جستجوی مقالات مرتبط با کلیدواژه « Ascorbic acid » در نشریات گروه « مواد و متالورژی »

Skin tissue serves as the body’s first defense barrier. Since this tissue is the most superficial one in the body, it is susceptible to damages from many incidents. Skin staples are one of the tools used in medicine to connect skin grafts. The purpose of this research is to make a degradable polymer skin stapler that uses electrospinning as an alternative to extruding and injecting into a mold. Physicochemical tests were done to determine the properties of the manufactured PLGA fibers. Silica nanoparticles SBA-15 made by hydrothermal method were added to improve the mechanical properties of polymer fibers. Then, FTIR test was carried out to detect the presence of nanoparticles in the polymer. The BET test was also performed to measure the size of the pores of SBA-15 silica nanoparticles as 6.77 nm, which is a confirmation of the mesoporous nature of the nanoparticles. To investigate the morphology of the electrospun fibers and silica nanoparticles, SEM image was used according to which, the average diameter of fibers and average diameter of nanoparticles were obtained as 400-500 nm and 185 nm, respectively. The results obtained from addition of SBA_15 silica nanoparticles to polymer fibers and those from comparing its mechanical properties with pure PLGA polymer fibers indicated that incorporating 1% SBA_15 silica nanoparticles into polymer improved its mechanical properties over pure polymer fibers, while fibers with 3% Silica nanoparticles showed SBA_15 comparable results. According to cytotoxicity investigation, no toxicity was observed in any group, and all groups supported the cell growth.

The aim of this study was to fabricate and characterize silk fibroin scaffold containing chitosan nanoparticle loaded with ascorbic acid. Therefore, ascorbic acid- chitosan nanoparticles were fabricated using the ionic gelation method. Scanning Electron Microscopy (SEM) images and Dynamic Light Scattering (DLS) results showed that the nanoparticles are spherical with the average size of 200 nm. Then, different amounts of nanoparticles were placed in the silk fibroin solution, and finally, the scaffolds were prepared by the freeze-drying method. The effect of nanoparticle concentrations on various properties such as morphology, structural changes, water absorption, drug release, toxicity, adhesion, and alkaline phosphatase activity of MG63 cells were studied. The results of Fourier Transform Infrared Spectroscopy (FTIR) confirmed the presence of nanoparticles in the scaffold. Morphological examinations of the cross-section of the scaffold showed that all scaffolds have a porous structure with interconnected pores. The mean size of the pores and porosity percentages reduced as the nanoparticle content rose. The release of ascorbic acid in all samples started with the burst release in the first 24 hours and then continued with a controlled release for up to 14 days. Higher amounts of ascorbic acid were released from the scaffold containing more nanoparticles. Cellular studies showed that the scaffold was non-toxic and that MG63 cells adhered well onto the surface of the scaffold and the pores’ wall. Also, the proliferation and alkaline phosphatase activity of MG63 cells increased with increasing ascorbic acid amounts.

In the present study, alkali roasting and oxalic acid leaching were used to extract titanium dioxide from ilmenite, and the effect of ethanol and ascorbic acid on the purity and recovery of titanium dioxide was investigated. In this research, ilmenite was alkali roasted with sodium carbonate for 4 hours at 900˚C. Then, the roasted ilmenite was leached with distilled water for 1 hour at room temperature. Finally, leaching with a mixture of 0.47M oxalic acid and different amounts of ascorbic acid and ethanol was performed at 65˚C. The results showed that using ethanol caused an increase in the amount of recovery and ascorbic acid increased the purity of the extracted titanium dioxide; also, the presence of these two factors at the same time simultaneously increased the amount of purity and recovery of the final product. Eventually, by choosing 0.47M oxalic acid, 0.005M ascorbic acid, and 48% ethanol as the appropriate conditions for leaching media and increasing the leaching time and temperature to 16 hours and 80˚C, it was possible to get titanium dioxide purities which were as high as 93.3% and 90.9%, respectively.