Development of docetaxel-loaded PEG–PLA nanoparticles using surfactant-free method for controlled release studies

Docetaxel (DTX)-loaded poly(ethylene glycol)–poly(D,L-lactide) is prepared by nanoprecipitation method in the absence of any surfactants. The average particle size of the copolymer was found to be 101?nm. The drug entrapment efficiency (%) and drug loading (%) of polymer were found to be 9.471?±?0.047 and 94.71?±?0.466, respectively. The in vitro drug release characteristics show the controlled release of 98% of docetaxel in 72?h. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and apoptosis measured in terms of cleaved Poly(ADP-ribose) Polymerase (PARP) and cleaved caspase-3 protein expression shows that the copolymer has better cytotoxicity effect and apoptosis in comparison to free DTX in HeLa cells.     

Synthesis and characterization of hybrid organic–inorganic materials based on sulphonated polyamideimide and silica

The preparation of hybrid organic–inorganic membrane materials based on a sulphonated polyamideimide resin and silica filler has been studied. The method allows the sol–gel process to proceed in the presence of a high molecular weight polyamideimide, resulting in well dispersed silica nanoparticles (<50 nm) within the polymer matrix with chemical bonding between the organic and inorganic phases. Tetraethoxysilane (TEOS) was used as the silica precursor and the organosilicate networks were bonded to the polymer matrix via a coupling agent aminopropyltriethoxysilane (APTrEOS). The structure and properties of these hybrid materials were characterized via a range of techniques including FTIR, TGA, DSC, SEM and contact angle analysis. It was found that the compatibility between organic and inorganic phases has been greatly enhanced by the incorporation of APTrEOS. The thermal stability and hydrophilic properties of hybrid materials have also been significantly improved.     

Preparation of a new nano-layered materials and organic–inorganic nano-hybrid materials, Zn–Si LDH

Layered double hydroxides are nano-ordered layered compounds. Layered double hydroxide (LDH) well known for its ability to intercalate anionic compounds has been prepared conventionally only with divalent and trivalent cations. In this study, Zn–Si LDH consisting of divalent and tetravalent cations was prepared, and reacted with organic acids and formed nano-hybrid materials. X-Ray diffraction patterns of the prepared LDH (Zn–Si–CO₃) showed that interlayer spacing of the LDH was 0.67 nm and increased to be 4.2 nm in the case of stearate anion as the guest. The spacing 0.67 nm was small compared to the usual LDH (Zn–Al–CO₃) of 0.76 nm in the case of carbonate anion as the guest. Also, DTA, TG and DTG analyses indicated that the electrostatic force between the layers and carbonate anions increased where the carbonate anions in Zn–Si LDH decomposed at 259 °C while those in Zn–Al–CO₃ decomposed at 230–240 °C.     

Development of CO2-Philic Blended Membranes Using PIM–PI and PIM–PEG/PPG

Blending is a simple method through which one can effectively tailor new polymers exhibiting the properties of their parent ones. Because the original properties of polymers are maintained after blending, various studies have used these films as gas separation membranes. In this study, a new CO₂ separation membrane is developed by physically mixing a polymer of intrinsic microporosity (PIM) with high gas permeability, polyimide (PIM-PI), as the hard segment and CO₂-philic PIM-poly(ethylene glycol)/poly(propylene glycol), or PIM-PEG/PPG, as the soft segment. Prepared by adding 5 mol.% of PIM-PEG/PPG to PIM-PI, the blended membrane PPB-5, with a tensile strength of 54 MPa and 35.5% elongation at break, shows better mechanical properties than commercial high-performance polymer membranes developed for gas separation, PEG-based blended membranes, and corresponding copolymer membranes with similar compositions developed in a previous study. In addition, it shows high CO₂ permeability (1552.6 Barrer) and CO₂/N₂ selectivity (29.3) due to the well-developed microphase separation characteristics originating from the optimal two-component composition, and the gas separation performance is close to the Robeson (2008) upper bound.     

Development,characterization and optimization of a new bone cement based on calcium–strontium aluminates and chitosan-glycerin solution

Bioceramic bone cements are increasingly studied, developed, and improved to become a viable alternative to polymethyl methacrylate (PMMA)-based cements. In this regard, we aimed to develop a new cement composed of calcium aluminate (C₁₂A₇) and strontium aluminate (S₃A) powders obtained via solution combustion synthesis (SCS) and chitosan/glycerin solution. The cement properties were optimized through a design of experiments. The approach used in the optimization process was the 2^k factorial experimental design with insertion of 3 repetitions of the central point, which resulted in 11 compositions. All compositions were tested to determine the liquid/powder ratio (L/P), final setting time (ST), maximum hydration temperature (T_max), compressive strength and radiopacity. The results were statistically evaluated by analyzing the effects, Pareto diagram, ANOVA analysis and response surface plot. The models obtained in this study could precisely predict three responses: T_max, compressive strength, and radiopacity. An optimized composition for possible application as bone cement had an average T_max of 40.34 °C, compressive strength of 7.75 MPa and radiopacity of 3.76 mm Al, all above the standard requirements.     

Physicochemical properties and biomimetic behaviour of α-TCP-chitosan based materials

In this paper we present a complex study on the preparation and characterization of the cement-type implant material composed of α-tricalcium phosphate and chitosan. α-TCP has already been used as an initial component of bone cement formulations. In most cases, however, it was synthesized using a solid state reaction. In our studies, highly reactive α-TCP powder was obtained by a wet chemical method. Chitosan is well known as a safe and biocompatible polymer. In our studies it was used to improve the characteristic of the cements. Chitosan was introduced into the bone cements in the form of acetic acid solution and acted as a binder for agglomerates of calcium phosphate grains but at the same time the impeded creation of interconnections inside the agglomerates. The concentration of acetic acid influenced the pore size distribution. In vitro investigations proved the high bioactive potential of the examined materials.     

Development of reaction–diffusion DFT and its application to catalytic oxidation of NO in porous materials

The reaction–diffusion (RD) process is an important and complex subject that involves nonequilibrium modeling and multiscale calculations and may be applied to multiple fields. State-of-art theories are computationally too expensive for real-world applications. We propose a novel classical density functional theory (CDFT) for RD modeling by combining ordinary time-dependent density functional theory (TDDFT) and reaction kinetic models to examine the multiscale RD process. The theory is applied to NO oxidation in porous materials. The uptake, flux, and density profiles are examined, to reveal that the shape of the pore could influence the selectivity of adsorption between the reactant and product, which further leads to variations in the catalytic efficiency. It is noted that open pores are more favorable for catalytic reactions. The importance of adsorption is examined in the presence as well as the absence of pore–gas attraction. Without attraction, the catalytic efficiency is decreased by three orders of magnitude.     

High-temperature synthesis of composite materials based on (Cr,Mn, V)–Al–C MAX phases

Composite materials based on (Cr, Mn, V)–Al–C MAX phases were obtained by self-propagating high-temperature synthesis (SHS). Regularities of synthesis of composite materials from mixtures containing chromium (III) oxide, manganese (IV) oxide, vanadium (V) oxide, calcium (IV) oxide, aluminum, and carbon powders were studied. The synthesis of 30-g blend was carried out in an SHS reactor with a volume of 3 l under Ar pressure (5 MPa). Variation in the amount of the starting reagents markedly affected the process parameters, phase composition, and microstructure of combustion products. The combustion products were characterized by XRD, SEM, and EDS analysis. For Cr–Al–C system, MAX Cr₂AlC phase in addition to chromium aluminide Cr₅Al₈ and chromium carbides (Cr₇C₃, Cr₃C₂) was detected. SEM studies showed that Cr₂AlC has a laminated structure with layer thickness varying from 3 to 20 nm. XRD pattern of Mn–Cr–Al–C composite material were found to have signals belonging (Cr_xMn_1–x)₂AlC solid solution, Mn₃AlC, and Cr₂Al. It was shown that V–Al–C composite material contains nano-layered MAX V₂AlC phase and particles VC_х, VAl₃.     

Development and application of perovskite‐based catalytic membrane reactors

The preparation and characterization of catalytic membranes containing La‐based perovskites are reported. The membranes were prepared by in situ crystallization of different perovskites inside a porous α‐alumina matrix. Preponderance of the Knudsen‐diffusion regime during membrane operation was obtained with perovskite loads of 2 wt% and higher. The catalytic membranes obtained were used as combustors of VOCs (toluene and methyl ethyl ketone) contained in air streams, at concentrations between 875 and 3450 ppmV, and space velocities of up to 27200 h^-1. The membranes were operated in the flow‐through mode, which resulted in total VOC combustion at moderate temperatures. This revised version was published online in July 2006 with corrections to the Cover Date.     

Development of stabilized zirconia–alkali salts dual membranes for carbon dioxide capture

Molten Na₂CO₃–K₂CO₃ (NKC, 56–44 mol%) eutectic compositions were vacuum-impregnated, at the eutectic temperature, into two porous ZrO₂:8.6 mol% MgO (magnesium-partially stabilized zirconia, MgPSZ) and ZrO₂:8 mol% Y₂O₂ (yttria-fully stabilized zirconia, 8YSZ) ceramics. Thermogravimetric analyses were performed in mixtures of that composition with MgPSZ and 8YSZ ceramic powders. Before impregnation, porosity was achieved in the two compounds by addition and thermal removal of 30 vol.% NKC. To ascertain the carbonates had filled up through the ceramic body, both sides of the parallel and fracture surfaces of the disk-shaped impregnated compositions were observed in a scanning electron microscope and analyzed by energy-dispersive X-ray spectroscopy. The electrical conductivity of the two ceramics, before and after impregnation, was evaluated by electrochemical impedance spectroscopy in the 5 Hz–13 MHz frequency range from approximately 530 to 740°C. The permeation of the carbonate ions through the membranes via the eutectic composition was assessed by the threshold temperatures of the onset of the carbonate ion percolation. The objectives were to prepare dual-phase membranes for the separation of carbon dioxide and for the development of carbon dioxide sensors.     

Search of high-capacity cathode materials based on lithium–iron silicate compounds

The crystal structures of 197 lithium–silicate compounds have been analyzed using the method of crystal chemistry analysis (TOPOS software package). The compounds whose structures are characterized with a combination of high values of such parameters as the channel radius, stability, gravimetric capacity, and capacity per volume unit have been revealed: LiFeSiO₄ (R3?), Li₄Fe₂Si₃O₁₀ (C2/c), Li₂FeSiO₄ (Pc2₁ n), and Li₂FeSiO₄ (C222₁). It has been demonstrated that lithium–iron silicates of the monoclinic syngony have high values of the capacity per volume unit, as compared to those of the rhombic syngony. The structural stability of the Li₂FeSiO₄ (Pc2₁ n) framework has been corroborated using the method of computer simulation within the scopes of the electron density functional theory. The obtained information could facilitate creation of novel cathode materials of high capacity and specific accumulated energy.     

Synthesis and Characterization of Linear and Tri-Block PLLA–PEG–PLLA Blends

This study was conducted to synthesize poly(L-lactide)–poly(ethylene glycol)–poly(L-lactide) triblock copolymer (PEGLA) with different poly(L-lactide) block length, and explore its applicability in a blend with linear poly(L-lactide) (3051D NatureWorks) with the intention of improving heat seal and adhesion properties at extrusion coating on paperboard. Poly(L-lactide)–poly(ethylene glycol)–poly(L-lactide) was obtained by ring opening polymerization of L-lactide using poly(ethylene glycol) (molecular weight 6000 g mol^?1) as an initiator and stannous octoate as catalyst. The structures of the PEGLAs were characterized by proton nuclear magnetic resonance spectroscopy. The melt flow and thermal properties of all PEGLAs and their blends were evaluated using dynamic rheology and differential scanning calorimeter. All blends containing 10 wt% of PEGLAs displayed similar zero shear viscosities to neat poly(L-lactide), while blends containing 30 wt% of PEGLAs showed slightly higher zero shear viscosity. However, all blends displayed higher shear thinning and increased melt elasticity (based on tan δ). No major changes in thermal properties were distinguished from differential scanning calorimetric studies. High molecular weight PEGLAs could be used in extrusion coating with 3051D without problems.     

Synthesis,characterization of β-CD based novel hydrogels with dual objectives of drug release and dye removal

Iranian Polymer Journal - In our recent work, we have reported on hydrogels devoid of cross-linkers. After observing the successful swelling and water retention properties, we have introduced...     

Zn based nanoparticle–carbon nanotube hybrid materials: Interaction and charge transfer

The interaction and charge transfer between Zn-based nanoparticles (NPs) and carbon nanotubes (CNTs) is investigated by X-ray Auger and photoelectron spectroscopy. Charge transfer from Zn NPs toward the CNTs is demonstrated by the presence of an additional feature revealed in the C 1s spectrum of CNTs. This charge transfer was found to vanish after thermal oxidation due to the transformation of the metal Zn into ZnO. Photoluminescence (PL) spectroscopy shows that in the samples ZnO(Nps)/CNTs the PL intensity is quenched.     

Influence of sodium alginate and methylcellulose on hydrolysis and physicochemical properties of α-TCP based materials

The effect of the sodium alginate and methylcellulose modifiers on hydrolysis, setting reaction, microstructure, mechanical and in vitro properties of α-TCP based materials was investigated. It was found that the presence of sodium alginate impeded α-TCP hydrolysis to hydroxyapatite, which may have a significant influence on resorbability, biodegradation and biological behavior of biomaterials. There were several reasons for these phenomena, such as: (I) the gelation of sodium alginate in the presence of Ca²⁺, (II) the creation of an organic layer which impedes the diffusion of water molecules to α-TCP and (III) the uptake of water molecules by sodium alginate. The inhibitory effect was not observed for methylcellulose and it was diminished in simulated body fluid. Additionally, it was demonstrated that the examined cements varied in their microstructure, setting times and compressive strengths, depending on the applied kind of a polymer additive. The cement containing sodium alginate had a higher compressive strength (20 ± 8 MPa) than the one with methylcellulose (17 ± 4 MPa) and the one lacking polymer (14 ± 4 MPa). All the developed materials exhibited high bioactivity in vitro.     

Gelatin–PEG based metronidazole-loaded vaginal delivery systems: preparation,characterization and in vitro antimicrobial efficiency

Bacterial vaginosis (BV) is a condition often associated with the overgrowth of pathogenic microbes with a subsequent decrease in lactic acid producing bacteria in vagina. BV is predominant in reproductive women. It has been reported not only to cause pre-term labor but is also one of the major causes of fetal morbidity and mortality. There is an increase in the vaginal discharge in BV. Due to this reason, the locally applied drug formulations are quickly washed off. It is expected that the mucoadhesive delivery vehicles will improve the bioavailability of the drug for prolonged periods. Keeping this in mind, gelatin/PEG based composite hydrogels were developed and characterized as vaginal delivery systems for the treatment of BV. The hydrogels were prepared by varying the concentration of gelatin and PEG. The hydrogels were thoroughly characterized using SEM, FTIR, DSC, and impedance spectroscopy techniques and swelling, mucoadhesive, and texture analysis studies. The in vitro release behavior of metronidazole from the hydrogels was analyzed in-depth. The antimicrobial efficiency of the MZ-loaded hydrogels was tested against E. coli, occurrence of which is predominant in BV. The properties of the hydrogels were found to be dependent on the composition of the hydrogels. The hydrogels were found to be mucoadhesive and the MZ-loaded hydrogels have shown effective antimicrobial activity against E. coli. Based on the preliminary studies, the composite hydrogels were found to be suitable for controlled drug delivery for vaginal applications.     

Synthesis and characterisations of aminophosphonate styrene–divinylbenzene–silica hybrid materials

Abstract

The aminophosphonate styrene–divinylbenzene–silica hybrid materials are obtained in two step reactions: synthesis of alkoxysilane containing polymer precursors and preparation of organic/inorganic hybrid materials by sol–gel process. The prepared materials were characterised by infrared spectroscopy, thermogravimetric analysis and scanning electron microscopy.     

Engineering nanostructured thermal spray coatings: process–property–performance relationships of ceramic based materials

Abstract

Nanostructured powders were deposited using thermal spraying to produce coatings having internal features of nanosized dimensions. Several ceramic based materials were studied, including WC–12 wt-%Co, TiO₂, hydroxyapatite, Al₂O₃–13 wt-%TiO₂ and yttria stabilised zirconia. The effect of the thermal spray conditions on the microstructure, phase composition, properties and performance was investigated. Key nanostructural features of the coatings were identified and their potential benefit in contributing to enhanced behaviour explored. Issues relating to design strategies and process control for engineering these types of coatings with performance characteristics tailored for targeted applications are discussed.     

Use of new ceramic and refractory materials — an important factor in improving the economic and energy efficiency of enterprises,and their ecological security

In productions costs of enterprises the proportion expended in energy resources often becomes predominant, and therefore the competitiveness of a product from domestic enterprises depends considerably on rational consumption of energy resources. One main areas for resolving the problem of economic and energy efficiency and the ecological cleanliness of enterprises in the industrial and social sphere should be the creation of fundamentally new materials, organization of the production of a variety of components based on these materials, and also different devices based upon them, and application of these components and devices instead of obsolescent examples used traditionally.