Influence of pH upon surface-enhanced enzyme-catalyzed luminol chemiluminescence at vicinity of nanoscale-corrugated gold and silver films

Abstract Au and Ag biochips were fabricated to investigate the influence of pH upon the chemiluminescence (CL) of luminol at vicinity of surface-adsorbed peroxidase. A nanoscaled-corrugation of the metal induces an enhancement of the luminol CL which is maximal in the pH range favoring peroxidase catalysis and greater for gold than for silver. This is the proof that, in the CL process, the reactions involving peroxidase are surface-enhanced near corrugated surfaces.     

Recent advances in DNA sensors

The concept of DNA biosensors is sustained by the need for rapid and highly sensitive analytical tools for genetic detection. Their implementation is based on three key steps: (i) immobilization of single-stranded oligonucleotide probes onto a substrate; (ii) hybridization and (iii) reading. These steps involve complementary knowledge in various disciplinary fields such as surface physics and chemistry, molecular electrochemistry, micro-technologies, optics, electronics and biochemistry. We present here, in a non-exhaustive way, the recent advances in the two steps of immobilization and detection that rely upon increasing integration of the number of reading points or/and of the reading strategy.     

Bonding mode of a bifunctional P approximately Si-H ligand in the ruthenium complex "Ru(PPh2CH2OSiMe2H)3"

The phosphinosilane compound PPh 2CH 2OSiMe 2H is potentially a bifunctional P approximately Si-H ligand. By treatment with the Ru (II) precursor RuH 2(H 2) 2(PCy 3) 2, the complex Ru(PPh 2CH 2OSiMe 2H) 3 ( 2), resulting from the coordination of three ligands and the displacement of two PCy 3 and two dihydrogen ligands, was formed. The different bonding modes for each of the three bifunctional P approximately Si-H ligands are discussed on the basis of multinuclear NMR, X-ray diffraction, and density functional theory studies. One ligand acts as a monodentate phosphine ligand with a pendant Si-H group, whereas the two others act as bidentate ligands with different Si-H bond activations. Indeed, an intermediate structure between two arrested forms 2a and 2b can be proposed: a dihydrido(disilyl)ruthenium(IV) species (form 2a) resulting from two Si-H oxidative additions or a hydrido(silyl)ruthenium(II) species (form 2b) presenting an agostic Si-H bond and only one oxidative addition.     

Gas-phase nitrosation of ethylene and related events in the C2H4NO+ landscape

The C2H4NO(+) system has been examined by means of quantum chemical calculations using the G2 and G3B3 approaches and tandem mass spectrometry experiments. Theoretical investigation of the C2H4NO(+) potential-energy surface includes 19 stable C2H4NO(+) structures and a large set of their possible interconnections. These computations provide insights for the understanding of the (i) addition of the nitrosonium cation NO(+) to the ethylene molecule, (ii) skeletal rearrangements evidenced in previous experimental studies on comparable systems, and (iii) experimental identification of new C2H4NO(+) structures. It is predicted from computation that gas-phase nitrosation of ethylene may produce C2H4(*)NO(+) adducts, the most stable structure of which is a pi-complex, 1, stabilized by ca. 65 kJ/mol with respect to its separated components. This complex was produced in the gas phase by a transnitrosation process involving as reactant a complex between water and NO(+) (H2O.NO(+)) and the ethylene molecule and fully characterized by collisional experiments. Among the other C 2H 4NO (+) structures predicted by theory to be protected against dissociation or isomerization by significant energy barriers, five were also experimentally identified. These finding include structures CH3CHNO(+) (5), CH 3CNOH (+) ( 8), CH3NHCO(+) (18), CH3NCOH(+) (19), and an ion/neutral complex CH2O...HCNH(+) (12).     

Nanorubbing of polythiophene surfaces

This work describes a new orientation method for semicrystalline poly(3-hexylthiophene) (P3HT) thin films, coupling nanorubbing and subsequent crystallization. Using the stylus of an atomic force microscope, we align the polymer chains on P3HT surfaces with a spatial and geometrical control of the oriented domains (nanorubbing). These chain-aligned structures can be made permanent thanks to the crystallization process, which propagates the orientation obtained at the surface to the bulk.     

Two new irregular acyclic sesquiterpenes aldehydes from Santolina corsica essential oil

Two isomeric irregular sesquiterpene aldehydes, namely 3,9-dimethyl-6-isopropyl-2(E),7(E),9-decatrienal and 3,9-dimethyl-6-isopropyl-2(Z),7(E),9-decatrienal, were isolated from the essential oil of Santolina corsica and their structures were elucidated by 1D and 2D NMR spectroscopy.     

Hamiltonian Stationary Tori in the Complex Projective Plane

Hamiltonian stationary Lagrangian surfaces are Lagrangian surfacesin a four-dimensional Kähler manifold which are criticalpoints of the area functional for Hamiltonian infinitesimaldeformations. In this paper we analyze these surfaces in thecomplex projective plane: in a previous work we showed thatthey correspond locally to solutions to an integrable system,formulated as a zero curvature on a (twisted) loop group. Herewe give an alternative formulation, using non-twisted loop groupsand, as an application, we show in detail why Hamiltonian stationaryLagrangian tori are finite type solutions, and eventually describethe simplest of them: the homogeneous ones. 2000 MathematicsSubject Classification 53C55 (primary), 53C42, 53C25, 58E12(secondary).     

Charge transport in self-organized pi-stacks of p-phenylene vinylene oligomers

We have studied the mobility of charge carriers along self-organizing pi-stacks of hydrogen-bonded phenylene vinylene oligomers in solution, by time-resolved microwave conductivity measurements. The value deduced for the mobility along the stacks is 3 x 10(-3) and 9 x 10(-3) cm2/(V s) for holes and electrons, respectively. Additionally, we have calculated the mobility along the pi-stacks using a hopping model based on parameters from density functional theory. The mobility values obtained from these calculations are in good agreement with the experimental values if it is assumed that there are relatively large twist angles between neighboring molecules in the stack. It is shown that a significantly higher mobility can be attained if the twist angle between neighboring oligomers is reduced.