal cases and emerge as adult flies. The team found no significant differences in the adult weight of nanotube- fed flies when compared to control groups that were not fed carbon nanotubes, and the nanotube-fed larvae also survived to adulthood just as well as the control group. This work is supported by NSF under award EEC-0647452.
The micrograph (400X magnification)demonstrates necrotic tumor cells, inflammatory cells, and long collections of coalesced SWNTs (black strands, arrow) after SWNT injection and RF irradiation.
Cancer cells treated with single-walled carbon nanotubes (SWNTs) can be destroyed by noninvasive radio waves that heat up the nanotubes while sparing untreated tissue, a research team from Rice University and the University of Texas M.D. Anderson Cancer Center (MDACC) found in preclinical experiments. The scientists show that the technique completely destroyed liver cancer tumors in rabbits. No side effects were noted. However, some healthy liver tissue within 2-5 mm of the tumors sustained heat damage due to nanotube leakage from the tumor. Targeting the nanotubes solely to cancer cells is the major challenge to advancing the therapy. Research is under way to bind the nanotubes to antibodies, peptides, or other agents that in turn target molecules expressed on cancer cells. To complicate matters, most such molecules are also expressed in normal tissue. In the liver cancer experiment, a solution of SWNTs was injected directly into the tumors. Four treated rabbits were then exposed to 2 min of radiofrequency (RF) treatment, resulting in thermal destruction of their tumors. Control group tumors that were treated only by RF exposure or only by nanotubes were undamaged. This work was published in the December 2007 edition of Cancer journal and was supported by NSF under award EEC-0647452.
From Atwater, Scientific American, 2007.Nanoshells are injected intravenously and then accumulate in tumor tissue due to vascular malformations. NIR light can be applied from outside the body, pass harmlessly through normal tissue, and then induce rapid heating upon absorption by nanoshells within the tumor tissue.
Under the name AuroLaseTM, a cancer therapy developed within the Center for Biological and Environmental Nanotechnology has entered human clinical trials. Auro-Lase Therapy combines the unique physical and optical properties of AuroShell™ (gold nanoshell) particles with a NIR laser source to thermally destroy cancer cells without significant damage to surrounding tissue. These AuroShell particles are injected intravenously and specifically collect in the tumor through the associated leaky vasculature (the Enhanced Permeability and Retention effect, or EPR). After the particles accumulate in a tumor, the area is illuminated with an NIR laser at wavelengths chosen to allow the maximum penetration of light through tissue. Unlike solid metals and other materials, AuroShell particles are designed to specifically absorb this wavelength, converting the laser light into heat. This results in the rapid destruction of the tumor along its irregular boundaries. In recent studies greater than 90% of treated animals experienced complete tumor regression without regrowth, with minimal side effects or damage to normal tissues. NanoSpectra Biosciences recently received FDA approval to commence a human trial in patients with head and neck cancer. This trial will be limited to those patients who have a reoccurrence of prior disease and/or who have failed other therapies. This work was featured in the June 2006 issue of National Geographic and in the April 2007 Scientific American, and was supported by NSF under award EEC-0647452.
Replacing the standard alkylphosphonic acid compounds with cetyltrimethylammonium bromide results with 90% efficiency in cadmium selenide tetrapods.
Rice University scientists revealed a breakthrough method for producing molecular specks of semiconductors called quantum dots (QDs), a discovery that could clear the way for better, cheaper solar energy panels. The research, by scientists at Rice's CBEN describes a new chemical method for making four-legged cadmium selenide QDs, which previous research has shown to be particularly effective at converting sunlight into electrical energy. QDs are “megamolecules” of semiconducting materials that are smaller than living cells. They interact with light in unique ways, to give off different-colored light or to create electrons and holes, due partly to their tiny size, partly to their shape, and partly to the material they're made of. Scientists have studied QDs for more than a decade, with an eye toward using them in medical tests, chemical sensors, and other devices. One way toward cheaper solar cells is to make them out of QDs. Prior research by others has shown that four-legged QDs, which are called tetrapods, are many times more efficient at converting sunlight into electricity than regular QDs. But the problem is that there is still no good way of producing tetrapods. Current methods lead to a lot of particles with uneven-length arms, crooked arms, and even missing arms. Even in the best recipe, 30% of the prepared particles are not tetrapods. CBEN's formula produces same-sized particles, in which more than 90% are tetrapods. This work was supported by NSF under award EEC-0647452.
Taking a cue from self-cleaning, nanostructured Taro leaves, researchers Alvarez and Li are incorporating nanoparticles into water filtration membranes to prevent biofouling. Silver nanoparticles were embedded in polysulfone membranes at a low concentration (0.89 wt%). The nanostructured membranes prevented Escherichia coli growth by 97% compared to the control. Moreover, after immersion for 3 hr in a culture of nutrient-deprived cells, E. coli was not able to adhere to the surface of the nAg membranes (see figure). Further studies with the biofilm-forming bacterium, Pseudomonas mendocina, showed prevention of biofilm formation and deactivation of cells suspended in the surrounding medium. This work was supported by NSF under award EEC-0647452.
Synthesizing a ferrofluid in the Rice University undergraduate chemistry lab.
CBEN, in partnership with Project GRAD, hosted 30 students from Houston Independent School District in a new inquiry Science Academy. The goal of this program is to identify and focus specifically on those students who have the academic capability and motivation to pursue a college education but who may lack the resources, access, or basic support to provide the bridge to that future, and whose high schools are underresourced. Students were selected on the basis of their ranking (top 10% of their class) and their attendance at schools that serve economically disadvantaged communities in Houston. The Nanochemistry Academy is a 17-day, 3 hr per day, on-campus program that includes both classroom and laboratory experiences, as well as tours of CBEN research labs and chemistry demonstrations. Students who completed the entire program received a stipend to offset lost income opportunities from summer employment, thus making it possible for them to pursue their education while also helping out their families. Curriculum development for the summer institute was led by Dr. Carolyn Nichol, Associate Director for Education at CBEN, and Dr. Mary McHale, laboratory coordinator in the Department of Chemistry. This work was supported by NSF under award EEC-0647452.
Dr. Kulinowski and six participants in the Civic Science Educational Program at the nation's capitol.
Students from CBEN participated in Rice's first-ever public policy training program for graduate students. The goal of this Civic Science Educational Program is to help students understand how government decision-making affects their work as scientists and to inform government officials about the importance and relevance of scientific research to the economic strength, security, health, and well-being of our nation. During the training program, the students learned about the federal budget process from one of the nation's leading experts on the scientific budget and congressional culture and practiced speaking with a member of Congress during a mock office visit exercise. Each student developed a one-page “leave behind” describing their individual research and its societal significance. Seven students who successfully completed the program of seminars and training traveled to Washington, DC for 2 days of meetings with elected officials as part of the American Chemical Society delegation to Science, Engineering and Technology Congressional Visits Day. This work was supported by NSF under award EEC-0647452.
ICON, a program of CBEN, sponsored two workshops to describe research needed to predict nanomaterial interactions with living systems based on their physical and chemical properties. The first workshop, held at the National Institutes of Health in Bethesda, MD, focused on cataloguing the physical and chemical properties for six types of nanomaterials and identifying “hot spots” in the lifecycle where hazard or exposure are likely to be high. The second workshop, held at the Swiss Re Global Dialogue Centre in Rüschlikon, Switzerland, explored the mechanisms of nanomaterial interactions with biological systems and the nature of the interactions at cell-free, cellular, tissue, and whole-animal levels. Altogether, the workshops drew over 70 participants from 13 countries and engaged experts from academia, industry, government, and nongovernmental organizations. The importance of these activities was recognized by the U.S. House of Representatives, which invited ICON testimony on the workshops at a hearing held by the House Science Committee on October 31, 2007. This work was supported by NSF under award EEC-0647452 and BES-0646107.
Artistic rendering of amyloid protein fibrillation in the presence of nanoparticles. Insulin fibrils on mica were the basis for this imagery. (A) Depicted here are large NPs (blue) and an amyloid protein (green) in its monomeric and folded state. (B) This artistic rendering shows the association of the amyloid protein with the NP surfaces, perhaps with the generation of small oligomers, which are the precursors to fibrils. In solution, larger protein fibrils appear as their growth is enhanced by the surface association of proteins.
ICON puts potentially a contentious paper in context with the publication of its first "backgrounder" (Kulinowski, Colvin) In April 2007, ICON published its first backgrounder on the potential of nanoparticles to induce protein fibrillation, a process that has been linked to amyloid diseases such as Alzheimer's and Parkinson's and dialysis-related amyloidosis. The purpose of these backgrounders is to convey the technical content of important research papers or themes to a variety of audiences so that the information can be put into context. Colvin and Kulinowski published a technical commentary on a paper linking nanoparticles to induction of protein fibrillation in the Proceedings of the National Academy of Sciences and posted a nontechnical summary on the Virtual Journal website. Background information on the use of nanoparticles in the diagnosis and treatment of amyloid diseases was posted in addition to an analysis of a paper that potentially implicated nanoparticles in causing these diseases. Original artwork was created to visually display the proposed fibrillation mechanism. This work was supported by NSF under award EEC-0647452.