The platinum-based anticancer drugs cisplatin, carboplatin, and oxaliplatin are an important component of chemotherapy but are limited by severe dose-limiting side effects and the ability of tumors to develop resistance rapidly. These drugs can be improved through the use of drug-delivery vehicles that are able to target cancers passively or actively. In this study, we have tethered the active component of the anticancer drug oxaliplatin to a gold nanoparticle for improved drug delivery. Naked gold nanoparticles were functionalized with a thiolated poly(ethylene glycol) (PEG) monolayer capped with a carboxylate group. [Pt(1R,2R-diaminocyclohexane)(H₂O)₂]2NO₃ was added to the PEG surface to yield a supramolecular complex with 280 (±20) drug molecules per nanoparticle. The platinum-tethered nanoparticles were examined for cytotoxicity, drug uptake, and localization in the A549 lung epithelial cancer cell line and the colon cancer cell lines HCT116, HCT15, HT29, and RKO. The platinum-tethered nanoparticles demonstrated as good as, or significantly better, cytotoxicity than oxaliplatin alone in all of the cell lines and an unusual ability to penetrate the nucleus in the lung cancer cells.

Micro-light emitting diode (LED) arrays with diameters of 4 to 20 μm have been fabricated and were found to be much more efficient light emitters compared to their broad-area counterparts, with up to five times enhancement in optical power densities. The possible mechanisms responsible for the improvement in performance were investigated. Strain relaxation in the microstructures as measured by Raman spectroscopy was not observed, arguing against theories of an increase in internal quantum efficiency due to a reduction of the piezoelectric field put forward by other groups. Optical microscope images show intense light emission at the periphery of the devices, as a result of light scattering off the etched sidewalls. This increases the extraction efficiency relative to broad area devices and boosts the forward optical output. In addition, spectra of the forward emitted light reveal the presence of resonant cavity modes [whispering gallery (WG) modes in particular] which appear to play a role in enhancing the optical output.

We identify a dominant light-emitting center in ion-implanted $\text{GaN}:{\text{Eu}}^{3+}$ for which the lattice damage has been completely healed, according to x-ray diffraction and Rutherford backscattering spectrometry measurements, by high-temperature, high-pressure annealing. This center is likely to be the isolated substitutional ${\text{Eu}}_{\text{Ga}}$ defect. It lacks a “subgap” excitation band and therefore has no state in the GaN band gap, shows threefold splitting of its ${{}^7\text{F}}_2$ level, with two sublevels nearly degenerate, and exhibits a long, single-exponential luminescence decay. Competing luminescent centers of GaN:Eu involve this prime center with intrinsic lattice defects, one of which may also be responsible for the GaN yellow band.

Light-emitting diodes (LEDs) based on an interconnected array of GaN/InGaN micro-ring elements have been demonstrated. The devices have electrical characteristics similar to those of conventional broad-area devices. However, due to the large surface areas provided by the sidewalls, the extraction efficiency is greatly enhanced. Intense light emission at the periphery of the micro-rings is observed upon excitation by an electron beam, suggesting scattering of the photons which are extracted through the sidewalls. The devices provide a doubling in total light output compared to a broad-area reference LED of equal light-generation area.

We give an overview of the use of cathodoluminescence (CL) in scanning electron microscopy (SEM) for the nano-scale characterization of semiconducting materials and devices. We discuss the technical aspects of the measurement, such as factors limiting the spatial resolution and design considerations for efficient collection optics. The advantages of more recent developments in the technique are outlined, including the use of the hyperspectral imaging mode and the combination of CL and other SEM-based measurements. We illustrate these points with examples from our own experience of designing and constructing CL systems and applying the technique to the characterization of III-nitride materials and nanostructures.