Crystallinity Of Chitosan Research Articles

Biologically active Co (II), Cu (II), Zn (II) centered water soluble novel isoniazid grafted O-carboxymethyl chitosan Schiff base ligand metal complexes: Synthesis, spectral characterisation and DNA nuclease activity

In this study, the new N, N, O tridentate donor water soluble isoniazid based biopolymer Schiff base ligand and their Co (II), Cu (II), Zn (II) metal complexes were prepared. The compounds were designed for potential biological application such as antibacterial, antifungal, anti-inflammatory, total antioxidant, antidiabetic and DNA binding studies. The synthesized compounds were illuminated in different light sources of various spectra were used to explore the functional groups of Biopolymer derivatives. Thermal degradation, thermal stability and percentage of mass loss for the prepared compounds were investigated through thermo gravimetric and differential thermal (TGA-DTA) analyses. Crystalline structure of synthesized biopolymer derivatives were explored by X-ray diffraction (XRD) studies, the crystallinity of chitosan is gradually decreased after the Schiff base and complex formation. Surface morphology and structures of the prepared compounds were examined using SEM analysis. The magnetic moment and magnetism of the metal complexes were studied using Vibrating-sample magnetometer (VSM). Antidiabetic studies of Biopolymer Schiff base and metal complexes were carried out by α-amylose inhibitory method. DNA nuclease activities of synthesized metal complexes were investigated by Ultra-Violet (UV) and viscometry methods. The Cu (II) complexes showed better DNA binding results than Co (II) and Zn (II) complexes.

Degradation of chitosan with self-resonating cavitation

For the degradation of chitosan, a novel physical method of self-resonating cavitation with strong cavitation effects was investigated in this paper. The effects of initial concentration, pH, temperature, inlet pressure and cavitation time on the degradation efficiency of chitosan were evaluated. It was found that the degradation efficiency was positively correlated with temperature and cavitation time, but was negatively correlated with the solution concentration. The degradation efficiency was maximized at pH of 4.4 and inlet pressure of 0.4 MPa. Under the experimental conditions, the intrinsic viscosity of chitosan solution was reduced by 92.2%, which was twice as high as the degradation efficiency where a Venturi tube cavitator was used. The viscosity-average molecular weights of initial and degraded chitosan were 651 and 104 kD, respectively. The deacetylation degree of chitosan slightly decreased from 89.34% to 88.05%. Structures and polydispersity of initial and degraded chitosan were measured by Fourier-transform infrared spectroscopy (FT-IR), nuclear magnetic resonance hydrogen spectroscopy (1H NMR), X-ray diffraction (XRD) and gel permeation chromatography (GPC). The results showed that the degradation process did not change the natural structure of chitosan. XRD peaks of the original chitosan were observed at 2θ of 9.59° and 20.00°, and the one at 2θ of 20.00° was obviously weakened after the degradation process, which indicated that the crystallinity of chitosan decreased significantly after the degradation. The polydispersity index of chitosan samples decreased from 3.17 to 2.75, indicating that the molecular-weight distribution of products after the degradation was more concentrated. The results proved that self-resonating cavitation prompted the degradation of chitosan and could reduce the polydispersity of the products for the production of oligochitosan with homogeneous molecular weights.

Biologically Active Water Soluble Novel Biopolymer/Hydrazide Based O-Carboxymethyl Chitosan Schiff Bases: Synthesis and Characterisation

Six new N,N,O tridentate water soluble hydrazide based O-carboxymethyl chitosan Schiff base derivatives have been prepared through in-situ synthesis. The degree of substitution of schiff base derivatives was calculated theoretically and the derivatives were prepared with 1:1 proportion. Biopolymer Schiff base derivatives with their various bonding sites and different proton-carbon environment were characterised by FT-IR and 1H, 13C NMR. The crystallinity of synthesized Schiff bases was studied by X-ray diffraction. Thermal decomposition of all synthesized O-carboxymethyl chitosan Schiff base ligands was investigated by thermo gravimetric analysis which revealed the presence of Schiff base functionality to elongate the temperature to > 300 oC. Scanning electron microscopic studies revealed that O-carboxymethyl chitosan Schiff base derivatives were affecting the crystallinity of chitosan. Additionally, the synthesized novel Schiff base derivatives were characterized for anti-inflammatory, total antioxidant and antidiabetic studies and they showed better biological and pharmaceutical results with standard drug.

Preparation of magnetic chitosan microspheres using iron sand particles prepared by ball milling method

Iron sand particles prepared by ball milling method have been used in the magnetic chitosan microspheres preparation. FTIR, XRD and SEM analyses were performed to characterize the magnetic chitosan microspheres. SEM images and FTIR spectra confirmed the formation of magnetic chitosan microspheres. The patterns of XRD showed the presence of iron sand particles reduced the crystallinity of chitosan. The adsorption experiments were conducted for mercury removal from aqueous solutions. AAS was performed to determine the mercury concentrations in the solutions after the adsorption process. The results showed the adsorption capacity (Q) of the magnetic chitosan microspheres was not significantly different from magnetic chitosan microspheres prepared using iron oxide.

Investigation of mechanisms for simultaneous adsorption of iron and sulfate ions onto chitosan with formation of orthorhombic structures

The study confirms the interaction of sulfate ions (SO42−) into the polymer chains of chitosan under acidic conditions. As a result the crystallinity of chitosan decreases with (1) increasing protonation of the amino groups and (2) increasing SO42− concentration. The adsorption of iron ions (Fe2+/3+) resulting from (FeSO4)aq onto the chitosan surface takes place incidentally by the oxidative effect of Fe2+/3+ with formation of orthorhombic α-FeOOH and γ-FeOOH. The separation of iron and sulfate ions correlates stoichiometrically. Chitosan with different degrees of deacetylation (DD) were used in order to investigate the influence of DD on the adsorption behavior of iron and sulfate ions. The higher the DD of chitosan, the more iron and sulfate ions can be adsorbed. Langmuir isotherms showed good agreement with the adsorption data obtained (qDD=90 %(Fe) = 2.36 mmol g-1; qDD=90 %(SO42−) = 2.58 mmol g-1). After adsorption process, the adsorber was analyzed extensively via X-ray diffraction, FTIR, 13C-NMR, SEM/EDX measurements and Mössbauer spectroscopy.

Preparation and Characterization of Biopolymer Chitosan Nanofiber from Coconut Crab Shell

The use of coconut crab shell waste as a chitosan product has the potential to be developed as a multifunctional product, especially in the form of the nanofiber. This study aims to prepare and characterization of biopolymer chitosan nanofiber from coconut crab shell. The method used in this study is an ionic gelation method using chitosan coconut crabs (chitosan CC) as the main medium, and the dispersion media is namely tripolyphosphate (TPP) with different concentrations to produce chitosan CC/TPP nanofibers. The chitosan is dissolved using glacial acetic acid 1% (v/v) low pH. Then the solution is dropped into a TPP solution with a concentration of 0.01, 0.03, 0.05, 0.07 % (w/v), using a magnetic stirrer at 600 rpm for 30 minutes. The precipitate obtained is then homogenized using 30 minutes of ultrasonic at λ 60 kHz. The characterization of nanofiber is made with Scanning Electron Microscopy (SEM) with a magnification of 10.0kV. The morphological shape of the nanofiber size average value of 73 nm - 610 nm at the concentration of chitosan CC/TPP 0.25% (w/v) and 0.03% (w/v). Particle size analysis (PSA) of chitosan CC/TPP nanofibers (D50) at 536 - 625 nm with an average polydispersity index (PI) of 1.3 - 1.7. FT-IR analysis showed that the presence of functional groups NH, OH, C-C, CH varied in the concentration of 0.03% chitosan CC/TPP with the adsorption peak at wave 3257 cm-1. X-Ray Diffraction shows that chitosan crystallinity obtained from various concentrations of chitosan CC/TPP shows amorphous properties because there are diffraction patterns with peaks between 18.06° - 19.04°. The conclusion is that the best-recommended selection is a concentration of 0.25% chitosan and 0.03% TPP to form nanofibers. The nanofiber biopolymers with the natural suspension of chitosan CC/TPP polymer produce the best pore size and can be considered as a filler in the manufacture of edible films.

PREPARATION OF CHITOSAN-CELLULOSE COMPOSITE BEADS USING CELLULOSE ISOLATED FROM SUGARCANE BAGASSE

Chitosan-cellulose composite beads had been prepared using cellulose isolated from sugarcane bagasse. Sugarcane bagasse was hydrolyzed with H2SO4 with various concentrations (30, 40, and 50%). Cellulose obtained was characterized using Fourier Transform Infrared (FTIR), X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM). FTIR analysis results inform the existence of typical functional groups of cellulose in the sample. XRD patterns show H2SO4 concentration on the hydrolysis process influence the crystallinity of cellulose. Cellulose was used as a filler in the preparation of chitosan-cellulose composite beads. The results show that cellulose decrease the crystallinity of chitosan.

Preparation of Magnetic Chitosan Beads for Heavy Metal Ions Removal from Water

Magnetic chitosan beads have been successfully prepared using Fe3O4 and applied for Hg(II) and Cd(II) removal from water. Fe3O4 was extracted from Aceh iron sand using co-precipitation method. The preparation of magnetic chitosan beads was conducted with several contents of chitosan and Fe3O4. The obtained magnetic chitosan beads were characterized using XRD, FTIR, and SEM. XRD pattern of magnetic chitosan bead was broader and has a lower intensity than chitosan that confirmed the decrease in chitosan crystallinity. FTIR and SEM data confirmed the formation of magnetic chitosan beads. Adsorption study was performed for Hg(II) and Cd(II) removal from water. The adsorption capacities of magnetic chitosan beads for Hg(II) and Cd(II) were 0.4 and 3.04 mg/g, respectively which were higher than adsorption capacities of pure chitosan.

Preparation of magnetic chitosan using local iron sand for mercury removal

Preparation of magnetic chitosan for mercury removal from polluted water had been conducted. Magnetic particles (Fe3O4) were isolated from local iron sand to provide magnetic properties of chitosan. Glutaraldehyde was used as crosslinking agent of chitosan. The obtained magnetic chitosan was characterized by using FTIR, TGA, DSC, XRD, and SEM. Adsorption experiments were conducted with various contact time, pH and initial concentration of mercury. The results showed glutaraldehyde and Fe3O4 decreased crystallinity of chitosan. Low crystallinity of polymer is favorable for adsorption due to the high accessibility of adsorbate to reach active sites of adsorbent. FTIR and SEM confirmed the formation of magnetic chitosan. Based on correlation coefficient (R2) values, the adsorption mercury by magnetic chitosan fitted with Langmuir and Freundlich isotherm models.

Study on Preparation of Water-Soluble Chitosan with Varying Molecular Weights and Its Antioxidant Activity

The preparation of water-soluble chitosan (WSC) with various molecular weights by gamma Co-60 irradiation of chitosan solution (5%) in the presence of hydrogen peroxide (1%) combined with acetylated reaction was carried out. The average molecular weight (Mw) of chitosan was measured by gel permeation chromatography (GPC). The chemical structure and the crystallinity of chitosan and WSC were characterized by Fourier-transform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD), respectively. The antioxidant activity of WSC and chitosan was investigated using the free radical 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS•+). Obtained results showed that chitosan with Mw of 18–90 kDa could be efficiently prepared by this technique in the dose range from 10 to 24.5 kGy. After the acetylated process, the resulting WSC possesses good solubility in a wide pH level of 2–12, and WSC with low molecular weight exhibited significantly higher antioxidant activity than the one with high molecular weight. In detail, the antioxidant activity was 14.7%, 70.5%, 84.2%, 89.4%, and 97.5% for WSC samples prepared from chitosan with Mw of 140.2 kDa, 91.4 kDa, 51.2 kDa, 35.3 kDa, and 18.1 kDa, respectively, at the same reaction time of 90 min. Moreover, the antioxidant activity of WSC was higher than that of chitosan. Thus, WSC prepared by gamma Co-60 irradiation and acetylated process can be potentially applied as a natural antioxidant agent.

Intensification in biological properties of chitosan after γ-irradiation.

Chitosan, a functional biopolymer, was irradiated with 100 kGy gamma irradiation and used to access its physical, antioxidant, plant growth promoting and antimicrobial properties. The molecular weight of chitosan reduced to 82.2 kDa from 337.7 kDa after irradiation. UV-Vis spectroscopy and FTIR results revealed slight changes in chitosan skeleton after irradiation but the degree of acetylation of both chitosan was ~18%. DSC profile indicated a prominent decline in enthalpy and energy for phase transition, TGA indicated shift in decomposition temperature, while XRD analysis showed a reduction in chitosan crystallinity after irradiation. DPPH and ABTS radical scavenging activity of chitosan (2-10 mg/mL) enhanced significantly by 1.25-1.45 and 1.80-3.14 folds after irradiation. There was a considerable improvement in morphological parameters (number of leaves, nodes, height, fresh weight and dry weight) and biochemical parameters (chlorophyll, total soluble sugars and soluble proteins content) of in vitro potato plant in chitosan supplemented medium at 75 mg/L concentration than the control. The minimum inhibitory concentration of normal and irradiated chitosan for Alternaria spp. was 2500 and 2000 mg/L and for Fusarium spp. was 1750 and 1500 mg/L, respectively. IC50 value of normal and irradiated chitosan for Fusarium spp. was 1387.9 ± 9.2 and 954.3 ± 6.1 mg/L, and for Alternaria spp. was 1536.1 ± 24.3 and 1416.8 ± 3.5 mg/L, respectively.

Chitosan-g-poly(4-acrylamidobenzenesulfonamide) copolymers: synthesis, characterization, and bioactivity

The monomer, 4-acrylamidobenzenesulfonamide (ABS), was synthesized via reaction of acryloyl chloride with 4-aminobenzenesulfonamide in acetone at 0 °C. This monomer was then grafted onto chitosan using solution containing 2% acetic acid and mixture of K2S2O8 and Na2SO3 as the redox promoter. An optimal G% of 150% was obtained when the process is conducted at 60 °C for 3 h employing 3.0 × 10−3 M K2S2O8 and 1.5 × 10−3 M Na2SO3. The graft copolymers, chitosan-g-poly(4-acrylamidobenzenesulfonamide), were characterized by using FTIR, XRD, and SEM. The results were shown that the crystallinity of chitosan is enhanced by increasing the monomer content through the grafting process. Potential Antimicrobial activities of the permethyl ammonium salt forms of chitosan and its grafted copolymers against selected microorganisms were evaluated. The results show that the graft copolymers display better inhibitory effects on the growth of bacteria and some fungi than does chitosan.

Enhanced Enzymatic Hydrolysis of Chitosan by Surfactant Addition

Less attention has been paid for the effects of surfactant on the hydrolysis of chitosan. This paper presents the influence of the surfactant Tween 80 addition on the chitosan hydrolysis catalyzed by cellulase enzyme. The hydrolyzed chitosan was characterized by measuring its reducing sugar content, its chemistry by Fourier transforms infrared spectroscopy (FT-IR), its formation of aldehyde groups by ultraviolet - visible spectra (UV-Vis), and its crystallinity degree by X-ray diffraction (XRD). The results showed that Tween-80 could increase the hydrolysis rate and decrease the crystallinity of chitosan. The formation of reducing sugar increased by increasing reaction time up to 24 hours and then leveled off. A more significant effect of surfactant was observed when the hydrolysis was performed at a low surfactant concentration and a low substrate concentration. IR spectra showed that both raw and hydrolyzed chitosan have similar chemical structure.

The Optimum Conditions of Carboxymethyl Chitosan Synthesis on Drug Delivery Application and Its Release of Kinetics Study

In this paper, carboxymethyl chitosan (CMC) was synthesized and studied as a carrier to encapsulate vitamin (as drug model) and controlled release. Chitosan (CS) is a polycationic derivated from chitin, which suitable for active substance carrier system on biomedical function. CS has good properties such as non-toxic, biodegradable, and biocompatible. However, CS insoluble in an aqueous solvent so CS was modified chemically into CMC. CMC was formed by reacting CS and monochloroacetic acid with sodium hydroxide (NaOH) as a catalyst. Optimation was performed by varying the NaOH concentration during alkalizing the CS and the temperature reaction. The functional group and crystallinity of CS and CMC were estimated by FTIR and XRD. The degree substitution of carboxymethylation has an average value of 0.60. The results show optimum temperature reaction and NaOH concentration were 60 °C and 40% (w/v). The nicotinamide (NA), a hydrophilic vitamin, was loaded within CMC matrix system through in vitro precipitation method. To confirm the encapsulation of NA in CMC and the release kinetics of NA from CMC in distilled water was studied through UV-Vis spectrophotometry. The release profile of NA from CMC matrix system carried out for 3 h and 12 h. The rate of NA release from CMC increases with increasing time and the follows a zero order, Higuchi, and Korsmeyer-Peppas kinetics rules.

Preparation and Characterization of Chitosan by a Novel Deacetylation Approach Using Glycerol as Green Reaction Solvent

Traditional methods for chitin deacetylation require aqueous solution with high alkali content as reaction solvent, which generate huge environmental pressure for the treatment of vast alkaline wastewater. In this work, glycerol, a nontoxic, biodegradable, and sustainable liquid from biodiesel production, is employed as a novel reaction solvent for chitin deacetylation at elevated temperature. The results showed that the chitosan deacetylation degree (DD) was up to 85.36 ± 1.04% and the corresponding viscosity-average molecular weight (MV) was 30 874 ± 1123 g mol–1 under the optimized conditions of this process. The subsequent Fourier transform infrared (FTIR) characterization structurally demonstrated the occurrence of deacetylation and the fracture of glucosidic bond. Thermogravimetric analysis (TGA) and X-ray diffraction (XRD) analysis further revealed that the DD presented a negative effect on the thermal stability and crystallinity of chitosan. Consequently, the study successfully indicated that usin...

In vivo study on the biocompatibility of chitosan-hydroxyapatite film depending on degree of deacetylation.

Chitosan, produced from chitin, is one of the polymers with promising applications in various fields. However, despite diverse research studies conducted on its biocompatibility, its uses are still limited. The main reason is the degree of deacetylation (DOD), which represents the proportion of deacetylated units in the polymer and is directly correlated with its biocompatibility property. In this article, the in vivo biocompatibility of three chitosan-hydroxyapatite composite films composed of chitosan with different DOD values was investigated by traditional biological protocols and novel optical spectroscopic analyses. The DOD of the chitosan obtained from three different manufacturers was estimated and calculated by Raman spectroscopy, Fourier transform infrared spectroscopy, and proton nuclear magnetic resonance spectroscopy. The chitosan with the higher DOD induced a higher incidence of inflammation in skin cells. The amino group density, biodegradability, and crystallinity of chitosan are the three possible factors that need to be considered when determining the biocompatibility of the films for in vivo application, as they led to complicated biological results, resulting in either better or worse inflammation even when using chitosan products with the same DOD. This basic study on the relationship between the DOD and inflammation is valuable for the development of further chitosan-based researches. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1637-1645, 2017.

Preparation of N, N, N-trimethyl chitosan via a novel approach using dimethyl carbonate

N,N,N-trimehtyl chitosan (TMC) is a water-soluble derivate of chitosan, which has been widely used as a biomedical material due to its excellent biocompatibility, biodegradability and bacterial properties. To date, TMC can only be prepared by the quaternization of chitosan using alkyl halide or dimethyl sulfate. However, alkyl halide and dimethyl sulfate are highly toxic, cancerigenic for humans, and harmful to the environment. This paper puts forward a novel approach to preparing TMC using dimethyl carbonate as a methylation reagent in an ionic liquid. The as-synthesized O-methyl-free TMC was characterized using NMR, FTIR, XRD and TG analyses. The results showed that TMC with a degree of quaternization of 9.11% was successfully obtained and the crystallinity of chitosan decreased with the increasing degree of N-methylation, the thermal stability of TMC was lower than that of chitosan. Furthermore, the effects of the dose of ionic liquid and dimethyl carbonate were disscussed.

Preparation and Blood Coagulation Property of Ortho Hydroxytoluene Chitosan

The aim of this paper was to synthesize ortho hydroxytoluene chitosan for hemostatic use. A series of modified chitosan were prepared by reductive amination through adjusting the dosages of salicylaldehyde and sodium borohydride. FTIR, elemental analysis and XRD tests were performed to analyze the composition, degree of substitution (DS) and crystallisability of chitosan derivatives. Rheological and blood coagulation experiments were carried out to measure its gel-forming and hemostasis property in vitro. The results showed ortho hydroxytoluene groups could be grafted on chitosan, DS value can be adjusted by the dosage of reactive agents, and the crystallinity of chitosan changed obviously after modification. The rheological results indicated high substituted (≥26.79 mol-%) ortho hydroxytoluene chitosan could gel blood and showed better blood coagulation property. High substituted ortho hydroxytoluene chitosan could improve hemostatic property significantly.

Preparation, characterization, and antioxidant activity of water-soluble oligochitosan

Abstract The preparation of oligochitosan through the heterogeneous degradation of chitosan/H2O2 combined with the homogeneous reaction of chitosan with H2O2 under gamma radiation was studied. Oligochitosan with weight-average molecular weight (Mw) of less than 10 kDa could be efficiently prepared by gamma Co60 irradiation of chitosan solution (4%) and hydrogen peroxide (0.5%) at doses ranging from 8 to 24 kGy. The Mw, chemical structure, and the crystallinity of chitosan and oligochitosan were characterized by GPC, FT-IR, and XRD. The solubility and antioxidant activity of chitosan and of oligochitosan with the different molecular weights were investigated. Results showed that oligochitosan CS5 (20 kGy) and CS6 (24 kGy) have good solubility in the pH range of 3 to –11. The scavenge percentage of CS5 against 2,2-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical is 99.2% in 90 min. The antioxidant activity of oligochitosan is effective in a short time period; therefore, it has potential application as an effective and natural antioxidant.

Tuning the Hydrophilic/Hydrophobic Balance to Control the Structure of Chitosan Films and Their Protein Release Behavior.

The control over the crystallinity of chitosan and chitosan/ovalbumin films can be achieved via an appropriate balance of the hydrophilic/hydrophobic interactions during the film formation process, which then controls the release kinetics of ovalbumin. Chitosan films were prepared by solvent casting. The presence of the anhydrous allomorph can be viewed as a probe of the hydrophobic conditions at the neutralization step. The semicrystalline structure, the swelling behavior of the films, the protein/chitosan interactions, and the release behavior of the films were impacted by the DA and the film processing parameters. At low DAs, the chitosan films neutralized in the solid state corresponded to the most hydrophobic environment, inducing the crystallization of the anhydrous allomorph with and without protein. The most hydrophilic conditions, leading to the hydrated allomorph, corresponded to non-neutralized films for the highest DAs. For the non-neutralized chitosan acetate (amorphous) films, the swelling increased when the DA decreased, whereas for the neutralized chitosan films, the swelling decreased. The in vitro release of ovalbumin (model protein) from chitosan films was controlled by their swelling behavior. For fast swelling films (DA = 45%), a burst effect was observed. On the contrary, a lag time was evidenced for DA = 2.5% with a limited release of the protein. Furthermore, by blending chitosans (DA = 2.5% and 45%), the release behavior was improved by reducing the burst effect and the lag time. The secondary structure of ovalbumin was partially maintained in the solid state, and the ovalbumin was released under its native form.