A novel nano drug delivery system based on tigecycline-loaded calciumphosphate coated with poly-dl-lactide-co-glycolide

The purpose of the study presented in this paper has been to examine the possibility of the synthesis of a new nanoparticulate system for controlled and systemic drug delivery with double effect. In the first step, a drug is released from bioresorbable polymer; in the second stage, after resorption of the polymer, non-bioresorbable calcium phosphate remains the chief part of the particle and takes the role of a filler, filling a bone defect. The obtained tigecycline-loaded calcium-phosphate(CP)/poly(dl-lactide-co-glycolide)(PLGA) nanoparticles contain calcium phosphate coated with bioresorbable polymer. The composite was analyzed by FT-IR, XRD and AFM methods. The average particle size of the nanocomposite ranges between 65 and 95 nm. Release profiles of tigecycline were obtained by UV–VIS spectroscopy in physiological solution at 37°C. Experimental results were analyzed using Peppas and Weibull mathematical models. Based on kinetic parameters, tigecycline release was defined as non-Fickian transport. The cytotoxicity of the nanocomposite was examined on standard cell lines of MC3T3-E1, in vitro. The obtained low values of lactate dehydrogenase (LDH) activity (under 37%) indicate low cytotoxicity level. The behaviour of the composite under real-life conditions was analyzed through implantation of the nanocomposite into living organisms, in vivo. The system with the lowest tigecycline content proved to be an adequate system for local and controlled release. Having in mind the registered antibiotics concentration in other tissues, delivery systems with a higher tigecycline content show both local and systemic effects.     

Optimization of Parameters for Synthesis of MFI Nanoparticles by Taguchi Robust Design

MFI‐type zeolite was successfully synthesized by hydrothermal crystallization of clear synthesis mixtures. A statistical experimental design method (the Taguchi method with an L8 orthogonal array) was implemented to optimize the experimental conditions for the preparation of MFI nanocrystals with respect to particle size and distribution as the desirable properties. In the Taguchi experimental design, crystallization temperature, water content, template/silica molar ratio, aluminum content, as well as the presence of alkaline cations were chosen as significant parameters affecting the properties. It was shown that water and aluminum content of the synthesis solution were the most important parameters affecting particle size and distribution. The MFI nanocrystals with an average particle size of 95 nm and the narrow particle size distribution of ± 8.5 nm were synthesized under optimum conditions.     

Fabrication of Homogenous Polymer‐Zeolite Nanocomposites as Mixed‐Matrix Membranes for Gas Separation

Interfacial void‐free mixed‐matrix membranes (MMMs) of polyimide (PI)/zeolite were developed using 13X and Linde type A nano‐zeolites and tested for gas separation purposes. Fabrication of a void‐free polymer‐zeolite interface was verified by the decreasing permeability developed by the MMMs for the examined gases, in comparison to the pure PI membrane. The molecular sieving effect introduced by zeolite 13X improved the CO₂/N₂ and CO₂/CH₄ selectivity of the MMMs. Separation tests indicated that the manufactured nanocomposite membrane with 30 % loading of 13X had the highest permselectivity for the gas pairs CO₂/CH₄ and CO₂/N₂ at the three examined feed pressures of 4, 8 and 12 atm.     

Enhancement of fracture toughness in bioactive glass-based nanocomposites with nanocrystalline forsterite as advanced biomaterials for bone tissue engineering applications

In this research, the replacement effects of bioactive glass (BG) by nanocrystalline forsterite (NF) on the biomineralization, microstructural and mechanical properties of BG-based nanocomposites were investigated. The hybrid nanocomposites with different NF contents (0, 10, 20, and 30 wt%) were prepared from the nanopowders by means of conventional cold pressing method. Surprisingly, the addition of NF provided redundant mechanisms to improve the toughness of the BG matrix without deteriorating its biomineralization properties. In addition, the resulting enhancement in the fracture toughness, observed for the first time in highly bioactive BG/NF nanocomposites, indicated the potential of the prepared nanocomposites as advanced biomaterials for load-bearing bone tissue engineering applications.     

Investigating the production and properties of Ag/TiO2/PP antibacterial nanocomposite filament yarns

In this research, investigating the possibility of producing, processing and also characterization of antibacterial organic/inorganic nanocomposite polypropylene fiber has been presented. For this purpose, PP powder and inorganic nanocomposite filler were mixed using a twin screw extruder and modified granule was produced. After producing as-spun filament yarns by a pilot plant melt spinning machine at the take-up speed of 2000 m/min, samples were drawn, textured and finally weft knitted. Physical and structural properties of as-spun and drawn yarns with constant and variable draw ratios were investigated. The experimental results revealed that the crystallinity reduction of modified as-spun yarns could be compensated by drawing process. Tensile properties of modified drawn yarns with the variable draw ratio were higher than the pure PP, whereas the inverse observation was noticed in the case of constant draw ratio. The investigation of antimicrobial activity showed a high percentage of biostatic efficiency on the modified samples.     

Voltammetric determination of 4-nitrophenol using a modified carbon paste electrode based on a new synthetic crown ether/silver nanoparticles

A novel modified carbon-paste electrode (CPE) with a new synthetic ligand: 6,7,9,10,17,18,19, 20,21, 22-decahydrodibenzo[h,r][1,4,7,11,15]trioxadiazacyclonanodecine-16,23dione(DTD)/Ag nanoparticles (AgNP) was employed for 4-nitrophenol measurement in natural water. Various parameters such as pH, modifier, accumulation time and scan rate were optimized. The proposed electrode showed a good response towards 4-nitrophenol determination. Under the optimized conditions the reduction peak current, showed a good linear relationship with the nitrophenol concentration in the range comprised between 1 × 10^− 6 mol L^− 1 and 1 × 10^− 4 mol L^− 1. The developed electrode was successfully applied for the determination of 4-nitrophenol in water samples.     

Neuro-Fuzzy Control for MPEG Video Transmission Over Bluetooth

The application of a neuro-fuzzy (NF) controller to moving picture expert group (MPEG-2) video transmission over a Bluetooth asynchronous connectionless (ACL) is presented in this paper. MPEG variable bit rate (VBR) data sources experience unpredictability, long delay, and excessive loss, due to sudden variations in bit rate. Therefore, it is practically impossible to transmit MPEG-2 VBR video sources over a Bluetooth channel with a limited transmission speed and considerable wireless interferences without loss of data or image quality degradation. In this work, a traffic-shaping buffer is introduced before the host controller interface (HCI) of the Bluetooth protocol stack to obstruct excessive MPEG VBR data sources during the peak transmission periods. An integrated neuro-fuzzy controller monitors and reduces the burstiness of the traffic-shaper output rate to facilitate the MPEG VBR video sources to conform to the token-bucket contract before entering the Bluetooth channel. A conventional rule-based-fuzzy (RBF) controller oversees the arrival rate to the traffic-shaper to avoid saturation or starvation of the buffer. The computer simulation results demonstrate that applications of the NF and RBF schemes reduce excessive delay and data loss at the HCI as compared with conventional video transmission in Bluetooth ACL links     

Synthesis and characterization of poly(catechol) catalyzed by porphyrin and enzyme

Catalytic polymerization of catechol was performed employing the cationic porphyrin and horseradish peroxidase (HRP) as catalysts. The obtained results demonstrate that the cationic metalloporphyrin is a more-efficient catalyst than the HRP in the catechol polymerization. The oxidative polymerization was carried out in the presence of polystyrene sulfonate (PSS) as a template. According to TGA data, poly(catechol) that is synthesized by porphyrin catalyst exhibits more thermal stability than the enzymatic catalyzed product. The GPC indicate higher molecular weight of polymer synthesized by porphyrin as a catalyst. Cyclic voltammetry measurements show that the synthesized polymers have convenient electroactivity. The poly(catechol) and its methyl and methoxy derivatives that are synthesized by porphyrin catalyst show low electrical conductivity.     

In vitro deposition of lysozyme on etafilcon A and balafilcon A hydrogel contact lenses: effects on adhesion and survival of Pseudomonas aeruginosa and Staphylococcus aureus.

PURPOSE: To compare lysozyme adsorption and absorption and bacterial adhesion interactions on conventional (etafilcon A) and silicone (balafilcon A) hydrogel contact lenses. METHOD: Lysozyme concentrations and activities associated with the lenses were determined after solvent extraction (trifluoroacetic acid/acetonitrile) and directly on the lenses without extraction with micrococcal- and micro-bicinchoninic acid (BCA) assays. Cells of bacteria with radiolabeled leucine and a cell recovery procedure were used in determinations of bacterial adhesion to lenses. RESULTS: Lysozyme was adsorbed and absorbed to the conventional etafilcon A lens at about a 10-fold greater concentration than to the balafilcon A silicone hydrogel lens. Enzyme activities on the surfaces of both lenses were similar but replenished after saline extraction only with the etafilcon A lens. Lysozyme on the lens surface showed significant lysis of Micrococcus luteus but had a negligible effect on the adhesion and survival of Staphylococcus aureus. Lysozyme did not appear to affect the survival of Pseudomonas aeruginosa on lenses. CONCLUSION: In vitro experiments show that concentrations of active lysozyme on the surface of the etafilcon A lens, unlike the balafilcon A lens which showed negligible absorption, may be sustained from the lens matrix. Lysozyme deposited on hydrogel lenses had marked activity against M. luteus but relatively minor effects on the primary adhesion of P. aeruginosa and S. aureus.     

Transient heat transfer in a fixed bed of slab-shaped and spherical particles with intraparticle conduction

The mathematical equations for heat transfer between a flowing fluid and both slab-shaped and spherical particles with intraparticle conduction in a fixed bed, are numerically solved using the method of lines. The solution for spherical particles was used to confirm previous results for zero and non-zero Biot numbers. Conditions are identified under which heat transfer to beds of slabs should not be approximated by available solutions for spheres.