N°30 I quarterly I july 2013 Live from the Labs | 13 w Physics Osmotic Power Gets a Jolt Nasal Spra ys to Fight Canc er BY Clémentine Wallace w Administering a vaccine directly through the mucosal membrane might be more effective than traditional vaccination methods to fight tumors that develop in mucosal tissues.1 In the past three years, “therapeutic vaccines,” which boost the body’s natural defenses against tumors, have proved successful against non-mucosal tumors such as prostate cancer in humans. Yet these vaccines were ineffective when tested against mucosal cancers in the lungs or in the head and neck. “We tested whether administering the vaccine directly in the mucosal area, by inhalation for instance, would increase efficiency,” explains study leader Eric Tartour.2 The team grafted tumors under the skin and in the lung, head, and neck tissues of mice. They observed that with intramuscular vaccination, © L. Joly /ILM only the skin tumors regressed, while a nasal spray vaccination also resulted in mucosal tumor regression. In vitro immunofluorescence staining revealed that immune cells had strongly infiltrated the mucosal tumor sites in mice nasally vaccinated. The authors showed that the spray increased the expression of CD 49a, a protein at the surface of lymphocytes that allows them to migrate. The team hopes to soon be able to test this mode of administration in humans. 01. F . Sandoval et al., “Mucosal imprinting of vaccine induced-CD 8+T cells is crucial to inhibit the growth of mucosal tumors,” Sci. Transl. Med., 2013. 5: 172ra20. 02. H ôpital Européen Georges Pompidou (Paris) / Université Paris-Descartes / Inserm U970. Contact information: HEG P, Paris. Eric Tartour > eric.tartour@egp.aphp.fr BY Fui Lee Luk w Dwindling fossil fuel supplies and the need for cutting greenhouse emissions 01 Nasal vaccination 02 make the switch to renewable energy sources a global priority. While it is every scientist’s dream to stumble upon a novel device with great clean energyyielding potential, the dream came true for physicists at the ILM1 and Institut Néel.2 The team initially set out to study the transport of fluids on a nanometric scale by passing them through a boron nitride nanotube a few dozen nanometers in diameter.3 But their system proved to be extremely effective in harvesting osmotic power, an energy generated by the difference in osmotic pressure when waters with varying salt levels meet. Occurring naturally when freshwater flows into seawater at river mouths, this relatively untapped energy source has a theoretical worldwide production capacity of 1 terawatt, the energy produced by 1000 nuclear reactors. Existing prototype osmotic power plants consist in freshwater and seawater chambers separated by a semi- permeable membrane. As the freshwater molecules are pulled from their chamber to dilute salt in the other, the increased pressure drives a turbine to generate power. Using a similar principle, the researchers inserted a boron-nitride nanotube (via scanning tunneling microscope) within an otherwise impermeable and electrically-insulating membrane separating the two fluids. The nanotube was therefore the only passageway for water molecules. Electrodes on both ends of the nanotube recorded the electric current produced. Measuring osmotic flow through a nanotube was a world first in itself, but not the project’s only one. When the tube linked saltwater and freshwater, a current on the order of the nanoampere was generated. On a larger scale, this translates to a 1 m2 boron nitride nanotube membrane producing 30 megawatt-hours per year—three orders of magnitude above what today’s membranes can potentially yield. For Contact information: ILM , Lyon. Alessandro Siria > alessandro.siria@univ-lyon1.fr Nasal spray vaccination (01) triggered more killing lymphocytes (pink) against cancerous cells (blue) than intramuscular vaccination (02). © photos : INSERM U970. Uni versit É Paris -Descartes Intramuscular vaccination q Diagram representing the osmotic transport of water through a boron nitride nanotube. Alessandro Siria of the ILM, this high current results from the strong attraction of the saltwater’s positively charged ions to “the huge negative charge on the surface of the boron nitride tube.” The current is further intensified by the tube’s minute length and diameter as “fluids can behave differently at the nanoscale.” Osmotic power is a valuable addition to the world’s energy mix, especially as it is “a non-intermittent energy source,” Siria points out. The team’s next challenges are to “optimize nanotubes for energy conversion,” for example by testing them in other materials, and to make a “macroscopic porous membrane from nanotubes for large-scale energy production.” 01. Institut lumière matière (CNRS / Université Lyon-I). 02. CNRS. 03. A. Siria et al., “Giant osmotic energy conversion measured in a single transmembrane boron nitride nanotube.” Nature, 2013. 494: 455-8. Lyon Paris
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