Three-dimensional nanostructures can be fabricated by the glancing angle deposition technique. By rotating the substrate in both polar and azimuthal directions, one can fabricate desired nanostructures, such as nano-rod arrays with different shapes, nano-spring arrays, and even multilayer nanostructures. This method offers a fully three-dimensional control of the nanostructure with additional capability of self-alignment. There is almost no limitation on materials that can be fabricated into desired nanostructures. In this presentation, we will discuss the current status of the glancing angle deposition technology, its potential applications, and its future challenges.

We report the creation of an unusual simple cubic β-phase W(100) nanorods with a pyramidal tip having four (110) facets using an oblique-angle sputter deposition technique with substrate rotation (also known as glancing-angle deposition). During the oblique-angle deposition, both β-phase W(100) and α-phase W(110) islands exist at the initial stages of growth. The β-phase W(100) islands grow taller due to the lower adatom mobility on these islands. The taller islands survive in the competition and form isolated nanorods in the later stages of growth. This is in contrast to the sputter deposition at normal incidence, where only the thermodynamically stable bcc α-phase W(110) polycrystalline films were formed when the film grows to a certain thickness.

The refractive-index contrast in dielectric multilayer structures, optical resonators, and photonic crystals is an important figure of merit that creates a strong demand for high-quality thin films with a low refractive index. A $\mathrm{Si}{\mathrm{O}}_2$ nanorod layer with low refractive index of $n=1.08$, to our knowledge the lowest ever reported in thin-film materials, is grown by oblique-angle electron-beam deposition of $\mathrm{Si}{\mathrm{O}}_2$. A single-pair distributed Bragg reflector employing a $\mathrm{Si}{\mathrm{O}}_2$ nanorod layer is demonstrated to have enhanced reflectivity, showing the great potential of low-refractive-index films for applications in photonic structures and devices.

We report the melting of nanorod arrays of copper at temperatures much lower than its bulk melting point $(1083°\mathrm{C})$ . The Cu nanorods were produced by an oblique angle sputter deposition technique through a physical self-assembly mechanism due to the shadowing effect. The as-deposited nanorods were $\sim 2300\mathrm{nm}$ in length, $\sim 100\mathrm{nm}$ in diameter, and separated from each other with gaps varying between $\sim 10$ and $\sim 30\mathrm{nm}$ . The melting process was investigated through the analysis of scanning electron microscopy, transmission electron microscopy, and x-ray diffraction measurements. Start of premelting (or surface melting) has been observed to occur at annealing temperature $\sim 400°\mathrm{C}$ under vacuum $({10}^{-6}\text{Torr}$ ). As the temperature was raised the arrays of Cu nanorods started to coalesce and formed a dense continuous film with a (111) texture at $\sim 550°\mathrm{C}$ . The results of this work may be useful for low temperature soldering applications.

In our effort to develop effective neuroprotectants as potential treatments for Alzheimer’s disease (AD), hybrid compounds of curcumin and melatonin, two natural products that have been extensively studied in various AD models, were designed, synthesized, and biologically characterized. A lead hybrid compound (7) was discovered to show significant neuroprotection with nanomolar potency (EC₅₀ = 27.60 ± 9.4 nM) in MC65 cells, a cellular AD model. Multiple in vitro assay results established that 7 exhibited moderate inhibitory effects on the production of amyloid-β oligomers (AβOs) in MC65 cells, but not on the aggregation of Aβ species. It also exhibited significant antioxidative properties. Further mechanistic studies demonstrated that 7’s antioxidant effects correlate well with its neuroprotective potency for MC65 cells, and these effects might be due to its interference with the interactions of AβOs within the mitochondria of MC65 cells. Furthermore, 7 was confirmed to cross the blood-brain barrier (BBB) and deliver a sufficient amount to brain tissue after oral administration. Collectively, these results strongly support the hybridization approach as an efficient strategy to help identify novel scaffolds with a desired pharmacology, and strongly encourage further optimization of 7 to develop more potent neuroprotectants for AD.