Benzimidazole carbamate residues in milk: Detection by Surface Plasmon Resonance-biosensor, using a modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method for extraction

A surface plasmon resonance (SPR) biosensor screening assay was developed and validated to detect 11 benzimidazole carbamate (BZT) veterinary drug residues in milk. The polyclonal antibody used was raised in sheep against a methyl 5(6)-[(carboxypentyl)-thio]-2-benzimidazole carbamate protein conjugate. A sample preparation procedure was developed using a modified QuEChERS method. BZT residues were extracted from milk using liquid extraction/partition with a dispersive solid phase extraction clean-up step. The assay was validated in accordance with the performance criteria described in 2002/657/EC. The limit of detection of the assay was calculated from the analysis of 20 known negative milk samples to be 2.7 mu g kg(-1). The detection capability (CC beta) of the assay was determined to be 5 mu g kg(-1) for 11 benzimidazole residues and the mean recovery of analytes was in the range 81-116%. A comparison was made between the SPR-biosensor and UPLC-MS/MS analyses of milk samples (n = 26) taken from cows treated different benzimidazole products, demonstrating the SPR-biosensor assay to be fit for purpose. (C) 2009 Elsevier B.V. All rights reserved.

A novel reversible relative-humidity indicator ink based on methylene blue and urea

A new relative-humidity sensitive ink based on methylene blue and urea is described which can utilise the deliquescent nature of urea.

A Novel, Fast-Responding, Indicator Ink for Thin Film Photocatalytic Surfaces

A new photocatalyst indicator ink based on methylene blue (MB) is described that allows the presence and activity of a thin (15 nm) photocatalytic film to be assessed in seconds. The ink is very stable (shelf life > 6 months) and the color change (blue to colorless) striking. The ink utilizes a sacrificial electron donor, glycerol, to trap the photogenerated holes, leaving the photogenerated electrons to react with MB to produce its. reduced, leuco, form (LMB). The efficacy of the MB ink is due to the presence of acid in its formulation, which curtails significantly. the otherwise usual, rapid reoxidation of LMB by ambient O-2.

A rapid method of assessing the photocatalytic activity of thin TiO2 films using an ink based on the redox dye 2,6-dichloroindophenol

An indicator ink based on the redox dye 2,6-dichloroindophenol ( DCIP) is described, which allows the rapid assessment of the activity of thin, commercial photocatalytic films, such as Activ. The ink works via a photoreductive mechanism, DCIP being reduced to dihydro-DCIP within ca. 7.5 minutes exposure to UVA irradiation of moderate intensity ( ca. 4.8mW cm(-2)). The kinetics of photoreduction are found to be independent of the level of dye present in the ink formulation, but are highly sensitive to the level of glycerol. This latter observation may be associated with a solvatochromic effect, whereby the microenvironment in which the dye finds itself and, as a consequence, its reactivity is altered significantly by small changes in the glycerol content. The kinetics of photoreduction also appear linearly dependent on the UVA light intensity with an observed quantum efficiency of ca. 1.8 x 10(-3). Copyright (C) 2008.

A solvent-based intelligence ink for oxygen

A solvent-based, irreversible oxygen indicator ink is described, comprising semiconductor photocatalyst nanoparticles, a solvent-soluble redox dye, mild reducing agent and polymer. Based on such an ink, a film - made of titanium dioxide, a blue, solvent-soluble, coloured ion-paired methylene blue dye, glycerol and the polymer zein - loses its colour rapidly (

An intelligence ink for photocatalytic films

An ink is described which, when printed or coated onto a photocatalyst film, changes colour irreversibly and rapidly upon UV activation of the photocatalyst film and at a rate commensurate with its activity.

An intelligence ink for oxygen

A generic ink formulation is described, comprising semiconductor photocatalyst particles, a brightly-coloured redox dye, a mild reducing agent, a polymer and a solvent, that creates an irreversible, reusable, UV-light-activated, colorimetric indicator or intelligence ink for oxygen.

Proteomic profiling of human retinal pigment epithelium exposed to an advanced glycation-modified substrate

Purpose The retinal pigment epithelium (RPE) and underlying Bruch’s membrane undergo significant modulation during ageing. Progressive, age-related modifications of lipids and proteins by advanced glycation end products (AGEs) at this cell–substrate interface have been implicated in RPE dysfunction and the progression to age-related macular degeneration (AMD). The pathogenic nature of these adducts in Bruch’s membrane and their influence on the overlying RPE remains unclear. This study aimed to identify alterations in RPE protein expression in cells exposed to AGE-modified basement membrane (AGE-BM), to determine how this “aged” substrate impacts RPE function and to map the localisation of identified proteins in ageing retina. Methods Confluent ARPE-19 monolayers were cultured on AGE-BM and native, non-modified BM (BM). Following 28-day incubation, the proteome was profiled using 2-dimensional gel electrophoresis (2D), densitometry and image analysis was employed to map proteins of interest that were identified by electrospray ionisation mass spectrometry (ESI MS/MS). Immunocytochemistry was employed to localise identified proteins in ARPE-19 monolayers cultured on unmodified and AGE-BM and to analyze aged human retina. Results Image analysis detected altered protein spot densities between treatment groups, and proteins of interest were identified by LC ESI MS/MS which included heat-shock proteins, cytoskeletal and metabolic regulators. Immunocytochemistry revealed deubiquitinating enzyme ubiquitin carboxyterminal hydrolase-1 (UCH-L1), which was upregulated in AGE-exposed RPE and was also localised to RPE in human retinal sections. Conclusions This study has demonstrated that AGE-modification of basement membrane alters the RPE proteome. Many proteins are changed in this ageing model, including UCHL-1, which could impact upon RPE degradative capacity. Accumulation of AGEs at Bruch”s membrane could play a significant role in age-related dysfunction of the RPE.

Selective hydrogenation of acetylene in ethylene rich feed streams at high pressure over ligand modified Pd/TiO2

The selective hydrogenation of acetylene from ethylene rich streams was conducted at high pressure and in the presence of CO over two 1 wt% loaded Pd/TiO2 catalysts with differing dispersions. Although, the more poorly dispersed sample did not result in high acetylene conversion only a small proportion of the total available ethylene was hydrogenated to ethane. The more highly dispersed sample was able to remove acetylene to a level below the detection limit but this was at the expense of significant proportion (ca. 30%) of the available ethylene. Modification of the catalysts by exposure to triphenyl phosphine or diphenyl sulfide and subsequent reduction at 393 K led to improved performance with increased conversion of acetylene and decreased propensity to hydrogenate ethylene resulting in an overall net gain in ethylene. The higher dispersed sample which had been ligand modified provided the best results overall and in particular for the diphenyl sulfide treated sample which was able to completely eliminate acetylene and still obtain a net gain in ethylene. The differences observed are thought to be due to the creation of appropriate active ensembles of Pd atoms which are able to accommodate acetylene but have limited ability to adsorb ethylene. Sub-surface hydrogen formation was suppressed, but not eliminated, by exposure to modifier.

Photocontrolled Binding and Binding-Controlled Photochromism within Anthracene-Modified DNA

Modified DNA strands undergo a reversible light-induced reaction involving the intramolecular photodimerization of two appended anthracene tags. The photodimers exhibit markedly different binding behavior toward a complementary strand that depends on the number of bases between the modified positions. By preforming the duplex, photochromism can be suppressed, illustrating dual-mode gated behavior.