Foley catheters functionalised with a synergistic combination of antibiotics and silver nanoparticles resist biofilm formation

Foley catheters are inevitable in health care unit. Pathogens colonise and form biofilm on catheter causing catheter‐associated urinary tract infection. Therefore, the authors aimed to functionalise catheter to resist biofilm formation. The authors impregnated urinary catheters with a synergistic combination of antibiotics and silver nanoparticles (SNPs) to evaluate antibiofilm efficacy in vitro and in vivo. SNPs were synthesised using Spirulina platensis. Synergy between the SNPs and antibiotics was determined by the checker‐board method. In vivo efficacy of the functionalised catheters was assessed in mice. Liver and kidney function tests of mice were performed. The in vitro anti‐adherence activity of the functionalised catheters was evaluated after 2 years. Nanoparticle sizes were 42–75 nm. Synergistic activity was observed among SNPs (2 µg/ml), amikacin (6.25 µg/ml), and nitrofurantoin (31.25 µg/ml). In mice, catheters functionalised with combinations of antibiotics and SNPs exhibited no colonisation until Day 14. Blood, liver, and kidney tests were normal. After 2 years, catheters functionalised with antibiotics exhibited 25% inhibition of bacterial adhesion, and catheters functionalised with the nanoparticle‐antibiotic combination exhibited 90% inhibition. Impregnation of urinary catheters with a synergistic combination of antibiotics and SNPs is an efficient and promising method for preventing biofilm formation.Inspec keywords: catheters, drugs, silver, nanoparticles, nanomedicine, liver, kidney, blood, microorganisms, adhesion, biomechanics, cellular biophysicsOther keywords: Foley catheters, synergistic nanoparticle‐antibiotics combination, silver nanoparticles, biofilm formation resitance, health care unit, pathogens, urinary tract infection, SNP, Spirulina platensis, checker‐board method, liver function, kidney function, vitro antiadherence activity, amikacin, nitrofurantoin, blood, bacterial adhesion, size 42 nm to 75 nm, Ag     

Synthesis of novel chitosan–silica/CpG oligodeoxynucleotide nanohybrids with enhanced delivery efficiency

Chitosan–silica/CpG oligodeoxynucleotide (ODN) nanohybrids were synthesized to stimulate Toll-like receptor 9-mediated induction of interleukin-6 (IL-6). The chitosan–silica hybrid was first synthesized from a mixture of chitosan and 3-glycidoxypropyl trimethoxysilane under acidic conditions via a sol–gel process, and then used to condense CpG ODN2006x3-PD to yield chitosan–silica/CpG ODN nanohybrids. Scanning electron microscopy and atomic force microscopy showed that the chitosan–silica/CpG ODN nanohybrids had an elliptic shape with a diameter of 100–200 nm. After soaking in HAc–NaAc buffer solution (pH 5.5), the nanohybrids exhibited sustained release of CpG ODN. When the nanohybrids were separately exposed to 293XL-hTLR9 cells and peripheral blood mononuclear cells, no significant toxicity was observed. An immunochemical assay for cellular uptake revealed that the nanohybrids were taken up by the cells and located in endolysosomes. An enzyme-linked immunosorbent assay for cytokines indicated that the nanohybrids effectively stimulated the induction of IL-6. Chitosan–silica/CpG ODN nanohybrids underwent cellular uptake and enhanced induction of IL-6 to a greater degree than conventional chitosan/CpG ODN nanocomplexes, indicating that they have an enhanced delivery efficiency.     

Hemocompatible biomaterials of zwitterionic sulfobetaine hydrogels regulated with pH-responsive DMAEMA random sequences

Polyzwitterionic biomaterial with pH-responsive and hemocompatible dual functions is formulated by the copolymerization of 2-(N, N-dimethyl amino) ethyl methacrylate (DMAEMA) sequences and sulfobetaine methacrylate (SBMA) moieties. Hydrogels are salt responsive, due to the interplay between hydrogen bonds formation, ions solvation, and antipolyelectrolyte effect, while DMAEMA sequences provide pH-responsiveness. Their low-fouling nature is demonstrated using plasma proteins and bacteria. Improved hemocompatibility with SBMA content is unveiled by the resistance to platelet and erythrocyte attachment, as well as from delayed plasma clotting time. Overall, this study suggests that dual-functional zwitterionic hydrogels are promising pH-responsive and hemocompatible polymeric biomaterials.     

Crystal Structure and Microwave Dielectric Properties of LiRE9(SiO4)6O2 Ceramics (RE = La,Pr, Nd,Sm, Eu,Gd, and Er)

The crystal structure and microwave dielectric properties of apatite‐type LiRE₉(SiO₄)₆O₂ ceramics (RE = La, Pr, Nd, Sm, Eu, Gd, and Er) have been investigated. The densification of lithium apatites has been greatly improved with the addition of 1 wt% LiF. Selected area electron diffraction and X‐ray diffraction (XRD) Rietveld analysis confirm that these compounds belong to the P6₃/m (No. 176) space group with hexagonal crystal symmetry. The porosity‐corrected relative permittivity was found to decrease with decreasing ionic polarizability of RE³⁺ ions. Relationships between the structural parameters and microwave dielectric properties have been examined. The observed variation in the quality factor of LiRE₉(SiO₄)₆O₂ + 1 wt% LiF ceramics (RE = La, Pr, and Nd) was correlated with average cation covalency (%). The temperature coefficient of resonant frequency was found to depend on the bond valence sum of cations. LiEr₉(SiO₄)₆O₂ + 1 wt% LiF ceramics showed good microwave dielectric properties with ε_r = 12.8, Q_u × f = 13000 GHz and τ_f = +17 ppm/°C. All the compositions showed low coefficient of thermal expansion with thermal conductivity in the range 1.3–2.8 W (m K)^?1.     

Flexible Thermoelectric Devices of Ultrahigh Power Factor by Scalable Printing and Interface Engineering

Printing is a versatile method to transform semiconducting nanoparticle inks into functional and flexible devices. In particular, thermoelectric nanoparticles are attractive building blocks to fabricate flexible devices for energy harvesting and cooling applications. However, the performance of printed devices are plagued by poor interfacial connections between nanoparticles and resulting low carrier mobility. While many rigid bulk materials have shown a thermoelectric figure of merit ZT greater than unity, it is an exacting challenge to develop flexible materials with ZT near unity. Here, a scalable screen‐printing method to fabricate high‐performance and flexible thermoelectric devices is reported. A tellurium‐based nanosolder approach is employed to bridge the interfaces between the BiSbTe particles during the postprinting sintering process. The printed BiSbTe flexible films demonstrate an ultrahigh room‐temperature power factor of 3 mW m^?1 K^?2 and ZT about 1, significantly higher than the best reported values for flexible films. A fully printed thermoelectric generator produces a high power density of 18.8 mW cm^?2 achievable with a small temperature gradient of 80 °C. This screen‐printing method, which directly transforms thermoelectric nanoparticles into high‐performance and flexible devices, presents a significant leap to make thermoelectrics a commercially viable technology for a broad range of energy harvesting and cooling applications.     

Design of hemocompatible poly(DMAEMA‐co‐PEGMA) hydrogels for controlled release of insulin

This works aims at (i) studying the antiadhesive properties and the hemocompatibility of poly[2‐(dimethylamino)ethyl methacrylate]‐co‐poly[(ethylene glycol)methacrylate] [poly(DMAEMA‐co‐PEGMA)] copolymers and (ii) investigating the insulin delivery kinetics through hydrogels at physiological pH. A series of poly(DMAEMA‐co‐PEGMA) hydrogels have been synthesized, and their controlled composition was confirmed by X‐ray photoelectron spectroscopy. Then, antibiofouling properties of hydrogels—fibrinogen, erythrocytes, and thrombocytes adhesion—are correlated to their molecular compositions through their hydrophilic properties. As DMAEMA/PEGMA ratio of 70/30 (D70) offers the best compromise between pH sensitivity and hemocompatibility, it is selected for investigating the kinetic rate of insulin release at physiological pH, and the diffusion coefficient of insulin in gel is found to be 0.64 × 10^?7 cm² s^?1. Overall, this study unveils that poly(DMAEMA‐co‐PEGMA) copolymers are promising hemocompatible materials for drug delivery systems. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42365.     

Catalytic-assisted synthesis, characterization and low frequency AC conduction of nanostructured conducting polyaniline

Polymerizations of aniline at the reaction temperatures of 25 and 50 °C have been performed in the presence of iron catalyst. The prepared conducting polyaniline at different reaction periods was investigated for physicochemical and electrical properties, through X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–Visible spectroscopy (UV–Vis), Fourier transform infrared spectroscopy (FTIR) and frequency-dependent electrical conductivity measurements, respectively. XRD studies established the improved nanostructured crystalline nature for the polymer prepared at 50 °C. Size of the particles ranging from 10 to 20 nm was calculated for the prepared polyaniline. SEM analysis shows the cauliflower-like morphology for optimized reaction temperature. The study further establishes the attainment of uniform distribution of polyaniline at the reaction temperature of 50 °C. The charge transitions between benzenoid (B-band) and quinonoid (Q-band) bands were witnessed by UV–Vis spectrum analysis. The band gap analysis revealed the narrow band gap direct transition semiconducting nature of the conducting polymer. Quinonoid and phenylene rings were identified through vibrational bands between 1570 and 827 cm^?1 via FTIR spectroscopy analysis. The AC conductivity of the sample synthesized at 50 °C showed 1.50 × 10^?1 S cm^?1. Enhancement in conductivity with increasing temperature represented the improved crystalline nature of the polyaniline prepared at 50 °C.     

Development of a Power Management Algorithm for PV/Battery Powered Plug-In Dual Drive Hybrid Electric Vehicle (DDHEV)

Abstract

In this paper, a Three-Port Dual Boost (TPDB) DC-DC converter operated Hybrid Electric Vehicle (HEV) based on dual motor drive system is presented to minimize Carbon Dioxide (CO₂) emission and to increase the fuel efficiency. The Dual Drive Hybrid Electric Vehicle (DDHEV) system composed of Photovoltaic (PV) system/plug-in, dual drive system and power management algorithm improves the fuel efficiency of the DDHEV. The DDHEV system designed with the PV system needs efficient and simple DC-DC converter to export the power generated by the PV system to motor/battery. The simulation results of the HEV structured in the MATLAB/Simulink and the experimental prototype models are introduced to evaluate the proposed PV-DDHEV under various conditions. From the results, it is found that the dual motor drive system operated by the TPDB provides better stability and reduces the power consumption.     

Generation of microgrooved silica nanotube membranes with sustained drug delivery and cell contact guidance ability by using a Teflon microfluidic chip

Abstract

Silica nanotubes have been extensively applied in the biomedical field. However, very little attention has been paid to the fabrication and application of micropatterned silica nanotubes. In the present study, microgrooved silica nanotube membranes were fabricated in situ by microgrooving silica-coated collagen hybrid fibril hydrogels in a Teflon microfluidic chip followed by calcination for removal of collagen fibrils. Scanning electron microscopy images showed that the resulting silica nanotube membranes displayed a typical microgroove/ridge surface topography with ～50 μm microgroove width and ～120 μm ridge width. They supported adsorption of bone morphogenetic protein 2 (BMP-2) and exhibited a sustained release behavior for BMP-2. After culturing with osteoblast MC3T3-E1 cells, they induced an enhanced osteoblast differentiation due to the release of biologically active BMP-2 and a strong contact guidance ability to directly align and elongate osteoblasts due to the presence of microgrooved surface topography, indicating their potential application as a multi-functional cell-supporting matrix for tissue generation.     

Effect of Ca2+ Substitution on the Structure,Microstructure, and Microwave Dielectric Properties of Sr2Al2SiO7 Ceramic

The effect of Ca²⁺ substitution on the structure, microstructure, and microwave dielectric properties of Sr–gehlenite (Sr₂Al₂SiO₇) ceramic has been investigated. The structure and microstructure of Sr_2?xCa_xAl₂SiO₇ ceramics were analyzed via X‐ray diffraction (XRD) as well as scanning and transmission electron microscopic techniques. While the end‐members (x = 0 and 2) form isostructural compounds, a highly defective, nonstoichiometric, Ca‐rich secondary phase was observed via bright‐field transmission electron microscopy and energy dispersive X‐ray spectroscopy in compositions corresponding to x = 0.75 and 1.5. The concentration of secondary phase in x = 0.75 is too low to be detected via XRD or scanning electron microscopy. Identical selected‐area electron‐diffraction patterns of the compounds (x = 0, 1, and 2) confirmed that they belong to the space group P2₁m (no. 113) with tetragonal crystal symmetry. The porosity‐corrected relative permittivity at microwave frequencies showed a gradual increase with Ca²⁺ content; however, Ca²⁺ substitution made only marginal changes to the microwave dielectric properties except in the case of x = 1.5, in which the secondary phase reduced the quality factor considerably. Thermal conductivity decreased with increasing Ca²⁺ content, and the compounds with defective structures showed the lowest thermal conductivity. All the compounds exhibited low coefficients of linear thermal expansion, with values varying in the range 2.3–3.6 ppm/°C.