جستجوی مقالات مرتبط با کلیدواژه "antibacterial property" در نشریات گروه "مهندسی شیمی، نفت و پلیمر"

Hypothesis:

Ultrafiltration (UF) membranes play a vital role in chemical processes through the separation of high molecular weight compounds, but suffer from a fouling phenomenon in which materials precipitate or adhere on the membrane surface; since the UF membrane feed is susceptible to the growth of microorganisms, biofouling can occur more often, which reduces the membrane performance. Some methods have been suggested to overcome the biofouling phenomenon which one of the best methods is the application of nanoparticles in the membrane.

ZnO and CuO nanoparticles and ZnO/CuO nanocomposite at three different concentrations (1, 3 and 5% by weights) were used to improve the antibacterial properties of PVC membrane. First, nanoparticles were synthesized through co-precipitation method and characterized by XRD and FTIR analyses. Then, the mixed matrix membranes were prepared and their properties were investigated in terms of permeation flux, porosity and contact angle. 

To study the antibacterial properties of the fabricated membranes, the disk diffusion method using Escherichia coli as gram-negative model was applied. The membrane containing 5% (by weight) ZnO with clear zone diameter equal to 9 mm and the membranes containing 3% (by weight) ZnO and 5% (by weight) CuO with clear zone diameter equal to 8.1 mm showed the best antibacterial activities. The results showed that the synthesized nanoparticles can improve the characteristics of the PVC membranes such as hydrophilicity (reducing contact angle from 86.28° to 67.55°) and impart antibacterial activities in the membranes. This method can be utilized to reduce the biofouling of membranes in the separation processes.

Research Subject: 

One of the important methods in the treatment of skin wounds is the use of wound dressings. Recently, the use of polymer-based wound dressings has become increasingly common. The use of natural polymers is very important in wound dressings. The aim of the present study is to design and manufacture a polyvinyl alcohol/aloe vera wound dressing with the capability of healing skin wounds.

Research Approach:

 The electrospinning method was applied to prepare the samples. Aloe vera gel was first extracted, purified, and powdered by freeze-drying. In all samples, the amount of polyvinyl alcohol and aloe vera powder was fixed at 8 wt.%. This value was selected empirically based on the quality of the produced fibers. Different samples including different amounts of polyvinyl alcohol and aloe vera were produced and their properties including morphology, tensile strength, swelling, degradability, and antimicrobial properties were investigated.

The results showed that the dropless random oriented fibers with uniform diameter were produced. The diameter increased with increasing aloe vera contribution, which was attributed to an increase in viscosity due to the presence of aloe vera. With increasing aloe vera contribution in the samples, tensile strength decreased and the elongation percentage increased. The swelling behavior of the specimens was evaluated by measuring the weight of the specimens in a simulated skin environment and the results showed that the presence of aloe vera increased the hydrophilic properties of the specimens. Antimicrobial activity of the samples against two gram-positive Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa was investigated using the disk diffusion method and it was found that the presence of Aloe vera in the samples brought antimicrobial activity against Pseudomonas aeruginosa. Finally, the findings of this study confirm the feasibility of using polyvinyl alcohol /aloe vera for the production of the electrospun wound dressing.

Polyvinyl chloride based heterogeneous cation exchange membranes were prepared by solution casting technique. The effect of multi walled carbon nano tubes and also MWCNTs-co-Ag nanolayer composite nanoparticles on electrochemical and antibacterial properties of membranes was studied. The MWCNTs-co-Ag nanolayer composite nanoparticles were prepared by magnetron sputtering method. Scanning optical microscopy images showed uniform particles distribution for the membranes. Also surface modification of MWCNTs by Ag nanolayer caused to more uniformity for the membranes. Results showed that membrane electrochemical properties were improved by using of nanoparticles in membrane matrix. Also the modified membrane containing Multi Walled Carbon Nano Tubes-co-Ag nanolayer showed more suitable electrochemical characteristics and antibacterial property in E-Coli removal compared to others.