Seed Projects

Seed Project 1:

Engineering of the Static Interface Dipole in Metal/Organic Nanohybrid Materials

Axel Enders (UNL Physics and Astronomy)

The surface dipole at the interface between organic and metallic nanomaterials is a key parameter for the properties of organics-metal hybrid materials. It determines the spindependent charge transfer at the interfaces between metals and organics, and such critical for the performance of sensors and organic spintronics devices. In this project, we will explore avenues to engineer the surface dipole in metal-organic hybrid nanostructures. We will study families of molecules with large intrinsic electrical dipole that are intrinsically good organic conductors, self-assemble well on metallic surfaces, and have enough flexibility in their design to allow many variations in pending or functional groups. Hallmarks of this project are the imaging and spectroscopy with ultimate atomic resolution and prototype device fabrication, resulting in fundamental understanding and mastering of the metal-organic interface.

Seed Project 2:

Nanohybrid Biomaterial Interfaces for Surface Mediated Gene Delivery

Angela Pannier (UNL Biological Systems Engineering)

Gene expression within a cell population can be directly altered through gene delivery approaches, which have tremendous potential for therapeutic uses, such as gene therapy or tissue engineering, or in research and diagnostic applications. However, inefficient gene delivery is a critical factor limiting the development of these applications. The adaptation of controlled release technologies to the delivery of DNA (typically complexed with cationic polymers or lipids) has the potential to overcome extracellular barriers that limit gene transfer, including aggregation of complexes, degradation of complexes, and in particular mass transport limitations that result in low concentration of DNA at the cell surface. Substrate-mediated delivery, also termed solid phase delivery, describes the immobilization of plasmid DNA or DNA complexed with nonviral vectors, to a biomaterial or substrate through specific or nonspecific interactions. In this delivery system, DNA complexes are immobilized to a substrate or biomaterial that supports cell adhesion, thus placing the DNA directly in the cellular microenvironment and increasing its local concentration. In this proposal we hypothesize that substrate-mediated gene delivery can be improved using novel nanohybrid surfaces, prepared using glancing angle deposition (GLAD) technqiues, with the capability to modulate cell function and increase surface loading of DNA complexes to maximize DNA transfer. The goal of this project is to develop a system to load exogenous genetic material (i.e. DNA complexes) into nanostructured surfaces and subsequently deliver these complexes to cells adhered to the surfaces. GLAD nanostructures will serve two purposes in the proposed application, first to “prime” adhered cells for optimal uptake of delivered DNA as a result of nanotopographical influence, and second to deliver DNA in a controlled and enhanced fashion. This goal of the project will be accomplished by two objectives: 1) Design and characterize GLAD nanostructures that optimally load and release DNA complexes; and 2) Characterize transfection profiles and cellular attributes on GLAD nanostructures. The proposed exploratory project focuses on the Center for Functional Nanohybrid Materials (CFNM) Research Clusters (1, 2, and 3), and intersects with many of CFNM’s current interests including 3-D ordered nanostructures, chemical/biochemical sensing, nanohybrid characterization, polymer matrix inclusion, and the study of interactions of various materials with nanohybrid substrates. The results of this project wil impact the medical and biotechnological communities, including applications in gene therapy, tissue engineering, and diagnostics. For instance, surface nanohybrid structures, loaded with DNA, could be used in biomaterial implants, providing for genetic modification of cells interacting with the implants (e.g. hip implants, stents for restenosis, or bone fixation screws), which could promote healing and decease inflammation., or for tissue engineering scaffolds that promote tissue regeneration or cell cutlutre sbustrates used in bitochnolical assays.

Seed Project 3:

An Alternative Motif for the Controlled and Reversible Self-assembly of Nanoparticles

James Takacs (UNL Chemistry)

We have pioneered the use of chirality directed self-assembly of bisoxazoline (box) complexes for the synthesis of functional materials, specifically, novel donor-acceptor complexes and supramolecular catalysts. In this present proposal we are aim to carry out proof-of-principle experiments to demonstrate the use programmable metal-directed self-assembly for fabricating complex self assembled patterns of nanoparticles and make samples available others in the CNFM to develop collaborative studies. While space does not permit a detailed discussion of the chemistry proposed in scheme on the right, it follows from our previously published results. Box-functionalized silver nanoparticles (S, grey spheres) will be combined with a complementarily box-functionalized gold nanoparticle (G, yellow spheres) to give the nanoparticle assemblies SnG (where n = the number of silver nanoparticles). Among the advantages offered by this approach are the ability to introduce of a variety of functional groups, electronic characteristics (i.e., insulating or conducting) and display profiles via the choice of the linkers. For example, the box derivative and variable linker can be modified so that the functional group point of attachment to the James M. Takacs: An Alternative Motif for the Controlled and Reversible Self-assembly of Nanoparticles page 2 of 2 nanoparticles can be SH, NH2, COOH, PO(OH)2 or PPh2. This is important to enable the assembly of two different types of nanoparticles. For example, one linker may contain a thiol terminus while the other has a carboxylic acid. This enables selectively bonding to a gold nanoparticle via the thiol and to a titanium nanoparticle via the carboxylic acid.

Self-assembly will be characterized using standard microscopic and spectroscopic methods. As seen in picture, microscopic methods will give direct visualization of self-assembly and its pattern. Changes in plasmon resonance as well as Soret bands will give an idea about nanoparticle connectivity. In some cases it may be possible to detect self-assembly process by naked eye due to color changes of the solution. By judicious choice of the variable linkers, it is expected that it will be possible to control the length scale of the self-assembled band, that is, program the distance between nanoparticles. Self assembly can be controlled in two dimensions using branched or dendritic linkers; this also opens the possibility of precisely controlling the number of nanoparticles in SnG and related systems, a feature that, to date, has only demonstrated for oligonucleotide systems. By tuning the linkers it should be possible to make selfassembly patterns in various forms including, for example, super-lattices, satellite nanoparticles, nanoflowers, single or multiple nanotriangles having one nanoparticle as the common corner etc.

Conjugated linkers can be used to make a molecular wire like connection between different nanoparticles. Self-assembly is readily reversed by changing the pH or by the addition of certain ions and small organics that affect the co-ordinate bonds between nitrogen atoms and Zn. Thus, it is expected that SnG or related systems can be used in sensing, for example, by designing fluorescence quenching or generation upon self-assembly for the detection of the species that promote or reverse self-assembly.

Seed Project 4:

Detection and Quantitation of Influenza Virus Particles Using Nanohybrid Materials

Therese McGinn (Nebraska Wesleyan University Biology)

Colleagues in the Center for Nanohybrid Functional Materials at UNL have recently established methods for production of columnar nanoscaffolds, which may serve as a novel platform for the detection of influenza virus particles. The influenza hemagglutinin (HA) protein is present on the outer surface of the virus particle, where it functions as the point of virus attachment to host cells. The external location of the HA protein and its inherent immunogenic properties indicate that it is a reasonable target for methods intended to capture influenza particles on the surface of a nanohybrid biosensor. Development and testing of a nanohybrid biosensor for influenza virus is proposed in order to detect virus particles in solution. This will be achieved by sequential attachment of Staphylococcus aureus protein A and HA-sensing antibodies to three-dimensional nanostructures by known linker chemistry. The resulting nanohybrid sensors will be exposed to solutions containing known quantities of influenza virus particles, and virus attachment will be detected using quartz crystal microbalance with dissipation (QCM-D) and generalized ellipsometry (GE). We hypothesize that this approach will facilitate quantitation of influenza virions adsorbed to the nanostructures.