Integrated Calendar

Our group studies the anti-aging protein, Klotho. Klotho deficient mice suffer from many phenotypes seen in aging humans including cognitive decline, while Klotho overexpressing mice live longer and are more resistant to oxidative stress. We discovered that Klotho expression is downregulated in the brain during normal aging and in Alzheimer's disease animal models, and identified the cause for this downregulation. Klotho is a type I transmembrane protein shed by ADAM10 and 17 that circulates in the blood and CSF. Recent results from our laboratory indicate that Klotho can rescue neurons from a variety of insults and can induce oligodendrocyte maturation. Thus, Klotho is a neuroprotective protein that is gradually lost as we age. To increase Klotho levels in the brain, we performed a high throughput screen of 150,000 small compounds, expected to cross the blood-brain-barrier, and identified several lead molecules that enhance Klotho expression. Optimized compounds could be tested in animal models of Alzheimer's disease and multiple sclerosis.

Nature utilizes simple building blocks such as nucleic acids, phospholipids and amino acids to create complex functional structures by the process of molecular self-assembly. In an effort to mimic this process in vitro, numerous studies have demonstrated the ability of DNA molecules, peptides and lipids to assemble into ordered structures. The potential of these structures in a wide range of nanotechnological and biotechnological applications is immense.
Peptides, specifically, hold a great promise as biomolecular building blocks since they present diversity, easy to synthesize in large scale, and can be easily modified with biological and chemical groups. The ability to spontaneously form peptide-based structures with the degree of complexity found in nature is still a challenge.
The lecture will present a new strategy for the formation of complex biomolecular architectures using the spontaneous self-assembly of peptides. Using this strategy we discovered a unique structure of beaded strings spontaneously formed by the self-assembly of simple peptides. These structures can potentially serve as a scaffold in bioengineering applications.

Ion-irradiation of semiconductor surfaces has emerged as a promising approach to generate a variety of self-organized nanostructures, ranging from islands to ripples to nanorods. We have examined ion-induced transformations for a wide variety of focused¬ion-beam (FIB) irradiated III-V compound semiconductor surfaces. On Ga-V and In-V surfaces, FIB-irradiation beyond a threshold ion dose leads to the formation of Ga-rich droplets [1] and In-rich islands, respectively. Interestingly, the threshold ion dose increases with increasing surface binding energy, suggesting a key role of sputtering on nanostructure formation. For low binding energy compounds, the surface morphology evolves from pits to ripples, followed by the nucleation of islands on the ripple crests, and the subsequent formation of nanorods [2]. Together, these results suggest a nanostructure formation mechanism based upon ion-induced non-erosive surface response, followed by preferential Group V sputtering and island-induced self-shielding. In this talk, I will discuss our investigations of nanostructure array formation on a wide variety of III-V surfaces, with a focus on the formation mechanisms and electronic and optical properties of InSb nanorods and Ga nanodroplets. I will also discuss progress towards the design and fabrication of 3D Ga nanodroplet arrays.