Chitosan In Water Research Articles

Synthesis, Characterization and Inhibition Performance of Vanillin‐Modified Chitosan Quaternary Ammonium Salts for Q235 Steel Corrosion in HCl Solution

AbstractIn order to enhance the solubility of chitosan in water and its corrosion inhibition performance on Q235 steel in 1 M HCl solution, N‐vanillyl‐O‐2′‐hydroxypropyltrimethylammonium chloride chitosan (VHTC) was synthesized. The structure of VHTC was characterized by FT‐IR and 1H‐NMR spectroscopy. The corrosion inhibition performance of VHTC on Q235 steel in 1 M HCl solution was studied by weight loss, polarization, electrochemical impedance spectroscopy (EIS) and stereo microscope analysis. Experimental results indicate that VHTC shows better inhibition efficiency compared to chitosan. When the concentration of VHTC increases to 200 mg L−1, the inhibition efficiency reaches 90 %, which is almost equal to the conventional corrosion inhibitors (e.g., imidazoline). The polarization study demonstrates that VHTC is a mixed‐type inhibitor caused by a geometrical blanketing effect. The charge transfer resistance is proportional to the inhibitor concentration as revealed by the EIS results, indicating that the protective film on the Q235 steel surface is formed by adsorption of the inhibitor molecules. The inhibition efficiency of VHTC achieves the maximum value within 24 h when the concentration of VHTC is 200 mg L−1. The morphology observation of the corroded steel surface indicates that the corrosion of Q235 steel in 1 M HCl solution is significantly inhibited after introducing VHTC into the acidic solution.

Potential of Chitosan for the Control of Tomato Bacterial Wilt Caused by Ralstonia solanacearum (Smith) Yabuuchi et al

Bacterial wilt is an important constraint to tomato production. The search for an effective and safe method of managing bacterial wilt is imperative. Chitosan, adeactylated chitin was reported to possess direct antimicrobial property against certain pathogens and is a plant resistance booster. This study was conducted to: evaluate the effectiveness of varying chitosan concentrations and sources against bacterial wilt in vitro and in vivo and compare different application methods in bacterial wilt control. Varying chitosan concentrations (100, 200, 300, 400 and 500 ppm) immersed/dissolved in water, 1% acetic acid, and streptomycin were evaluated against R. solanacearum in laboratory and pot experiments. Three chitosan sources were also evaluated against the pathogen. Different methods of application were compared. Regardless of source, chitosan in water has no direct antimicrobial activity against R.solanacearum but when dissolved 1% acetic acid, it was able to inhibit the bacteria. Inhibition of chitosan/acetic acid was best at 300 ppm and significantly higher than 1% acetic acid alone indicating that its antimicrobial property was enhanced by the acid. Two hundred ppm chitosan/acetic acid-treated plants delayed the onset of disease and produced the lowest percentage infection, lowest disease severity rating, and highest percentage survival in inoculated tomato. The action of 200 ppm chitosan/acetic acid treatment was due to a dual effect, i.e., antimicrobial and as an elicitor of resistance. All application methods were effective in controlling bacterial wilt but one time root dipping to 200 ppm chitosan/acetic acid before transplanting was enough to protect the plants against the disease.

Simple and green technique for sequestration and concentration of silver nanoparticles by polysaccharides immobilized on glass beads in aqueous media.

BackgroundEngineered nanoparticles have unique properties compared to bulk materials and their commercial uses growing rapidly. They represent a potential risk for environment and health and could be eventually released in water. Silver nanoparticles (Ag NP) are applied in various products and are well-known for their antibacterial properties. Nowadays, pre-concentration and separation methods for Ag NP possess some limitations. Here, we present a simple, green method to sequestrate and concentrate Ag NP from different aqueous media.ResultsSupported polysaccharides on glass beads synthesized in water by a single step reaction show high sequestration capacity of citrate-coated Ag NP in aqueous media. Supported polysaccharides were characterized by infrared spectroscopy, scanning electron microscopy (SEM) and elemental analysis. Sequestration of 83.0 % of Ag NP was attained from a 20 μg.L−1 aqueous solution with supported chitosan in water whereas supported 2-hydroxyethylcellulose (HEC) reached 64.0 % in synthetic seawater in 2 h. The influence of polymer/glass beads ratio and molecular weight of polysaccharides was also studied. The effect of the salinity and humic acids on sequestration of Ag NP was investigated. Supported polymers have shown high performance for sequestration of ionic silver. Sequestration of 82.5 % and 80.8 % were obtained from a 60 μg.L−1 silver ion (as nitrate salt) with supported HEC and chitosan, respectively. Sequestrated Ag NP was characterized with transmission electron microscopy (TEM) where images showed Ag NP with unchanged size and shape.ConclusionsThis sequestration method, involving green synthesis, allows efficient concentration and characterization of Ag NP from different aqueous media. This simple and fast method is a potential sustainable technique for elimination of Ag NP and ionic silver from waste waters and waters at different salinities.

Excited-state proton transfer of weak photoacids adsorbed on biomaterials: proton transfer to glucosamine of chitosan.

UV-vis steady-state and time-resolved techniques were employed to study the excited-state proton-transfer process from two weak photoacids positioned next to the surface of chitosan and cellulose. Both chitosan and cellulose are linear polysaccharides; chitosan is composed mainly of d-glucosamine units. In order to overcome the problem of the high basicity of the glucosamine, we chose 2-naphthol (pKa* ≈ 2.7) and 2-naphthol-6-sulfonate (pKa* ≈ 1.7) as the proton emitters because of their ground state pKa (≈9). Next to the 1:1 cellulose:water weight ratio, the ESPT rate of these photoacids is comparable to that of bulk water. We found that the ESPT rate of 2-naphthol (2NP) and 2-naphthol-6-sulfonate (2N6S) next to chitosan in water (1:1) weight ratio samples is higher than in bulk water by a factor of about 5 and 2, respectively. We also found an efficient ESPT process that takes place from these photoacids in the methanol environment next to the chitosan scaffold, whereas ESPT is not observed in methanolic bulk solutions of these photoacids. We therefore conclude that ESPT occurs from these photoacids to the d-glucosamine units that make up chitosan.

Quasi-static magnetic measurements to predict specific absorption rates in magnetic fluid hyperthermia experiments

In this work, the issue on whether dynamic magnetic properties of polydispersed magnetic colloids modeled using physical magnitudes derived from quasi-static magnetic measurement can be extrapolated to analyze specific absorption rate data acquired at high amplitudes and frequencies of excitation fields is addressed. To this end, we have analyzed two colloids of magnetite nanoparticles coated with oleic acid and chitosan in water displaying, under a radiofrequency field, high and low specific heat power release. Both colloids are alike in terms of liquid carrier, surfactant and magnetic phase composition but differ on the nanoparticle structuring. The colloid displaying low specific dissipation consists of spaced magnetic nanoparticles of mean size around 4.8 nm inside a large chitosan particle of 52.5 nm. The one displaying high specific dissipation consists of clusters of magnetic nanoparticles of mean size around 9.7 nm inside a chitosan particle of 48.6 nm. The experimental evaluation of Néel and Brown relaxation times (∼10−10 s and 10−4 s, respectively) indicate that the nanoparticles in both colloids magnetically relax by Néel mechanism. The isothermal magnetization curves analysis for this mechanism show that the magnetic nanoparticles behave in the interacting superparamagnetic regime. The specific absorption rates were determined calorimetrically at 260 kHz and up to 52 kA/m and were well modeled within linear response theory using the anisotropy density energy retrieved from quasi-static magnetic measurement, validating their use to predict heating ability of a given polydispersed particle suspension. Our findings provide new insight in the validity of quasi-static magnetic characterization to analyze the high frequency behavior of polydispersed colloids within the framework of the linear response and Wohlfarth theories and indicate that dipolar interactions play a key role being their strength larger for the colloid displaying higher dissipation, i.e., improving the heating efficiency of the nanoparticles for magnetic fluid hyperthermia.

Ruthenium on chitosan: a recyclable heterogeneous catalyst for aqueous hydration of nitriles to amides

Ruthenium has been immobilized over chitosan by simply stirring an aqueous suspension of chitosan in water with ruthenium chloride, and has been utilized for the oxidation of nitriles to amides; the hydration of nitriles occurs in high yield and excellent selectivity, which proceeds exclusively in aqueous medium under neutral conditions.

ChemInform Abstract: Copper on Chitosan: A Recyclable Heterogeneous Catalyst for Azide—Alkyne Cycloaddition Reactions in Water.

Copper sulfate has been immobilized over chitosan by simply stirring an aqueous suspension of chitosan in water with copper sulfate; the ensuing catalyst has been utilized for the azide–alkyne cycloaddition in aqueous media and it can be recycled and reused many times without losing its activity.

Copper on chitosan: a recyclable heterogeneous catalyst for azide–alkyne cycloaddition reactions in water

Copper sulfate has been immobilized over chitosan by simply stirring an aqueous suspension of chitosan in water with copper sulfate; the ensuing catalyst has been utilized for the azide–alkyne cycloaddition in aqueous media and it can be recycled and reused many times without losing its activity.

Biomedical Activity of Chitin/Chitosan Based Materials—Influence of Physicochemical Properties Apart from Molecular Weight and Degree of N-Acetylation

The physicochemical nature of chitin and chitosan, which influences the biomedical activity of these compounds, is strongly related to the source of chitin and the conditions of the chitin/chitosan production process. Apart from widely described key factors such as weight-averaged molecular weight (MW) and degree of N-acetylation (DA), other physicochemical parameters like polydispersity (MW/MN), crystallinity or the pattern of acetylation (PA) have to be taken into consideration. From the biological point of view, these parameters affect a very important factor—the solubility of chitin and chitosan in water and organic solvents. The physicochemical properties of chitosan solutions can be controlled by manipulating solution conditions (temperature, pH, ionic strength, concentration, solvent). The degree of substitution of the hydroxyl and the amino groups or the degree of quaternization of the amino groups also influence the mechanical and biological properties of chitosan samples. Finally, a considerable research effort has been directed towards developing safe and efficient chitin/chitosan-based products because many factors, like the size of nanoparticles, can determine the biomedical characteristics of medicinal products. The influence of these factors on the biomedical activity of chitin/chitosan-based products is presented in this report in more detail.

Characterization and antimicrobial activity of water-soluble N-(4-carboxybutyroyl) chitosans against some plant pathogenic bacteria and fungi.

Water-soluble N-(4-carboxybutyroyl) chitosan derivatives with different degrees of substitution (DS) were synthesized to enhance the antimicrobial activity of chitosan molecule against plant pathogens. Chitosan in a solution of 2% aqueous acetic acid-methanol (1:1, v/v) was reacted with 0.1, 0.3, 0.6 and 1mol of glutaric anhydride to give N-(4-carboxybutyroyl) chitosans at DS of 0.10, 0.25, 0.48 and 0.53, respectively. The chemical structures and DS were characterized by 1H and 13C NMR spectroscopy, which showed that the acylate reaction took place at the N-position of chitosan. The synthesized derivatives were more soluble than the native chitosan in water and in dilute aqueous acetic acid and sodium hydroxide solutions. The antimicrobial activity was in vitro investigated against the most economic plant pathogenic bacteria of Agrobacterium tumefaciens and Erwinia carotovora and fungi of Botrytis cinerea, Pythium debaryanum and Rhizoctonia solani. The antimicrobial activity of N-(4-carboxybutyroyl) chitosans was strengthened than the un-modified chitosan with the increase of the DS. A compound of DS 0.53 was the most active one with minimum inhibitory concentration (MIC) of 725 and 800mg/L against E. carotovora and A. tumefaciens, respectively and also in mycelial growth inhibiation against B. cinerea (EC50=899mg/L), P. debaryanum (EC50=467mg/L) and R. solani (EC50=1413mg/L).

Synthesis and property studies of N‐carboxymethyl chitosan

AbstractN‐carboxymethyl chitosans (N‐CMC) were synthesized from chitosan in water with chloroacetic acid instead of comparatively expensive glyoxylic acid. The optimal reaction conditions were 90°C and 4 h with a ratio of chloroacetic acid to chitosan 5 : 1(w/w). The degree of substitution of product exceeded 1.32. The N‐carboxymethyl chitosans were characterized by XRD, FTIR, 1H‐NMR, and the water solubility and isoelectric point of N‐CMC with different degrees of substitution were determined. FTIR and 1H‐NMR data has confirmed that the substitution reaction occurred on the amino groups. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Exploring the Factors Affecting the Solubility of Chitosan in Water

AbstractWe explore the role of crystallinity and inter‐ or intramolecular forces in chitosan for its solubility in water and demonstrate the expansion of its solubility to a wider pH range. Due to its semicrystalline nature, derived mainly from inter‐ and intramolecular hydrogen bonds, chitosan is water‐soluble only at pH < 6. In acidic conditions, its amino groups can be partially protonated resulting in repulsion between positively charged macrochains, thereby allowing diffusion of water molecules and subsequent solvation of macromolecules. We show that chemical disruption of chitosan crystallinity by partial re‐acetylation or physical disruption caused by the addition of urea and guanidine hydrochloride broadens the pH‐solubility range for this biopolymer.magnified image

Synthesis, characterization, cytotoxicity and antibacterial studies of chitosan, O-carboxymethyl and N, O-carboxymethyl chitosan nanoparticles

Chitosan (CS) is a naturally occurring biopolymer. It has important biological properties such as biocompatibility, antifungal and antibacterial activity, wound healing ability, anticancerous property, anticholesteremic properties, and immunoenhancing effect. Recently, CS nanoparticles have been used for biomedical applications. However, due to the limited solubility of CS in water its water-soluble derivatives are preferred for the above said applications. In this work, the nanoparticles of CS and its water-soluble derivatives such as O-carboxymethyl chitosan ( O-CMC) and N,O-carboxymethyl chitosan ( N,O-CMC) was synthesized and characterized. In addition, cytotoxicity and antibacterial activity of the prepared nanoparticles was also evaluated for biomedical applications.

Bulk properties of nonionic surfactant and chitosan mixtures

Bulk properties in mixtures of the nonionic surfactant Lutrol ® F127 and cationic polyelectrolyte chitosan in water and acetate buffer (pH 6.0 and 6.5 and ionic strength 0.1 and 0.5, respectively) were studied by fluorescence spectroscopy, dynamic light scattering and zeta potential measurements. It was observed that the addition of chitosan to F127 systems in water had little effect on critical micelle concentration (cmc) values. On the contrary, the addition of chitosan to F127 systems in acetate buffer shifted cmc to higher values. Independently of pH and ionic strength, the cmc increase was more pronounced as the chitosan concentration in the system increased. The antagonistic mixing behaviour of the present nonionic surfactant and polyelectrolyte was observed at pH 6.5 and an ionic strength of 0.5 at 34 °C. The micelles in mixed F127/chitosan systems had an average hydrodynamic diameter of 25 nm and were larger than F127 micelles themselves (22.5 nm). The zeta potential of micelles in F127 water systems and in both acetate buffer systems was almost neutral, due to the nonionic nature of F127. In water and both acetate buffer mixed F127/chitosan systems, the zeta potential of micelles was positive and increased with increasing chitosan concentration, due to the electropositive charge of chitosan. The effect was more pronounced in water systems. Results are discussed in terms of electrostatic, hydrophobic and interpolymer interactions.

Study on radiation‐induced grafting of hydrophilic monomers onto chitosan

AbstractThe graft polymerization of 2‐Hydroxyethyl acrylate, 2‐Hydroxyethyl methacrylate, and N‐vinylpyrrolidone onto chitosan in aqueous solution initiated by γ‐ray irradiation was carried out. The effect of various conditions such as the absorbed dose, concentration of monomer, and solvent on grafting was investigated. The grafting yield increased with the increase in absorbed dose. The degree of grafting increased with increase in the radiation dose. The obtained graft copolymers showed the solubility in water in wide pH interval. The interactions between grafted chitosan copolymers with sodium dodecyl sulfate (SDS) were studied in an aqueous solution. It was found that there is a narrow molar ratio of SDS/cation (∼ 0.40–0.70) depending on different grafted copolymers, at which the turbidity of SDS‐grafted chitosan complex has a maximum due to the formation of water insoluble interpolymer aggregates via the SDS attached on the polymer chain. The turbidity falls sharply with the further addition of excessive SDS, which forms micelle in the solution and causes the de‐aggregation of the interpolymer aggregates and also because of the precipitation of complexes and returns to the original level. The morphologic properties of thin films of SDS‐ grafted chitosan complex were investigated. It was observed that upon heating the insoluble complex of SDS and grafted chitosan in water, superstructures were formed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Polyethylene film surface functionalized with chitosan via γ-ray irradiation in aqueous system: An approach to induce copper(II) ion adsorptivity on PE

Functionalization of the surface of polyethylene (PE) film with chitosan via γ-ray irradiation technique followed by copper ion immobilization on this surface is proposed. The solubilization of chitosan in water by forming an organic salt with hydroxybenzyl triazole is a key factor in accomplishing the surface functionalization of PE with chitosan by γ-ray irradiation. The chitosan induces the metal ion adsorptivity on PE film surface resulting in the successful copper ion immobilization. The work demonstrates an approach to convert a commodity polymer, such as PE, to a functional polymer with chitosan.

Decoloration of chitosan by UV irradiation

Decoloration of chitosan by UV irradiation, which was used to replace a bleaching step during chitosan preparation, was evaluated under four separate treatments (effect of irradiation time, chitosan/water ratio, stirring speed, and UV light source). The optimal decoloration condition was defined as that producing white chitosan with higher viscosity. Decoloration of chitosan could be achieved effectively using a UV-C light by stirring unbleached chitosan in water (1:8, w/v) for 5 min at 120 rpm. UV irradiation applied under the optimal conditions could be used to produce chitosan with desirable white color ( L ∗ = 76.95, a ∗ = −0.37, and b ∗ = 14.04) and high viscosity (1301.7 mPa s at 0.5% w/v in 1.0% v/v acetic acid).

Synthesis and Characterization of Chitosan‐graft‐Poly(3‐(trimethoxysilyl)propyl methacrylate) Initiated by Ceric (IV) Ion

The grafting of 3‐(trimethoxysilyl)propyl methacrylate (TMSPM) onto chitosan by ceric ion initiation was studied under homogeneous conditions in 2% acetic acid solution. The grafted polymer was characterized by FT‐IR, 1H‐NMR, TGA and XRD and swelling studies. TGA results showed that the incorporation of TMSPM to the chitosan chains decreased the thermal stability of the grafted chitosan. Due to the grafting of TMSPM, the crystallinity of chitosan derivatives was found to be destroyed. The solubility of the grafted chitosan in water was improved. The effects of reaction conditions such as initiator concentration, monomer concentration, reaction temperature and reaction time were studied by determining the grafting parameters such as grafting and grafting efficiency. Under optimum conditions, the grafting parameters were achieved as 1440 and 97%, respectively.

Chitosan‐phosphorylated chitosan polyelectrolyte complex hydrogel as an osteoblast carrier

To simulate extra-cellular matrix, a novel three-dimensional scaffold of polyelectrolyte complex (PEC) hydrogel as an osteoblast carrier was synthesized. First, chitosan, a natural glycosaminoglycan, was modified by phosphorylation to obtain a water-soluble phosphorylated chitosan (P-content: 10.7 mass%). The PEC hydrogel was then formed from equal volumes of 0.173 mass% phosphorylated chitosan in water and 1 mass% chitosan in 1% (V/V) acetic acid solution. Rat osteoblasts were seeded in the hydrogel. The PEC hydrogel had a three-dimensional hierarchically-porous structure and good cytobiocompatibility for osteoblasts in vitro. It is concluded that the PEC hydrogel is a promising material as an osteoblast carrier.

Biomimetic Synthesis of Apatite - Polyelectrolyte Complex (Chitosan - Phosphorylated Chitosan) Hydrogel as an Osteoblast Carrier

A novel three-dimensional scaffold of hydroxyapatite(HA)-polyelectrolyte complex (PEC) composite hydrogel was synthesized by a biomimetic method. PEC hydrogel was formed from equal volumes of 1% phosphorylated chitosan in water and 1% chitosan in 1% acetic acid solution. This PEC hydrogel was soaked in saturated Ca(OH)2 solution for 4 d and then in accelerated calcification solution (ACS) for 7 d, both at 37 oC. The PEC hydrogel was a nano-composite material with multiple levels of hierarchical porosity; hydroxyapatite (HA) crystals nucleated and grew on the fiber surfaces of the hydrogel; Rat osteoblasts were then seeded in this three-dimensional scaffold of HA-PEC composite hydrogel, the three-dimensional scaffold of HA-PEC hydrogel revealed excellent biocompatibility.