Jose J. Gutierrez

Energetically Biased DNA Motor Containing a Thermodynamically Stable Partial Strand Displacement State

Current work in tuning DNA kinetics has focused on changing toehold lengths and DNA concentrations. However, kinetics can also be improved by enhancing the completion probability of the strand displacement process. Here, we execute this strategy by creating a toehold DNA motor device with the inclusion of a synthetic nucleotide, inosine, at selected sites. Furthermore, we found that the energetic bias can be tuned such that the device can stay in a stable partially displaced state. This work demonstrates the utility of energetic biases to change DNA strand displacement kinetics and introduces a complementary strategy to the existing designs.

Analysis of Electromagnetic Effect on the Electrorheological Properties of Nano-Laden Systems

The potential electrorheological characteristics of suspensions of carbon nanofibers in nematic liquid crystals were investigated. Previous data showed that suspensions of < 1% carbon nanofibers in silicone oil were not viscous enough to obtain appreciable electrorheological behavior. Short circuit was noticed below 200 V when higher loads of carbon nanofibers were used due to the high conductivity of the carbon nanofibers. In order to increase the concentration of fillers at which the percolation of the electrical conductivity is noticed, the research concentrated on carbon nanofibers coated with insulating macromolecular chains. The systems under study were polypyrrole-coated carbon nanofibers and polyurea-coated carbon nanofibers dispersed within a liquid crystal.

Hollow Disc and Sphere-Shaped Particles from Red Blood Cell Templates

Colloidal gold particles with uniform size distributions were fabricated utilizing human red blood cells (RBCs) as templates. The gold shells were charged with a metal chelating agent to prevent flocculation. The procedure described here allows control over the shape of the colloidal particles. Thus, it was possible to fabricate discs and spheres by controlling the osmotic pressure.

Apoptosis method for biomimetic artificial cell membranes employing nanophotonic theranostics

Colloidal biomimetic disc shaped metallic gold shells with a uniform size distribution were synthesized using red blood cells as sacrificial templates. Red blood cells do not reproduce by dividing; hence they are truly colloidal particles. They are almost completely filled with hemoglobin allowing for an extremely dynamic work cycle with long intercellular vacations separated by self-destructive workloads on the cell surface. This method of exchange is emulated in the presented research. The colloidal disc shaped gold shells were coated with multiple layers of 50nm fluorescent polystyrene spheres followed by chemical removal of the gold core. This process yielded hollow synthetic biomimetic membranes with a strong optical signature that are diffusely permeable to water and impervious to particles larger than a few nanometers. Currently, the most successful synthetic intravascular oxygen carrying materials are perfluorocarbons; however, they break down quickly in roughly 50 hours from overexposure to their in vivo workload. The meso-porous membrane cages will be filled with hundreds of fibrous spheroid conglomerates composed of perfluorocarbon chains that can protrude through the meso-porous membrane as they thermally jostle about the cage. This is to statistically limit the exposure time of individual polymer strands to the self-destructive work at the surface and hopefully will greatly increase the effective functioning lifetime of the perfluorocarbon-based synthetic red blood cell. The artificial membranes are intentionally designed to be weak allowing them to flex under normal pressures and to hopefully burst under more extreme conditions such as blockage.

Synthesis of gold nano-wire and nano-dumbbell shaped colloids and AuC60 nano-clusters

A technique for the fabrication of colloidal gold nano-wire and nano-dumbbell shaped particles using carbon nanotubes and rod shaped viruses as templates is described. The gold (Au) encapsulation process was accomplished by the precipitation of gold chloride from aqueous solutions. When this process was conducted in the presence of hydroxylated C60, small pieces of phase-separated composites of AuC60 appeared to have formed. These nano-clusters may turn out to be large noble metal analogs of the alkali metal fullerides with the smallest geometrically possible Au aggregate consisting of 55 gold atoms. The existence of noble metal fullerene composites has been previously theorized. The alkali metal fullerides are examples of phase separated solids and have exhibited superconductivity with temperatures as high 33K. The mechanism required for the binding energy between C60 and gold has been observed to exist between C60 and many of the mirror metals (Al, Ag, Au, Cu, Ni). This binding energy is a charge transfer from the metal Fermi level into the C60 LUMO. If this bonding energy, is greater than the metals coagulation energy an Au/C60 size terminated mechanism during the formation of the gold aggregates by the adhesion of C60 to the surface is energetically favorable.