Enzymatic activity of lipase-nanoparticle conjugates and the digestion of lipid liquid crystalline assemblies.

Variants of lipase were attached to gold nanoparticles (NPs) and their enzymatic activity was studied. The two bioengineered lipase variants have been prepared with biotin groups attached to different residues on the protein outer surface. The biotinylation was evidenced by denaturing polyacrylamide gel electrophoresis and quantified by the ([2-(4'-hydroxyazobenzene)]benzoic acid spectrophotometric test.

Photonic and electrochemical properties of adsorbed [Ru(dpp)2(Qbpy)]2+ luminophores.

Dense monolayers of [Ru(dpp)2Qbpy]2+, where dpp is 4,4'-diphenylphenanthroline and Qbpy is 2,2':4,4' ':4'4' '-quarterpyridyl, have been formed by spontaneous adsorption onto clean platinum microelectrodes. The cyclic voltammetry of these monolayers is nearly ideal, and three redox states are accessible over the potential range of +/-1.3 V.

Bionanoconjugation via click chemistry: The creation of functional hybrids of lipases and gold nanoparticles.

A simple and versatile method for the preparation of functional enzyme-gold nanoparticle conjugates using "click" chemistry has been developed. In a copper-catalyzed 1,2,3-triazole cycloaddition, an acetylene-functionalized Thermomyces lanuginosus lipase has been attached to azide-functionalized water-soluble gold nanoparticles under retention of enzymatic activity. The products have been characterized by gel electrophoresis and a fluorometric lipase activity assay.

Thiol-specific and nonspecific interactions between DNA and gold nanoparticles.

The contribution of nonspecific interactions to the overall interactions of thiol-ssDNA and dsDNA macromolecules with gold nanoparticles was investigated. A systematic investigation utilizing dynamic light scattering and cryogenic transmission electron microscopy has been performed to directly measure and visualize the changes in particle size and appearance during functionalization of gold nanoparticles with thiol-ssDNA and nonthiolated dsDNA. The results show that both thiol-ssDNA and dsDNA do stabilize gold nanoparticle dispersions, but possible nonspecific interactions between the hydrophobic DNA bases and the gold surface promote interparticle interactions and cause aggregation within rather a short period of time.

Electron hopping dynamics in monolayer-protected au cluster network polymer films by rotated disk electrode voltammetry.

Electrons are transported within polymeric films of alkanethiolate monolayer-protected Au clusters (MPCs) by electron hopping (self-exchange) between the metal cores. The surrounding monolayers, the molecular linkers that generate the network polymer film, or both, presumably serve as tunneling bridges in the electron transfers. This paper introduces a steady-state electrochemical method for measuring electron hopping rates in solvent-wetted and swollen, ionically conductive MPC films.

Ground vs. excited state electron transfer: adsorbed monolayers and trimers in solution.

Transient emission spectroscopy has been used to probe the rate of photoinduced electron transfer between metal centres within a novel trimeric complex [[Os(bpy)2(bpe)2][Os(bpy)2Cl]2]4+, where bpy is 2,2'-bipyridyl and bpe is trans-1,2-bis-(4-pyridyl)ethylene. Transient emission experiments on the trimer, and on [Os(bpy)2 (bpe)2]2+ in which the [Os(bpy)2 Cl]+ quenching moieties are absent, reveal that the rate of photoinduced electron transfer (PET) across the bpe bridge is 1.3 +/- 0.