Glucose oxidase kinetics using MnO nanosheets: confirming Michaelis-Menten kinetics and quantifying decreasing enzyme performance with increasing buffer concentration.

MnO nanosheets and ultraviolet-visible (UV-Vis) absorbance spectroscopy are used to study glucose oxidase (GOx) kinetics. Glucose oxidation by GOx produces HO, which rapidly decomposes the nanosheets and reduces their absorption. This direct approach for monitoring glucose oxidation enables simpler, real time kinetics analysis compared to methods that employ additional enzymes.

Ultrathin Surface Chemistry to Delay Anion Fouling.

The unwanted fouling of surfaces by ionic adsorption has received little research attention. In this context, ultrathin organic adlayer surface chemistry-featuring monoethylene glycol based molecular residues-is described that is capable of noticeably decreasing the rate of anion depletion from solution. The strategy is exemplified with glass as the substrate material and fluoride as the anion foulant.

Gating of enhanced electron-charging thresholds in self-assembled nanoparticle films.

Films of butanedithiol interconnected nanoparticles can exhibit a percolation-driven insulating to metal transition. To explore properties of materials with interpolating behavior, we have measured conductance of these films with systematically varying thickness. Films below a certain threshold coverage exhibit thermally assisted conductance and conductance suppression near zero bias indicative of single-electron-charging barriers.

Metal to insulator transition in films of molecularly linked gold nanoparticles.

We report a metal to insulator transition (MIT) in disordered films of molecularly linked gold nanoparticles (NPs). As the number of carbons (n) of alkanedithiol linker molecules (C(n)S2) is varied, resistance (R) at low temperature (T = 2 K) and at 200 K, as well as trends in R vs T data at intermediate temperatures, all point to an MIT occurring at n = 5. We describe these results in a context of a Mott-Hubbard MIT.

Influence of linker molecules on charge transport through self-assembled single-nanoparticle devices.

We investigate electrical characteristics of single-electron electrode/nanoisland/electrode devices formed by alkanedithiol assisted self-assembly. Contrary to predictions of the orthodox model for double tunnel junction devices, we find a significant ( approximately fivefold) discrepancy in single-electron charging energies determined by Coulomb blockade (CB) voltage thresholds in current-voltage measurements versus those determined by an Arrhenius analysis of conductance in the CB region. The energies do, however, scale with particle sizes, consistent with single-electron charging phenomena.