Supersaturation-Based Drug Delivery Systems: Strategy for Bioavailability Enhancement of Poorly Water-Soluble Drugs

At present, the majority of APIs synthesized today remain challenging tasks for formulation development. Many technologies are being utilized or explored for enhancing solubility, such as chemical modification, novel drug delivery systems (microemulsions, nanoparticles, liposomes, etc.), salt formation, and many more. One promising avenue attaining attention presently is supersaturated drug delivery systems. When exposed to gastrointestinal fluids, drug concentration exceeds equilibrium solubility and a supersaturation state is maintained long enough to be absorbed, enhancing bioavailability. In this review, the latest developments in supersaturated drug delivery systems are addressed in depth.     

Physical-chemical conditions for production of combined alkyd-acrylic dispersion

When preparing the mixing of acrylic polymer and copolymer dispersions with alkyd oligomer emulsions it is necessary to provide agregative stability of the combined dispersions. It was established that transfer of polymer particles mass of highly dispersed systems onto particles of less dispersed systems is seen during geterocoagulation of combined dispersions. Optimal physical-chemical and hydrodynamic conditions of the emulsification of alkyd oligomers with the required dispersion degree for producing the mixed systems were established. The combined dispersion stability is determined from the ratio of electrokinetic potentials of particles of polymers and oligomers being combined as well as ratio of their isoelectric points. The zone of dispersion incompatibility was established by method of microelectrophoresis.     

Electro‐Optical Properties of Polymer‐Dispersed Liquid Crystals

This paper deals with the electro‐optic (EO) properties of polymer‐dispersed liquid crystals (PDLCs). Several systems are considered to analyze the effects of preparation conditions and film characteristics on the EO response functions. Particular emphasis is put on systems based on mixtures of the commercial compound ASX‐95, the difunctional acrylate tripropylene diacrylate and the eutectic mixture of low‐molecular‐weight liquid crystals E7. Other systems are considered to assess the influence of monomer functionality on EO properties using for example the trifunctional glycerylpropoxytriacrylate. Various modes of preparing PDLCs are considered based on the mechanism of polymerization‐induced phase separation using either electron‐beam (EB) or UV radiation curing processes. The dose is changed in both techniques to improve film strength and determine which method leads to the best samples in terms of EO response functions. Other important parameters, such as film thickness, composition and applied voltage, are also considered to evaluate the impact on these functions. The article focuses on a comparison of EO performances of films elaborated by exposure to EB and UV radiations. Under similar conditions, one definitively finds a net superiority of the former technique. In addition this technique does not require any photoinitiator and leads to a higher conversion of the monomeric compounds, i.e. higher mechanical strength and less severe aging conditions.     

Ink‐Jet Printing of Metallic Nanoparticles and Microemulsions

Summary: Two types of ink‐jet inks are presented: ink containing an aqueous dispersion of silver nanoparticles and an oil‐in‐water microemulsion‐based ink. The metallic ink contains nanoparticles of silver, which are formed in the presence of an ionic polymeric stabilizer. Sintering of the printed image obtained with the use of such silver‐based inks at temperatures as low as 300 °C results in formation of patterns possessing noticeable conductivity. The microemulsion inks are based on a thermodynamically stable microemulsion, in which the dispersed oil phase is a volatile solvent containing a water‐insoluble colorant. After contact of the jetted ink droplets with a substrate, nanodroplets of the microemulsion are converted into nanoparticles of the solubilized colorant. In some cases, it was found that the evaporation of microemulsion ink droplets leads to formation of rings composed of ordered nanoparticles.

Scheme of ink‐jet printing of an oil‐in‐water microemulsion followed by conversion of the nanodroplets into nanoparticles, caused by quick evaporation of the solvent within the microemulsion droplets. Therefore, the ink behaves as a dye‐based ink prior to printing, but after printing it behaves like a pigment‐based ink.     

Synthesis and structural characterization of copper nanoparticles doped activated carbon derived from coconut coir for drinking water purification

Modifying and functionalizing activated carbon using metal nanoparticles have received great scientific attention in recent decades as a method to improve its inherent properties. The synergistic effects between the dopant and the activated carbon could lead to advanced properties in the hybrid material compared to individual counterparts. In this study, copper-doped activated carbon from coconut coir (Cu-ACC) is synthesized by an in-situ reduction method. The successful doping of zerovalent copper nanoparticles (Cu np) into the activated carbon matrix was confirmed using several characterization techniques. Peaks related to zerovalent Cu np in the X-ray diffractogram confirmed the successful formation of zerovalent Cu np. The dopant-matrix interactions were confirmed through peak shifts in the Fourier Transform Infrared Spectroscopy and D and G band changes in the Raman spectrum of Cu-ACC. The Cu 2p band in XPS of the Cu-ACC showed a sharp doublet at 932.7 eV, confirming the presence of metallic Cu. As indicated in the TEM/SEM images, Cu np demonstrated a spherical morphology with an average diameter of 5 nm. It was further observed that the Cu-ACC nanohybrid material could remove fluoride (63%) and hardness (69%) in synthetic water. Cu-ACC further demonstrates an enhanced antimicrobial activity against three commonly found water pathogens; E. coli, S. typhi, and S. flexneri. The material is expected to be used in next-generation domestic water filters formulated as single-use sachet bags.     

New low viscous polyisocyanates for VOC compliant systems

Since 1961, aliphatic polyisocyanates based on HDI-biurets are used as light stable hardeners for 2-K polyurethane coatings. The market introduction of the HDI-isocyanurates or simply 'trimers' in the early 1980's was driven by their lower viscosity and their better monomer stability. The most recent development in HDI-polyisocyanate research are the iminooxadiazinediones (asymmetric trimers). In this paper, a new product based on that technology with a very low viscosity (700 mPas@23°C) and a NCO-functionality of more than 3 is presented. Because of its low viscosity, this hardener can be easily incorporated into aqueous systems and is the solution for high and full solids coatings as well.     

Waterborne Dispersions of a Polymer‐Encapsulated Inorganic Particle Nanocomposite by Phase‐Inversion Emulsification

Inorganic silica nanoparticles were encapsulated with an epoxy resin to give waterborne nanocomposite dispersions, using the phase‐inversion emulsification technique. Sub‐micron‐sized waterborne particles with narrow size distribution were prepared such. Microscopy results indicate that all the silica nanoparticles are encapsulated within the composites and uniformly dispersed therein. Curing of the nanocomposite dispersions proceeded in a controlled manner.     

Influence of processing method and components molecular structure on the phase behaviour of polyethylenes/dye blends

The phase dispersion of terthiophene alkyl derivatives on different polyethylene matrices was investigated. The PE affinity toward dichroic dyes with different structure, the effect of blending process and the influence of a polyolefinic compatibilizer on the homogeneity of host-guest blends were comparatively investigated by calorimetry, DSC and SEM analyses. For these purposes, polyethylenes with different molecular weights and densities and EVAc were used as host matrices. The polymeric compatibilizer was prepared by radical functionalization of a commercial low density polyethylene. The dichroic nature of the guest phase allowed to perform UV-Vis measurements in polarized light on oriented blend film samples. The dyes affinity toward PE is one of the key factor in obtaining oriented polyolefinic films with high optical performances for several applications.     

Antibacterial and Alkali-responsive Cationic Waterborne Polyurethane Based on Modification of Aloe Emodin

Cationic water-based polyurethane(CWPU) was synthesized to explore aloe-emodin modifies to obtain CWPU materials with better comprehensive performance. It provides a simple way to synthesize antibacterial waterborne polyurethane, which is to introduce the end-blocking group of herbal extracts into the structure. It contains synergistic antibacterial effect of herbal antibacterial and quaternary ammonium ion on Escherichia coli. It makes the material resist the erosion of bacterial, and increase the service life of materials. When the pH value of the environment changes, the UV absorbance of the aloe-emodin modified cationic water-based polyurethane(AE-CWPU) also changes. Therefore, within a certain detection range, AE-CWPU has great applications in the field of smart response materials. The modified thermodynamic properties have been improved, and the mechanical properties basically maintained the maximum stress, and the elongation at break was reduced.     

Nonstoichiometric interpolyelectrolyte complexes as colloidal dispersions based on NaPAMPS and their interaction with colloidal silica particles

Preparation and characterization of some nonstoichiometric interpolyelectrolyte complexes (NIPECs) as stable colloidal dispersions by the interaction between poly(sodium 2-acrylamido-2-methylpropanesulfonate) (NaPAMPS) and three strong polycations bearing quaternary ammonium salt centres in the backbone, poly(diallyldimethylammonium chloride) (PDADMAC) and two polycations containing N,N-dimethyl-2-hydroxypropyleneammonium chloride units (PCA₅ and PCA₅D₁), have been followed in this study as a function of the polycation structure and polyelectrolyte concentration. Complex characteristics were followed by polyelectrolyte titration, turbidity and quasi-ellastic light scattering. Almost monodisperse NIPECs nanoparticles with a good storage stability were prepared when total concentration of polyelectrolyte was varied in the range 0.85-6.35 mmol/L, at a ratio between charges (n⁻/n⁺) of 0.7. NIPECs as a new kind of flocculants were used to flocculate a stable monodisperse silica suspension. The main advantage of NIPECs as flocculants is the broad flocculation window, which is a very important aspect for industrial applications.