Protein Attachment on Nanodiamonds.

A recent advance in nanotechnology is the scale-up production of small and nonaggregated diamond nanoparticles suitable for biological applications. Using detonation nanodiamonds (NDs) with an average diameter of ∼4 nm as the adsorbents, we have studied the static attachment of three proteins (myoglobin, bovine serum albumin, and insulin) onto the nanoparticles by optical spectroscopy, mass spectrometry, and dynamic light scattering, and electrophoretic zeta potential measurements. Results show that the protein surface coverage is predominantly determined by the competition between protein-protein and protein-ND interactions, giving each protein a unique and characteristic structural configuration in its own complex.

Reflected shock tube studies of high-temperature rate constants for OH + NO2 --> HO2 + NO and OH + HO2 --> H2O + O2.

The motivation for the present study comes from the preceding paper where it is suggested that accepted rate constants for OH + NO2 --> NO + HO2 are high by approximately 2. This conclusion was based on a reevaluation of heats of formation for HO2, OH, NO, and NO2 using the Active Thermochemical Table (ATcT) approach. The present experiments were performed in C2H5I/NO2 mixtures, using the reflected shock tube technique and OH-radical electronic absorption detection (at 308 nm) and using a multipass optical system.

Active Thermochemical Tables: accurate enthalpy of formation of hydroperoxyl radical, HO2.

Through the use of the Active Thermochemical Tables approach, the best currently available enthalpy of formation of HO2 has been obtained as delta(f)H(o)298 (HO2) = 2.94 +/- 0.06 kcal mol(-1) (3.

Stabilization of yeast cytochrome C covalently immobilized on fused silica surfaces.

The surface-enhanced conformational stability of yeast cytochrome c (YCC) covalently immobilized on a fused silica prism with heterobifunctional cross-linkers has been studied by attenuated total reflection absorption spectroscopy using the Soret band of the heme prosthetic group as a probe. Comparison of the results to those of horse cytochrome c physisorbed on the same substrate as well as to the corresponding proteins in solution indicates that the surface plays a significant role in stabilizing the native conformation of the surface-bound YCC. Unfolding to extended configurations was so hindered that the native conformation of the covalently immobilized protein is essentially unaffected by the presence of denaturants such as methanol and 1-propanol.

H+H2 thermal reaction: a convergence of theory and experiment.

New experimental and theoretical rate constants for two isotopologs of the simplest chemical reaction, H+H2-->H2+H, are presented. The theoretical results are obtained using accurate quantum dynamics with a converged Born-Oppenheimer potential energy surface and include non-Born-Oppenheimer corrections. The new experiments are carried out using a shock tube and complement earlier investigations over a very large T range, 167 to 2112 K.