جستجوی مقالات مرتبط با کلیدواژه « Chitosan » در نشریات گروه « علوم پایه »

The design of absorbents to remove toxic dyes has made significant progress. Absorbents based on polymer composites are important with diverse potential applications. The use of natural chitosan polymer as the continuous phase of composite has been expanded due to its biocompatibility, biodegradability, and distinctive properties. In this research, the absorbent based on chitosan composite containing montmorillonite (MMT) clay and egg shell inspired by nature was used to remove methylene blue (MB) dye from aqueous solution. The ratios of 0.25, 0.5 and 0.75 g of clay and eggshell absorbent in chitosan composite were used to remove the dye after immersion in aqueous medium. The proportion of 0.25 g was chosen as the optimal sample based on the results of the maximum removal. The amount of dye removal was evaluated by the final composite as the optimal sample in the concentration of 15 ppm of methylene blue pollutant and 0.25 g/l of absorbent by the final composite. Samples were investigated by dynamic light scattering (DLS) to examine size and size distribution, scanning electron microscope (SEM) and transmission electron microscope (TEM) to evaluate shape and size, energy dispersive spectroscopy (EDS) for chemical spectroscopy analysis, Fourier transform infrared (FTIR) to determine functional groups, X-ray diffraction (XRD) to check the crystal structure, BET analysis to measure the surface area, and UV-vis spectrophotometer to study the amount removal. Based on the results of the chitosan composite containing 0.25 g of clay and eggshell as the optimal sample, it showed the highest (94%) removal of methylene blue dye from the aqueous solution.

Many dyes, such as malachite green, produce toxic by-products due to various reactions, which are harmful to aquatic organisms and humans. Surface absorption technology has wide applications in water and wastewater treatment. In this study, the natural biopolymer chitosan was modified with the organic compound of ethyl acrylate and was used for the surface absorption of malachite green cationic dye. The obtained compound was identified using infrared spectroscopy. To investigate the decolorization characteristics of the synthesized compound, effective factors such as pH, concentration of absorbent, concentration of dye, temperature and the effect of different salts were investigated. The results showed that increasing the pH and amount of adsorbent has a positive effect on the amount of color removal, Taguchi method was used to investigate the effect and determine the optimal conditions of each of these parameters. The results of the experiment design showed the highest parameter, gram of bioabsorbent compared to other parameters and the lowest effect related to temperature in surface absorption.

In this research, nylon 6 nanofiber/chitosan nanoparticles (CS/N6NFs) adsorbent was fabricated by combining electrospinning and electrospraying methods. First, the nylon 6 nanofibrous substrate was made by electrospinning method, and then chitosan nanoparticles were electrosprayed on this substrate to make a adsorbent. The adsorbent was characterized by, field emission scanning electron microscopy (FESEM), contact angle and tensile test. FESEM studies showed that chitosan nanoparticles are uniformly distributed on the surface of nylon 6 electrospun nanofibers and are well connected to the fibers. The production of chitosan nanoparticles by electrospraying showed an almost uniform particle size distribution with an average size of about 110 nm. The role of chitosan in improving wettability was observed by reducing the contact angle from 64.06 to 53.80. Young's modulus values were obtained for N6NFs and Cs/N6NFs equal to 4.82 and 5.28 MPa, respectively. The performance of Cs/N6NFs adsorbent in removing acid red 8 (AR8) dye from aqueous solutions was investigated. Experiments showed that the value of 0.015 g of Cs/N6NFs adsorbent has the ability to remove more than 95% of AR8. Adsorption tests in batch mode indicate that the adsorbent designed to absorb AR8 after 5 times of reduction by NaOH still has a high absorption efficiency of 70%. The adsorption capacity of the adsorbent was calculated to be 195.16 mg.g-1 for AR8. The Langmuir model had a good fit with the experimental data of the adsorption isotherm. Kinetic studies showed that the adsorption data followed a pseudo-quadratic model.

The present study was conducted in a randomized complete block design (RCBD) with three replications to investigate the effect of elicitors on the morpho-physiological characters and essential oil quantity and quality of Satureja bachtiarica. Three irrigation regimes (3, 6, 9 day interval) in main plots and foliar application of organic (chitosan, salicylic acid, phenylalanine) and alcoholic elicitors (ethanol, methanol, acetone) with control level (without any spraying) in sub plots were done. According to obtained results, applied elicitors significantly influenced the morpho-physiological and phytochemical characters of S.bachtiarica. In two years, the highest chlorophyll content (1.37-1.41 mg.g-1FW) and total phenol content (2.34-2.51 mg.g-1FW) were obtained in chitosan (0.25 mg.l-1), ethanol (10 %) and phenylalanine (1 mg.l-1) treatments by irrigation regimes 3 and 6 day interval, respectively. The highest essential oil contents (1.61-1.59%) were obtained from the plants treated by chitosan (0.25 mg.l-1) and phenylalanine (1g.l-1) by irrigation regime 3 day interval. The most important chemical compounds that determine the quality of S.bachtiarica essential oil included alcoholic monoterpenes such as P-cymene (35.4-20.1 %), gamma-terpinene (17.74-6.71 %), Carvacrol (36.54-22.14 %), Alpha-terpinene (2.56-0.65 %), Germacrene-D (2.01-0.65 %) and Thymol (1.45-0.54 %) made the most components of essential oil plants. Foliar application of chitosan (0.25 mg.l-1), ethanol (10 %) and phenylalanine (1g.l-1) significantly increased the monoterpene alcohols compounds in essential oils of S.bachtiarica. Generally, the application of chitosan at 0.25 gr.l-1 can be a good strategy to improve morpho-physiological characters and essential oil quantity and quality of S.bachtiarica in same climate.

In this study, the effect of electron beam (EB) irradiation of shrimp shells as well as the time and concentration of HCl and NaOH on the process of chitin extraction and chitosan production, were investigated. The products characteristics were evaluated by Fourier-transform infrared spectroscopy, atomic absorption spectroscopy, X-ray diffraction spectroscopy, thermogravimetric analysis, viscometry measurement, water and fat binding capacity determination and antimicrobial analysis. The extent and rate of demineralization and deproteinization increased initially by increasing of HCl and NaOH concentrations, respectively, and then leveled off. According to the results, demineralization with 0.5 M HCl for 6 h and deproteinization with 1.0 M NaOH at 65 °C for 6 h were proposed as suitable procedure for chitin extraction. EB irradiation of shrimp shells, in the range of 10-99 kGy, led to a decrease in the time required for both demineralization and deproteinization processes. Remained calcium in unirradiated and 30 kGy irradiated shells, after 6 h treatment with 0.5 M HCl, were 13.75 and 9.75 mg/g, respectively. Increasing of irradiation dose, led to a decrease in molecular weight (MW), an increase in deacetylation degree (DD) and a decrease in the crystallinity of chitosan. Depending on the irradiation dose and deacetylation reaction conditions, chitosan with DD varied between 60-95% and MW varied between 2.1×105-2.3×104 were produced. MIC and MBC of resultant chitosan samples, varied between             0.6-0.8 and 1.4-2.5 mg/ml against E. coli, as well as between 0.5-0.70 and 0.8-1.5 mg/ml against S. aureus, respectively. With increasing irradiation dose from 0 to 99 kGy, the diameter of inhibition zone against E. coli and S. aureus increased from 3.7 to 17.2 and from 5 to 18.8, respectively. According to the results, it seems that EB irradiation is a promising method for producing chitin and chitosan with unique properties suitable for different applications.

Abdominal adhesions are a common complication after laparotomy (abdominal surgery) that can cause intestinal obstruction, pelvic pain and infertility. Since inflammation plays an effective role in induction of intra-abdominal adhesions and galbanic acid has anti-inflammatory and anti-cancer effects, in the present research, its effect on inhibiting of pro-inflammatory factors such as TNF-α and IL-1β, in abdominal adhesions after laparotomy was investigated. For this purpose, after anesthetizing and opening the abdomen, adhesion was induced in male wistar rats and, adhesion was induced in male wistar rats, and in one group, 2 cc of chitosan gel was injected in the adhesion induction site and the abdomen was closed, and in one group, galbanic acid (10mg/ kg) was injected intraperitoneally for 7 days. At the end of 7 days, the abdomen was opened again and the abdominal adhesion was observed and a sample was taken from the adhesion sites. RT-PCR method was used to determine the gene expression of pre-inflammatory factors TNF-α and IL-1β. The results of the study showed that intra-peritoneal injection of galbanic acid like chitosan gel effectively reduced the incidence of intra-abdominal adhesions after laparotomy. This effect was accompanied by a decrease in TNF-α and IL-1β gene expression in both groups, which indicates the anti-inflammatory effect of these two natural substances.

Nanocomposites are prepared from various materials that may have antibacterial activity. This study aimed to investigate antibacterial and antifungal activityies of nanocomposites of bohemite-gold and bohemite-gold-chitosan by help of aqeous extract of peppermint.

In the current study, the nanocomposites were prepared by exextracellular biosynthesis and antibacterial properties were investigated by minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and killing-time curve by classic method of consecutive dilutions by Clinical & Laboratory Standards Institute.

The results showed that MIC and MBC were 10 µg/mL and 20 µg/mL for bohemite group, respectively. The results also showed that MIC and MBC were 2.50 µg/mL and 5 µg/mL against Acinetobacter baumannii and 5 µg/mL and 10 µg/mL against Escherichia coli, respectively. The greatest antibacterial activity for of bohemite-gold and bohemite-gold-chitosan was observed for a period of 6 to 24 h. Based on ourfindings, bohemite showed lower antibacterial activity compared with bohemite-gold and bohemite-gold-chitosan against the mentioned bacteria.

The prepared nanocomposites did not show any antifungal activity. Thus, bohemite-gold and bohemite-gold-chitosan nanocomposites have antibacterial activities against bacteria inducing infection in wound.

The volatility of essential oils and their instability against environmental factors limit their use. However, encapsulating these compounds in polymeric nanoparticles can significantly increase their half-life and make their use possible for longer periods. Chitosan, a biodegradable polymer with controlled release and low toxicity, is one of the polymers utilized in the encapsulation of essential oils. As a result, the present study was carried out with the aim of nanoencapsulation of carvacrol and thymol in chitosan using ionic gelation method and the concentration of chitosan (0.1-0.3%), TPP concentration (0.2-0.1%) and concentration of essential oil (0.1-0.2%) as three variables. The mean particle size of chitosan nanoparticles was optimized using response surface methodology and central composite design. The size and polydispersity index (PDI) were determined by DLS, essential oil loading confirmation was evaluated by FTIR, and the spectrophotometric method was used to measure the encapsulation efficiency. Then, the results of the optimization of nanoparticle synthesis were investigated. The optimum conditions for the synthesis of chitosan-thymol nanoparticles and achieving a size of 101 nm and encapsulation efficiency of 72%, a concentration of 0.11% chitosan, 0.19% TPP and 0.14% thymol were determined. In the case of chitosan-carvacrol nanoparticles, a concentration of 0.13% chitosan, 0.19% TPP and 0.15% carvacrol resulted in the formation of nanoparticles with a size of 95 nm and an encapsulation efficiency of 65%. In general, the results demonstrated the ability of the response surface methodology to predict the particle size and PDI of chitosan nano-formulations containing carvacrol and thymol.

In this research, using a suitable method and in line with the development of green chemistry, chitosan particles were prepared through the process of deacetylation from Persian Gulf shrimp shell waste, and then a copper-based complex was successfully synthesized on a substrate of chitosan particles, and with Techniques such as Fourier Transform Infrared Spectrometry (FT-IR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), X-ray Energy Diffraction Spectroscopy (EDX), Elemental Mapping, and Visible-Ultraviolet Spectroscopy (UV-Vis) was investigated. A wide variety of biaryl compounds were successfully synthesized through the developed catalytic process. The use of chitosan-copper (II) complex catalyst in the synthesis of biphenyl derivatives showed several advantages, including mild reaction conditions and short synthesis time, significant efficiency, avoiding the production of toxic waste, and easy separation of the catalyst. Furthermore, the chitosan-copper(II) complex was easily recovered by filtration and could be reused for five cycles without losing its structural integrity and catalytic activity.

Curcumin is a yellow polyphenol extracted primarily from the plant Curcuma longa, but also from several other members of the ginger family.Many nanoscale systems have been extensively used for drug loading and release to get around curcumin's low bioavailability and aqueous solubility, highlight its functional properties, and broaden its applications in the pharmaceutical industry.Chitosan has been used as a natural biopolymer extensively for many years. Its polycationic properties, biocompatibility, biodegradability, non-toxicity, and lack of allergenicity all led to studies on it. The main focus in the discovery of curcumin involves its anti-cancer properties. It is well known that curcumin inhibits the signal transmission of cancer cell growth and thus angiogenesis and also causes tumor cell apoptosis. The modification of chitosan for various applications can be easily achieved due to the abundant active groups (NH2 and OH) in the main chainFor the release of curcumin, numerous chitosan-based nanocarriers with distinct properties have been developed, including nanocomposites, nanoemulsions, nanotubes, and nanofibers. The controlled release of the drug is to maintain the optimal therapeutic concentration of the drug in the blood, which increases the shelf life and duration of activity of drugs with a short half-life. Controlled drug release makes the drug release rate predictable and repeatable for prolonged release drugs. Therefore, the development of colloidal systems for curcumin release encapsulation is a promising strategy to overcome the limitations of drug release. The physical and chemical characteristics of chitosan-based nanocarriers, including surface charge, morphology, encapsulation driving force, and release characteristics, are examined in this study and the effectiveness of chitosan-based nanocarriers for pharmaceutical applications is determined by these characteristics.

One of the methods to increase the secondary metabolites production in plants is to use elicitors and chitosan is a biotic elicitor obtained from the deacetylation of chitin in the outer shell of crustaceans such as shrimp. Shrimp shell is part of shrimp solid waste discarded in large amount every year. This research was carried out to investigate the effect of foliar application of chitosan elicitor (0.25 and 0.5 g/l) and shrimp shell powder (2.5 and 5 g/L) on medicinal plant Hyssopus officinalis in potted form at the Experimental Farm of Islamic Azad University, Shahre-kord Branch during spring to fall in 2017. The essential oils were obtained from aerial part of hyssop by Clevenger device. The essential oils were analyzed by GC-FID and GC/MS. Totally, 33 compounds و representing more than 89-95% of the oil composition, were identified. The predominant components of the essential oil in all treatments were cis-pinocamphon (43.19-55.09%) and beta-pinene (8.31-15.04%). Foliar application of chitosan, shrimp shell, and shrimp shell × chitosan increased the percentage of essential oil and cis-pinocamphon, but only the effect of chitosan 0.5 was statistically significant. Chitosan treatments decreased plant height, shoot fresh and dry weight, chlorophyll a, chlorophyll b and total chlorophyll of hyssop but shrimp shell and chitosan × shrimp shell solutions increased them, although no one was significant. According to the results of this study, it seems that in addition to chitosan, shrimp shell with higher concentrations can be used to increase effective substances of the medicinal plant Hyssopus officinalis.