Biocompatible chemical network of α-cellulose-ESBO (epoxidized soybean oil) scaffold for tissue engineering application.

Despite many desirable properties, the use of α-cellulose in biomedical applications is limited because of its poor processability. Here we demonstrate that the chemical network of α-cellulose and epoxidized soybean oil (ESBO) can be adequately processed into biocompatible, self-standing, highly-porous scaffolds for tissue engineering applications. First, α-cellulose was dissolved in N-Methylmorpholine N-oxide monohydrate (NMMO.MH) and chemically crosslinked by ESBO. Then, the porous scaffolds of α-cellulose-ESBO were fabricated by solvent exchange and freeze-drying techniques. The scaffolds were evaluated for morphology, thermal and mechanical stability, and in vitro cell attachment and cell viability. Scanning electron microscopy images and Brunauer-Emmett-Teller results suggested that porous scaffolds provide a good surface and internal structure for cell adhesion and growth. Specifically, the α-cellulose-ESBO scaffolds support the homogeneous attachment and proliferation of MG63 cells. Overall, our results suggest that α-cellulose-ESBO chemically crosslinked networks are biocompatible and demonstrate a remarkable capacity for the development of tissue engineering platforms.

Preparation of nanocapsules via emulsifier-free miniemulsion polymerization.

Nanocapsules containing hexadecane or paraffin as core materials and polystyrene as a shell were produced in a new method through emulsifier-free miniemulsion polymerization using 2,2' azobis (2-amidinopropane) dihydrochloride (V-50) as a cationic ionizable water-soluble initiator. The effect of some parameters such as hexadecane or paraffin amounts and polymerization duration on morphology and thermal properties of resulting nanocapsule particles was studied. Transmission electron microscopy (TEM) showed that the products had latex particles having a size range of about 200-700 nanometer and both nanocapsules with core-shell morphology and solid particles. The phase change temperature and phase transition heat of the produced nanocapsules were determined by differential scanning calorimetric (DSC) analyses. Thermogravimetric analysis (TGA) was also used to prove the capsulation and to determine the amount of hexadecane or paraffin in the nanocapsules.

Prediction of nanofiber diameter and optimization of electrospinning process via response surface methodology.

Response surface methodology (RSM) was used to obtain a more systematic understanding of the electrospinning conditions of polyamide 6 solutions. This method was used to establish a quantitative basis for the relationships between the electrospinning parameters such as applied electric field, the polymer concentrations, the rate of injection and nozzle-collector distance with the diameter of the produced nanofibers, and to predict the optimum conditions for electrospinning to produce nanofibers with controlled size. A response function was empirically determined by central composite design (CCD) using fiber diameter as an observed response and the electrospinning parameters as variables. The relationship between the response and the variables is visualized by a response surface or contour plots. The study of the graphical representations of contour plots, prediction formulas and prediction profiler can predict the operating conditions necessary to generate nanofibers with the desired diameters.

Synthesis of calcium carbonate-polyethylene oxide hybrid nanofibers through in-situ electrospinning.

In this work, calcium carbonate nanoparticles-polyethylene oxide nanofibers as organic-inorganic hybrid were prepared via in-situ electrospinning. Thus, electrospinning of polyethylene oxide solution saturated with calcium hydroxide was carried out in gaseous carbon dioxide atmosphere. Transmission electron microscopy (TEM) showed that calcium carbonate (CaCO3) nanoparticles were formed on the produced nanofibers of 200-300 nm in diameter. The existence of the formed CaCO3 was also proved by thermogravimetric analysis (TGA) via loss of gaseous CO2 related to the decomposition of CaCO3 at about 500-840 degrees C. X-ray diffraction (XRD) analysis of the nanofibers showed that the formed CaCO3 nanoparticles have vaterite morphology. DSC analysis was used to determine melting point and to calculate the crystallinity of the produced hybrid nanofibers. The TEM, TGA, XRD and DSC analyses results of the obtained nanofibers were compared with those of the nanofibers produced in electrospinning of pure polyethylene oxide solution and polyethylene oxide solution having calcium hydroxide, both in air.