Two nanoscale devices recently reported by University of Pittsburgh researchers in two separate journals harness the potential of carbon nanomaterials to enhance technologies for drug or imaging agent delivery and energy storage systems, in one case, and, in the other, bolster the sensitivity of oxygen sensors essential in confined settings, from mines to spacecrafts.
In a report published online by Advanced Materials Aug. 12, a team led by chemistry professors Alexander Star and Stéphane Petoud in Pitt's School of Arts and Sciences describe the creation of nanosized capsules that are universally compatible with a range of substances, particularly related to medicine and energy. When applied to medicine, the tiny vessels can potentially carry a sizable "cargo" of anticancer drugs or medical-imaging agents, and could be steered via antibodies and biological molecules to specific locations within the human body. Energy applications include the storage of lithium and hydrogen in batteries and fuel cells. Pitt graduate chemistry student Brett Allen was the paper's lead author. The project also included chemistry graduate student Chad Shade and Adrienne Yingling, now a graduate of Pitt's PhD chemistry program.
In a separate paper appearing online in Nature Chemistry Aug. 16, another team headed by Star and Petoud revealed the development of a highly sensitive, fluorescent oxygen sensor that can detect minute amounts of the gas. Oxygen detectors are important safety devices in mines, aircraft, submarines, and other confined spaces, the researchers note. The sensor consists of carbon nanotubes coated with a luminescent compound incorporating europium, a reactive metal found in fluorescent bulbs, television/computer screens, and lasers, among other applications.
The researchers gauged oxygen levels by measuring the intensity of its glow when exposed to ultraviolent light and the tubes' change in electrical conductance. The tubes demonstrated sensitivity to oxygen concentrations as low as 5 percent (normal atmospheric concentration is around 20 percent) with the team calculating that it can indicate a level as low as 0.4 percent, and they were unaffected by other atmospheric gases, such as carbon dioxide and nitrogen. The second paper was authored by Shade and Pitt chemistry graduate students Douglas Kauffman and Hyounsoo Uh.
For both technologies, the Pitt teams worked with carbon nanomaterials to create enhanced versions of existing technologies. For instance, the oxygen sensor combines the small scale of carbon nanotubes—they are one-atom thick rolls of graphite 100,000 times smaller than a human hair—with the reactivity of the europium compound coating to produce a platform for low-cost, room-temperature detectors that are notably sensitive to oxygen but less complicated than existing sensors, the researchers write in Nature Chemistry.
Regarding the nanocapsules described in Advanced Materials, existing technologies are typically constructed of polymers that are permeable like a sponge and can result in leakage, Star explained. Additionally, each capsule must be tailored to its particular cargo, he said. The Pitt version employs graphite carbon shells bonded with glutaraldehyde—a common biological adhesive—creating a hollow storage space. More importantly, the graphite shells are chemically inactive and are thus compatible with any cargo substance without costly and time-consuming chemical preparation, Star said.
"For decades, researchers have been searching for an optimal vessel for storing and transporting a variety of cargo to specified locations," Star said. "Our devices have the potential to be universal delivery vehicles for a range of materials. Our next steps will focus on controlling how and when the nanocapsules open by using different stimuli such as pH, light, and chemical agents."
To illustrate the capsules' adaptability, the team loaded them with a luminescent imaging agent developed in Petoud's lab made of zinc sulfide semiconductor nanocrystals incorporating terbium, a metal chemically similar to europium. Once in the body, the substance would emit a unique light that allows easier detection and a better image, Petoud said. But the inorganic nanocrystals have to be prepared before being introduced to a biological environment such as the body and is difficult and time-consuming. The graphite nanocapsules, however, could hold and transport the solution with no preparation.
Morgan Kelly | EurekAlert!
New value added to the ICSD (Inorganic Crystal Structure Database)
27.03.2017 | FIZ Karlsruhe – Leibniz-Institut für Informationsinfrastruktur GmbH
Argon is not the 'dope' for metallic hydrogen
24.03.2017 | Carnegie Institution for Science
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
27.03.2017 | Earth Sciences
27.03.2017 | Life Sciences
27.03.2017 | Life Sciences