Maghemite/poly(<Emphasis Type="SmallCaps">d,l</Emphasis>-lactide-<Emphasis Type="Italic">co</Emphasis>-glycolyde) composite nanoplatform for therapeutic applications

A reproducible methodology is described for the synthesis, by following the double emulsion/solvent evaporation technique, of magnetic nanocomposites (average diameter ≈ 135 nm) consisting of maghemite nuclei and a biodegradable poly(d,l-lactide-co-glycolide) matrix. The heterogeneous structure of the nanoparticles can confer them the responsiveness to magnetic gradients, giving both the possibility of their use as a drug delivery system and adequate heating characteristics for a hyperthermia effect. The physical chemistry of the nanocomposites was extensively characterized, this establishing that their surface properties were similar to that of pure poly(d,l-lactide-co-glycolide). From an electrokinetic point of view, zeta potential determinations (as a function of the ionic strength, and pH) pointed out that the nanocomposites were almost indistinguishable from the copolymer. The surface thermodynamic analysis agreed with the electrophoretic one in suggesting that the coverage of the magnetic nuclei was complete, since the hydrophilic nature of maghemite was modified and the nanoparticles turned into hydrophobic, just like the copolymer, when they were embedded into poly(d,l-lactide-co-glycolide). The magnetic behaviours of the composite nanoparticles were also checked. Their heating properties were studied in vitro in a high-frequency alternating gradient of magnetic field: a stable maximum temperature of 47 °C was satisfactorily achieved within 45 min. Blood compatibility of the nanocomposites was also defined in vitro. To our knowledge, this is the first time that such kind of magnetic-sensitive nanoformulation with very promising characteristics (e.g. blood compatibility, magnetic drug targeting capabilities, and hyperthermia) has been developed for therapeutic purposes.     

Evaluation of the antibacterial activity of poly-(<Emphasis Type="SmallCaps">d</Emphasis>,<Emphasis Type="SmallCaps">l</Emphasis>-lactide-co-glycolide) nanoparticles containing violacein

Since violacein—an antibiotic, antiviral, and antiparasitic compound—exhibits poor solubility in water, polymeric poly-(d,l-lactide-co-glycolide) nanoparticles containing this compound improved its solubility and biological activity. The nanoparticles were prepared by the nanoprecipitation method and characterized in terms of average diameter, zeta potential, drug loading, polymer recovery, in vitro release kinetic, and in vitro antibacterial activity. Nanoparticles with diameters between 116 and 139 nm and negative-charged outer surfaces were obtained. Drug-loading efficiency and polymer recovery were 87 and 93%, respectively. In vitro release kinetics assays showed that violacein loaded in these nanoparticles has sustained release behavior until 5 days. Both free and nanoparticles-loaded violacein exhibited in vitro antibacterial activity against Staphylococcus aureus ATCC 29213 and ATCC 25923 strains and exhibiting around two to five times lower minimum inhibitory concentration (MIC) than free violacein, respectively. The encapsulated violacein was efficient against methicilin-resistant Staphylococcus aureus (MRSA) strains. No significant activity against Escherichia coli and Salmonella enterica was found.     

New approach in synthesis,characterization and release study of pH-sensitive polymeric micelles,based on PLA-Lys-<Emphasis Type="Italic">b</Emphasis>-PEGm,conjugated with doxorubicin

Amphiphilic block copolymers are well established as building blocks for the preparation of micellar drug carriers. The functional polymer micelles possess several advantages, such as high drug efficiency, targeted delivery, and minimized cytotoxicity. The synthesis of block copolymers using nano-structured templates has emerged as a useful and versatile approach for preparing drug carriers. Here, we report the synthesis of a smart polymeric compound of a diblock PLA-Lys-b-PEG copolymer containing doxorubicin. We have synthesized functionalized diblock copolymers, with lysinol, poly(lactide) and monomethoxy poly(ethylene glycol) via thermal ring-opening polymerization and a subsequent six-step substitution reaction. A variety of spectroscopic methods were employed here to verify the product of our synthesis. ¹H-Nuclear magnetic resonance and Fourier transform infrared studies validated the expected synthesis of copolymers. Doxorubicin is chemically loaded into micelles, and the ex vitro release can be evaluated either in weak acidic or in SBF solution by UV–vis spectroscopy. Dynamic light scattering, thermo gravimetric analysis, and size exclusion chromatography have also been used.     

Multifunctional antitumor magnetite/chitosan-<Emphasis Type="SmallCaps">l</Emphasis>-glutamic acid (core/shell) nanocomposites

The development of anticancer drug delivery systems based on biodegradable nanoparticles has been intended to maximize the localization of chemotherapy agents within tumor interstitium, along with negligible drug distribution into healthy tissues. Interestingly, passive and active drug targeting strategies to cancer have led to improved nanomedicines with great tumor specificity and efficient chemotherapy effect. One of the most promising areas in the formulation of such nanoplatforms is the engineering of magnetically responsive nanoparticles. In this way, we have followed a chemical modification method for the synthesis of magnetite/chitosan-l-glutamic acid (core/shell) nanostructures. These magnetic nanocomposites (average size ≈340 nm) exhibited multifunctional properties based on its capability to load the antitumor drug doxorubicin (along with an adequate sustained release) and its potential for hyperthermia applications. Compared to drug surface adsorption, doxorubicin entrapment into the nanocomposites matrix yielded a higher drug loading and a slower drug release profile. Heating characteristics of the magnetic nanocomposites were investigated in a high-frequency alternating magnetic gradient: a stable maximum temperature of 46 °C was successfully achieved within 40 min. To our knowledge, this is the first time that such kind of stimuli-sensitive nanoformulation with very important properties (i.e., magnetic targeting capabilities, hyperthermia, high drug loading, and little burst drug release) has been formulated for combined antitumor therapy against cancer.     

Towards the higher solubility and thermal stability of poly(aniline-<Emphasis Type="Italic">co</Emphasis>-<Emphasis Type="Italic">m</Emphasis>-bromoaniline)

In the current study, we have described the synthesis and the physical properties of poly(aniline-co-m-bromoaniline) conducting copolymers. The copolymers of different composition are essentially obtained by varying the molar feed ratio of the two monomers. The higher solubility of the copolymers could be procured as compared to polyaniline (PA) in different solvents. The electrical conductivity has been studied by two-probe method; at room temperature, the conductivity of the copolymer decreases upon increasing the molar ratio of m-bromoaniline monomer. The introduction of bromine (–Br) group reduces the degree of conjugation in the polymer chain. Thus, conduction of electrons is prohibited along the conjugated system. In the thermogravimetric analysis (TGA), a three-stage decomposition of the copolymer has been observed. The copolymers of poly(aniline-co-m-bromoaniline) are thermally stable at high temperature. The composition of the copolymer has been confirmed from the binding energies of C–C, C–N, and C–Br in the XPS study.     

Enantiomeric PLA–PEG block copolymers and their stereocomplex micelles used as rifampin delivery

A novelty approach to self-assembling stereocomplex micelles by enantiomeric PLA–PEG block copolymers as a drug delivery carrier was described. The particles were encapsulated by enantiomeric PLA–PEG stereocomplex to form nanoscale micelles different from the microspheres or the single micelles by PLLA or PDLA in the reported literatures. First, the block copolymers of enantiomeric poly(l-lactide)–poly(ethylene–glycol) (PLLA–PEG) and poly(D-lactide)–poly(ethylene–glycol) (PDLA–PEG) were synthesized by the ring-opening polymerization of l-lactide and d-lactide in the presence of monomethoxy PEG, respectively. Second, the stereocomplex block copolymer micelles were obtained by the self-assembly of the equimolar mixtures of enantiomeric PLA–PEG copolymers in water. These micelles possessed partially the crystallized hydrophobic cores with the critical micelle concentrations (cmc) in the range of 0.8–4.8 mg/l and the mean hydrodynamic diameters ranging from 40 to 120 nm. The micelle sizes and cmc values obviously depended on the hydrophobic block PLA content in the copolymer. Compared with the single PLLA–PEG or PDLA–PEG micelles, the cmc values of the stereocomplex micelles became lower and the sizes of the stereocomplex micelles formed smaller. And lastly, the stereocomplex micelles encapsulated with rifampin were tested for the controlled release application. The rifampin loading capacity and encapsulation efficiency by the stereocomplex micelles were higher than those by the single polymer micelles, respectively. The drug release time in vitro was depending on the composites of the block copolymers and also could be controlled by the polymer molecular weight and the morphology of the polymer micelles.     

<Emphasis Type="SmallCaps">l</Emphasis>-Tryptophan-capped carbon quantum dots for the sensitive and selective fluorescence detection of mercury ion in aqueous solution

l-Tryptophan-capped carbon quantum dots (l-CQDs) were facilely synthesized through “green” methodology, and the obtained material was utilized as a sensitive and selective fluorescence sensor for mercury ion (Hg²⁺) in pure aqueous solutions. Carboxyl-functionalized CQDs were first green synthesized by a one-step hydrothermal route, and l-tryptophan was then attached to CQDs via direct surface condensation reaction in aqueous solution at room temperature. The as-synthesized l-CQDs had an average size of ca. 5 nm with a good dispersity in water, and exhibited a favorable selectivity for Hg²⁺ ions over a range of other common metal cations in aqueous solution (10 mM PBS buffer, pH 6.0). Upon the addition of Hg²⁺, a complete fluorescence quenching (ON–OFF switching) of l-CQDs was evident from the fluorescence titration experiment, and the fluorescence detection limit of Hg²⁺ was calculated to be 11 nM, which indicated that the obtained environmentally friendly l-CQDs had sensitive detection capacity for Hg²⁺ in aqueous solution.     

Drug delivery using novel nanoplexes against a <Emphasis Type="Italic">Salmonella</Emphasis> mouse infection model

A novel methodology for incorporating gentamicin into macromolecular complexes with anionic homo- and block copolymers via cooperative electrostatic interactions is described. Block copolymers of poly(ethylene oxide-b-sodium acrylate) (PEO-b-PAA^{− +}Na) or poly(ethylene oxide-b-sodium methacrylate) (PEO-b-PMA^{− +}Na) were blended with PAA⁻ Na⁺ and complexed with the polycationic antibiotic gentamicin. Gentamicin nanoplexes made with PEO-b-PMA^{− +}Na/PAA^{− +}Na (PMPG) and analogous nanoplexes with PEO-b-PAA^{− +}Na/PAA^{− +}Na (PAPG) had mean intensity average diameters of 120 and 90 nm, zeta potentials of −17 and −11 mv, and incorporated 26% and 23% by weight of gentamicin, respectively. Gentamicin release rates at physiological pH from nanoplexes were relatively slow. PAPG and PMPG as drug delivery systems for treating murine salmonellosis at doses similar to the free gentamicin experiments resulted in reduced numbers of viable bacteria in the liver and spleen. Polymeric nanoplexes developed by this methodology can potentially improve targeting of intracellular pathogens.     

两亲性类树枝状聚合物的合成与药物控释

结合阴离子开环聚合方法合成了内壳为聚(乙氧基乙基缩水甘油醚),外层为聚环氧乙烷的两亲性类树枝状嵌段共聚物PEEGE-G2-b-PEO(OH)₁₂. 使用核磁共振氢谱以及凝胶渗透色谱等表征了中间产物和目标产物. 选择阿霉素作为实验药物,研究了该聚合物的载药和控释行为. 聚合物的载药率和包覆效率分别为13.07%和45.75%,体外释放试验表现为持续性的释放,并受到释放介质pH影响.     

Shell effects for isovector <Emphasis Type="Italic">l</Emphasis>-forbidden <Emphasis Type="Italic">M</Emphasis>1 transitions in odd nuclei

It is inferred from the analysis of the experimental data that the reduced probabilities of isovector l-forbidden M1 transitions achieve maximum values in nuclei with a magic core. The minimum values are related to γ transitions in nuclei belonging to the region of stable deformation with A ≈ 25. Isovector l-forbidden M1 transitions in mirror nuclei are explored. The ratio of the reduced probabilities for proton and neutron transitions shows the maximum deviation from the theoretical evaluations for the pair of nuclei ⁴¹Ca-⁴¹Sc consisting of the even-even magic core ⁴⁰Ca and one nucleon outside the closed 1d2s shell.     

Electrocatalytic oxidation of <Emphasis Type="SmallCaps">l</Emphasis>-tyrosine at carboxylic acid functionalized multi-walled carbon nanotubes modified carbon paste electrode

The electrocatalytic oxidation of l-tyrosine (Tyr) was investigated on a carboxylic acid functionalised multi-walled carbon nanotubes modified carbon paste electrode using cyclic voltammetry and amperometry. The surface morphology of the electrodes was studied using field emission (FE)-SEM images, and the interface properties of bare and modified electrodes were investigated by electrochemical impedance spectroscopy (EIS). The influence of the amount of modifier loading and the variation of the pH of the solution on the electrochemical parameters have been investigated. Cyclic voltammetry was carried out to study the electrochemical oxidation mechanism of Tyr, which showed an irreversible oxidation process at a potential of 637.0 mV at modified electrode. The anodic peak current linearly increased with the scan rate, suggesting that the oxidation of Tyr at modified electrode is an adsorption-controlled process. A good linear relationship between the oxidation peak current and the Tyr concentration in the range of 0.8–100.0 μM was obtained in a phosphate buffer solution at pH 7.0 with a detection limit of 14.0?±?1.36 nM (S/N?=?3). The practical utility of the sensor was demonstrated by determining Tyr in spiked cow’s milk and human blood serum. The modified electrode showed excellent reproducibility, long-term stability and antifouling effects.     

Electrochemical,morphological, and spectroscopic study of poly(aniline-co-<Emphasis Type="Italic">o</Emphasis>-bromoaniline) (PA-co-<Emphasis Type="Italic">o</Emphasis>-BrA) conducting copolymer

A series of moderately conducting and soluble copolymers of poly(aniline-co-o-bromoaniline) (PA-co-o-BrA) having different compositions was obtained by in the situ copolymerization method using different concentrations of monomer units of aniline and o-bromoaniline in the feed. The physio-chemical properties of the copolymers have been studied with sophisticated instrumental techniques. The electrochemical study of the copolymers was conducted by cyclic voltammetry. The band gap of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of the copolymers was evaluated by UV-vis spectroscopy. The morphological study was conducted by scanning electron microscopy and transmission electron microscopy at high magnification which shows non-uniform tubular to globular morphology of the copolymers. Surface profiles of the polymers were studied by AFM analyses, and it has confirmed the smooth surface of the copolymers while the homopolymers possesses non-uniform surfaces. The particle size distribution curve indicates that the particle sizes vary in the range of 5 to 9000 nm, and a small fraction of particles possess a size in the range of 5–10 nm.     

Pyroelectric effect in composites based on copolymer <Emphasis Type="Italic">P</Emphasis>(<Emphasis Type="Italic">VDF-TrFE</Emphasis>) and ferroelectric ceramics BPZT

The pyroelectric response of composite polymer films based on poly(vinylidene fluoride-trifluoroethylene) copolymer (P(VDF-TrFE)) and powdered ceramic ferroelectric of barium lead zirconate titanate (BPZT) was investigated. The appearance of a near-surface layer with high pyroelectric activity was observed during the polarization of composite material samples in the electric field of corona discharge.     

Synthesis of 1<Emphasis Type="Italic">H</Emphasis>-imidazo[1,2-<Emphasis Type="Italic">b</Emphasis>]-1,2,4-triazol-6-amines via multicomponent reaction

A simple and effective method for the synthesis of bioactive imidazo[1,2,4]triazole analogues has been developed utilizing the MCR technique, which involved the reaction of aminotriazoles, isocyanides and aldehydes. The products were characterized by ¹H, ¹³C NMR spectroscopy, MS and elemental analysis. Interestingly, compounds 19d, 21a, 21b and 21h displayed good cytotoxic activities at 10⁻⁴ M concentration in the inhibition of tumor cell growth as evaluated by the MTT method.     

Conformal behavior of a single chain <Emphasis Type="Italic">AB</Emphasis> block copolymer with mobile <Emphasis Type="Italic">B</Emphasis>-blocks

Monte-Carlo computer modeling was used to investigate the conformal behavior of a single chain AB block copolymer with mobile hydrophobic B-blocks and hydrophilic A-links. The formation of a “tailed globule” was observed with an increase of the energy of attraction between hydrophobic links. A comparison between the collapsing of a chain with mobile blocks and the behavior of regular and random block copolymers of the same structure was conducted.     

Structural,Spectroscopic, Antimicrobial Activity and DFT Studies on 4-Methyl-<Emphasis Type="Italic">N</Emphasis>-(4-methylphenylsulfonyl)-<Emphasis Type="Italic">N</Emphasis>-phenylbenzenesulfonamide

This study reports the structural characterization of a disulfonimide derivative, 4-methyl-N-(4-methylphenylsulfonyl)-N-phenylbenzenesulfonamide (MPBSA), using spectroscopic and quantum chemical methods. The molecule was characterized with FT-IR, ¹H ¹³C NMR and UV-Vis spectroscopies. Quantum chemical calculations of molecular geometry, vibrational wavenumbers and gauge including atomic orbital (GIAO) ¹H and ¹³C-NMR chemical shifts of the compound were carried out by using density functional method (DFT) at B3LYP/6?311++G(d,p) level of theory. Electronic absorption spectra of the compound have been computed using the time-dependent density functional theory (TD-DFT) method at the same level. A satisfactory consistency between the experimental and theoretical findings was obtained. The antimicrobial activity screening of the compound was performed on some bacteria and fungus species using microdilution method. The results showed that the title molecule have noteworthy antibacterial and antifungal activities.     

Polyethylene-supported poly(methyl methacrylate<Emphasis Type="Italic">-co-</Emphasis>butyl acrylate)-based novel gel polymer electrolyte for lithium ion battery

A new copolymer, poly(methyl methacrylate-co-butyl acrylate) (P(MMA-co-BA)), was synthesized by emulsion polymerization with different mass ratio of methyl methacrylate (MMA) and butyl acrylate (BA). The membranes were prepared by phase inversion and corresponding gel polymer electrolytes (GPEs) were obtained by immersing the membrane into a liquid electrolyte. In this design, the hard monomer MMA provided the copolymer with good electrolyte uptake, while the soft monomer BA provided the GPE with strong adhesion between the anode and cathode of lithium ion battery. The properties of the resulting product were investigated by Fourier transform infrared spectroscopy, nuclear magnetic resonance spectra, scanning electron spectroscopy, linear sweep voltammetry, thermogravimetric analysis, cyclic voltammetry, electrochemical impedance spectroscopy and charge/discharge test. The results show that the obtained GPE based on P(MMA-co-BA) with the mass ratios of MMA and BA = 6:1 exhibits good conductivity (as high as 1.2 × 10^?3 S cm^?1) at room temperature and high electrochemical stability (up to 4.9 V vs. Li/Li⁺). With the application of the polyethylene (PE)-supported GPE in Li/Li(Li_0.13Ni_0.30Mn_0.57)O₂ battery, the battery presents good cyclic stability (maintaining 95.4 % of its initial discharge capacity after 50 cycles) at room temperature.     

Preparation of nano-hydroxyapatite/poly(<Emphasis Type="SmallCaps">l</Emphasis>-lactide) biocomposite microspheres

Nano-hydroxyapatite (HA)/poly(l-lactide) (PLLA) composite microspheres with relatively uniform size distribution were prepared by a solid-in-oil-in-water (s/o/w) emusion solvent evaporation method. The encapsulation of the HA nanopaticles in microshperes was significantly improved by grafting PLLA on the surface of the HA nanoparticles (p-HA) during emulsion process. This procedure gave a possibility to obtain p-HA/PLLA composite microspheres with uniform morphology and the encapsulated p-HA nanoparticle loading reached up to 40 wt% (33 wt% of pure HA) in the p-HA/PLLA composite microspheres. The microstructure of composite microspheres from core-shell to single phase changed with the variation of p-HA to PLLA ratios. p-HA/PLLA composite microspheres with the diameter range of 2–3 μm were obtained. The entrapment efficiency of p-HA in microspheres could high up to 90 wt% and that of HA was only 13 wt%. Surface and bulk characterizations of the composite microspheres were performed by measurements such as wide angle X-ray diffraction (WAXD), thermal gravimetric analysis (TGA), environmental scanning electron microscope (ESEM) and transmission electron microscopy (TEM).     

A well-defined biodegradable 1,2,3-triazolium-functionalized PEG-<Emphasis Type="Italic">b</Emphasis>-PCL block copolymer: facile synthesis and its compatibilization for PLA/PCL blends

A novel biodegradable 1,2,3-triazolium-functionalized PEG-b-PCL copolymer (TAPEC) was synthesized by the “click” coupling of methoxypolyethylene glycol azide and α-propargyl-ω-hydroxyl-poly(ε-caprolactone), followed by the quaternization of the 1,2,3-triazole moiety with iodomethane. All the intermediates and TAPEC were characterized by ¹H NMR, FT-IR, and gel permeation chromatography (GPC). Taking advantage of the characteristics of ionic liquid and block copolymer, this ion-containing diblock copolymer is expected to be used as a novel compatibilizer in mixed biopolyester for regulating the interface and crystallization behaviors. Hence, the TAPEC was evaluated as a compatibilizer and an interface emulsifier in the blends of polylactic acid (PLA) and poly(ε-caprolactone) (PCL). Non-isothermal crystallization experimental results showed that the TAPEC with the higher amount of ε-caprolactone units induces a plasticization and nucleate effect that increased the crystallization ability of the PLA phase; meanwhile, in the PCL phase, the agminated ionic cluster acting as a nucleating agent significantly increased the crystalline of PCL.     

Rare meson decay in supersymmetric theory with nonconservation of <Emphasis Type="Italic">R</Emphasis>-parity

The decay of mesons K ⁺ → π ^? l ⁺ l′⁺ and D ⁺ → K ^? l ⁺ l′⁺ (l, l′ = e, μ) involving a change of lepton number ΔL = 2 is considered in a supersymmetric extension of the standard model in which R-parity is not conserved due to trilinear Yukawa interactions. The obtained estimates for the probabilities of these decays are significantly lower than the direct experimental upper limits.