Spectral characterization,antimicrobial and antibiofilm activity of poly(propylene imine) metallodendrimers in solution and applied onto cotton fabric

Abstract

Poly(propylene imine) dendrimers from first and third generation modified with 1,8-naphthalimide units and their Cu(II) complexes have been characterized by fluorescence and EPR spectroscopy. Cotton fabric has been modified with these dendrimers and their color characteristics were determined. The antimicrobial activity of dendrimer ligands and their Cu(II) complexes in solution and after their deposition on a cotton fabric was investigated. Good antibacterial effect of dendrimer ligands has been obtained, which is enhanced at their Cu(II) complexes. After their deposition on cotton fabric metallodendrimers exhibit good antibiofilm activity.     

Analyticity without differentiability

In this article we derive all salient properties of analytic functions, including the analytic version of the inverse function theorem, using only the most elementary convergence properties of series. Not even the notion of differentiability is required to do so. Instead, analytical arguments are replaced by combinatorial arguments exhibiting properties of formal power series. Along the way, we show how formal power series can be used to solve combinatorial problems and also derive some results in calculus with a minimum of analytical machinery.     

Triselenium dicyanide from malononitrile and selenium dioxide. One-pot synthesis of selenocyanates

Triselenium dicyanide is formed by the interaction of malononitrile and selenium dioxide in dimethylsulfoxide or dimethylformamide. Addition of aromatic amines, indoles and some active methylene compounds to this reaction mixture gives the corresponding selenocyanates in one-pot.     

Synthesis and characterization of well‐defined block and statistical copolymers based on lauryl methacrylate and 2‐(acetoacetoxy)ethyl methacrylate using RAFT‐controlled radical polymerization

Four well‐defined diblock copolymers and one statistical copolymer based on lauryl methacrylate (LauMA) and 2‐(acetoacetoxy)ethyl methacrylate (AEMA) were prepared using reversible addition‐fragmentation chain transfer (RAFT) polymerization. The polymers were characterized in terms of molecular weights, polydispersity indices (ranging between 1.12 and 1.23) and compositions by size exclusion chromatography and ¹H NMR spectroscopy, respectively. The preparation of the block copolymers was accomplished following a two‐step methodology: First, well‐defined LauMA homopolymers were prepared by RAFT using cumyl dithiobenzoate as the chain transfer agent (CTA). Kinetic studies revealed that the polymerization of LauMA followed first‐order kinetics demonstrating the “livingness” of the RAFT process. The pLauMAs were subsequently used as macro‐CTA for the polymerization of AEMA. The glass transition (T_g) and decomposition temperatures (ranging between 200 and 300 °C) of the copolymers were determined using differential scanning calorimetry and thermal gravimetric analysis, respectively. The T_gs of the LauMA homopolymers were found to be around ?53 °C. Block copolymers exhibited two T_gs suggesting microphase separation in the bulk whereas the statistical copolymer presented a single T_g as expected. Furthermore, the micellization behavior of pLauMA‐b‐pAEMA block copolymers was investigated in n‐hexane, a selective solvent for the LauMA block, using dynamic light scattering. pLauMA‐b‐pAEMA block copolymers formed spherical micelles in dilute hexane solutions with hydrodynamic diameters ranging between 30 and 50 nm. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5442–5451, 2008     

Determination of optimal penalties for antitrust violations in a dynamic setting

We analyze a differential game describing the interactions between a firm that might be violating competition law and the antitrust authority. The objective of the authority is to minimize social costs (loss in consumer surplus) induced by an increase in prices above marginal costs. It turns out that the penalty schemes which are used now in EU and US legislation appear not to be as efficient as desired from the point of view of minimization of consumer loss from price-fixing activities of the firm. In particular, we prove that full compliance behavior is not sustainable as a Nash Equilibrium in Markovian strategies over the whole planning period, and, moreover, that it will never arise as the long-run steady-state equilibrium of the model. We also investigate the question which penalty system enables us to completely deter cartel formation in a dynamic setting. We found that this socially desirable outcome can be achieved in case the penalty is an increasing function of the degree of offence and is negatively related to the probability of law enforcement.     

Creating hierarchical models of protein families based on Expressed Sequence Tags: the "Sprockets" analysis pipeline

We have created an analysis pipeline called Sprockets, which can be used to classify proteins into various hierarchical “families”, and build searchable models of these families. The construction of these families is based on data from Expressed Sequence Tags (ESTs) and Coding DNA Sequences (CDSs), making Sprockets clusters especially suitable for studying gene families in organisms for which the completely sequenced genome does not (yet) exist. The pipeline consists of two main parts: pair-wise analysis and grouping of sequences with Z-score statistics, followed by hierarchical splitting of clusters into alignable protein families. Various computational and statistical techniques applied in Sprockets allow it to act like a massive and selective multiple sequence alignment engine for combining individual sequence collections and related public sequences. The end result is a database of gene Hidden Markov Models, each related to the other by three levels of similarity: secondary structure, function and evolutionary origin. For a sample 20,000 EST set from Lactuca spp., Sprockets provided a 9% improvement in mapping of function to unknown sequences over traditional pair-wise search methods and InterPro mapping.     

The neglected Pt-N(sulfonamido) bond in Pt chemistry. New fluorophore-containing Pt(II) complexes useful for assessing Pt(II) interactions with biomolecules

Treatment of cis-Pt(Me2SO)2Cl2 with DNSH-tren afforded [Pt(DNSH-tren)Cl]Cl and with DNSH-dienH, under increasingly more basic conditions, led to Pt(DNSH-dienH)Cl(2), Pt(DNSH-dien)Cl, and Pt(DNS-dien). (DNSH = 5-(dimethylamino)naphthalene-1-sulfonyl, linked via a sulfonamide group to tris(2-aminoethyl)amine (DNSH-tren) and diethylenetriamine (DNSH-dienH); the H's in DNSH-dienH designate protons sometimes lost upon Pt binding, i.e., sulfonamide NH for the dienH moiety and H8 for the DNSH moiety). Respectively, the three neutral DNSH-dienH-derived complexes are difunctional, monofunctional, and nonfunctional and exhibit decreasing fluorescence in this order as the dansyl group distance to Pt decreases. 2D NMR data establish that Pt(DNS-dien) has a Pt-C8 bond and a Pt-N(sulfonamido) bond. Pt(DNSH-dien)Cl and [Pt(DNSH-tren)Cl]Cl bind to N7 of 6-oxopurines (e.g., 5'-GMP, 3'-IMP, and 9-ethylguanine) and sulfur of methionine (met). Competition and challenge reactions for Pt(II) with met and 5'-GMP typically reveal that met binding is favored kinetically but that 5'-GMP binding is favored thermodynamically. This common type of behavior was found for [Pt(DNSH-tren)Cl]Cl. In contrast, Pt(DNSH-dien)Cl had reduced kinetic selectivity for met. This unusual behavior undoubtedly arises as a consequence of the bound Pt-N(sulfonamido) group, which donates strongly to Pt (as indicated by relatively upfield dien NH signals) and which places the bulky DNSH moiety close to the monofunctional reaction site. The decrease in the relatively upfield shifts of the DNSH group signals indicates that this group stacks with the purine. This stacking could explain the unprecedented, relatively low reactivity of a Pt complex bearing a dien-type ligand toward met vs 5'-GMP.     

Novel example of a chain structure formed by 1,4-dioxane and cobalt(II) links. Chain [Co3(mu-OOCCF3)4(mu-H2O)2(OOCCF3)2(H2O)2(C4H8O2)].2C4H8O2

The trimer [Co3(mu-OOCCF3)4(mu-H2O)2(OOCCF3)2(H2O)2(C4H8O2)].2C4H8O2. (1) is composed of three tetragonally distorted Co(II) centers bridged by four trifluoroacetates and two bridging water molecules. 1,4-Dioxane is coordinated at a distance of 2.120(3) A from the terminal cobalt Co2; the remaining oxygen of this 1,4-dioxane links the terminal cobalt to a neighbor trimer, forming a one-dimensional chain. The crystal structure displays a network of hydrogen bonds between four noncoordinated 1,4-dioxane molecules and the coordinated terminal water molecules. The magnetic properties of 1 were analyzed with the use of the Hamiltonian including isotropic exchange interactions between real spins of a high-spin Co(II), spin-orbit coupling and a low-symmetry crystal field acting within the (4)T(1g) ground manifold of each cobalt ion. A weak antiferromagnetic exchange interaction between cobalt ions in 1 was found. The results of the magnetic model are in good agreement with the experimental observations.     

Hyperbolic systems of balance laws via vanishing viscosity

Global weak solutions of a strictly hyperbolic system of balance laws in one-space dimension are constructed by the vanishing viscosity method of Bianchini and Bressan. For global existence, a suitable dissipativeness assumption has to be made on the production term g. Under this hypothesis, the viscous approximations u^?, that are globally defined solutions to , satisfy uniform BV bounds exponentially decaying in time. Furthermore, they are stable in L¹ with respect to the initial data. Finally, as ?→0, u^? converges in to the admissible weak solution u of the system of balance laws u_t+(f(u))_x+g(u)=0 when A=Df.     

Ratiometric FRET-based detection of DNA and micro-RNA on the surface using TIRF detection

A new FRET-based method for the ratiometric detection of DNA oligomers on a surface using TIRF detection mode is reported. The dual-labeled system consisting of two hybridized oligomers, Cy3oligoY:Cy5oligoX was immobilized on the surface, and the total internal reflection fluorescence (TIRF) was used to detect emission signals from the surface. Two signals, green and red, which originated from the green donor Cy3 and the red acceptor Cy5, have been simultaneously detected. When the target single-stranded complimentary oligomer was present in the solution, this oligomer replaced the Cy3oligoY in the donor:acceptor complex on the surface and the ratio of red-to-green signal was dramatically changed. This detection scheme is generally applicable to the detection of DNA or RNA on a surface.