Preparation of Gentamicin Sulfate Nanoparticles using Eudragit RS-100 and Evaluation of Their Physicochemical Properties

Improving permeability and absorption of drugs are critical research challenges in pharmaceutical science. Gentamicin sulfate is an aminoglycoside antibiotic, which is very active against gram-negative bacteria; however, it has very poor bioavailability. This study aimed to prepare gentamicin nanoparticles with the intention of increased bioavailability. Accordingly, Eudragit RS-100 nanoparticles loaded with gentamicin sulfate were prepared by the double emulsification and solvent evaporation method, a proper technique for encapsulating hydrophilic molecules. Nanoparticles’ suspensions with polymer to drug ratios of 1:1 ([Formula: see text] and 2:1 ([Formula: see text]) were prepared, lyophilized and evaluated for their production yield, physicochemical properties and morphology. The mean particle size was 195.67[Formula: see text]nm and 228[Formula: see text]nm for [Formula: see text] and [Formula: see text], respectively. The formulations’ loading efficiencies were relatively high (85.73 for [Formula: see text] and 85.20 for [Formula: see text]). The nanoparticles’ surface charge (+40.5[Formula: see text]mV) was sufficient to inhibit their aggregation and facilitate the nanoparticles’ absorption through the gastrointestinal tract. The results of differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR) revealed that drug and polymer stabilized each other by physical interactions between their functional groups. Both formulations presented an initial burst drug release of nearly 20% after 30[Formula: see text]min in phosphate buffer (pH = 7.4). After 24[Formula: see text]h, [Formula: see text] did not release the drug completely, while [Formula: see text] released the whole drug. Overall, nanoparticles with proper characteristics were obtained. This study puts forward the necessity of conducting further research in order to explore the intestinal absorption of these nanoparticles and the possibility of being utilized for oral administration of gentamicin sulfate.

Evaluation of the Sorption Capacity of a Maleic Acid Copolymer Towards Gold(III) Ions and Production of Catalytically Active Gold Nanoparticles on Its Base

Two spectrophotometric approaches are suggested for the assessment of the concentration of gold(III) cations in an aqueous solution: direct recording of the optical density of gold cations and galvanic substitution of silver atoms in polymer-stabilized silver nanoparticles with gold cations. The sorption capacity of a maleic acid copolymer towards gold cations is estimated. A colloidal composite containing gold nanoparticles is obtained from the polymeric gold salt. The catalytic properties of the resulting polymer-stabilized nanogold are studied in the aerobic oxidation of glucose to gluconic acid.

Effect of Amorphous Crosslinker on Phase Behavior and Electro-Optic Response of Polymer-Stabilized Blue Phase Liquid Crystals

Blue phase liquid crystals (BPLCs) composed of double-twisted cholesteric helices are promising materials for use in next-generation displays, optical components, and photonics applications. However, BPLCs are only observed in a narrow temperature range of 0.5–3 °C and must be stabilized with a polymer network. Here, we report on controlling the phase behavior of BPLCs by varying the concentration of an amorphous crosslinker (pentaerythritol triacrylate (PETA)). LC mixtures without amorphous crosslinker display narrow phase transition temperatures from isotropic to the blue phase-II (BP-II), blue phase-I (BP-I), and cholesteric phases, but the addition of PETA stabilizes the BP-I phase. A PETA content above 3 wt% prevents the formation of the simple cubic BP-II phase and induces a direct transition from the isotropic to the BP-I phase. PETA widens the temperature window of BP-I from ~6.8 °C for BPLC without PETA to ~15 °C for BPLC with 4 wt% PETA. The BPLCs with 3 and 4 wt% PETA are stabilized using polymer networks via in situ photopolymerization. Polymer-stabilized BPLC with 3 wt% PETA showed switching between reflective to transparent states with response times of 400–500 μs when an AC field was applied, whereas the application of a DC field induced a large color change from green to red.

Fundamentals on Polyaniline based Composites

The background of work carried out highlighting on polyaniline, N-substituted polyaniline and acid-doped polyaniline. The problems associated with this polymer and promises it hold are also discussed. It also provides introduction to the nanocomposites of polyaniline/nanoclays, and polyaniline/polyacrylic acid. As well, we have described the polymer stabilized intrinsically conducting polymer composites. The state of the art polymer stabilised intrinsically conducting composites have been reviewed. At last, we have reviewed on the CH4 gas sensing since it has been recognized as one of the inflammable gas sensors. The main problem on the CH4 gas sensor lies on its room temperature operation and detection of low ppm level concentration.

Study of the Efficiency of Gel and Polymer-Stabilized Foam Systems for Gas Shut-Off in Horizontal Wells

This article describes the assessment of effectiveness of gel and foaming agents for gas shut-off treatments in horizontal wells. The research is carried out through the implementation of a complex of special laboratory studies and analysis of the results using numerical modeling methods. A list of necessary laboratory experiments to minimize risks when carrying out work to limit gas inflow has been formulated, and approaches to carrying it out have been described. The program includes: free volume studies, filtration on linear and parallel core models. The results confirm the importance of studying not only the agent's physical characteristics at the reservoir conditions, but their interaction with reservoir fluids. The influence of different agents on the mobility of gas and oil was assessed as a result of linear core flooding experiments. In addition, the filtration tests on parallel cores were carried out aimed to determining the saturation selectivity. The series of numerical calculations was performed for the subsequent determination of the technological and economic effects of the treatment with gas blockers.