The use of comet assay data with a simple reaction mechanism to evaluate the relative effectiveness of free radical scavenging by quercetin, epigallocatechin gallate and N-acetylcysteine in UV-irradiated MRC5 lung fibroblasts

Comet assay data (tail DNA %) have been gathered for the concentration dependent role of three antioxidants (AOs); quercetin (Q), epigallocatechin gallate (EGCG) and N-acetylcysteine (NAC) in reducing UV-induced damage to DNA in normal fetal lung fibroblasts (MRC5). All three compounds demonstrate a concentration dependent reduction maximum with a pro-oxidant effect at higher (though not cytotoxic) concentrations. Manipulation of a simple 4-step reaction mechanism for free radical (FR) scavenging by AOs produced rate constant ratios which allowed the relative effectiveness (Q > EGCG > NAC) of the AOs to be evaluated.     

Unveiling the elusive role of tetraethyl orthosilicate hydrolysis in ionic-liquid-templated zeolite synthesis

Despite previous reports showing that crystallization kinetics affects zeolite phase selectivity because zeolites are metastable species in their synthesis solution rather than thermodynamic end points, the critical kinetics-controlling parameter is yet to be determined. This work elucidated the effect of tetraethyl orthosilicate (TEOS) hydrolysis before hydrothermal treatment on the final zeolite phase selectivity in the ionic liquid-templated synthesis of 10-membered ring zeolites (MFI- or TON-type zeolites). The results showed that the dissolved silica concentration in the synthesis solution, which is controlled by varying the TEOS hydrolysis temperature and addition rate, induced heterogeneous nuclear growth. Specifically, in 1-butyl-3-methylimidazolium ([BMIM]Br)-directed syntheses, the high and low concentrations of dissolved silica species led to MFI and TON zeolite formation, respectively. The experimental results are supported by silica polymerization modeling using the Reaction Ensemble Monte Carlo method and theoretical calculations on composite building unit formation. The results are valuable for understanding the nucleation mechanism in zeolite crystallization.     

A C2-symmetric analogue of dppf: synthesis and structures of the indenyl-diphosphine complex 1,3-(Ph2PSe)2(C9H6) and the racemic and meso isomers of the heterobimetallic complex Mo(CO)4(1-PPh2-η-C9H6)2Fe

The preparation, isolation and characterisation of 1,3-bis(diphenylphosphino)indene (1) from indene and chlorodiphenylphosphine is described. The reaction of 1 with selenium gives the diselenide adduct 1,3-bis(diphenylselenophosphino)indene (2) which was characterised crystallographically. Deprotonation of 1 and treatment with ferrous chloride gives the unstable tetraphosphine complex bis(1,3-bis(diphenylphosphino)indenyl)iron(II) (3). Complex 3 decomposes to the diphosphine complex bis(1-diphenylphosphinoindenyl)iron(II) (4) via replacement of one diphenylphosphine substituent per indenyl ligand by a hydrogen atom. Complex 4 was also prepared by treatment of two equivalents of 1-diphenylphosphinoindenide with ferrous chloride. The heterobimetallic complex tetracarbonyl(bis(1-diphenylphosphinoindenyl)iron(II))molybdenum(0) (5) was also prepared and crystal structures of both the meso (5a) and C₂-symmetric racemic (5b) isomers are reported.     

Enzymatic synthesis of layered titanium phosphates at low temperature and neutral pH by cell-surface display of silicatein-alpha

We introduce a novel method of inorganic synthesis using the catalytic and structure-directing properties of the demosponge enzyme silicatein-alpha. Recombinant silicatein-alpha was displayed at the surface of Escherichia coli cells by fusion to outer membrane protein A and used to biocatalytically direct the formation of layered and amorphous titanium phosphates from a small water-soluble precursor at near-neutral pH at 16 degrees C. Synthesis of titanium phosphates, with potential applications in catalysis and separation technology, previously has required prolonged reactions with phosphoric acid at elevated temperatures. Additionally, we use library screening to isolate a 15-mer with affinity toward the silicatein active site (Kd ca. 50 nM) and introduce this new approach to demonstrate the success of our display strategy. Considering our previous findings with native silicatein filaments, we suggest that this scalable, efficient, cell-based system may have a broad utility for the synthesis of a range of structured metallophosphates and other inorganic materials.     

Construction of Ternary Iodine–Bromine–Chlorine Octahalides

A series of five ternary octanuclear iodine-bromine-chlorine interhalides, [I₂Br₂Cl₄]²⁻ ( 1 ), [I₃BrCl₄]²⁻ ( 2 ), [I₄Br₂Cl₂]²⁻ ( 3 ), [I₂Br₄Cl₂]²⁻ ( 4 ) and [I₃Br₃Cl₂]²⁻ ( 5 ), have been rationally constructed in two steps. Firstly, addition of a dihalogen (ICl or IBr) to the triaminocyclopropenium chloride salt [C₃(NEt₂)₃]Cl forms the corresponding trihalide salt with [ICl₂]⁻ or [BrICl]⁻ anions, respectively. Secondly, addition of a half-equivalent of a second dihalogen, followed by crystallization at low temperature, gives the corresponding octahalide: addition of Br₂ and IBr to [ICl₂]⁻ gives 1 and 2 , respectively, whereas addition of I₂, Br₂ and IBr to [BrICl]⁻ gives 3 , 4 and 5 , respectively. The five octahalides were characterized by X-ray crystallography and far–IR spectroscopy.     

The effect of air cooling pain relief on protoporphyrin IX photobleaching and clinical efficacy during dermatological photodynamic therapy

Methyl aminolevulinate photodynamic therapy (MAL-PDT) is utilized to successfully treat licensed indications (e.g. actinic keratosis (AK), superficial basal cell carcinoma (sBCC) and Bowen's disease (BD)) in the UK. Air cooling devices (ACD) are commonly utilized as a method of pain relief, however the effect of this on treatment outcome has never been extensively investigated. This non-randomized, retrospective observational controlled study investigated whether the application of the ACD limited photosensitiser (protoporphyrin IX - PpIX) photobleaching during irradiation and/or subsequent clinical outcome. Patients utilizing the ACD throughout treatment were observed to undergo significantly less PpIX photobleaching than the control group (P<0.001) and complete clinical clearances observed at 3 months were also reduced within the ACD group. Separate analysis of the different lesion types indicated that significantly less photobleaching occurred in AK lesions with ACD and all lesion types failed to fully utilize the accumulated PpIX when ACD was employed. The application of the ACD as pain relief during light irradiation therefore resulted in lower PpIX photobleaching which corresponded to a reduction in the efficacy of PDT treatment. Whilst the ACD is an effective method of dermatological PDT analgesia it should be utilized as sparingly as possible to minimize any deleterious effects on treatment outcome.