جستجوی مقالات مرتبط با کلیدواژه « کیتوسان » در نشریات گروه « پزشکی »

Activated textiles have created a new field of application apart from standard textile applications. Novel, functions, for example, antimicrobial properties have been enhanced in textiles. New textile application fields have been recognized for particular areas of healthcare as well as industry, sportswear, and, home textiles. Advances in the field of antibacterial textiles have fascinated enhancing attention because those are a means to solve serious health challenges such as bacterial overgrowth. A lot of research has been done in the field of adding synthetic and toxic materials to fabrics, such as nanosilver triclosan or other metals and organic materials to produce antimicrobial fabrics. These fabrics kill bacteria by binding to intracellular proteins and inactivating these proteins. Also, by using these chemicals, the content of heavy metals in these textiles can be increased. The application of heavy metals in antimicrobial textiles is limited by many environmental tags and standards. Therefore, it is recommended to use natural antimicrobial agents, such as nisin and chitosan to produce environmentally friendly and safe antimicrobial fabrics. Nowadays finishing process with the natural antibacterial agents that protect the environment and human health is gaining importance. Therefore, this study aims to produce fabric coated with chitosan and nisin and to investigate its antimicrobial properties.

In this research, chitosan was used to bind nisin to the surface of polypropylene span band non-woven fabric. The fabric samples were coated with a solution containing chitosan and nisin using a pad-dry-cure method. The appearance, color, and softness of the coated fabrics were compared to the uncoated fabric. The nisin and chitosan binding properties on the fabric were explored by using the Fourier-transform infrared (FTIR (technique. The diffusion method in agar and the standard method (ASTME2149-01) were used to check the antimicrobial properties of fabric samples. The antibacterial effectiveness of fabric samples was tested against common bacteria such as Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes, and Enterococcus faecalis. After ten washing cycles, the durability of the antimicrobial properties of these fabrics was checked by the method mentioned above. Also, the toxicity of this fabric on fibroblast cells was determined using the MTT colorimetry method after seven days.

Fabrics coated with chitosan and nisin do not differ much from the control sample in terms of appearance and softness. The changes observed in the FTIR spectrum, such as the appearance of new absorption peaks and additional peaks associated with peptide bonds, confirm the successful incorporation of nisin and chitosan into the fabric. Antibacterial results have shown that nisin improved the antibacterial effect of coated fabrics versus B. cereus, S. aureus, and P. aeruginosa. The antimicrobial properties of the fabric coated with chitosan-nisin were maintained at some of the efficacy after washing against B. cereus, S. aureus, E. faecalis, L. monocytogenes, E. coli, and P. aeruginosa respectively. Also, the chitosan-nisin coating showed that it did not cause significant toxicity in fibroblast cells even after one week.

However, the results showed that the chitosan/nisin coating might be used for medical textiles and antibacterial textiles. It also offers an innovative solution to protect human health and the environment.

Chitosan biopolymer, due to its antimicrobial, anti-inflammatory, and antioxidant properties, has become an ideal candidate for use in a wide range of cosmetic products and has opened up new horizons in the design of cosmetic formulations. The ability of this polymer to electrostatically interact with negatively charged surfaces (such as damaged skin) leads to the formation of polymeric films and ultimately imparts smoothness and moisture to cosmetic products. This review article revisits the potential of chitosan and its derivatives as raw materials in cosmetic and skincare products.

Antibiotics as emerging pollutants are harmful to environmental health. Therefore, this study was conducted to investigate the efficiency of Uio-66-NH2@CS-Iso-Gu nanohybrid for the removal of amoxicillin (AMX) from aqueous solutions.

In this study, for the first time, guanidine and isocyanate monomers are cross-linked with chitosan. The combination of this polymer with organometallic compounds contributes to its chemical/thermal stability and reusability. Uio-66-NH2@CS-Iso-Gu nanohybrid was characterized using X-ray diffraction (XRD), Scanning electronic microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Thermogravimetric analysis (TGA), and BET methods. Also, the effects of pH, initial concentration of AMX, contact time, and temperature were evaluated. Moreover, isotherm, kinetic and thermodynamics studies were performed.

The results of TGA analysis showed that Uio-66-NH2@CS-Iso-Gu nanohybrid was resistant to temperatures up to 400 °C. Also, optimal adsorption of AMX occurred in the first 25 min. The synthesized nanohybrid has a surface area of 101.2 m2/g and a type IV isotherm. Acidic groups were present on the synthesized nanohybrid surface based on the pHpzc = 4.7. Langmuir (for 25 °C and 45 °C) and Freundlich (for 65 °C) isotherm models and pseudo-second-order kinetic models are more appropriate to fit the adsorption data with the experimental data. The maximum adsorption capacity of the synthesized nanohybrid was equal to 56.49, 40.65, and 0.382 mg/g at temperatures of 25°C, 45°C, and 65°C, respectively. Based on the findings, Uio-66-NH2@CS-Iso-Gu nanohybrid could be used for up to five cycles without significantly reducing their performance.

The results showed that Uio-66-NH2@CS-Iso-Gu nanohybrid has a significant efficiency for removing AMX and could be used as an effective adsorbent for the treatment of wastewater containing pharmaceutical residues.

Zeolites are among the widely used adsorbents for the removal of arsenic-toxic pollutants. The objective of this study is to prepare granulated zeolite adsorbents using chitosan (CS/Fe-Clin) and alginate (Alg/Fe-Clin) and compare them in terms of physical appearance and arsenic adsorption efficiency.

Granular adsorbents were prepared via the ionotropic gelation method. The effects of the type and concentration of the cross-linking solution and the initial ratio of materials in granules formation, as well as the effect of initial arsenic concentration, and the amount of adsorbent used on the adsorption efficiency, were investigated. SEM, XRD, FTIR, and AAS analyses were used to confirm the results. Equilibrium data were matched with Freundlich and Langmuir isotherms.

A weight percentage of 2 % iron chloride (III) and an initial ratio of 1:4 of alginate: nanocomposite for Alg/Fe-Clin and a weight percentage of 2 % (1 % sodium hydroxide + 1 % sodium tripolyphosphate) and an initial ratio of 1:3 of chitosan: nanocomposite for CS/Fe-Clin were chosen as the optimal values. Maximum adsorption efficiency of Alg/Fe-Clin and CS/Fe-Clin adsorbents was determined 88.1 and 92.9 % at dosages of 0.6 and 1 g/L and at initial concentrations of 200 and 300 µg/L, respectively. The qmax values for Alg/Fe-Clin and CS/Fe-Clin adsorbents were 11.11 and 10 mg/g, respectively. Results better fitted with Freundlich isotherm.

Due to the proper adsorption capacity, both synthesized adsorbents showed the ability to effectively remove arsenic; whoever, alginate binder was more efficient.

Today, cancer is one of the health concerns in modern societies. The use of nanoparticles in diagnosis, drug delivery, imaging, and cancer treatment has received much attention in medical sciences.   The most important problem when treating cancer with chemotherapy is the lack of access to the central parts of the mass due to its less blood supply. This study aimed to investigate the toxicity of iron oxide nanoparticles coated with biopolymer chitosan/alginate on melanoma cancer cells (Hep G2 cells).

In this research, magnetic iron nanoparticles were coated with two biopolymers, namely chitosan and alginate. The size and surface morphology of these nanoparticles were checked by size measuring device and scanning electron microscope. Moreover, the binding of functional groups of chitosan and alginate to iron magnetic nanoparticles was checked by an infrared spectrometer. In this study, magnetic iron nanoparticles and modified nanoparticles were treated for 24 hours and the IC50 concentration of the compounds was estimated. The toxic properties of these nanoparticles were evaluated by MTT test and acridine orange/ethidium bromide staining.

After examining the photos of the scanning electron microscope and the size measuring device, the size of 50 nanometers was shown for the modified iron nanoparticles, and the shape of these nanoparticles was observed to be completely round and spherical.

The findings from the investigations of binanoparticles definitely confirmed the effective coating of nanoparticles by chitosan and alginate biopolymers. Furthermore, the findings showed that magnetic iron nanoparticles had higher toxic effects depending on the concentration and their IC50 concentration was about 134 µM/ml, while the coated nanoparticles had significantly lower toxic effects and did not have significant toxicity on Hep G2 cells at concentrations below 25 μM/ml. The coating of iron oxy nanoparticles significantly reduces their toxicity concentration.

In tissue engineering, a porous material is applied as the extracellular matrix or scaffold for cell growth. Then growth factors are added to this scaffold whose cytotoxicity must be assessed. In this study, the cytotoxicity effects of polyhydroxybutyrate/chitosan/bioglass nanocomposite scaffolds on human osteoblast-like cells (SAOS-2 cells) are explored.

This study was experimental and was done in Isfahan Dental School. The polyhydroxybutyrate/chitosan/bioglass nanocomposite scaffold was fabricated using the electrospinning method. Scanning Electron Microscopy (SEM) analysis was used to evaluate the morphological characteristics of the nanofibers and their diameter distribution. Additionally, bioglass nanoparticles in the fibers were identified via SEM. The MTT assay was performed to assess cell viability after 3, 5, and 7 days. The collected data were analyzed using SPSS 20.0 through statistical tests including Kruskal-Wallis test (p value ≤ 0.05).

According to SEM images, the scaffold fibers were fully porous and no beads were observed. Furthermore, the polyhydroxybutyrate/chitosan/bioglass scaffold showed greater cell viability and proliferation compared to the groups lacking bioglass.

The polyhydroxybutyrate/chitosan/bioglass scaffold has no cytotoxic effect on osteoblast– like cells.

Today, the use of magnetic nanomaterials promises purposeful and intelligent drug delivery. These magnetic drug nanocarriers can respond appropriately and intelligently to the external magnetic field, which can be used to selectively release the drug into the target tissue. Therefore, this study investigated the synthesis of zinc ferrite nanoparticles and some of their structural, electronic, and magnetic properties. The ultimate goal of this study is to use nanotechnology and quantum mechanics in intelligent and targeted drug delivery to improve the patient's quality of life and reduce the destructive effects of unwanted drug distribution in healthy tissues.

In this study, zinc ferrite nanoparticles were prepared using heat treatment, and then the structural and magnetic properties of these nanoparticles were investigated using imaging-measurement methods on the nanoscale. In addition, cytotoxicity test (MTT) was performed on mouse fibroblast cell line (NIH3T3), and the results were analyzed using SPSS software. Moreover, using the results of quantum calculations, the chitosan molecular system was proposed as a coating for this drug carrier.

Analysis of the results obtained from X-ray diffraction (XRD) and electron microscopy (SEM) spectra confirmed the existence of spinel structure and the small size of these particles (20-23 nm). Furthermore, the results obtained from the vibrating magnetometer and the paramagnetic resonance spectrometer showed the presence of paramagnetic properties in the synthetic nanoparticles. In addition, the analysis of the results obtained from the vibrating magnetometer shows the low magnetic residue of the synthetic magnetic nanoparticles. This can be useful in the mechanism of targeted drug release. In addition, analysis of cytotoxicity (MTT) test results on synthetic nanoparticles showed that the toxicity of these nanoparticles depends on the concentration (dose) and time. Therefore, at concentrations higher than 20 µg/ml and also over time, the vital activity of cells decreased.

Based on the results obtained in this study, the use of magnetic zinc ferrite nanoparticles (coated with chitosan) for targeted drug delivery to the target tissue was suggested. The unique properties of these drug-carrying nanoparticles, such as good magnetic field response, good particle size, and low toxicity, enable the physician to have more precise control over targeted drug delivery to the target tissue.

 Noninvasive treatments are preferred for tooth enamel remineralization, and metal nanocomposites could be used for this purpose. The present study investigated the effect of boron nanocomposites doped on the hydroxyapatite-chitosan surface on the microhardness of demineralized tooth enamel.

 In this laboratory study, boron nanocomposites doped on the hydroxyapatite-chitosan surface were made by the sol-gel method. A total of 45 healthy human teeth were selected and divided into buccal and lingual halves. The demineralization cycle of the samples was performed for 14 days to demineralize the tooth enamel surface. The samples were randomly divided into three equal groups based on the use of remineralizing materials, G1:hydroxyapatite-chitosan nanocomposites; G2:boron nanocomposites doped on the hydroxyapatite-chitosan surface, and G3:control group without nanocomposite. Nanocomposites were applied on the surface of the teeth for 28 days (twice a day). The microhardness of the samples was performed by the Vickers test at three points. The SPSS software (version 19), one-way analysis of variance, and Tukey's test were used for statistical analysis of the data (α=0.05). The surface morphology of the groups was examined by SEM[A1] .

 There was a statistically significant difference between the three studied groups (P<0.001). The highest mean was first observed in the G2(368.12) and then in the G1(342.62). Moreover, the lowest mean was related to the control group(267.53). Pair-by-pair comparison of groups showed that there was a significant statistical difference between groups 1 and 2, 1 and 3 as well as 2 and 3 (P<0.05).

 Both HApC and B@HApC compounds improve remineralization and increase the microhardness of tooth enamel; however, this increase was greater in the presence of a boron-containing compound.

Nanoparticles are effective in cancer cells and in the treatment of diseases due to their ability to induce toxicity and induce apoptosis and antibacterial properties. Pecan seeds are rich in carbohydrates, lipids, proteins, mineral salts, alkaloids, and amino acids; among its important alkaloids are harmaline, harmine, harmalol and vazisine can be mentioned, which have many uses in industry and medicine. The aim of this research is to investigate the effects of pecan smoke loaded with nano-chitosan on cytotoxicity, apoptosis induction and its antibacterial effects.

In this experimental study which was conducted in vitro, MTT test was used to investigate the toxicity effect of chitosan nanoparticles loaded with pecan smoke on ovarian cancer cell line A2780 and HFF normal fibroblast cell. Also, to investigate the induction of apoptosis, the method of determining the expression of the caspase 3 gene was used, and to investigate the antibacterial properties, the disk diffusion method was used on the gram-positive bacteria Staphylococcus aureus and Micrococcus luteus and the gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa. Statistical analysis was performed by SPSS software and one-way analysis of variance. P<0.05 was considered as significant.

The result of the MTT test showed the value of IC50 for ovarian cancer cells in 48 hours after treatment as 17.155 μg/ml; while at the same concentration for the normal cell line, the survival rate was 98%. Also, the induction of apoptosis of A2780 cancer cells was observed based on a significant increase in the expression of caspase 3 gene. In addition, these nanoparticles had an inhibitory effect on the growth of Staphylococcus aureus and Micrococcus luteus bacteria.

Chitosan nanoparticles synthesized by Peganum harmalla smoke had anti-cancer, apoptotic, and antibacterial activity.

Wound dressing materials allocate a great portion of skin and draught maintenance in the global medical market.  In previous times the conventional dressing materials as natural and synthesized bondage, Cotton and gas were used for caring of skin wounds. Nowadays the production of modern wound dressing of higher restorative capabilities has attracted the attentions. These modern wound dressing can precipitate the re-epithelization, collagen synthesis and angiogenesis. These modern wound dressing materials can reduce the PH and perform as a barrier to bacterial penetration. There are several methods available for production of fibers and nanofibers. Between these methods electrospinning has attracted much interests. By this procedure it is possible to produce composite fibers and porous mats. The cells can penetrate to these pores and grow appropriately. The manufactured fibers usually have proper uniformity and the dimensions can vary from several nanometers to micrometers. These fibers can be used in different applications such as the filters, the fortifiers, the scaffolds and the wound dressing materials. The biocompatible materials are among the best choices for fabrication of the wound dressing, They can provide the necessary condition for growth of derma and epidermal layers. The multi-polymers Mat fibers have been used for tissue engineering applications, as they have the capability of the simulation of the extracellular Matrix. Drug addition to these scaffolds can enhance the function of this system and improve the restoration capabilities.  The electrospun wound dressing materials facilitate the tissue growth. The electrospun nano-fibers have similar structures to that of the skin and have higher compatibility with blood. They make the wound and tissue restoration possible. In this research the production of two layers wound dressing materials has been conducted by the electrospinning Method. The downward layers of these wound dressing materials have been manufactured from polyvinyl alcohol. Polyvinyl alcohol is a synthetic polymer which has proper electrospinning properties, and therefore it can be used for nanofibers production. The fibers have high tensile strength and an appropriate flexibility. This material is one of the oldest and most common materials that have been utilized for drug delivery systems, wound dressing and wound maintenance, contact lens and artificial limbs. This polymer is biocompatible, and due to the hydroxyl groups, it has reasonable water absorption. Also for infection inhibition vancomycin drug has been loaded in this layer.

Many different wound dressing fabrication methods have been used for many years. Among these techniques, electrospinning has attracted a lot of attention. This simple and cost-effective method produces nano and micro fibers substrates which simulate extracellular matrixes and provide a suitable porous structure for cell adhesion and proliferation. In this study, electrospinning was used for the fabrication of two-layer wound dressing, consisted from chitosan and poly (lactide-co-glycolide) acid (PLGA) as the first layer and polyvinyl alcohol (PVA) and vancomycin as the second layer. For the first layer electrospinning, the solution of chitosan, poly-lactic co-glycolic acid has been provided and transmitted to 5 ml syringe and located in the place.  the syringe tip attached to the electrical current source and the electrospun fibers were collected it on a aluminum foil covered collector. The ejection action was performed by the flow rate of 2 ml per hour and the electrospun fibers were manufactured on a 50 mm diameter collector.  In this research, the distance between the nozzle and the collector was 120mm and the rotating speed of the collector was 16 RPM. The device voltage was set at 15 kilovolts. For electrospinning of the second layer the solution of polyvinyl alcohol and vancomycin was provided and transmitted into 5ml syringe, just like previous steps.  The injection process was performed by the volume rate of 1 ml per hour and electrospun fibers were gathered on the 15 mm diameter collector.  In this level, the distance between the nozzle and the Collector was 200mm, the rotating speed was 10 RPM and the device voltage was set at 15 kilovolts. For cross-linking, the samples were located on the vapor of glutaraldehyde and HCL by the molar ratio of 1:10 for 12 hours.

Electrospun two layer wound dressing microstructure was evaluated by scanning electron microscopy (SEM). It was observed that both layers have homogenous bead free interconnected porous structures. Image measurement software revealed that fiber diameters ranged from 0.2 to 1.2 micrometer, which can provide a proper substrate for cell proliferation. Functional groups of raw materials and chemical bonding between layers were assessed by FTIR analysis. In order to evaluate layers absorption capacity, they were soaked in PBS solution for 24 hours. They showed about 112.4±10.2 % PBS absorption after 24 hours. So they can absorb wound secretions and keep the wound environment dry. Biodegradation tests showed that 32.7 % of these two layer wound dressing was degraded after 3-weeks immersion in PBS solution. Drug release tests demonstrated a burst release of vancomycin in the first hours which followed by decreasing releasing rates. These releasing manner lowered infection appearance in the wound site. Antibacterial activity is an important factor in wound dressing and the co-existence of chitosan and vancomycin provided approximately 98.72 % bacterial reduction in the antibacterial assay. Although the antibacterial test showed a significant reduction in bacterial growth, the MTT test showed that these scaffolds are biocompatible and provide a favorable environment for cell attachment and proliferation.

The images of the microstructure electrospun substrates depicted that electrospun two-layer polyvinyl alcohol vancomycin and poly lactic co-glycolic acid chitosan substrate has a porous fiber structure, in a way that these pores are interconnected.  The fibers of two layers have no beads and they have relatively homogeneous distribution. The water absorption of these scaffolds showed suitable inflation strength in 24-hours of submerge in phosphate buffer saline.  Also the degradation capability of the samples demonstrated the approximately 32% degradation of the structure in 3-weeks.  It illustrated convenient degradation time of wound dressing and it is in good correspondence with previous researchers. Drug delivery assessment of vancomycin from these samples was relatively explosive in the initial hours.  But it reached an equilibrium state in some hours.  The initial explosive delivery can lead to eradication of the initial bacteria and it is a key factor in wound dressing applications. The antibacterial assessment of their structure demonstrated high antibacterial capabilities due to the existence of chitosan and vancomycin in these scaffolds. About 98% of the batteries at the dose of 10 mg/lit were perished.  Also the cellular viability investigation for these scaffolds proved non-toxicity and biocompatibility. The cultured cells on the scaffolds had normal morphology. According to acquired results in this study, it seems that these two layer electrospinning substrates can be useful for wound healing.

The present study was performed to identify nicotine (NIC) in seawater in the presence of cigarette butts, several plants and seaweed using a modified glassy carbon electrode (MGCE) by cyclic voltammetry (CV).

The electrode was synthesized using the electrospinning technique of carbon nanotubes and chitosan and can detect the NIC of floating cigarette butts in a saltwater aquarium with the presence of two types of marine plants and a model of algae planted in sea sand.

Oxidation signals at lower potentials and higher currents in the presence of cigarette butts for the three plants Acetabularia, Caulerpa Mexicana and the algae sponge Codium SP show the decomposition of nicotine by these plants during photosynthesis and over time, respectively. These numbers for these plants are 0.82, 0.81 and 0.83 mV with currents of 57.70, 56.56 and 51.49 mA, respectively. Changes in pH, voltage and electric current over time and scan rate were investigated and the results show that the present electrode for parallel detection of NIC for 5 repetitions, 97.2% with standard deviation of 4.08 was able to maintain its stability compared to the first cycle.  

Therefore, MGCE electrode has excellent repeatability and stability, and this electrode can be used for proper diving guidance in environments with hazardous municipal waste.

Increasing adhesion of restorative glass ionomer cement to the tooth surface leads to reduction of recurrent caries and improvement of restoration durability. In present study, effect of Chitosan and nanoparticles of Titanium dioxide on glass ionomer cement adhesion to the tooth surface was investigated.

On dentinal surface of 56 buccal and lingual surfaces of 28 extracted human third molar, four different kind of glass ionomer cement were bonded: 1.Non-modified galss ionomer cement 2.Chitosan 10%v/v modified glass ionomer cement 3.NanoTiO2 3%w/w modified glass ionomer cement 4.Dual modified (Chitosan 10%v/v and Nano TiO2 3%w/w) glass inomer cement. samples were kept in humidity of 100% and temperature of 37°C for 24 hours. Shear bond strength of the glass ionomer cements of four groups were measured by Universal Testing Machine and the results were analyzed using Tukey test and ANOVA. FTIR and XRD tests were conducted to evaluate the chemical structure of the glass ionomer cement of each group.

Only shear bond strength results of the group which was simultaneously modified with Chitosan 10%v/v and nanoparticles of Titanium dioxide 3%w/w had shown significant different with the control group (P=0.016). XRD and FTIR tests showed no changes in the chemical structure of the glass ionomer of any modified group in comparision to the control group.

Modification of the restorative glass ionomer cement by Chitosan 10%v/v and nanoparticles of Titanium dioxide 3%w/w simultaneously, leads to improvement of the shear bond strength of glass ionomer cement to the tooth structure.

Progressive neurodegeneration of nervous system as well as learning and memory disorders is characteristics of Alzheimer’s disease. Drug delivery is one of the research aspects for improving treatment of diseases. Chitosan nanoparticles were used for Donepezil transportation and its effect on
dimproving amnesia was investigated.

In this experimental study, 136 NMRI mice weighing 30-40 mg were used. All injections were done intraperitoneally. The first experiment aimed to determine the optimal dose of ethanol for inducing amnesia, the second experiment was performed to prove nano-chitosan loaded with Donepezil (0.25, 0.5, 0.75, 1 mg/kg) does not impair memory, and the third experiment assessed the effect of nano-chitosan loaded with different doses of Donepezil on amnesia induced by ethanol. Data were recorded as mean ± SD, analyzed in GraphPad Prism software using ANOVA and Tukey post hoc test. P<0.05 was considered as significant.    

The first experiment showed that ethanol (0.5, 0.75, 1 mg/kg) could significantly induce amnesia. The second experiment showed nano-chitosan loaded with Donepezil doid not impair memory. The third experiment showed that all nano-chitosan groups loaded with different doses of Donepezil could significantly improve amnesia induced by ethanol.

Chitosan nanoparticles used in this study can efficiently be used for drug delivery. However, further research should be done on this compound before it can be used for oral drug transportation.

Changes in drug concentration (release) in the body is one of the most important parameters affecting the health of patients, whose sharp increase or decrease can cause complications in patients. Therefore, it is very important to study the release of the drug and determine the concentration of the drug in the body. Drug release in the human body can be done through various mechanisms that by examining drug release at different times, effectiveness of each mechanism can be determined. Drug delivery systems can be divided into general categories: diffusion-controlled, swelling-controlled, and environmentally sensitive systems, each of which can release the stored drug under different conditions and through different mechanisms. Recently, drug release in swollen hydrogels has attracted many attentions from researchers, indicating the importance of this drug delivery system. Hydrogels are crosslinked polymeric networks that can absorb water more than twenty times their own weight. Depending on their environment, hydrogels can swell or release absorbed water. There are different types of hydrogels that can swell in response to changes in temperature, pH, glucose levels, etc. in the external environment. For example, environmentally sensitive hydrogels can be engineered to initiate drug release at a specific location.  Most of the studies on drug release from swollen hydrogels have been performed experimentally and its modeling has been limited and with many assumptions. Therefore, the aim of this study was to model the drug release kinetics in chitosan (CS), gelatin (Gel) and polyvinyl alcohol (PVA) hydrogels.

Drug release modeling in five hydrogels with different ratios of CS and Gel based on PVA with different swelling rates were compared. First, using Excel software, the swelling rate of each hydrogel was compared to time, then it was used to simulate drug release in each of the hydrogels. In this modeling, using MATLAB software and mass transfer relations, diffusion and bulk motion (hydrogel boundary swelling) mechanisms were numerically simulated and compared. The assumptions applied to solve the equations of changes in drug concentration were such that the concentration of drug around the hydrogel (drug discharge site) was equal to zero and the diffusivity coefficient was considered constant. The output of the modeling was in the form of two- and three-dimensional graphs showing the changes in drug concentration and swelling rate over time. One of the advantages of drug release modeling in swollen hydrogels is the independence of these results from the type of drug.

Modeling findings for all hydrogels showed that the mechanism of drug release through mass movement is very important, so that with increasing swelling rate in a hydrogel, less time is required to complete discharge of drug and then drug with higher dose is released in the body. Cs: Gel (1: 3) hydrogel, which is less swollen than other hydrogels, takes longer (150 minutes) to completely discharge the drug. In other hydrogels, the discharge time of the drug decreased with growth in the same way, which showed the effect of growth rate of the drug-carrying hydrogel on required time for drug release which decreased with increasing the ratio of chitosan to gelatin to make the hydrogel. For example, in the Cs: Gel (3: 1) hydrogel, which had the highest growth rate, the drug discharge time was approximately 90 minutes. Hydrogels with less chitosan in their structure had lower swelling rates leading to reduce the rate at which the drug was discharged through the mass movement in the polymer network of the hydrogel, and had a lower mass flux to discharge the drug. The findings of the modeling are consistent with the results of previous studies, so that in the research conducted by Islam et al., CP4 and HG2 hydrogels had highest swelling rate and release of progesterone, dexamethasone and aspirin at pH=6.8. However, at pH = 1.2, CP4 and HG2 had the lowest swelling and drug release rate. Considering the diffusivity coefficient in the equations, the expression of local volume changes in Equation (2) plays an important role in determining the time of complete discharge of the drug from the hydrogel. For drugs that need to be released at low flow rates and fluctuations in drug concentrations may cause side effects, hydrogels with lower growth rates can be used. Hydrogels with higher swelling rates can also be used for drugs that require high concentrations in the body.

From the modeling results obtained in this study and the results of previous researches, it can be seen that the mechanism of mass movement in swollen hydrogels is very important, so that in some hydrogels the contribution of drug discharge through the hydrogel boundary swelling is greater than the drug discharge through diffusion. In addition, to determine the contribution of each mechanism, different combinations of hydrogels can be used to produce the drug reservoir, and by reducing or increasing their swelling, the contribution of the mass movement mechanism can be reduced or increased, respectively. In this work, increasing the ratio of chitosan to gelatin increased swelling and consequently the role of mass movement mechanism in drug release. As a result, in order to increase the drug discharge time, the ratio of gelatin to chitosan should be increased, whereby the swelling rate and finally the discharge rate of the drug are reduced.

One of the goals of medical science in current communities is wound healing in shorter time and with less side effects. The nettle extract in the presence of chitosanchr('39')s natural polymer can have antimicrobial and repairing properties. It also improves the recovery speed with less complications and less time.

For different tests, we produced a chitosan film with different percentages of 10%, 20%, 40% of nettle extract and a control sample without plant extracts. These tests include scanning electron microscopy (SEM), percentage of water absorption, antibacterial properties, percentage of inflation, degradability rate.

The sample with high percentage of plant extract had a higher porosity surface than other samples and could be considered as a suitable wound dressing. Using two gram positive bacteria (Staphylococcus aureus) and gram negative (Pseudomonas aeruginosa) from the body of patients in Taleghani Hospital of Tehran to evaluate the antimicrobial activity of the film containing nettle extract and chitosan was used. The results of Staphylococcus aureus bacteria are better than Pseudomonas aeruginosa. Results were calculated with Prism software.

A wound dressing should be capable of absorbing extra secretions from the wound, antibacterial, smoot cutting without damaging the wound , biodegradable. The results of this study indicate that the wound dressing prepared in this project can have the conditions of an ideal wound dressing.

In addition to its protective role, dressings not only prevent infection, but also accelerate wound healing process. In this study, the influence of optimizing the properties of the calendered needle-punched nonwoven fabrics using the finishing materials of Honey, Aloe Vera, Chitosan and Nano Argentum Nitrate for the end-usage as dressing has been investigated.

The prepared samples of the needle-punched nonwoven fabrics were firstly calendered and then, tested for the fundamental expected physical characteristics in the dressing purpose, i.e. crease recovery magnitude, air permeability, etc. in order to distinct initial optimized sample. In the following, the antimicrobial finishing process was carried out on the primary sample by the four studied finishing materials. The finished samples were finally analyzed simultaneously from the antimicrobial aspect and also, for the same physical properties of the dressing, as tested before, to distinguish the ultimate optimized sample. The bacteria of Staphylococcus aureus and Escherichia coli (E.coli) were also employed for antimicrobial tests.

The results demonstrated that combination of four finishing materials of Nano Silver 1%, Aloe-Vera 20%, Honey 7% and Chitosan 1% improved desired properties for wound dressing application in comparison to the other samples from one side and, showed no cellular toxicity and allergy from the other side. The FTIR’s results also implied stretching bonding of hydroxyl group in 3200-3400 wavenumber.

The needle-punched nonwoven fabric finished by the recommended antimicrobial materials can be considered as wound dressing, regarding to sufficient physical properties and hygienic condition.

Chitosan is a natural polymer with special properties that are prepared and purified in the industry of crustaceans. In this study, Trametes versicolor fungus, which was obtained from the forests of northern Iran, was used due to its medicinal properties, and the extracted chitosan of this fungus was optimized and its antimicrobial properties were investigated.

To increase chitosan, four influential NaOH parameters, time, temperature, and biomass to NaOH ratio were performed by the Taguchi method. Fourier Transformed Infrared Spectrometry (FTIR) was identified, and the antibacterial properties of the disc release method were investigated against Escherichia coli and Staphylococcus aureus bacteria and the bacterial non-growth halo by millimeters.

The optimal conditions of the variables were: 5.94 Molar, 4 hours, and 40 minutes, 65.6 degrees Celsius, and 1:25 ratio, respectively. Under these conditions, the amount of chitosan produced was equal to 0.261 g/L and the degree of deacetylation 78% was obtained. The antibacterial properties against E. coli gram-negative bacteria and S. aureus gram-positive bacteria were found to be 12±1 and 18±2, respectively.

Evidence has shown that four parameters had a positive effect on more chitosan production and the S. aureus is more sensitive to the resulting chitosan.

Tissue engineering identifies degraded tissue components and provides rational solutions to improve and perform them. One of these approaches is to fabricate a mixed scaffold with polysaccharide and synthetic antioxidants for stem cells to be cultured inside. The aim of this study was to evaluate the potency of poly caprolactan-chitosan-tannic acid scaffold for proliferation of fibroblast cells.

In the present experimental study, polycaprolactane, chitosan powder and tannic acid scaffold were prepared for growth of fibroblast cells. Subsequently, the following groups were designed: Group 1: Polycaprolactane scaffold Group 2: Polycaprolactane-chitosan scaffold Group 3: Polycaprolactane-tannic acid scaffold Group 4: Polycaprolactane-chitosan-tannic acid scaffold. The human foreskin was prepared and the dermal layer fibroblast cells were isolated after laboratory tests, then the cells were placed in cell culture flasks with DMEM medium and stored in a 5% CO2 incubator. Ten thousand cell fibroblasts were transferred to 96-well wells containing DMEM solution and scaffolds and then fibroblast cell proliferation and viability were determined by MTT assay and by SEM microscopy to determine the infiltration of fibroblast cells into scaffolds and also in order to review of the chemical groups in the polymers was performed using a FTIR spectrometer. The results were analyzed by the SPSS software; ANOVA and Tukey's post hoc test after the data were analyzed uniformly

The mean survival rate of fibroblast cells based on MTT assay at 24 h was significantly increased in the polycaprolactone-tannic acid scaffold group (p<0.05) compared to the polycaprolactone scaffold group (p<0.05). The results also indicated that the mean survival of cells based on MTT assay at 24 h was significantly increased in the polycaprolactone-chitosan-tannic acid scaffold group (p<0.05) compared to the polycaprolactone scaffold group (p<0.05). Moreover, the mean cell viability in the polyprolactone-chitosan scaffold was not statistically significant compared to the polyprolactone group.

Due to its hydrophilic properties and biocompatibility of chitosan and tannic acid, poly caprolactone-chitosan-tannic acid scaffold may be a suitable scaffold for the activity of fibroblast cells in the scaffold.  It can also be a good environment for the growth and proliferation of other cells.