Nanoparticles for cancer therapy and imaging are designed to accumulate in the diseased tissue by exploiting the Enhanced Permeability and Retention (EPR) effect. This limits their size to about 100 nm. Here, using intravital microscopy and elemental analysis, we compare the in vivo localization of particles with different geometries and demonstrate that plateloid particles preferentially accumulate within the tumor vasculature at unprecedented levels, independent of the EPR effect. In melanoma-bearing mice, 1000×400 nm plateloid particles adhered to the tumor vasculature at about 5% and 10% of the injected dose per gram organ (ID/g) for untargeted and RGD-targeted particles respectively, and exhibited the highest tumor-to-liver accumulation ratios (0.22 and 0.35). Smaller and larger plateloid particles, as well as cylindroid particles, were more extensively sequestered by the liver, spleen and lungs. Plateloid particles appeared well-suited for taking advantage of hydrodynamic forces and interfacial interactions required for efficient tumoritropic accumulation, even without using specific targeting ligands.

Traditional single-fiber pull-out type experiments were conducted on individual multiwalled carbon nanotubes (MWNT) embedded in an epoxy matrix using a novel technique. Remarkably, the results are qualitatively consistent with the predictions of continuum fracture mechanics models. Unstable interface crack propagation occurred at short MWNT embedments, which essentially exhibited a linear load-displacement response prior to peak load. Deep embedments, however, enabled stable crack extension and produced a nonlinear load-displacement response prior to peak load. The maximum pull-out forces corresponding to a wide range of embedments were used to compute the nominal interfacial shear strength and the interfacial fracture energy of the pristine MWNT-epoxy interface.

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In the interest of developing a highly sensitive, low power radiation dosimeter, a series of tests were performed on single-wall carbon nanotube (SWCNT)-based nanomaterials to monitor their response to 10 and 30 MeV proton radiation. The SWCNT materials were deposited on an interdigitated electrode (IDE) that was developed at NASA Ames for chemical sensing. In order to investigate the effects of nanotube functionalization on the sensor properties, the SWCNTs were covalently or noncovalently functionalized prior to their incorporation into the devices. The functionalized nanotubes which were assayed included fluorinated SWCNT (F-SWCNT), alkylated F-SWCNT (F-SWCNT-C 11 H 23 ), refluorinated alkylated F-SWCNT (F-SWCNT-C 11 F 23 ), palladium doped SWCNTs (Pd-SWCNTs), and nanotubes noncovalently associated with cellulose (Cel-SWCNTs). These five functionalized nanotube types and pristine carbon nanotubes were investigated for their responses to proton radiation. The device response to irradiation, measured as a change in resistance, was found to vary with the type of functional group attached to the SWCNT. The samples were also characterized by Raman spectroscopy in order to observe changes in the disorder band (at 1350 cm -1 ) of the nanotube materials. Depending on nanotube functionalization, the devices showed a real-time response to radiation at the energy levels tested. The nature of the response indicates that these nanomaterials may potentially be used to produce a dosimeter that is memory-free, reusable, and reversible.