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The advent of nanotechnology has offered the development of promising new weapons against various cancers, including malignant brain tumors. From the bioengineering point of view, nanoparticles (NPs) exhibit many properties which enhance their suitability as therapeutic agents. A wide variety of NPs have been created, with ingenious strategies for binding and destroying cancer cells, including glioblastoma and medulloblastoma. This chapter discusses basic bioengineering principles, as well as in vitro and in vivo studies of NPs, as related to neuro-oncology. Critical issues such as NP delivery into brain tissue (across the blood-brain barrier (BBB) or by convection-enhanced delivery), toxicity, and binding to tumor cells in vivo, are beginning to be addressed. If the BBB is intact, NPs may be transported across it by means of adsorptive-mediated transcytosis, receptor-mediated endocytosis, or receptor-mediated transcytosis. Experimental studies of NPs should be standardized, in order to facilitate rational comparison of their therapeutic potential. There is a pressing need for more clinical trials aimed at evaluating the safety and efficacy of this form of therapy, which holds great potential for patients with malignant brain tumors.

CuCrO2 has been investigated as an alternative to conventionally used NiO in p-type dye sensitized solar cells (p-DSCs) using I–/I3–- and [Co(en)3]2+/3+-based redox mediators. The favorable valence band edge position of CuCrO2 affords open circuit voltages as high as 734 mV when [Co(en)3]2+/3+ is deployed as redox mediator. This is the highest reported open circuit voltage for any p-DSC to date, introducing mesoporous CuCrO2 electrodes as a promising alternative to traditional NiO.

BACKGROUND: Medulloblastoma cells notoriously disseminate within CSF pathways. Magnetic nanoparticles (MNPs) have potential for enhancing delivery of chemotherapy to these cells. Successful clinical use of MNPs within CSF has been hampered due to limited capacity for targeting at human-sized distances, and choice of therapeutic component. Here, we present data related to the creation and in vitro use of an MNP system containing: 1) AuFe base particles having streptavidin binding sites, and 2) biotinylated etoposide. Etoposide was chosen due to its previous use in the spinal subarachnoid space, and ease of biotinylation. Aggregates of MNPs were moved by a rotating magnet, with “surface walking” even at 10-15cm. METHODS: Etoposide-MNPs were characterized by electron microscopy, UV-vis spectroscopy, and dynamic light scattering (DLS). The rotating magnet was provided by Pulse Therapeutics. Cultured D283 cells were seeded into standard multiwell plates, and custom-made trays designed to measure translational motion. Videography was used to determine particle velocity. Cellular responses to etoposide-MNPs (vs. controls) were studied by light microscopy and MTT assay. RESULTS: Etoposide was successfully bound to base particles through the streptavidin-biotin interaction. 1 - 100uM etoposide was used. DLS showed the diameter of etoposide-MNPs to be 218+/-72nm. Etoposide-MNPs could be moved remotely by the rotating magnet, which produced a tangential velocity of 0.12+/-0.002cm/sec at 8-7cm. With 2 hours of treatment, 5uM etoposide-MNPs caused morphologic changes, and decreased D283 viability to 0.76+/-0.01% of controls. CONCLUSIONS: These data demonstrate that the novel etoposide-MNPs have cytotoxic effect, and can be targeted at physiologic distances. While further studies are underway, etoposide-MNPs, may ultimately prove useful for magnetic targeting within CSF pathways, after introduction via lumbar puncture or Ommaya reservoir. An improved ability to eradicate malignant cells within CSF would be a major step forward in the treatment of patients with disseminated medulloblastoma.

Sustainable plasmonic photocurrents are generated by gold and silver nanoparticles, located at a TiO2/hole conductor interface. The spectral photocurrent response closely follows the surface plasmon absorption bands of the metal particles. A simple nanoparticle self-assembly method for the solar cell fabrication is presented. Three mechanisms for plasmon-induced charge separation are proposed. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The photoinduced formation of silver nanoprisms from smaller silver seed particles in the presence of citrate anions is a classic example of a photomorphic reaction. In this case, light is used as a convenient tool to dynamically manipulate the shape of metal nanoparticles. To date, very little is known about the prevailing reaction mechanism of this type of photoreaction. Here we provide a detailed study of the shape transformation dynamics as a function of a range of different process parameters, such as photon energy and photon flux. For the first time, we provide direct evidence that the photochemical synthesis of silver nanoprisms from spherical seed nanoparticles proceeds via a light-activated two-dimensional coalescence mechanism. On the other hand, we could show that Ostwald ripening becomes the dominant reaction mechanism when larger silver nanoprisms are grown from photochemically synthesized smaller nanoprisms. This two-step reaction proceeds significantly faster and yields more uniform, sharper nanoprisms than the classical one-step photodevelopment process from seeds. The ability to dynamically control nanoparticle shapes and properties with light opens up novel synthesis avenues but also, more importantly, allows one to conceive new applications that exploit the nonstatic character of these nanoparticles and the ability to control and adjust their properties at will in a highly dynamic fashion.

We demonstrate modifications to the light yield properties of an organic liquid scintillator due to the localization of the tertiary fluorophore component to the surface of Ag-core silica-shell nanoparticles. We attribute this enhancement to the near-field interaction of Ag nanoparticle plasmons with these fluor molecules. The scintillation light yield enhancement is shown to be equal to the fluorescence enhancement within measurement uncertainties. With a suitable choice of plasmon energy and scintillation fluor, this effect may be used to engineer scintillators with enhanced light yields for radiation detection applications.

The photoconversion of photomorphic silver nanoparticles from discs to prisms via citrate mediated growth on the twin plane faces of the nanoparticles is demonstrated. This systematic shape evolution from discs to hexagons and then prisms of increasing aspect ratios is a result of the growth process being confined to specific faces of the growing nanoparticles.

A simple photoreduction method has been demonstrated for the preparation of prismatic silver nanoparticles (AgNPs) that reversibly transform into discs when placed in the dark. The photodevelopment and switchability of these particles were characterised by transmission electron microscopy (TEM) and optical absorption spectroscopy (UV-vis). The observed photomorphic particle transformations were attributed to the initial seeding concentrations that affect the morphological stability between the light- and dark-form shapes. The photomorphic effect was attributed to a competitive reaction that occurred between photochemical reduction of Ag+ onto the surface of AgNPs and the slower oxidation of AgNPs by 4,4′-(phenylphosphinidene)bis(benzenesulfonic acid)dipotassium salt (BSPP). The BSPP also acts as a limiting reagent by gradually oxidising to triphenylphosphine oxide (TPPO) which diminishes the reversibility of the photomorphic effect. Significantly, the light- and dark-state photomorphic capability of these AgNPs was successfully restored by the addition of BSPP.

Experimental measurements and theoretical calculations of gain for a cw CO2 gasdynamic laser were made for a CO2, N2, He mixture. A temperature range of 800 to 2000°K, pressure range of 2 to 16 atm, and a complete range of gas mixtures were studied. Optimum gain was achieved at a temperature of 1600°K, a helium mole fraction near 40%, and a CO2 mole fraction of approximately 20%. Gain was essentially independent of pressure.