Quantum confined peptide assemblies with tunable visible to near-infrared spectral range

Quantum confined materials have been extensively studied for photoluminescent applications. Due to intrinsic limitations of low biocompatibility and challenging modulation, the utilization of conventional inorganic quantum confined photoluminescent materials in bio-imaging and bio-machine interface faces critical restrictions. Here, we present aromatic cyclo-dipeptides that dimerize into quantum dots, which serve as building blocks to further self-assemble into quantum confined supramolecular structures with diverse morphologies and photoluminescence properties. Especially, the emission can be tuned from the visible region to the near-infrared region (420 nm to 820 nm) by modulating the self-assembly process. Moreover, no obvious cytotoxic effect is observed for these nanostructures, and their utilization for in vivo imaging and as phosphors for light-emitting diodes is demonstrated. The data reveal that the morphologies and optical properties of the aromatic cyclo-dipeptide self-assemblies can be tuned, making them potential candidates for supramolecular quantum confined materials providing biocompatible alternatives for broad biomedical and opto-electric applications.

Biomimetic engineering of non-adhesive glycocalyx-like surfaces using oligosaccharide surfactant polymers

The external region of a cell membrane, known as the glycocalyx, is dominated by glycosylated molecules, which direct specific interactions such as cell-cell recognition and contribute to the steric repulsion that prevents undesirable non-specific adhesion of other molecules and cells. Mimicking the non-adhesive properties of a glycocalyx provides a potential solution to the clinical problems, such as thrombosis, that are associated with implantable devices owing to non-specific adsorption of plasma proteins. Here we describe a biomimetic surface modification of graphite using oligosaccharide surfactant polymers, which, like a glycocalyx, provides a dense and confluent layer of oligosaccharides. The surfactant polymers consist of a flexible poly(vinyl amine) with dextran and alkanoyl side chains. We show that alkanoyl side chains assemble on graphite through hydrophobic interaction and epitaxial adsorption. This constrains the polymer backbone to lie parallel to the substrate, with solvated dextran side chains protruding into the aqueous phase, creating a glycocalyx-like coating. The resulting biomimetic surface is effective in suppressing protein adsorption from human plasma protein solution.

Visualization of dipole solutions to the neuromagnetic inverse problem

We have developed a computer program that computes and displays current-dipole solutions to the neuromagnetic inverse problem. The three-dimensional positions, orientations, and corresponding magnetic field values of the detection coils can be visualized with respect to a realistic representation of the subject's head shape. The topographies of the experimental data, theoretical fit, and residual field are represented without the use of data smoothing or interpolation, allowing more direct comparisons between them. A simple method for displaying dipole source location was implemented.

Spatiotemporal visualization of neuromagnetic data

We describe the development of a computer visualization tool that displays topographic maps of neuromagnetic data on realistic head shapes. Two topographic display modes are implemented--a raw mode that depicts the actual position, orientation, and corresponding magnetic field data of each detection coil with respect to the head shape, and an interpolated mode, where the magnetic data are smoothly interpolated over the scalp. False coloration is used to represent magnetic field strength. The topographic displays are coupled with wave form displays in order to integrate spatial and temporal visualization of the data. The X Window system is used to write device independent, network-transparent computer code.