Antimicrobial peptide incorporated poly(2-hydroxyethyl methacrylate) hydrogels for the prevention of Staphylococcus epidermidis-associated biomaterial infections

The effectiveness of the antimicrobial peptide maximin-4, the ultrashort peptide H-Orn-Orn-Trp-Trp-NH(2) , and the lipopeptide C(12) -Orn-Orn-Trp-Trp-NH(2) in preventing adherence of pathogens to a candidate biomaterial were tested utilizing both matrix- and immersion-loaded poly(2-hydroxyethyl methacrylate) (poly(HEMA)) hydrogels. Antiadherent properties correlated to both the concentration released and the relative antimicrobial concentrations of each compound against Staphylococcus epidermidis ATCC 35984, at each time point. Immersion-loaded samples containing C(12) -Orn-Orn-Trp-Trp-NH(2) exhibited the lowest adherence profile for all peptides studied over 1, 4, and 24 h. The results outlined in this article show that antimicrobial peptides have the potential to serve as an important weapon against biomaterial associated infections. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2012.

Bis{2-[(2-hydroxyethyl)iminomethyl]phenolato}gold(III) tetrachloroaurate(III)

The title compound, [Au-III(C9H10NO2)(2)][(AuCl4)-Cl-III], contains [Au-III(C9H10NO2)(2)](+) cations and [(AuCl4)-Cl-III](-) anions with each of the gold(III) ions in a typical four-coordinate square-planar geometry. Both gold(III) metal centers are located on inversion centers.

Di-mu-chloro-bis({2-[(2-hydroxyethyl)iminomethyl]phenolato-kappa N-3,O,O '} nickel(II)) methanol solvate

The title compound, [Ni2Cl2(C9H10NO2)(2)]center dot CH3OH, is a dinuclear unit built up by two nickel(II) complexes, bridged by two Cl atoms. The coordination geometry around each Ni-II atom can be considered as distorted square-pyramidal, with the tridendate chelate Schiff base ligands coordinating in a trans conformation through their imine N atom and phenoxy and alkoxy O atoms.

Visible and Near-Infrared Emission by Samarium(III)-Containing Ionic Liquid Mixtures

Highly luminescent anionic samarium(III) beta-diketonate and dipicolinate complexes were dissolved in the imidazolium ionic liquid 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C(6)mim][Tf2N]. The solubility of the complexes in the ionic liquid was ensured by a careful choice of the countercation of the samarium(III) complex. The samarium(III) complexes that were considered are [C(6)mim][SM(tta)(4)], where tta is 2-thenoyltrifluoroacetonate; [C(6)mim][Sm(nta)(4)], where nta is 2-naphthoyltrifluoroacetonate; [C(6)mim][Sm(hfa)(4)], where hfa is hexafluoroacetylacetonate; and [choline](3)-[Sm(dpa)(3)], where dpa is pyridine-2,6-dicarboxylate (dipicolinate) and [choline](+) is (2-hydroxyethyl)trimethyl ammonium. The crystal structures of the tetrakis samarium(III) P-diketonate complexes revealed a distorted square antiprismatic coordination for the samarium(III) ion in all three cases. Luminescence spectra were recorded for the samarium(III) complexes dissolved in the imidazolium ionic liquid as well as in a conventional solvent, that is, acetonitrile or water for the beta-diketonate and dipicolinate complexes, respectively. These experiments demonstrate that [C(6)mim][Tf2N] is a suitable spectroscopic solvent for studying samarium(III) luminescence. High-luminescence quantum yields were observed for the samarium(III) beta-diketonate complexes in solution.

Pyrimidine and pyrazine as N-donor ligands in mercurous complexes: [Hg-2(Pym)]NO3)(2), [Hg-2(Pym)](ClO4)(2), and [Hg-2(Pyp)(2)](ClO4)(2)

Colourless single crystals of [Hg-2(Pym)](NO3)(2), [Hg-2(Pym)](ClO4)(2) and [Hg-2(Pyp)(2)](ClO4)(2) were obtained from aqueous solutions of the respective components Hg-2(NO3)(2).2H(2)O, Hg-2(ClO4)(2).6H(2)O, pyrimidine (Pym) and pyrazine (Pyp). The crystal structures were determined from single-crystal X-ray diffractometer data. [Hg-2(Pym)](NO3)(2): monoclinic, C2/c, Z = 8, a = 1607.4(2), b = 652.79(7), c = 2000.5(2) pm, beta = 103.42(2)degrees, R-all = 0.0530; [Hg-2(Pym)](ClO4)(2): orthorhombic, Pnma, Z = 4, a = 1182.7(2), b = 1662.5(2), c = 607.9(1) pm, R-all = 0.0438; [Hg-2(Pyp)(2)](ClO4)(2): orthorhombic, Aba2, Z = 4, a = 1529.39(9), b = 1047.10(14), c = 1133.49(15) pm, R-all = 0.0381. The crystal structures of [Hg-2(Pym)](NO3)(2) and [Hg-2(Pym)](ClO4)(2) contain polymeric cationic chains [Hg-2(Pym)](+) that are arranged to corrugated layers between which the anions are situated. [Hg-2(Pyp)(2)](ClO4)(2) consists of polymeric cationic layers that are built from (Hg-2)(2)(Hg-2)(2/2)(Pyp)(4) rings connected to each other; the perchlorate tetrahedra are located between these layers.

Meal-induced 24-hour profile of circulating glycated insulin in type 2 diabetic subjects measured by a novel radioimmunoassay

Increasing evidence supports a role for glycated insulin in the insulin-resistant state of type 2 diabetes. We measured 24-hour profiles of plasma glycated insulin, using a novel radioimmunoassay (RIA), to evaluate the effects of meal stimulation and intermittent fasting on circulating concentrations of plasma glycated insulin in type 2 diabetes. Patients (n = 6; hemoglobin A(1c) [HbA(1c)], 7.2% +/- 0.6%; fasting plasma glucose, 7.4 +/- 0.7 mmol/L; body mass index [BMI], 35.7 +/- 3.5 kg/m(2); age, 56.3 +/- 4.4 years) were admitted for 24 hours and received a standardized meal regimen. Half-hourly venous samples were taken for plasma glycated insulin, glucose, insulin, and C-peptide concentrations between 8 Am and midnight and 2-hourly overnight. The mean plasma glycated insulin concentration over 24 hours was 27.8 +/- 1.2 pmol/L with a mean ratio of insulin:glycated insulin of 11:1. Circulating glucose, insulin, C-peptide, and glycated insulin followed a basal and meal-related pattern with most prominent increments following breakfast, lunch, and evening meal, respectively. The mean concentrations of glycated insulin during the morning, afternoon, evening, and night-time periods were 24.4 +/- 2.5, 28.7 +/- 2.3, 31.1 +/- 2.1, and 26.2 +/- 1.5 pmol/L, respectively, giving significantly higher molar ratios of insulin:glycated insulin of 18.0:1, 14.2:1, and 12.7:1 compared with 7.01 at night (P

Synthesis and characterization of star polymers and cross-linked star polymer model networks containing a novel, silicon-based, hydrolyzable cross-linker

An acid-labile dimethacrylate cross-linker, dimethyldi(methacryloyloxy-l-ethoxy)silane (DMDMAES), was synthesized by the reaction of 2-hydroxyethyl methacrylate (HEMA) and dichlorodimethylsilane in the presence of triethylamine. Group transfer polymerization (GTP) was employed to use this cross-linker in the preparation of six hydrolyzable polymer structures: one neat cross-linker network, one randomly cross-linked network of methyl methacrylate (MMA), two star-shaped polymers of MMA, and two cross-linked star polymer model networks (CSPMNs) of MMA. A nonhydrolyzable CSPMN of MMA, based on a stable cross-linker, was also synthesized. Gel permeation chromatography (GPC) in tetrahydrofuran (THF) confirmed the narrow molecular weight distributions (MWDs) of the linear polymer precursors and demonstrated the increase in molecular weight (MW) upon each successive addition of cross-linker or monomer. Characterization by static light scattering (SLS) and GPC showed that star polymers with DMDMAES cores bear a relatively small number of arms, around 7. All star polymers and polymer networks were hydrolyzed using hydrochloric acid in THF. While the MWs of the products from the hydrolysis of the star polymers, the neat cross-linker network, and the randomly cross-linked network were as expected, those from the CSPMNs were of a much higher than expected MW, indicating extensive star-star coupling.

An Infection-Responsive Approach to Reduce Bacterial Adhesion in Urinary Biomaterials

Infection is an inevitable consequence of chronic urinary catheterisation, with associated problems of recurrent catheter encrustation and blockage experienced by approximately 50% of all long-term catheterised patients. In this work we have exploited, for the first time, the reported pathogen-induced elevation of urine pH as a trigger for ‘intelligent’ antimicrobial release from novel hydrogel drug delivery systems of 2-hydroxyethyl methacrylate and vinyl-functionalised nalidixic acid derivatives, developed as candidate infection-resistant urinary catheter coatings. Demonstrating up to 20-fold faster rates of drug release at pH 10, representing infected urine pH, than at pH 7, and achieving reductions of up to 96.5% in in vitro bacterial adherence, our paradigm of pH-responsive drug delivery, which requires no external manipulation, therefore represents a promising development towards the prevention of catheter-associated urinary tract infections (CAUTIs) in vivo.