ABCG2 Protein Levels and Association to Response to First-Line Irinotecan-Based Therapy for Patients with Metastatic Colorectal Cancer.

In this study we investigated the use of cancer cell protein expression of ABCG2 to predict efficacy of systemic first-line irinotecan containing therapy in patients with metastatic colorectal cancer (mCRC). From a Danish national cohort, we identified 119 mCRC patients treated with irinotecan containing therapy in first-line setting. Among these, 108 were eligible for analyses.

Real-time monitoring of lycopene content in tomato-derived products during processing: implementation of a novel double-slit Raman spectrometer.

Lycopene is a very attractive antioxidant associated with cancer prevention in humans. Therefore, it is important to develop new analytical methods that allow for differentiation of food production streams that contain various antioxidant concentrations. The lycopene content in tomato juice, an intermediate between raw tomatoes and the final tomato paste product, was monitored on-line for 46 days at a production plant with a novel, patented double-channel Raman setup.

Microbial growth studies in biodiesel blends.

Introduction of biofuels to the fuel matrix poses new questions and challenges. The present study investigates the microbiological stability of biodiesel blends in small scale microcosms. The study presents results from incubations of diesel-biodiesel blends with contaminated inoculation water collected from diesel storage tanks to ensure the presence of relevant fuel degrading bacteria.

Determination of binding strengths of a host-guest complex using resonance Raman scattering.

The detection of analyte-binding events by receptors is drawing together the fields of Raman spectroscopy and supramolecular chemistry. This study is intended to facilitate this cohering by examining a model in the solution phase. The resonance Raman scattering (RRS) spectra of the complexation between tetrathiafulvalene (TTF) and cyclobis(paraquat-p-phenylene) (CBPQT(4+)) has been used as the model system to characterize the binding event of a host-guest system.

Structure-property relationships in redox-gated single molecule junctions--a comparison of pyrrolo-tetrathiafulvalene and viologen redox groups.

We demonstrate that the electrical "switching" behavior of single molecules connected between two electrode contacts can be controlled by altering their structure and electrochemical characteristics. The electrical properties of gold|molecule|gold single molecule junctions incorporating HS(CH2)6-X-(CH2)6SH, where X = viologen (4,4'-bipyridinium) or pyrrolotetrathiafulvalene, are determined using a scanning tunneling microscopy based technique. The switching behavior, controlled through a tuneable electrochemical gate, changes from an on-off response (viologen) to an off-on-off response (pyrrolotetrathiafulvalene) on changing the central redox group.

Two classes of alongside charge-transfer interactions defined in one [2]catenane.

A [2]catenane, which incorporates hydroquinone (HQ) and a sterically bulky tetrathiafulvalene (TTF) into a bismacrocycle, has been designed to probe the alongside charge-transfer (CT) interactions taking place between a TTF unit and one of the bipyridinium moieties in the tetracationic cyclophane cyclobis(paraquat-p-phenylene) (CBPQT4+). A template-directed strategy employs the HQ unit as the primary template for formation of the tetracationic cyclophane CBPQT4+, affording the desired [2]catenane structure but as an uncharacteristic green solid. The X-ray crystal structure and detailed 13C NMR assignments have identified a stereoselective preference for catenation about the cis isomer.

Binding studies between triethylene glycol-substituted monopyrrolotetrathiafulvalene derivatives and cyclobis(paraquat-p-phenylene).

The synthesis of several pi-electron-donating monopyrrolotetrathiafulvalene (MPTTF) derivatives, which conceptually can be divided into three classes containing none, one, or two triethylene glycol (TEG) substituents, is described. In all cases, the complexation between the pi-electron donating MPTTF unit and the pi-electron-deficient tetracationic cyclophane cyclobis(paraquat-p-phenylene) (CBPQT(4+)) has been investigated using UV-vis dilution techniques. The results reveal that the strength of the binding between MPTTF derivatives and CBPQT(4+) is directly correlated to the pi-electron donating properties of the MPTTF derivatives.

Functionally rigid bistable [2]rotaxanes.

Two-station [2]rotaxanes in the shape of a degenerate naphthalene (NP) shuttle and a nondegenerate monopyrrolotetrathiafulvalene (MPTTF)/NP redox-controllable switch have been synthesized and characterized in solution. Their dumbbell-shaped components are composed of polyether chains interrupted along their lengths by (i) two pi-electron-rich stations-two NP moieties or a MPTTF unit and a NP moiety-with (ii) a rigid arylethynyl or butadiynyl spacer situated between the two stations and terminated by (iii) flexibly tethered hydrophobic stoppers at each end of the dumbbells. This modification was investigated as a means to simplify both molecular structure and switching function previously observed in related bistable [2]rotaxanes with flexible spacers between their stations and incorporating a cyclobis(paraquat-p-phenylene) (CBPQT4+) ring.

Cis- and trans-bis(2-cyanoethylsulfanyl)(decane-1,10-diyldithio)tetrathiafulvalene.

The isomeric title compounds, 2,7-bis(2-cyanoethylsulfanyl)-3,6-(decane-1,10-diyldithio)tetrathiafulvalene and 2,6-bis(2-cyanoethylsulfanyl)-3,7-(decane-1,10-diyldithio)tetrathiafulvalene, both C22H28N2S8, comprise bis(2-cyanoethylsulfanyl)tetrathiafulvalene units tethered by a saturated decamethylenedithio linker attached in either a cis or a trans manner. The tetrathiafulvalene (TTF) group is planar in the cis isomer, but distorted significantly from planarity and twisted about its long axis in the trans isomer. In both structures, intermolecular interactions are segregated into regions in which TTF units are brought into close contact and regions where the polymethylene chains are brought into close contact.

Locking down the electronic structure of (monopyrrolo)tetrathiafulvalene in [2]rotaxanes.

[reaction: see text] The redox potentials of a highly constrained [2]rotaxane have been measured and used to model the energy of the HOMO of tetrathiafulvalene-based bistable [2]rotaxanes in their two co-conformationally isomeric states. Restrained from co-conformational movements, the measured oxidation and reduction potentials provide insights into the orbital energies and electronic structure of a (monopyrrolo)tetrathiafulvalene unit when encircled by a tetracationic cyclobis(paraquat-p-phenylene) ring.

Quantifying the working stroke of tetrathiafulvalene-based electrochemically-driven linear motor-molecules.

A highly constrained [2]rotaxane, constructed in such a way that the tetracationic cyclobis(paraquat-p-phenylene) ring is restricted to reside on a monopyrrolotetrathiafulvalene unit, has been synthesised and characterised. This design allows the deslipping free energy barrier for the tetracationic ring in all three redox states of the rotaxane to be determined.

Ground-state equilibrium thermodynamics and switching kinetics of bistable [2]rotaxanes switched in solution, polymer gels, and molecular electronic devices.

We report on the kinetics and ground-state thermodynamics associated with electrochemically driven molecular mechanical switching of three bistable [2]rotaxanes in acetonitrile solution, polymer electrolyte gels, and molecular-switch tunnel junctions (MSTJs). For all rotaxanes a pi-electron-deficient cyclobis(paraquat-p-phenylene) (CBPQT4+) ring component encircles one of two recognition sites within a dumbbell component. Two rotaxanes (RATTF4+ and RTTF4+) contain tetrathiafulvalene (TTF) and 1,5-dioxynaphthalene (DNP) recognition units, but different hydrophilic stoppers.

Counterion-induced translational isomerism in a bistable [2]rotaxane.

Translational isomerization can be induced by changing the anions associated with a bistable rotaxane in which the tetracationic cyclophane (blue box), cyclobis(paraquat-p-phenylene), encircles a dumbbell component containing bispyrrolotetrathiafulvalene (green) and a dioxynaphthalene (red) recognition sites. The rotaxane was isolated as both its hexafluorophosphate and tris(tetrachlorobenzenediolato)phosphate(v) (TRISPHAT(-)) salts. Photophysical measurements and NMR spectroscopy carried out in acetone (CD(3)COCD(3)) and acetonitrile (CD(3)CN) solutions reveal that the much larger TRISPHAT(-) anion favors predominantly the encirclement of the green site by the blue box.