Voltage gated inter-cation selective ion channels from graphene nanopores

With the ability to selectively control ionic flux, biological protein ion channels perform a fundamental role in many physiological processes. For practical applications that require the functionality of a biological ion channel, graphene provides a promising solid-state alternative, due to its atomic thinness and mechanical strength. Here, we demonstrate that nanopores introduced into graphene membranes, as large as 50 nm in diameter, exhibit inter-cation selectivity with a ~20x preference for K+ over divalent cations and can be modulated by an applied gate voltage. Liquid atomic force microscopy of the graphene devices reveals surface nanobubbles near the pore to be responsible for the observed selective behavior. Molecular dynamics simulations indicate that translocation of ions across the pore likely occurs via a thin water layer at the edge of the pore and the nanobubble. Our results demonstrate a significant improvement in the inter-cation selectivity displayed by a solid-state nanopore device and by utilizing the pores in a de-wetted state, offers an approach to fabricating selective graphene membranes that does not rely on the fabrication of sub-nm pores

LDRD Progress Report: Radioimmunotherapy using oxide nanoparticles: Radionuclide contaiment and mitigation of normal tissue toxicity.

Radionuclides with specific emission properties can be incorporated into metal-chalcogenide and metal-oxide nanoparticles. Coupled to antibodies, these conjugates could be injected into the bloodstream to target and destroy non-solid tumors or target organs for radioimaging. In the first year of this project, two types of radioactive nanoparticles, CdTe: {sup 125m}Te and Y{sub 2}O{sub 3}: {sup 170}Tm were synthesized and coupled to antibodies specific to murine epithelial lung tissue. The nanoparticles successfully target the lung tissue in vivo. Some leaching of the radioisotope was observed. The coming year will explore other types of nanoparticles (other crystal chemistries) in order to minimize leaching