Mixture Of Chitosan Research Articles

Fe3O4/Fe3C@Nitrogen‐Doped Carbon for Enhancing Oxygen Reduction Reaction

AbstractOxygen reduction reaction (ORR) catalysts play a key role in energy conversion and storage devices. The preparation of iron‐based carbon materials as non‐precious metal catalysts with a simple and scalable method still presents significant challenges. In this work, partially oxidized Fe embedded in Fe3C nanoparticles encased in nitrogen‐doped carbon shells (Fe3O4/Fe3C@NC) were prepared by directly pyrolyzing a mixture of Prussian blue (PB) and chitosan using a facile one‐step carbon‐bath route. The long‐term stability and methanol tolerance of the optimal catalyst were good and superior to those of commercial Pt/C (20 wt%). More importantly, the catalyst showed stronger ORR activities than Pt/C. We conclude that the high ORR activity of Fe3O4/Fe3C@NC catalysts should be attributed to the synergetic effect between Fe3C nanoparticles wrapped in carbon shells, which improves the activity of ORR and Fe3O4 nanoparticles neighbouring Fe‐Nx and significantly increases the number of active sites on the catalysts. Therefore, we believe that the one‐step carbon‐bath method provided in this work to synthesize highly active Fe‐based carbon materials as ORR catalysts is expected to be widely used in practical applications.

Synthesis and characterization of new honey incorporated double‐network hydrogels based on poly(vinyl alcohol) and acylated chitosan

AbstractA new honey‐hydrogel arrangement was developed by incorporating honey into a hydrogel containing polyvinyl alcohol and acylated chitosan. A water‐soluble acylated chitosan as the second network was synthesized via reaction of maleic anhydride with chitosan in water. A freeze–thaw process was employed to cross‐link the polyvinyl alcohol chains and a calcium chloride solution was used to cross‐link the acylated chitosan mixture in the presence of honey to precipitate out a flexible and tough hydrogel. The CaCl2content was optimized for the best results which was 0.1 mass%. The characterization such as mechanical, thermal, water content, and cell culture studies of all the synthesized double‐network hydrogel systems were investigated. In the presence of the acylated chitosan and honey almost all the investigated properties of the samples were improved. The formulation was optimized using deferent amount of CaCl2. Mechanical testing of the optimized formulation displayed a maximum value of 0.55 MPa and 310% for tensile strength and elongation at break. Swelling studies indicated that optimized formulation hydrogel absorbed much water as compare with honey‐free hydrogels due to increased amounts of network connectivity and higher hydrophilicity. Thermal analysis of the samples indicated that synthesized double‐network hydrogel network also decreased thermal stability and showed synergistic effects on the improvement of char residues. In addition, cell culture studies showed an appropriate biocompatibility behavior without showing any sign of cytotoxicity.

Application of Bioactive Coatings Based on Chitosan and Propolis for Pinus spp. Protection against Fusarium circinatum

Pine pitch canker (PPC) is a major threat to pine forests worldwide because of the extensive tree deaths, reduced growth, and degradation of timber quality caused by it. Furthermore, the aggressive fungus responsible for this disease (Fusarium circinatum) can also infect pine seeds, causing damping-off in young seedlings. This study proposes an approach based on coating treatments consisting of natural products to ensure seed protection. Seeds from two pine species (the most sensitive to this disease, Pinus radiata D. Don, and a more resistant one, Pinus sylvestris L.) were coated with single and binary mixtures of low and medium molecular weight chitosan and/or ethanolic-propolis extract. The germination rate, pre- and post-emergence mortality, total phenolic content, and radical scavenging activity were assessed. All treatments, and especially the one based on chitosan oligomers, had a beneficial impact on P. sylvestris seedlings, significantly enhancing survival rates and displaying a positive influence on the total phenolic content and on the seedlings’ radical scavenging activity. Conversely, non-significant negative effects on germination percentages were observed in the case of P. radiata seeds. The proposed treatments show promise for the protection of P. sylvestris seedlings against PPC.

Fabrication and characterization of composite cryobeads based on chitosan and starches-g-PAN as efficient and reusable biosorbents for removal of Cu2+, Ni2+, and Co2+ ions

Novel composite biosorbents were developed in this work as cryobeads by dual cross-linking of a mixture of chitosan (CS) and starch coming from different botanical sources, such as potato, wheat, and rice, grafted with poly(acrylonitrile) (PAN). Glutaraldehyde and poly(ethylene glycol diglycidyl ether) were used as cross-linkers. Composite cryobeads were characterized by FTIR, SEM-EDX, and swelling kinetics. Sorption of Cu2+, Ni2+, and Co2+ onto the novel biosorbents was investigated as a function of time and the concentration of the metal ion, at the optimum pH and sorbent dose. Pseudo-second-order kinetic model and Elovich model well fitted the kinetic results, indicating chemisorption as the most probable mechanism of sorption, while the Langmuir, and Sips isotherm models described the sorption at equilibrium for all metal ions. The values of the maximum sorption capacity of Cu2+, Ni2+, and Co2+ onto the composite sorbent based on CS and rice starch-g-PAN were as follows: 100.6 mg/g, 83.25 mg/g, and 74.01 mg/g, respectively. The nitrile groups present in the biocomposites CS/starch-g-PAN constitute a source to further increase the sorption capacity by their hydrolysis. A remarkable level of reusability was found for the composite cryobeads, no decrease of the sorption capacity being observed after five consecutive sorption/desorption cycles.

Composites Based on Cellulose and Chitosan

Mixtures of cellulose and chitosan have been obtained under shear deformation conditions using different types of equipment. The presence of an intense interaction between chitosan and cellulose has been revealed. On the basis of IR spectroscopy, a conclusion was drawn that there were qualitative changes in the system of hydrogen bonds between cellulose hydroxyl groups and chitosan amino groups, which indicated mixing of polysaccharides on the molecular level. The possibility of obtaining cellulose–chitosan mixtures in the presence of alkali under shear deformation conditions has been demonstrated.

Concentration of Chlorella Sorokiniana Microalga Biomass at Combined Usage of Coagulants and Flocculants

In this work there were studied various methods for concentrating the algae biomass, and mechanisms of concentration processes of the microalgae cells. Presented are papers devoted to usage of various coagulants and flocculants (iron (III) chlorides and sulphates, titanium tetrachloride, slaked lime, potassium chloride, potassium permanganat, aluminum potassium sulphates, Flopam FO 4550 SH). In the experimental part there is studied the usage of FeCl3*6H2O coagulant in the amount of 4, 6, 8, 10, 20, 30 mg/l of microalga Chlorella Sorokiniana suspension. Microstructure investigations have shown that at addition of ferrous chloride of concentration more than 20 mg/l, the cell death is more than 50%. Concentrations from 4 to 10 mg/l achieve low degree of precipitation (not more than 18%). Aiming at increasing degree of precipitation we investigated usage of two-component system coagulant-flocculant. Usage of two-component system results in a significant increase of precipitation degree of microalga Chlorella Sorokiniana: at addition of chitosan the degree reaches 53%, at addition of PAA it is 79%. It was determined the volume of the thickened biomass sludge. It shows that usage of chitosan results in more tightened biomass layer, which occupies minimal volume (V = 140 ml). The following three-component mixture is an optimum variant for high-efficient precipitation of biomass: coagulant FeCl3 in the amount of 6 mg/l; flocculants as a mixture of chitosan 2% and PAA 1% in the amount of 10 ml/l. Addition of chitosan solution as a flocculant results in decrease of pH value, which is caused by usage of acetic acid for preparation of chitosan solution. Microstucture analysis of the precipitated biomass shows that at coloration of Chlorella Sorokiniana cells by methylene blue, the amount of dead (colored) cells is not less than 5%. Consequently, the precipitated biomass might be used for obtaining of valuable components.

Application of novel hybrid bioadsorbent, tannin/chitosan/sericite, for the removal of Pb(II) toxic ion from aqueous solution

We addressed the development of a novel, low-cost, and high-efficient material from hybrid materials, known as microcapsules. Microcapsules are a composite adsorbent made of a mixture of tannin, sericite and chitosan. The FT-IR analysis showed that the microcapsules contain hydroxyl, carboxyl, carbonyl, and amino groups, which play an important role in the adsorption of heavy metals. The microcapsules were able to remove 99% of Pb(II) in 30 min, and obtained a removal efficiency of more than (13-50)%, compared with the single adsorbents of tannin, chitosan, and sericite. In adsorption kinetic analysis, pseudo-second-order adsorption was more suitable than pseudo-first-order adsorption, and chemical adsorption did not limit the adsorption rate of Pb(II) ion. In isothermal adsorption, Langmuir adsorption was more suitable than Freundlich adsorption, and the maximum Langmuir adsorption capacity was 167.82 (mg/g). Furthermore, desorption and reusability studies, as well as the applicability of the material for wastewater treatment, demonstrated that microcapsules offer a promising hybrid material for the efficient removal of significant water pollutants, i.e., Pb(II) from aqueous solutions.

Properties of Aqeous Solutions of O,N-Carboxymethyl Chitosan with Various Additives

Samples of carboxymethyl chitosan have been synthesized with different extents of substitution by changing the reaction conditions. Carboxymethyl chitosan completely dissolves in water when the extent of substitution exceeds 90%. The theological properties were studied for 4% aqueous solutions of carboxymethyl chitosan with CaCl2 and Ca(OH)2 as additives as well as for a mixture of carboxymethyl chitosan and polyethylene oxide with added CaCl2. The introduction of additives to aqueous solutions of carboxymethyl chitosan leads to enhanced viscosity and gel formation.

Fabrication and characterization of gold nanoparticle-doped electrospun PCL/chitosan nanofibrous scaffolds for nerve tissue engineering.

In the field of nerve tissue engineering, nanofibrous scaffolds could be a promising candidate when they are incorporated with electrical cues. Unique physico-chemical properties of gold nanoparticles (AuNPs) make them an appropriate component for increasing the conductivity of scaffolds to enhance the electrical signal transfer between neural cells. The aim of this study was fabrication of AuNPs-doped nanofibrous scaffolds for peripheral nerve tissue engineering. Polycaprolactone (PCL)/chitosan mixtures with different concentrations of chitosan (0.5, 1 and 1.5) were electrospun to obtain nanofibrous scaffolds. AuNPs were synthesized by the reduction of HAuCl4 using chitosan as a reducing/stabilizing agent. A uniform distribution of AuNPs with spherical shape was achieved throughout the PCL/chitosan matrix. The UV-Vis spectrum revealed that the amount of gold ions absorbed by nanofibrous scaffolds is in direct relationship with their chitosan content. Evaluation of electrical property showed that inclusion of AuNPs significantly enhanced the conductivity of scaffolds. Finally, after 5 days of culture, biological response of Schwann cells on the AuNPs-doped scaffolds was superior to that on as-prepared scaffolds in terms of improved cell attachment and higher proliferation. It can be concluded that the prepared AuNPs-doped scaffolds can be used to promote peripheral nerve regeneration.

Physicochemical properties of scaffolds based on mixtures of chitosan, collagen and glycosaminoglycans with nano-hydroxyapatite addition

Scaffolds based on chitosan (CTS), collagen (Coll), and glycosaminoglycans (GAGs) mixtures with nano-hydroxyapatite (HAp) were obtained with the use of the freeze-drying method. They were characterized by different analyses, e.g. SEM images and mechanical testing. Moreover, swelling behavior and biocompatibility tests were carried out.The results showed that the scaffolds based on the blends of chitosan, collagen, and glycosaminoglycans with hydroxyapatite are stable in aqueous environment. SEM images allowed the observation of a porous scaffolds structure with the pores size ~250 μm. The main purpose of the research was to detect the influence of hydroxyapatite addition on the glycosaminoglycans-enriched scaffolds properties. The physicochemical properties as swelling and mechanical parameters were tested. The scaffolds structure was observed by SEM. Moreover, the preliminary assessment of scaffolds suitability for cell growth, human osteosarcoma cell line SaOS-2 was used. The obtained results indicate that the addition of hydroxyapatite improves the mechanical parameters and cells biological response of the studied materials.

Several melanosis-inhibiting formulas to enhance the quality of deepwater pink shrimp (Parapenaeus longirostris)

Abstract The aim of this work was to assess the effect of several melanosis-inhibiting formulations on quality of deepwater pink shrimp (Parapenaeus longirostris) during storage. The formulations tested were as follows: one containing 4-hexylresorcinol (0.1%) in combination with organic acids (citric, ascorbic and acetic) and chelating agents (ethylenediaminetetraacetic acid [EDTA] and di-sodium di-hydrogen pyrophosphate [PPi]); a commercial formula based on sulphites (3%), and another formulation containing a mixture of chitosan (0.3%) and commercial sulphites. Non-treated shrimp were used as control. The 4-hexylresorcinol-based formulation was more effective than 3% of commercial sulphite solutions in preventing melanosis. This treatment prolonged the sensory acceptability of shrimp by up to six days in ice storage. During chilled storage, the treatment with the 4-hexylresorcinol-based formula inhibited the growth of microorganisms by 1.5–2 log cycles as compared to commercial sulphites, especially H2S-producers and pseudomonads. At the end of the experimental period, TVB-N levels were slightly higher in the lot treated with 4-hexylresorcinol (33 mg/100 mg) and reflected greater endogenous enzymatic activity, since the counts of the spoiler microorganisms remained around log 5 cfu/g or even lower. In general, the incorporation of chitosan to sulphites did not improve or produce a marked effect on shrimps during storage. During the sensory analysis, the panellists rated all the lots very similar, although the 4-hexylresorcinol formulation was the only one with a neutral odour at the end of the period. The 4-hexylresorcinol-based formulation induced yellow-green colorations to some extent in the cephalothorax, possibly due to the effect of organic acids and chelants, while the rest of the lots presented greyish/blackish colorations. Therefore, the formulation based on 4-hexylresorcinol may safely substitute traditional sulphites to improve the quality of fresh shrimp and prolong their shelf life during storage.

Modulation of physical properties of microfluidized whey protein fibrils with chitosan

There is an increasing market for food and beverage products enriched in proteins and dietary fibers due to their potential health benefits. In this study, the effect of heating (85 °C, 20 min), microfluidization (20,000 psi), and pH (2 to 6.5) on the physicochemical properties of aqueous solutions containing mixtures of whey protein fibrils (7.5%; WPF) and chitosan (0.5%; CN) were examined. Heating of the mixed systems increased their turbidity and apparent viscosity, which was attributed to the formation of protein-rich particles. Interestingly, heating the mixed systems and then applying microfluidization led to phase separation and a lower apparent viscosity, which was attributed to high-pressure disruption of the whey protein fibrils. The pH of the systems significantly influenced their appearance, turbidity, particle size, and apparent viscosity, with high turbidity and viscosity, and large particle size occurring from pH 3.5 to 5.5. These effects were attributed to protein aggregation close to its isoelectric point (pH 5) coupled with electrostatic attraction between anionic groups on the whey protein and cationic groups on the chitosan. The addition of chitosan increased the net isoelectric point from pH 5 for pure whey protein to pH 6 for the mixed system. Overall, this study showed that the appearance and rheological properties of protein-dietary fiber mixtures could be manipulated by heating, microfluidization, and pH adjustment. This information may be useful for designing protein and fiber enriched food and beverage products with desirable physical and sensory properties.

Influence of Chitosan Molecular Weight and Poly(ethylene oxide): Chitosan Proportion on Fabrication of Chitosan Based Electrospun Nanofibers

Fabrication of electrospun chitosan nanofibers is still a controversial issue in publications. Although regarding the lots of reports, mixtures of chitosan with a hydrophilic synthetic polymer such as polyethylene oxide (PEO) have been electrospun successfully, abundance of partly contradictory protocols in which one variable has been surveyed in each study is unfortunately baffling. In the present study, influence of three considerable parameters including the average molecular weight of chitosan, chitosan solution concentration and the mass ratio of polyethylene oxide to chitosan at the mixtures on electrospinning possibility as well as the quality of as-spun fibers is investigated. Eventually, the necessities for obtaining the best results are introduced followed by further analysis of optimized nanofibers using atomic force microscopy. According to our results, the blend solutions prepared from the low molecular weight (LMW) chitosan and PEO are efficient for reproducible production of bead-free electrospun nanofibers even in low proportion of polyethylene oxide.

Interfacial and emulsifying properties of chitosan/sodium lauryl ether sulfate system

Many pharmaceutical, cosmetic and chemical products exist in form of emulsions. A common problem with emulsions is their instability. Interaction between polymer and surfactant could change the adsorption layer around the oil droplets in emulsion which affects their stability. In order to understand the stabilization mechanism, the interface of oil/water systems that contained mixtures of chitosan (Ch), cationic polyelectrolyte and oppositely charged anionic surfactant, sodium lauryl ether sulfate (SLES) was studied by measuring the interfacial tension. Considering the fact that the properties of the oil phase influence the adsorption process, three different types of oil were investigated: medium-chain triglycerides (semi-synthetic oil), paraffin oil (mineral oil) and natural oil obtained from the grape seed. Based on the results of the measurements of interfacial tension, system medium-chain triglycerides/water was selected, for obtaining the 20% oil-in-water (O/W) emulsions. Emulsions were stabilized by Ch/SLES mixture, in mass ratios that correspond to different regions of their interaction. Also investigation on the emulsions characteristics (stability, droplet size and size distribution, zeta potential) was carried out. Results of this study are important for understanding the influence of polymer-surfactant interactions on the properties of solution and stability of dispersed systems that could be useful in microencapsulation processes.

Karakter Edible Film Ulva lactuca-kitosan sebagai Pengemas Bumbu Mi Instan

In this research, the edible films based on Ulva lactuca flour, chitosan, corn starch, and glycerol were prepared. The edible films was for wrapping of instant noodle seasoning. The aim of this research was to investigate the effect of weight ratio of Ulva lactuca flour-chitosan on the properties of the prepared edible flims. Innitialy, the mixture of Ulva lactuca flour, corn starch, and chitosan were stirred in acetic acid solution 1%. After the chitosan was dissolved, the glycerol was added. The mixture was heated at 80 O C and stirred for 30 minutes. The obtained edible film solution was then poured into antisticky surface and dried at oven until a constant weight was attained. The dried films were characterized, including moisture content, E. coli resistivity, hydration index, thickness, and solubility in hot water. Based on experimental data, it was found that the best composition of edible film was 2 g Ulva lactuca flour, 2 g Chitosan, 2 g corn starch, 100 ml acetic acid 1%, and 1 mL glycerol.

Mimicking peroxidase activity of Co2(OH)2CO3-CeO2 nanocomposite for smartphone based detection of tumor marker using paper-based microfluidic immunodevice

We present a paper-based microfluidic colorimetric immunosensor for the detection of carcinoembryonic antigen (CEA), using Co2(OH)2CO3-CeO2 nanocomposite with extraordinary intrinsic peroxidase like activity. The morphology and composition of the nanocomposite characterized with Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) techniques. The proposed immunosensor facilely fabricated by loading mixture of ionic liquid and chitosan functionalized primary antibodies (Ab1) on the surface of paper. Compared to traditional paper based immunodevice, when ionic liquid was used the nonspecific binding protein from the paper surface was more effectively removed. Secondary antibodies (Ab2) were stacked on the surface of the carboxylated Co2(OH)2CO3-CeO2 nanocomposite. The immunosensor response was obtained by a color change resulting from Co2(OH)2CO3-CeO2 nanocomposite catalyzing the oxidation of 3,3′,5,5′-tetramethyl benzidine in the presence of H2O2. The colorimetric sensing was accomplished on the paper, using smartphone for taking a photo and then analyzing the colors with an installed application. Detection of CEA was performed by this method with a linear range from 0.002 to 75.0 ng mL−1 and a detection limit of 0.51 pg mL−1. In this paper we developed simple, cost-effective and portable design for sensitive immunoassay and point-of-care diagnostics of cancer marker.

A New Photosensitized Oxidation-Responsive Nanoplatform for Controlled Drug Release and Photodynamic Cancer Therapy.

Abnormal biochemical alteration such as unbalanced reactive oxygen species (ROS) levels has been considered as a potential disease-specific trigger to deliver therapeutics to target sites. However, in view of their minute variations in concentration, short lifetimes, and limited ranges of action, in situ generation of ROS with specific manipulations should be more effective for ROS-responsive drug delivery. Here we present a new delivery nanoplatform for photodynamic therapy (PDT) with on-demand drug release regulated by light irradiation. Rose bengal (RB) molecules, which exhibit a high yield of ROS generation, were encapsulated in a mixture of chitosan (CTS), poly(vinyl alcohol) (PVA), and branched polyethylenimine ( bPEI) with hydrophobic iron oxide nanoparticles through an oil-in-water emulsion method. The as-prepared magnetic nanoclusters (MNCs) with a tripolymer coating displayed high water dispersibility, efficient cellular uptake, and the cationic groups of CTS and bPEI were effective for RB loading through electrostatic interaction. The encapsulation efficiency of RB in MNCs could be further improved by increasing the amount of short bPEI chains. During the photodynamic process, controlled release of the host molecules (i.e., RB) or guest molecules (i.e., paclitaxel) from the bPEI-based nanoplatform was achieved simultaneously through a photooxidation action sensitized by RB. This approach promises specific payload release and highly effective PDT or PDT combined therapy in various cancer cell lines including breast (MCF-7 and multidrug resistant MCF-7 subline), SKOV-3 ovarian, and Tramp-C1 prostate. In in vivo xenograft studies, the nanoengineered light-switchable carrier also greatly augments its PDT efficacy against multidrug resistant MCF-7/MDR tumor as compared with free drugs. All the above findings suggest that the substantial effects of enhanced drug distribution for efficient cancer therapy was achieved with this smart nanocarrier capable of on demand drug release and delivery, thus exerting its therapeutic activity to a greater extent.

A disposable, simple, fast and low-cost paper-based biosensor and its application to the determination of glucose in commercial orange juices

A new biosensor for monitoring glucose levels in beverages is presented. The measurements are performed using potentiometric detection. Working electrodes are made using platinised paper as support and a biocompatible polymeric membrane made of a mixture of polyvinyl alcohol and chitosan containing glucose oxidase as the recognition layer. The system is based on the detection of the hydrogen peroxide generated by an enzymatic reaction performed in a highly sensitive, selective and simple way. The biosensors display suitable analytical performance (sensitivity −119.6 ± 6.4 mV/dec in the 0.03–1.0 mM range with a limit of detection of 0.02 mM). Determination of glucose in commercial orange juices is presented. These results were validated against conventional standard methods, showing good accuracy and fast analytical response. The methodology presented herein does not require complex samples treatment, offering an alternative to conventional methods, particularly for determinations performed with minimal expertise and without a laboratory infrastructure.

A General and Robust Strategy for Fabricating Mechanoresponsive Surface Wrinkles with Dynamic Switchable Transmittance

AbstractPreparation of surface wrinkles on a skin layer/elastomer substrate bilayer film has attracted extensive attention because of their unique and broad applications in flexible electronic devices, tunable diffraction gratings, and smart windows. However, it still remains a great challenge to develop a general strategy for fabricating mechanoresponsive surface wrinkles using various skin layer materials with wide tunability of wrinkles' wavelength and amplitude, large optical modulation range, rapid optical switching rate, and high stability. Here, a general, simple, and cost‐effective strategy is reported, through uniaxially stretching and subsequently releasing skin layer/elastomer substrate bilayer films, for producing highly ordered, crack‐free, 1D surface wrinkles on elastomeric polydimethylsiloxane (PDMS) substrates with various skin layer materials, including polyvinyl alcohol (PVA), chitosan (CS), hydroxyethyl cellulose, and the mixtures of PVA and CS. The surface wrinkles on PVA/PDMS bilayer film exhibit excellent mechanoresponsive optical switching properties, such as large transmittance modulation range (transmittance from ≈6% to 91% at visible region), high optical sensitivity with small mechanical strain (less than 20%), and long optical switching cycles (over 2000 times). It is anticipated that this method will enable a new path to the fabrication of mechanoresponsive surface wrinkles with outstanding performance for applications in dynamic optical switching fields and beyond.

Chiral betulin-imino-chitosan hydrogels by dynamic covalent sonochemistry

A series of chiral hydrogels was prepared from a homogeneous mixture of chitosan and betulinic aldehyde in different molar ratios, under the effect of ultrasound. The hydrogelation mechanism has been investigated by FTIR and CD spectroscopy, wide angle X-ray diffraction and polarized light microscopy. The morphology of hydrogels was examined by SEM. The swelling ability has been tested in three media of different pH. It was concluded that hydrogelation occurred by different pathways, closely related to the peculiarities of the chitosan-betulin systems. Circular dichroism measurements revealed chiroptical properties of the hydrogels, correlated to their content and crosslinking pathway.