This work explores using self-assembled DNA nanostructures as carriers for drug delivery. We have recently developed an organic nanotube system that is assembled from a single component: a 52-base-long DNA single strand. In this work, functional agents (folate as a cancer cell target agent and Cy3 as a fluorescence imaging agent) are conjugated with the DNA strands; the conjugates selfassemble into micrometers-long nanotubes (NTs). The conjugated DNA-NTs can be effectively taken by cancer cells as demonstrated by fluorescence imaging and fluorescence activated cell sorting (FACS). No obvious toxicity has been observed under current experimental conditions.

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We report a fast, versatile photocurrent imaging technique to visualize the local photo response of solar energy devices and optoelectronics using near-field cathodoluminescence (CL) from a homogeneous quantum dot layer. This approach is quantitatively compared with direct measurements of high-resolution Electron Beam Induced Current (EBIC) using a thin film solar cell (n-CdS / p-CdTe). Qualitatively, the observed image contrast is similar, showing strong enhancement of the carrier collection efficiency at the p-n junction and near the grain boundaries. The spatial resolution of the new technique, termed Q-EBIC (EBIC using quantum dots), is determined by the absorption depth of photons. The results demonstrate a new method for high-resolution, sub-wavelength photocurrent imaging measurement relevant for a wide range of applications

A thin film of quantum dots (QD) was used to visualize the local photo-response of polycrystalline CdTe solar cells by downconverting an electron beam of high energy to photons of visible light. The efficient photon generation in the QD film is compared to cathodoluminescence of the high-purity bulk semiconductors and phosphor.Author Keywords quantum dot; thin film; cathodoluminescence; scanning electron microscopy.

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