جستجوی مقالات مرتبط با کلیدواژه « antibacterial » در نشریات گروه « مهندسی شیمی، نفت و پلیمر »

In this research, the colorimetric characteristics and antibacterial properties of two herbal dyes, oak bark (Jaft) and henna, were compared and evaluated on silk yarn. These dyes, which are widely used to provide red-brown shades in handwoven carpets, are used in traditional medicine, due to the presence of plant secondary metabolites. On the other hand, the surface of textiles with natural fibers, including handwoven carpets, in the presence of moisture and heat, is exposed to the growth and proliferation of bacteria and leads to problems in the durability, appearance and health of the goods. In this research, in addition to evaluating colorimetric parameters (a*, b*, L*), color strength (K/S), general fastness of dyed wool by aqueous and alcoholic extracts of henna and jaft, their antibacterial effect on two Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria was also compared. Dyeing was performed using the simultaneous mordanting method in the presence of potassium aluminum double sulfate. Spectrophotometric evaluation proved that both dyes produced red and yellow tones, with a slight color difference, and the ethanolic extract had the highest color strength on the fibers in both dyes in this research. The results of antibacterial test showed that both types of dyes showed an acceptable bacteria growth inhibition percentage against Escherichia coli and Staphylococcus aureus bacteria, and among them, the ethanolic extracts showed a higher antibacterial power against bacteria due to the presence of higher amounts of Lawson and Quercetin active ingredients.

Nowadays dyeing of textiles with natural dyes has been considered according to environmental effects based on lower using of the synthetic dyes and chemical auxiliaries. In present research, the dyeing parameters including; type of mordant, concentration of mordant and concentration of clove have been investigated. The color strength (K/S) value and the color coordinates (L*, a*, b*, C*) of samples were obtained using calorimeter in CIELab color space. The results showed the dyed samples in presence of Cu and Al as mordant have higher lightness (L*) compare with dyed samples dyed with Fe. The ultraviolet protection results showed higher blocking effect of sample in presence of clove against photodegradation of methylene blue (MB) under sunlight irradiation. The antibacterial assessment of the dyed samples showed reduction of bacteria rate against S. aureus (95%). Also washing fastness assessment of the dyed samples showed the great durability of clove on wool in presence of mordant.

Notwithstanding the indefatigable endeavor to explore antibacterial drugs and agents, achieving improved antibacterial properties and minimizing hazardous matters has always been challenging. Garlic extract was utilized to reduce and dope graphene oxide simultaneously, considering the astonishing antibacterial characteristics of garlic extract instead of using dangerous reducing agents. A hydrothermal method was used to reduce/ dope graphene oxide. Copper cations were also loaded on the graphene oxide nanosheets doped with garlic extract. The successful synthesis of the products was confirmed by Fourier transform infrared spectroscopy. X-ray photoelectron spectroscopy was used to affirm the doping of graphene oxide using garlic extract. Furthermore, according to the results obtained from X-ray photoelectron spectroscopy, the atomic percentage of S and N elements was 1.4 % and 1 %, respectively. The result revealed that double-doped graphene oxide in water base acrylic coating on PVC panels showed a 100 percent decrease in the growth of bacteria after 6 hours.

In this research, silk as a source of protein fibroin, with very good mechanical properties, has been used to prepare hydrogels. For this purpose, 20% fibroin was dissolved in water and calcium chloride was added to accelerate the gelation process. The pH of the liquid was adjusted to 4 with HCl. Then, the solution was sonicated using an ultrasonic apparatus for 3 minutes. Finally, 5% chamomile extract was added to the hydrogel under ultrasonic condition and applied on cotton fabrics. The morphology, chemical structure, and swelling of the specimens, the release rate of the extract and antibacterial properties of the hydrogel were evaluated. SEM images showed the proper coating of cotton with silk hydrogel. FTIR spectra confirmed the presence of functional groups in the hydrogel and chamomile extract. The results of swelling showed that the incorporation of hydrogel increased the water absorption of fabrics and there was a slight reduction in water absorption after loading the extract in the hydrogel. Besides, the antibacterial test confirmed the antibacterial properties of the hydrogel against both gram-positive and gram-negative bacteria

Today, for various reasons, including environmental problems, natural ingredients are used instead of synthetic materials in the textile industry, specially the dyeing process. In addition, in the dyeing process, the use of some other herbal compounds gives special properties.  Antibacterial or antimicrobial chemical compounds in the production and using process induce a lot of wastewater into the environment, which is costly to clean and recycle. Textiles are one of the inevitable requirements that all humans use in their lives abundantly. Today, for various reasons, including environmental problems, the tendency to use natural compounds instead of synthetic materials has increased in the textile industry, including the dyeing process. Furthermore, using the herbal compounds can create special properties such as antibacterial and antimicrobial properties in textiles. A lot of research has been done in this regard. This research has been reviewed the results of researches in this area and classified them that will be easy for using in the new research and application of results.

This study examined an innovative approach for imparting enhanced mechanical, antimicrobial and coloration properties on wood-plastic composite. In this regard, the wood fibers were primarily bleached with sodium chlorite and then dyeing of fibers were carried out with green walnut shells as a natural dye. In the next step, wood plastic composite was prepared by mixing treated wood fibers into polyvinyl chloride. After bleaching, 58.8 wt.% of lignin was removed. Delignin wood fibers had brighter color compared to original wood fibers. The structure and morphology of the composite has been examined by field emission scanning electron microscopy (FE-SEM). Influences of bleaching and natural dyeing on color, antibacterial and mechanical properties of the composite were investigated. The wood/polyvinyl chloride composite showed excellent antibacterial activity measured against two common pathogenic bacteria including Escherichia coli and Staphylococcus aureus. The composite sample exhibited 100% reduction for both bacteria. Furthermore, the color variation of the bleached sample after sunlightsun light irradiation was negligible, which demonstrated the proper color fastness of the composite.

Wound environment is susceptible to growth of microorganisms and infection. To prevent the infection and accelerate the process of wound healing, antibacterials are sometimes required. The purpose of this study is to develop a bacterial resistant wound dressing based on Henna , a natural bioactive agent. After separating impurity of Henna leaves, they were milled and dissolved in ethanol. In the next step, cotton or polyester fabrics were impregnated with filtered ethanol extract of Henna leaves using exhaustion method. The antimicrobial properties of cotton and polyester fabrics were quantitatively measured by the standard penetration test (AATCC 100-190) against Staphylococcus aureus as gram-positive and E. Coli as gram-negative bacteria. The findings show that the cotton fabric impregnated with Henna extract has an acceptable antibacterial properties against gram-positive bacteria with poor antibacterial effect against gram-negative bacteria. Moreover, the polyester fabric treated with Henna extract did not show any antibacterial properties against both gram negative and gram-positive bacteria. This was attributed to the high temperature which was used for treatment of polyester fabrics with Henna extract.

Hypothesis: Water pollution has been emphasized as one of the major threats to environment and human health. In this regard, various adsorbents with high adsorption capacities and rapid sorption rates have been synthesized. In the present study, we report the synthesis, structure characterization and methylene blue adsorption of a novel hydrogel nanocomposite based on sodium alginate and silver nanoparticles.
The hydrogel nanocomposite was prepared using grafting of acrylic monomers onto sodium alginate by using ammonium persulfate (APS) as free radical initiator and methylene bisacrylamide (MBA) as crosslinker in the presence of Ag nanoparticles synthesized by an in situ chemical reduction method. The structure of hydrogel nanocomposite was then characterized by FTIR, SEM, TEM, EDX, XRD, and TGA techniques.
Findings: The adsorption behavior of methylene blue dye on the synthesized hydrogel nanocomposites was studied. In order to obtain the maximum adsorption capacity, the effects of various parameters were optimized with respect to dye adsorption capacity of hydrogel nanocomposites in detail. The thermodynamic parameters also demonstrated that the dye adsorption process was spontaneous and exothermic in nature. Moreover, the hydrogel nanocomposite adsorbents showed a high selectivity for the adsorption of cationic dyes with a high adsorption capacity of 168 mg/g. The antibacterial activity of the nanocomposites was examined against E. coli using disk diffusion method. In general, the results indicated that the synthesized hydrogel nanocomposite with antibacterial and dye adsorption properties is a potential material for medical applications as well as wastewater treatment.

Polyurethanes and their counterparts, polyurethane-ureas (PUUs), a favorable group of polymers, are prepared from a wide variety of materials. PUs/PUUs offer a wide range of controllable properties and therefore, are known as good candidates for a broad range of applications. Among the very broad field of applications known for this group of polymers, biomedical devices and prosthesis, drug delivery vehicles and tissue engineering scaffolds have attracted most attention over recent decades. This study systematically reviews the current literature for biomedical applications of polyurethanes (PUs) and polyurethane-ureas. On the other hand, in addition to different qualities that are required for successful performance of a biomaterial (including biocompatibility, bio-stability and/ or biodegradability, hydrophilicity and/or hydrophobicity, adjustable mechanical properties, etc), antibacterial behavior is considered as an inevitable prerequisite in many applications. Therefore, the especial emphasis of this review paper is placed on polymers with antibacterial activity and the strategies towards preparation of antibacterial PUs and PUUs, in particular. Current strategies applied for preparation of antibacterial polyurethanes and polyurethane-ureas are reviewed. Among such approaches, adoption of nano-silver, blending with natural polymers of well-known inherent antibacterial activity such as chitosan, loading of antibacterial drugs and surface modification with antibacterial agents are discussed in details.

Chitosan (Chito) as a biopolymer with high antibacterial, biocompatibility and biodegradability and polyaniline (PANI) as a conductive polymer and silver (Ag) nanoparticles to enhance antibacterial property were used to prepare polyanilin-chitosan-silver (PANI-Chito-Ag) nanocomposites. The synthesis of PANIChito composite and PANI-Chito-Ag nanocomposite was performed through aniline polymerization in the presence of Chito and Ag. In order to evaluate the physicochemical and antibacterial properties of synthesized composite and nanocomposites, several combinations of components with different weight ratios were used. Antibacterial tests were performed using two different types of bacteria: Escherichia coli (gram-negative bacteria) and Staphylococcus aureus (gram-positive bacteria) to determine the antibacterial capability of the PANI-Chito-Ag nanocomposite. The obtained results showed that higher Chito and silver contents produced stronger antibacterial property. The biodegradability test results confirmed that,the biodegradability increased as the content of Chito increased. Also, by increasing Streptomyces (gram-positive bacteria) concentration in natural soil, the biodegradability rate of nanocomposite was enhanced. The results obtained from thermogravimetric analysis (TGA) tests also indicated improvement in thermal stability of PANI-Chito-Ag nanocomposite compared to that of pure Chito. Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) were used to analyze and characterize the composition and structure of PANIChito-Ag triple hybrid nanocomposite. The results confirmed uniform distribution of Ag nanoparticles within the polymer matrix.

In recent years, fabrication of polymeric antibacterial wound dressing has gained most attention in controlling wound infections. Silk is also a member of the broad family of protein-based polmers. The silk produced by the lepidopteran insect Bombyx mori is a highly accepted material due to its long history as a very valuable textile fiber. Recently, additional applications have been developed for silk, mainly in the field of biotechnology. Regarding its importance in wound healing, silk fabric was incorporated with ciprofloxacin, as an antibiotic, on its surface coated with electro-spun PVA/ciprofloxacin nanofibers. Before coating, degumming was carried out using autoclave technique and properties of the silk fabric, before and after degumming process, was investigated by SEM, FTIR, mechanical properties and moisture absorbance measurement. The results of all analyses showed a reduction in fibers diameter, mechanical strength and moisture absorption after degumming process. Electrospinning condition was optimized and diameter of the nanofibers, with and without drug, was measured before coating. The results showed that addition of the drug increased electrical conductivity of electrospinning solution and resulted in finer nanofibers. Antibacterial test was performed using "disk diffusion method" with Escherichia coli (EC) and Staphylococcus aureus (SA) bacteria to compare the antibacterial properties of degummed and non-degummed silk fabrics alone and coated with nanofibers. Measurement of bacterial inhibition zone diameter showed no antibacterial activity for degummed and non-degummed silk fabrics alone. However, the sample coated with PVA/ciprofloxacin showed antibacterial activity. The antibacterial property for SA in both cases was the same, but for EC, the antibacterial activity of degummed silk fabric was more than that of non-degummed material.

The bed of an open wound is prone to infection because of good conditions for microorganisms to grow in a moist, warm and nutritious environment. Using an antibacterial wound dressing, the healing of the wound can be accelerated. Antibacterial properties of natural dyes have been studied by researchers in recent years. On the other hand, the efficiency of fine fibers in wound dressing has been demonstrated due to increasing its contact area with the skin and simulation of extracellular matrix. In this study, polyvinyl alcohol (PVA) microfibers were fabricated by electrospinning process and heat treatment was used to increase the stability of microfibers against aqueous solutions. It is notable to say that untreated PVA microfibers dissolve in aqueous solutions easily. XRD spectrum was used for structural characterization of PVA microfibers after heat treatment. The results showed an increase in the crystallinity of the microfibers after heat treatment. Antibacterial properties of some natural dyes (green walnut shells, Punicagranatum, Urticadioica) were investigated by dipping PVA microfibers in the natural dyes solutions extracted by different solvents such as water and ethanol. In the end, the antibacterial property of PVA microfibers dipped in Punicagranatum extract solution for both pathogenic strains of gram-positive (Staphylococcus aureus) and gram-negative (Pseudomonas aeruginosa) was demonstrated. PVA microfibers dipped in aqueous solution of Punicagranatum showed stronger antibacterial property than those dipped in ethanolic Punicagranatum extract solution. The SEM images indicated that morphology of PVA microfibers preserved after dipping in the natural dyes solution extracted by water and ethanol, confirming stability of PVA microfibers after heat treatment.

In this research, zinc oxide (ZnO) nanoparticles were selected as reinforcing agent with the aim of improving antibacterial and mechanical properties of polyvinyl chloride (PVC). PVC-ZnO nanocomposite was prepared by dispersing ZnO nanoparticles into a PVC solution. Taguchi experimental design method was used to determine the optimal conditions for preparation of nanocomposite. The effects of five factors including ZnO weight percentage, kind of solvent, the addition method of ZnO, film drying temperature and stirring time were investigated on different levels. Optimal conditions were determined by using the signal/noise (S/N) method. It was distinguished that, kind of solvent, the addition method of ZnO and ZnO weight percentage are three significant factors in the confidence level of 95%. Staphylo coccus aureus and Escherichi coli, two different types of bacteria (one gram-positive bacteria and one gram-negative bacteria) were used in Mueller-Hinton broth for antimicrobial testing. This test confirmed the antibacterial property of the optimal nanocomposite in respect to pure polyvinyl chloride. A scanning electron microscope (SEM) coupled with an energy dispersive X-ray system (EDX) was used to characterize the composition and structure of the optimal nanocomposite film.