Chitosan-polyethylene oxide/clay-alginate nanofiber hydrogel scaffold for bone tissue engineering: Preparation, physical characterization, and biomimetic mineralization

This study aimed to prepare a novel organic-mineral nanofiber/hydrogel of chitosan-polyethylene oxide (CS-PEO)/nanoclay-alginate (NC-ALG). The effects of NC particles on the mineralization and biocompatibility of the scaffold were investigated. A layer-by-layer scaffold composed of CS-PEO and NC-ALG was prepared. The morphological properties, swelling, biodegradation, and mechanical behaviors of the scaffolds were evaluated. Furthermore, scaffolds were characterized by the Fourier Transform Infrared (FTIR), the Field Emission Scanning Electron Microscope (FE-SEM), and X-Ray Diffraction (XRD) techniques. Bone-like apatite formation ability of the scaffolds was determined by the mineralization test in a simulated body fluid (M-SBF). In addition, the crystalline phase of bone-like apatite precipitates was investigated by XRD analysis. The cell compatibility of the scaffolds was also studied with osteoblastic cell line MC3T3-E1 by MTT assay. Notably, the incorporation of NC particles in CS-PEO/ALG scaffolds is suitable for bone tissue regeneration which enhances bone-like apatite formation. Further, the hemolysis and MTT assays demonstrated that CS-PEO/NC-ALG scaffold was compatible and safe for MC3T3 cells.

Covalent immobilization of lipase from Candida rugosa on epoxy-activated cloisite 30B as a new heterofunctional carrier and its application in the synthesis of banana flavor and production of biodiesel

In this paper, an epoxy-activated cloisite (ECL) was prepared as a new heterofunctional carrier via a reaction between cloisite 30B (CL) and epichlorohydrin and utilized for covalent immobilization of lipase from Candida rugosa. The lipase immobilized on the ECL (LECL) was successfully used in the olive oil hydrolysis, synthesis of isoamyl acetate (banana flavor), and biodiesel production. The TGA, FT-IR, SEM, and XRD were used to characterize CL, ECL, and LECL. The influences of temperature, pH, thermal stability, and storage capacity were examined in the olive oil hydrolysis. The effects of solvent, temperature, time, water content, and substrates molar ratio on the yields of ester and biodiesel were also investigated. In the optimized conditions, the hydrolytic activity of LECL was 1.85 ± 0.05 U/ mg, and the maximum yield of ester and biodiesel was 91.6% and 95.4%, respectively. The LECL showed good thermal stability and storage capacity compared to the free lipase. Additionally, LECL was reusable for both esterification and transesterification after being used for nine cycles.

Mild halogenation of polyolefins using an N-haloamide reagent

A new methodology for the chlorination of PE and PP without the use of chlorine gas.

Thermodynamic Compatibility, Crystallizability, Thermal, Mechanical Properties and Oil Resistance Characteristics of Nanostructure Poly (ethylene-co-methyl acrylate)/Poly(acrylonitrile-co-butadiene) Blends

This paper addresses the compatibility, morphological characteristics, crystallization, physico-mechanical properties and thermal stability of the melt mixed EMA/NBR blends. FTIR spectroscopy reveals considerable physical interaction between the polymers that explain the compatibility of the blends. DSC results confirm the same (compatibility) and reveals that NBR hinders EMA crystallization. Mechanical and thermal properties of the prepared EMA/NBR blends notably enhance with increasing the fraction of EMA in the blends. Morphology study exhibit the dispersed particles in spherical shape in the nanometer level. Swelling and oil resistance study have also been carried out in details to understand the performance behaviour of these blends at service condition

Nanoclay/Polymer Composite Powders for Use in Laser Sintering Applications: Effects of Nanoclay Plasma Treatment

Plasma-etched nanoclay-reinforced Polyamide 12 (PA12) powder is prepared with its intended use in selective laser sintering (LS) applications. To replicate the LS process we present a downward heat sintering (DHS) process, carried out in a hot press, to fabricate tensile test specimens from the composite powders. The DHS parameters are optimized through hot stage microscopy, which reveal that the etched clay (EC)-based PA12 (EC/PA12) nanocomposite powder melts at a temperature 2°C higher than that of neat PA12, and 1-3°C lower than that of the nonetched clay-based nanocompsite (NEC/PA12 composite). We show that these temperature differences are critical to successful LS. The distribution of EC and NEC onto PA12 is investigated by scanning electron microscopy (SEM). SEM images show clearly that the plasma treatment prevents the micron-scale aggregation of the nanoclay, resulting in an improved elastic modulus of EC/PA12 when compared with neat PA12 and NEC/PA12. Moreover, the reduction in elongation at break for EC/PA12 is less pronounced than for NEC/PA12.