The Effect of Complex Modifier Consisting of Star Macromolecules and Ionic Liquid on Structure and Gas Separation of Polyamide Membrane.

A novel hybrid membrane was developed on the basis of poly(m-phenylene isophthalamide) (PA) by introducing an original complex modifier into the polymer; this modifier consisted of equal amounts of heteroarm star macromolecules with a fullerene C60 core (HSM) and the ionic liquid [BMIM][Tf2N] (IL). The effect of the (HSM:IL) complex modifier on characteristics of the PA membrane was evaluated using physical, mechanical, thermal, and gas separation techniques. The structure of the PA/(HSM:IL) membrane was studied by scanning electron microscopy (SEM). Gas transport properties were determined by measuring He, O2, N2, and CO2 permeation through the membranes based on PA and its composites containing a 5 wt% modifier. The permeability coefficients of all gases through the hybrid membranes were lower than the corresponding parameters for the unmodified membrane, whereas the ideal selectivity in the separation of He/N2, CO2/N2, and O2/N2 gas pairs was higher for the hybrid membrane. The position of the PA/(HSM:IL) membrane on the Robeson's diagram for the O2/N2 gas pair is discussed.

Hydrophilic polyelectrolyte microspheres as a template for poly(3,4-ethylenedioxythiophene) synthesis.

Conducting polymer polyelectrolyte microspheres are typically composed of a cationic conducting polymer and an anionic polymer. The polymer chains inside these microspheres are physically or chemically cross-linked, creating a network that enables high water retention. Poly(3,4-ethylenedioxythiophene) (PEDOT) being an electrically conductive polymer exhibits a high conductivity and has great biotechnological applications. The unique combination of properties of PEDOT containing polyelectrolyte microspheres makes them widely investigated materials for electroresponsive cells, tissue engineering, and bio-sensors. The demand to produce PEDOT with varied properties depending the specific application requires the understanding of the basic principles of template formation. In the present work, we studied the inverse suspension polymerization of p-styrenesulfonic acid in the presence of a cross-linking agent as a synthetic way for the formation of porous polyelectrolyte microspheres. We traced how the nature of the emulsifier affected both the structure of the surface layer of the microspheres and the degree of their cross-linking. The porous structure of polyelectrolyte microspheres obtained is found to promote the polymerization of EDOT in their presence throughout the entire microsphere volume. The structural characteristics of the polyelectrolyte/PEDOT complexes in relation to their electrochemical properties have been studied.

Application of Cyclized Polyacrylonitrile for Ultrafiltration Membrane Fouling Mitigation.

In this study, novel composites were produced by blending partially cyclized polyacrylonitrile (cPAN) and poly(amide-imide) (PAI) in N-methylpyrrolidone in order to fabricate asymmetric membranes via phase inversion method. The compatibility of PAI and cPAN through possible intermolecular interaction was examined by quantum chemical calculations. The composite membranes were characterized by FTIR, SEM, contact angle measurements, etc. A considerable reduction in the contact angles of water and ethylene glycol (EG) was observed after adding cPAN to the PAI membrane, which is evidence of improved membrane hydrophilicity. Membrane transport properties were investigated in ultrafiltration tests by measuring the pure water flux, rejection of proteins, and flux recovery ratio (FRR). The best properties were found for the membrane containing 5 wt% cPAN; an increase in BSA rejection and a remarkable increase in FRR were observed, which can be explained by the hydrophilization of the membrane surface provided by the presence of cPAN.

Impact of Layered Perovskite Oxide La0.85Yb0.15AlO3 on Structure and Transport Properties of Polyetherimide.

This study aims to improve properties of Ultem® polyetherimide (PEI) by incorporating up to 2 wt% additives of the perovskite oxide La0.85Yb0.15AlO3 (LYA). The structure of dense PEI/LYA films was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) in combination with an analysis of their elemental composition using energy-dispersive spectroscopy (EDS). The PEI/LYA films exhibit a two-layer structure. Contact angle measurements revealed hydrophilization of the membrane surface enriched with the perovskite. The transport properties were tested via gas separation and pervaporation processes. The separation selectivity of He/N2 and O2/N2 gas pairs increased with the growth of the LYA content in the membranes. Pervaporation of a methanol(MeOH)-cyclohexane(CH) mixture was effective due to the high sorption of MeOH in the PEI/LYA membranes. The maximal pervaporation separation index was found for the PEI/LYA(2%) membrane.

Linear/Ladder-Like Polysiloxane Block Copolymers with Methyl-, Trifluoropropyl- and Phenyl- Siloxane Units for Surface Modification.

Multiblock copolymers containing linear polydimethylsiloxane or polymethyltrifluoropropylsiloxane and ladder-like polyphenylsiloxane were synthesized in a one-step pathway. The functional homopolymer blocks and final multiblock copolymers were characterized using solution and solid-state multinuclear 1H, 13C, 19F, and 29Si NMR spectroscopy. It was shown that the ladder-like block contains silanol units, which influence the adhesion properties of multiblock copolymers and morphology of their casted films. The adhesion to metals and mechanical properties of multiblock copolymers were tested. The SEM study of casted films of multiblock copolymers shows the variety of formed morphologies, including long-strip-like or globular.

Enhancing Pervaporation Membrane Selectivity by Incorporating Star Macromolecules Modified with Ionic Liquid for Intensification of Lactic Acid Dehydration.

Modification of polymer matrix by hybrid fillers is a promising way to produce membranes with excellent separation efficiency due to variations in membrane structure. High-performance membranes for the pervaporation dehydration were produced by modifying poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) to facilitate lactic acid purification. Ionic liquid (IL), heteroarm star macromolecules (HSM), and their combination (IL:HSM) were employed as additives to the polymer matrix. The composition and structure of hybrid membranes were characterized by X-ray diffraction and FTIR spectroscopy. Scanning electron microscopy was used to investigate the membranes surface and cross-section morphology. It was established that the inclusion of modifiers in the polymer matrix leads to the change of membrane structure. The influence of IL:HSM was also studied via sorption experiments and pervaporation of water‒lactic acid mixtures. Lactic acid is an essential compound in many industries, including food, pharmaceutical, chemical, while the recovering and purifying account for approximately 50% of its production cost. It was found that the membranes selectively remove water from the feed. Quantum mechanical calculations determine the favorable interactions between various membrane components and the liquid mixture. With IL:HSM addition, the separation factor and performance in lactic acid dehydration were improved compared with pure polymer membrane. The best performance was found for (HSM: IL)-PPO/UPM composite membrane, where the permeate flux and the separation factor of about 0.06 kg m-2 h-1 and 749, respectively, were obtained. The research results demonstrated that ionic liquids in combination with star macromolecules for membrane modification could be a promising approach for membrane design.

Doxorubicin delivery systems based on doped CaCO3 cores and polyanion drug conjugates.

In order to prolong the release and reduce the toxicity of anticancer drug - doxorubicin (DOX), delivery systems (DS) using different polyanions have been developed. Structural (size, morphological stability) and functional (encapsulation efficiency, DOX release) characteristics of three types of DS are compared: CaCO3 porous vaterites doped with polyanions by co-precipitation and coating techniques, and DOX-polyanion conjugates. Using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS), it was shown that the doping enhances the morphological stability of CaCO3-based DS during the DOC loading. Doping of CaCO3 cores by co-precipitation reduces its sizes (up to 1 µm) and DOX encapsulation efficiency. Polyanion-coated CaCO3 cores and polyanion drug conjugates show about 98 w/w% DOX encapsulation. For the first time, it was shown that the release of DOX from developed DS into human blood plasma is more intense (from 1.3 to 3.0 times for different DS) than into model tumour environment.

Star-Shaped Poly(2-ethyl-2-oxazoline) and Poly(2-isopropyl-2-oxazoline) with Central Thiacalix[4]Arene Fragments: Reduction and Stabilization of Silver Nanoparticles.

The interaction of silver nitrate with star-shaped poly(2-ethyl-2-oxazoline) and poly(2-isopropyl-2-oxazoline) containing central thiacalix[4]arene cores, which proceeds under visible light in aqueous solutions at ambient temperature, was studied. It was found that this process led to the formation of stable colloidal solutions of silver nanoparticles. The kinetics of the formation of the nanoparticles was investigated by the observation of a time-dependent increase in the intensity of the plasmon resonance peak that is related to the nanoparticles and appears in the range of 400 to 700 nm. According to the data of electron and X-ray spectroscopy, scanning and transmission electron microscopy, X-ray diffraction analysis, and dynamic light scattering, the radius of the obtained silver nanoparticles is equal to 30 nm. In addition, the flow birefringence experiments showed that solutions of nanoparticles have high optical shear coefficients.

Two-level delivery systems based on CaCO3 cores for oral administration of therapeutic peptides.

Two-level systems for oral delivery of therapeutic peptides were developed; the carriers consist of CaCO3 cores included into alginate granules. Such systems were first used for the delivery of low molecular weight drugs. It was shown that efficiency of encapsulation of peptides depends on their pI value, hydrophobicity, characteristics of the compounds used for doping CaCO3 cores, their surface potential and the techniques employed for loading peptides into the first-level carriers. Doping CaCO3 cores with dextran sulphate save their viability compared to the pristine CaCO3 cores, but ensures delivery of the desired quantity of peptide when using a smaller amount of delivery systems. Introducing the inhibitor of peptidases leads to an increase in the concentration of peptide in rat blood after intragastric administration of the developed delivery systems. Scanning electron microscopy and energy-dispersive X-ray spectroscopy demonstrated the presence of fragments of destructed first-level carriers in blood and plasma of experimental animals.

Two-level delivery systems for oral administration of peptides and proteins based on spore capsules of Lycopodium clavatum.

Two-level delivery systems (DSs) for oral administration of therapeutic proteins and peptides were developed. The first level consists of outer walls of Lycopodium clavatum spores (sporopollenin exine capsules, SECs) with included target objects; the alginate microgranules serve as the second (outer) level. Alginate (a pH-dependent natural polymer) protects peptides from gastric acidity and enzyme exposure and provides slow release of target objects in an alkaline intestinal medium. Introducing ovomucoid (a peptidase inhibitor) into alginate coatings prevents enzymatic hydrolysis of peptide objects in the intestinal medium. The elemental composition of spores and SECs was controlled using energy-dispersion spectroscopy and combustion analysis; their morphology was visualized by SEM. The efficiencies of different methods of SEC loading were compared. It was demonstrated that the load value was controlled by molecular mass and the value of the isoelectric point of target objects. A comparison of peptide in vitro release profiles from DSs of various structures into simulated gastric and intestinal fluids was carried out. The mechanism of peptide release from two-level DSs was suggested. SECs were found in rat blood after intragastric administration of the two-level DSs. Time profiles of therapeutic peptide release were obtained in vivo.

Alginate-containing systems for oral delivery of superoxide dismutase. Comparison of various configurations and their properties.

The regularities of release of therapeutic antioxidant enzyme superoxide dismutase (SOD) from various alginate-based delivery systems (DS) into simulated gastric and intestinal fluids were determined. The following systems were used: Ca-alginate granules (AG) prepared by various methods, porous carbonate cores with multilayer polyelectrolyte coating as well as the new two-level DS (Ca-AG containing carbonate cores loaded with proteins). The influence of the method of granule preparation, composition of gelation bath and ionic composition of the simulated fluids on release profiles of the protein from different DS was revealed. SEM images demonstrated changes in DS structures in various simulated fluids. The correlation between these changes and in vitro protein release was shown. The comparison of enzymatic activity of SOD encapsulated in DS of various configurations (including the systems containing different peptidase inhibitors) was made. The efficiency of protection of SOD activity in simulated intestinal fluid with trypsin was demonstrated.

Triple-responsive inorganic-organic hybrid microcapsules as a biocompatible smart platform for the delivery of small molecules.

We designed novel hybrid inorganic/organic capsules with unique physicochemical features enabling multimodal triggering by physical (UV light, ultrasound) and chemical (enzymatic treatment) stimuli. Notably, the UV- and ultrasound response was achieved by a synergetic combination of TiO2 and SiO2 nanostructures which were in situ deposited into the polymer shell of microcapsules during sol-gel synthesis. This results in the formation of a composite hybrid shell with enhanced mechanical stability. Such sol-gel modification reduces the permeability of the capsule shell to allow for small molecule encapsulation. At the same time, these hybrid capsules consist of degradable polypeptides and polysaccharides and can be decomposed in response to enzymatic reaction. Upon employing different modes of treatment (UV-light, ultrasound or enzymatic degradation) we can stimulate different mechanisms of cargo release at desired times. Importantly, such capsules have been shown to be non-cytotoxic and can be internalized into human mesenchymal stem cells (MSCs) and cervical cancer cell lines (HeLa) revealing intracellular degradation. This work demonstrates that our hybrid capsules possess a triple stimuli-responsive effect, which is of capital importance for the future design and application of multimodal responsive platforms to improve externally stimulated release of bioactive compounds and their healthcare performance.

Structural optimization of calcium carbonate cores as templates for protein encapsulation.

The calcium carbonate (CaCO3) cores being templates for model proteins encapsulation were obtained for developing oral drug delivery systems. The influence of the characteristics of the core formation (the time, the temperature, the stirring intensity, the ultrasound treatment and drying conditions) on the size and morphology of the carbonate cores was studied. The core size was shown to decrease with increasing the stirring time and stirring intensity. Statistical analysis of the scanning electron microscopy images of the carbonate cores allowed finding a correlation between their mean diameter and the parameters of the core formation. The regularities of proteins loading into porous CaCO3 cores were determined, and different loading methods were compared quantitatively. The co-precipitation method gives cores with the proteins load about five times as much as the adsorption method. The influence of protein properties and the ionic environment of protein molecules on the loading parameters were shown.