Terminal Amine Groups Research Articles

Development of mannose functionalized dendrimeric nanoparticles for targeted delivery to macrophages: use of this platform to modulate atherosclerosis

Dysfunctional macrophages underlie the development of several diseases including atherosclerosis where accumulation of cholesteryl esters and persistent inflammation are 2 of the critical macrophage processes that regulate the progression as well as stability of atherosclerotic plaques. Ligand-dependent activation of liver-x-receptor (LXR) not only enhances mobilization of stored cholesteryl ester but also exerts anti-inflammatory effects mediated via trans-repression of proinflammatory transcription factor nuclear factor kappa B. However, increased hepatic lipogenesis by systemic administration of LXR ligands (LXR-L) has precluded their therapeutic use. The objective of the present study was to devise a strategy to selectively deliver LXR-L to atherosclerotic plaque-associated macrophages while limiting hepatic uptake. Mannose-functionalized dendrimeric nanoparticles (mDNP) were synthesized to facilitate active uptake via the mannose receptor expressed exclusively by macrophages using polyamidoamine dendrimer. Terminal amine groups were used to conjugate mannose and LXR-L T091317 via polyethylene glycol spacers. mDNP-LXR-L was effectively taken up by macrophages (and not by hepatocytes), increased expression of LXR target genes (ABCA1/ABCG1), and enhanced cholesterol efflux. When administered intravenously to LDLR-/- mice with established plaques, significant accumulation of fluorescently labeled mDNP-LXR-L was seen in atherosclerotic plaque-associated macrophages. Four weekly injections of mDNP-LXR-L led to significant reduction in atherosclerotic plaque progression, plaque necrosis, and plaque inflammation as assessed by expression of nuclear factor kappa B target gene matrix metalloproteinase 9; no increase in hepatic lipogenic genes or plasma lipids was observed. These studies validate the development of a macrophage-specific delivery platform for the delivery of anti-atherosclerotic agents directly to the plaque-associated macrophages to attenuate plaque burden.

High-resolution structure of a lytic polysaccharide monooxygenase from Hypocrea jecorina reveals a predicted linker as an integral part of the catalytic domain

For decades, the enzymes of the fungus Hypocrea jecorina have served as a model system for the breakdown of cellulose. Three-dimensional structures for almost all H. jecorina cellulose-degrading enzymes are available, except for HjLPMO9A, belonging to the AA9 family of lytic polysaccharide monooxygenases (LPMOs). These enzymes enhance the hydrolytic activity of cellulases and are essential for cost-efficient conversion of lignocellulosic biomass. Here, using structural and spectroscopic analyses, we found that native HjLPMO9A contains a catalytic domain and a family-1 carbohydrate-binding module (CBM1) connected via a linker sequence. A C terminally truncated variant of HjLPMO9A containing 21 residues of the predicted linker was expressed at levels sufficient for analysis. Here, using structural, spectroscopic, and biochemical analyses, we found that this truncated variant exhibited reduced binding to and activity on cellulose compared with the full-length enzyme. Importantly, a 0.95-Å resolution X-ray structure of truncated HjLPMO9A revealed that the linker forms an integral part of the catalytic domain structure, covering a hydrophobic patch on the catalytic AA9 module. We noted that the oxidized catalytic center contains a Cu(II) coordinated by two His ligands, one of which has a His-brace in which the His-1 terminal amine group also coordinates to a copper. The final equatorial position of the Cu(II) is occupied by a water-derived ligand. The spectroscopic characteristics of the truncated variant were not measurably different from those of full-length HjLPMO9A, indicating that the presence of the CBM1 module increases the affinity of HjLPMO9A for cellulose binding, but does not affect the active site.

Covalently Assembled Monolayers of Homo- and Heteroleptic FeII -Terpyridyl Complexes on SiOx and ITO-Coated Glass Substrates: An Experimental and Theoretical Study.

Well-defined FeII -terpyridyl monolayers were fabricated on SiOx and conductive ITO-coated glass substrates through covalent-bond formation between the metallo-organic complexes and a preassembled coupling layer. Three different homo- and heteroleptic complexes with terminal pyridyl, amine, and phenyl groups were tested. All the films were found to be densely packed and homogeneous, and consist of molecules standing upright. They exhibited high thermal (up to ≈220 °C) and temporal (up to 5 h at 100 °C) stability. The UV/Vis spectra of the monolayers showed pronounced metal-to-ligand charge-transfer bands with a significant redshift compared with the solution spectra of the metallo-ligands with a pendant pyridyl group quaternized with the coupling layer, whereas the shift was significantly smaller when the coupling layer was bonded to the primary amine (-NH2 ) group of the complex. Cyclic voltammograms of the monolayers showed reversible, one-electron redox behavior and suggested strong electronic coupling between the confined molecules and the underlying substrate. Analysis of the electrochemistry data allowed us to estimate the charge-transfer rate constant between the metal center and the substrate. Additionally, detailed quantum-chemical calculations were performed to support and rationalize the experimentally observed photophysical properties of the FeII -terpyridyl complexes both in the solution state and when bound to a SiOx -based substrate.

Mediatorless Impedance Studies with Titanium Dioxide Conjugated Gold Nanoparticles for Hydrogen Peroxide Detection.

An impedimetric-based biosensor constructed using gold nanoparticles (AuNP) entrapped within titanium dioxide (TiO2) particles for hydrogen peroxide (H2O2) detection is the main feature of this research. The matrix of the biosensor employed the surface of TiO2, which was previously modified with an amine terminal group using 3-Aminopropyltriethoxysilane (APTS) at a low temperature to create a ready to immobilise surface for the biosensor application. Hemoglobin (Hb), which exhibits peroxidase-like activity, was used as the bioreceptor in the biosensor to detect H2O2 in solution. The analysis was carried out using an alternative impedance method, in which the biosensor exhibited a wide linear range response between 1 × 10−4 M and 1.5 × 10−2 M and a limit of detection (LOD) of 1 × 10−5 M without a redox mediator.

Robust Red Organic Nanoparticles for In Vivo Fluorescence Imaging of Cancer Cell Progression in Xenografted Zebrafish

Bright and red‐emissive organic nanoparticles (NPs) are demonstrated as promising for in vivo fluorescence imaging. However, most red organic dyes show greatly weakened or quenched emission in the aggregated state. In this work, a robust red fluorophore (t‐BPITBT‐TPE) with strong aggregate‐state photoluminescence and good biocompatibility is presented. The NPs comprised of t‐BPITBT‐TPE aggregates encapsulated within 1,2‐distearoyl‐sn‐glycero‐3‐phosphoethanolamine‐N‐[methoxy(polyethylene glycol) (DSPE‐mPEG) micelles exhibit a photoluminescence peak at 660 nm with a high fluorescence quantum yield of 32% in aqueous media. The NPs can be facilely charged by using the same polymeric matrix with different terminal groups, e.g., methoxy (DSPE‐mPEG), amine (DSPE‐PEG‐NH2), or carboxymethyl (DSPE‐PEG‐COOH) groups. The biocompatibility, toxicity, circulation, and biodistribution of the NPs are assessed using the zebrafish model through whole embryo soaking and intravenous delivery. Furthermore, HeLa and MCF‐7 cells tagged with t‐BPITBT‐TPE in DSPE‐PEG‐NH2‐TAT polymer NPs are xenografted into zebrafish larvae to successfully track the cancer cell proliferation and metastasis, demonstrating that these new NPs are efficient cancer cell trackers. In addition, the NPs also show good in vivo imaging ability toward 4T1 tumors in xenografted BALB/c mice.

Catalase Immobilized on Poly(Acrylic Acid-co-Vinyl Alcohol)

The paper studies the reaction of catalase’s immobilization on a synthetic polymer (copolymer of the acrylic acid with vinyl alcohol), through amidation of enzyme’s terminal amine groups with the lateral<br />carboxylic group of the macromolecular support, as activated by dicycloxexyl carbodiimide. The support, possessing the properties of a hydrogel, has been synthesized through copolymerization of the acrylic acid with vinyl acetate, followed by hydrolysis of the acetate groups to the hydroxylic groups. The influence of some reaction parameters (such as the activator/support and enzyme/support ratios, duration) on the efficiency of the enzyme’s coupling was studied. The coupling reactions were realized conformely to a centered, rotator, composed, second order experimental program, which permitted the establishment of the conditions necessary for obtaining a coupling product containing the highest amount of immobilized enzyme. Kinetic study of the reaction catalyzed by the coupling products has indirectly evidenced enzyme’s immobilization to the macromolecular support, and also, a sufficiently high catalytic activity of the enzymatic preparation obtained.

New insight of the photocatalytic behaviors of graphitic carbon nitrides for hydrogen evolution and their associations with grain size, porosity, and photophysical properties

The development of efficient catalysts for hydrogen evolution reaction (HER) presents a huge technical challenge. Graphitic carbon nitride (g-C3N4) is a promising metal-free, low cost, environment-friendly photocatalyst for HER that is driven by visible light. In this work, the authors provide new insight into the photocatalytic natures of g-C3N4 materials and their dependences on grain size, porosity, chemical structure, and photophysical properties. Three different precursors (urea, melamine, and dicyandiamide) and two gas atmospheres (air or N2) are used to produce various g-C3N4 materials. The use of urea and air leads to the formation of small grain C3N4 networks and porous structures with large surface areas. HER catalytic activity is promoted by large surface areas and the presence of terminal amine groups, and generation of small-sized Pt nanoparticle co-catalysts with narrow size distribution on the surface of g-C3N4. For samples with similar surface areas, band gaps and lifetimes of photogenerated charge carriers critically determine photocatalytic activities. By examining combinations of the above-mentioned factors, urea driven g-C3N4 produced in a N2 atmosphere is found to exhibit the best photocatalytic activity (up to 130μmolh−1g−1).

67Ga-labeled deferoxamine derivatives for imaging bacterial infection: Preparation and screening of functionalized siderophore complexes

IntroductionDeferoxamine (DFO) is a siderophore that bacteria use to scavenge iron and could serve as a targeting vector to image bacterial infection where current techniques have critical limitations. [67Ga]-DFO, which is a mimetic of the corresponding iron complex, is taken up by bacteria in culture, however in vivo it clears too rapidly to allow for imaging of infection. In response, we developed several new DFO derivatives to identify those that accumulate in bacteria, and at sites of infection, and that could potentially have improved pharmacokinetics. MethodsA library of DFO derivatives was synthesized by functionalizing the terminal amine group of DFO using three different carbamate-forming reactions. Uptake of [67Ga]-DFO and the 67Ga-labeled derivatives by bacteria and the biodistribution of lead compounds were studied. Results67Ga-labeled DFO derivatives were prepared and isolated in >90% radiochemical yield and >95% radiochemical purity. The derivatives had significant but slower uptake rates in Staphylococcus aureus than [67Ga]-DFO (6% to 60% of the control rate), with no uptake for the most lipophilic derivatives. Biodistribution studies in mice with a S. aureus infection in one thigh revealed that the ethyl carbamate derivative had an excellent infected-to-non-infected ratio (11:1), but high non-specific localization in the gall bladder, liver and small intestine. ConclusionsThe work reported shows that it is possible to functionalize DFO-type siderophores and retain active uptake of the 67Ga-labeled complexes by bacteria. Novel 67Ga-labeled DFO derivatives were specifically taken up by S. aureus and selected derivatives demonstrated in vivo localization at sites of infection. Advances in knowledge and implications for patient care67Ga-labeled DFO derivatives were actively transported by bacteria using the iron-siderophore pathway, suggesting that it is possible to develop siderophore-based radiopharmaceuticals for imaging bacterial infection.

Copper(I)-Mediated Denitrogenative Macrocyclization for the Synthesis of Cyclic α3 β-Tetrapeptide Analogues.

A copper(I)-mediated denitrogenative reaction has been successfully developed for the preparation of cyclic tetrapeptides. The key reactive intermediate, ketenimine, triggers intramolecular cyclization through attack of the terminal amine group to generate an internal β-amino acid with an amidine linkage. The chemistry developed herein provides a new synthetic route for the preparation of cyclic α3 β-tetrapeptide analogues that contain important biological properties and results in rich structural information being obtained for conformational studies. With the success of this copper(I)-catalyzed macrocyclization, two histone deacetylase inhibitor analogues consisting of the cyclic α3 β-tetrapeptide framework have been successfully synthesized.

Geometry dependence of electron donating or accepting abilities of amine groups in 4,4′-disulfanediylbis(methylene)dithiazol-2-amine: Pyramidal versus planar

The molecular and crystal structure of the title compound in which two thiazole-2-amine rings are linked to each other by disulfide bridge (CSSC) were studied by single-crystal X-ray diffraction, FT-IR, NMR spectroscopy, quantum chemical calculations and topological analyses on the electron density. A novel synthesis route for the compounds having symmetrical disulfide bridge is reported. The most important result regarding the compound is about electron donating or accepting properties of the terminal amine groups. Planar amine group acts as an electron-donating group, while pyramidal amine behaves as electron-accepting group. This inference was confirmed by scrutiny of crystallographic geometry and quantum chemical studies. To ascertain underlying reasons for this fact, intermolecular interactions (NH⋯N type H-bonds and CH···π interactions) were studied. These interactions involving aromatic thiazole rings are verified by topological electron density and Hirshfeld surface analyses. Intermolecular interactions do not have an effect on the differentiation in electron donating or accepting ability of amine groups, because both amine groups are involved in NH⋯N type H-bonds. In methodological sense, it has been understood that Ehrenfest forces acting on electron density are useful theoretical probe to analyze intra-molecular charge transfer processes.

PAMAM dendrimers: A multifunctional nanomaterial for ECL biosensors

Polyamido amine (PAMAM) dendrimers have been shown to function as electrochemiluminescence (ECL) co-reactant and have the inherent capability of improving immobilization of molecules on surfaces due to their dendritic structure. Here, we investigated the combination of both of these properties as the basis for biosensor development. Dendrimers with 5, 8, 10 and 16 terminal amine groups, respectively, were used. These were covalently coupled to biotin as model recognition site, and tagged with Ru(bpy)32+ via adsorption. Due to their hydrophilicity, Ru-dendrimers showed significantly improved electrochemical activity in comparison to the standard tripropylamine (TPA) assisted ECL and similar luminescence yields even though 10 fold less dendrimer concentration was required in comparison to TPA. Best signals were obtained for D8 and D10 dendrimers. These Ru-dendrimers were subsequently used for the quantification of streptavidin, as its binding to the biotin-tag caused a proportional decrease in ECL signal with a dynamic range of 5nM to 1μM. These preliminary studies demonstrate that PAMAM dendrimers can function as responsive signal generators in solution-based ECL-bioassays with an assumed even higher impact when being immobilized directly on the electrode-surface.

Adamantyl- and other polycyclic cage-based conjugates of desferrioxamine B (DFOB) for treating iron-mediated toxicity in cell models of Parkinson’s disease

The death of dopaminergic neurons is a major pathological hallmark of Parkinson’s disease (PD). Elevated iron within the substantia nigra of the PD brain is thought to catalyze this neuronal death through hydroxyl radical-derived oxidative damage. Removing this excess iron presents a potential therapeutic strategy for PD. Seventeen derivatives of the non-toxic iron chelator desferrioxamine B (DFOB) were prepared by the conjugation of adamantyl- (1–4, 8–12), deconstructed adamantyl units (5–7), norborna(e)ne- (13–16) or bicyclo[2.2.2]octane-based (17) ancillary fragments to the terminal amine group. The range of experimental logP values of 1–17 (logP=0.15–2.82) was greater than water soluble DFOB (logP −2.29), with the increased hydrophobicity designed to improve cell membrane carriage to facilitate intracellular iron sequestration. The first activity screen showed compounds with methyl-substituted adamantyl (1–3), noradamantyl (5), or 1-pentylbicyclo[2.2.2]octane (17) ancillary groups significantly rescued iron-mediated oxidative stress in confluent PD-relevant SK-N-BE2-M17 neuroblastoma cells (M17 cells) exposed to 1,1ʹ-dimethyl-4,4ʹ-bipyridinium (paraquat, PQ) or H2O2. The second dose-dependence screen ranked 1–3 and 17 as the top candidates (EC50 ∼10µM) in the rescue of PQ-treated M17 cells. The ancillary fragments of 1–3 and 17 clustered in a region defined by a close-to-zero dipole moment, logP values of 2–2.8 and a surface area:volume ratio of 0.60–0.61. Results of iron leaching studies indicate that the compounds may be operating via mechanisms beyond solely removing intracellular iron. The DFOB conjugates with methyl-substituted adamantyl ancillary groups (1–3) were the top and most consistent performers in this class of compound designed for PD.

A one-pot synthesis of water soluble highly fluorescent silica nanoparticles.

We report a one-pot synthesis of water dispersible fluorescent silica nanoparticles (NPs) functionalized with terminal amine groups, starting from silicon tetrabromide (SiBr4) and aminopropyltriethoxy silane (APTES). The NPs range from 1 to 2 nm in diameter, and exhibit an intense blue emission with a quantum yield (QY) of around 34% in water. They were characterized using XRD, XPS, TEM and FTIR spectroscopy for structural analysis. A tentative mechanism explaining the origin of the NPs emission in the blue region is presented based on the distinctive features of their low temperature photoluminescence (PL), photoluminescence excitation (PLE) spectrum and time correlated single photon counting lifetime decay profiles. The outstanding PL QY and photostability of the NPs, together with their water dispersibility and biocompatibility, constitute a unique set of properties among existing silica NPs and enable the application of the NPs in various fields.

A theoretical study of the inhibition effect of PAMAM molecule on silica scale.

In this work, the molecular modeling method was performed to study adsorption interaction between PAMAM molecules of different generations and silicic acid molecules, and the inhibition effect on silica scale were discussed. The results show that adsorption energies of PAMAM molecule of generation 1.0 with amine-terminated groups are stronger than those of generation 1.5 with terminated carboxyl group. The composition of adsorption interactions are the dominating electrostatic interactions and van de Waals interactions as well as H-bond interactions. It is qualitatively discussed that the inhibition effect of generation 1.0 on silica scale is stronger than that of generation 1.5 in the neutral solution.

Comparative investigation of two methods for Acetylcholinesterase enzyme immobilization on modified porous silicon

In this work, Acetylcholinesterase enzyme (AChE) was immobilized on porous silicon (PSi) surface using two strategies. In the first method, acid chains were covalently grafted on the hydrogenated PSi by hydrosilylation reaction. The obtained acid-terminated surface was activated by a reaction with N-hydroxysuccinimide (NHS) in the presence of a peptide-coupling agent N-ethyl-N′-(3-dimethylaminopropyl)-carbodiimide (EDC), and then reacted with the amino linker of the lysine residues AChE to anchor the enzyme by a covalent amide bond. In the second procedure, the PSi surface was first hydroxylated in piranha solution, followed by a silanization reaction with 3-aminopropyltriethoxysilane (APTES) to form amine-terminated surface. Finally, AChE was attached to the terminal amine groups by an aminolysis reaction with carboxylic acid groups of AChE in the presence of NHS/EDC mixture. Fourier transform infrared spectroscopy (FTIR) confirmed the efficiency of the surface modifications. The enzymatic activity of immobilized AChE was determined by means of a colorimetric test and was discussed according to the enzyme orientation on the surface which was revealed by contact angle measurements.

Cellulose fibers functionalized by metal nanoparticles stabilized in dendrimer for formaldehyde decomposition and antimicrobial activity

Viscose rayon cellulose fiber was selectively oxidized so that carboxylate functional group was introduced on the fiber. Enough dispersed platinum nanoparticles and silver nanoparticles having average sizes of around 5nm with small size distribution were prepared with capping of amine-terminated fourth generation poly(amido amine) dendrimer and they were immobilized on oxidized fibers through amidation between terminal amine groups of dendrimer and carboxylic acids on oxidized fibers. The fiber containing dendrimer (1wt%) and platinum (2wt%) exhibited the 84 times higher adsorption capacity for formaldehyde gas on dendrimer site than on fiber site and the catalytic efficiency (65%) towards decomposition of formaldehyde gas adsorbed on the dendrimer site, and the silver (0.2wt%)-loaded fiber revealed excellent biocidal activity against E. coli. Thus, it can be noted that the immobilization of functional metal nanoparticles protected by dendrimer on cellulose fibers is effective to produce efficient textile products with smart functions like the degradation of causative agents for sick building syndromes.

Covalent immobilization of cellulase in application of biotransformation of ginsenoside Rb1

Cellulase was immobilized on the surface of carrageenan beads activated by using polyethyleneimine and glutaraldehyde, then immobilized cellulase was used to transform ginsenoside Rb1. In this work, we studied the functionalization of carrageenan with amine terminal functional group for the covalent immobilization of cellulase. The process of immobilization was performed by amination process on the surface of the carrageenan gel beads with polyethylenimine followed by activation with glutaraldehyde to finally immobilize the enzyme. Different factors affecting the amination and activation processes were studied and their effects on the catalytic activity of the immobilized cellulase were followed, then Fourier transform infrared spectroscopy and scanning electron microscopy were applied to verify the process. Furthermore, the optimum conditions of transformation of ginsenoside Rb1 were also studied and showed better stability for the immobilized enzyme. The best results were obtained using carrageenan as support and covalent binding method, which consisted of amination process (0.5% PEI (pH 8))) for 3h and 3% GA in activation process for 3h. These experiments gave optimum reaction condition of temperature at 60°C and pH 5.0. Enzyme after immobilization exhibited high activity with broader pH and temperature range. Full conversion and kinetic parameters Km and Vmax for them were also studied. The Km of immobilized enzyme, 3.64mM, is lower than free one, 4.82mM; and the Vmax of immobilized enzyme, 0.04mM, is lower than free one, 0.06mM. Results detected also show after using for 5 consecutive times, the immobilized enzyme can retain 60% of its initial activity.

Template synthesis and X-ray structure of the tris-glyoximate iron(II) clathrochelates with terminal reactive groups

One-pot template condensation of glyoxime with the corresponding functionalized phenylboronic acids on an iron(II) ion as a matrix afforded 3- and 4-substituted phenylboron-capped tris-glyoximate iron(II) clathrochelates with terminal amine, formyl (acetal) and vinyl groups; those with acetal groups were converted into the formyl-terminated cage complexes using H+-catalyzed hydrolysis. The complexes obtained were characterized using elemental analysis, MALDI-TOF mass spectrometry, IR, UV–Vis, 1H and 13C NMR spectroscopies, and by single crystal X-ray diffraction (for three of these clathrochelates). Their molecules possess a geometry intermediate between a trigonal prism (TP) and a trigonal antiprism (TAP) and the bite angles α remain almost constant being in the range 77–79°, whereas the heights h of FeN6-coordination polyhedra depend on the distortion angle φ values (from 12.2 to 20.7°) thus being in the range 2.36–2.37Å. An encapsulated iron(II) ion is situated almost in the centre of cage frameworks and the average chelate CC bonds in these tris-glyoximate frameworks are substantially shorter than those for their aliphatic and aromatic analogs. The crystal packings are governed by weak supramolecular hydrophobic interactions and an absence of the steric hindrances between the ribbed substituents (hydrogen atoms) allowed to form intermolecular π…π interactions.As follows from single crystal X-ray diffraction data, the synthesized macrobicyclic tris-glyoximates with reactive terminal groups, which the macrobicyclic molecules contain no bulky ribbed substituents, have large ligand aspect ratio and, therefore, they seem to be promising syntones and building blocks for preparation of covalent (including imine and amine) and coordination metallomacrocycles, MOFs and cages (capsules) with big voids and cavities as hosts, suitable for inclusion of various organic and inorganic guests.

Thin film composite nanofiltration membrane prepared by the interfacial polymerization of 1,2,4,5-benzene tetracarbonyl chloride on the mixed amines cross-linked poly(ether imide) support

A novel thin film composite (TFC) nanofiltration (NF) membrane was prepared by the interfacial polymerization of 1,2,4,5-benzene tetracarbonyl chloride (BTC) on the cross-linked poly(ether imide) (PEI) support via the mixed amines of the linear ethylenediamine (EDA) and the hyperbranched poly(ethyleneimine) (HPEI). Characterized by attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, Raman mapping, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), etc.; it is indicated that the TFC NF membrane is synthesized through the interfacial polymerization between BTC and the terminal amine groups on the EDA-HPEI cross-linked PEI support. The optimal TFC NF membrane exhibited the methanol permeance of 14.2Lm−2h−1MPa−1 and a RB rejection of 100%. After the solvent activation of dimethylformamide (DMF) and dimethylsulfoxide (DMSO), the TFC NF membrane exhibited the methanol permeance of 30.4Lm−2h−1MPa−1 and 51.5Lm−2h−1MPa−1 with the RB rejection of 90.4% and 74.4%, respectively. Characterized by ATR-FTIR, SEM and Doppler broadening energy spectroscopy (DBES), the effects of solvent activation via DMF and DMSO respectively were investigated on the PEI-based TFC NF membranes.

Fluorescent probes based on side-chain chlorinated benzo[a]phenoxazinium chlorides: Studies of interaction with DNA

The interaction of DNA with six water soluble benzo[a]phenoxazinium chlorides mono- or di-substituted with 3-chloropropyl groups at the O and N of 2- and 9-positions, along with methyl, hydroxyl and amine terminal groups at 5-positions, was investigated by photophysical techniques. The results indicated that almost all compounds intercalated in DNA base pairs at phosphate to dye ratio higher than 5. At lower values of this ratio, electrostatic binding mode with DNA was observed. Groove binding was detected mainly for the benzo[a]phenoxazinium dye with NH2·HBr terminal. The set of six benzo[a]phenoxazinium chlorides proved successful to label the migrating DNA in agarose gel electrophoresis assays. These finding proves the ability of these benzo[a]phenoxazinium dyes to strongly interact with DNA.