Modified Chitosan Polymers Research Articles

Application of a novel polymer cross-linked with magnetite for efficient norfloxacin adsorption at a wide pH range

Nowadays, NOR-containing wastewater has placed huge pressure on global ecology. In this study, a chemically-modified chitosan-based polymer was cross-linked with magnetite to prepare a novel magnetic composite adsorbent named Fe3O4/CS-P(AM-SSS) for norfloxacin (NOR) removal. The preparation conditions were optimized by single factor experiments and response surface methodology. A series of characterization analyses were carried out on the morphology, structure, and properties of Fe3O4/CS-P(AM-SSS), verifying that Fe3O4/CS-P(AM-SSS) was successfully prepared. Batch adsorption experiments showed that NOR was efficiently removed by Fe3O4/CS-P(AM-SSS), with a broad pH applicability of 3–10, short adsorption equilibrium time of 60 min, maximum adsorption capacity of 268.79 mg/g, and high regeneration rate of 86% after eight adsorption-desorption cycles. Due to the three-dimensional network structure and abundant functional groups provided by modified chitosan polymer, the superior adsorption capability of Fe3O4/CS-P(AM-SSS) was achieved through electrostatic interaction, π-π stacking, hydrophobic interaction, and hydrogen bonding. Adsorption process was exothermic and well fitted by the pseudo-second-order kinetic model and the Langmuir isothermal model. The presence of cations had a slight inhibitory effect on NOR adsorption, while humic acid nearly had no effect. In model swine wastewater, 90.3% NOR was removed by Fe3O4/CS-P(AM-SSS). Therefore, with these superior characteristics, Fe3O4/CS-P(AM-SSS) was expected to be an ideal material for treating NOR-containing wastewater in the future.

Synergetic integrations of bone marrow stem cells and transforming growth factor-β1 loaded chitosan nanoparticles blended silk fibroin injectable hydrogel to enhance repair and regeneration potential in articular cartilage tissue.

The cartilage repair and regeneration show inadequate self‐healing capability and have some complications, which are inordinate challenges in clinical therapy. Biopolymeric injectable hydrogels, a prominent type of cell‐carrier as well tissue engineering scaffolding materials, establish promising therapeutic potential of stem cell‐based cartilage‐regeneration treatment. In addition, injectable scaffolding biomaterial should have rapid gelation properties with adequate rheological and mechanical properties. In the present investigation, we developed and fabricated the macromolecular silk fibroin blended with polylysine modified chitosan polymer (SF/PCS) using thermal‐sensitive glycerophosphate (GP), which contains effective gelation ability, morphology, porosity and also has enhanced mechanical properties to induce physical applicability, cell proliferation and nutrient exchange in the cell‐based treatment. The developed and optimised injectable hydrogel group has good biocompatibility with human fibroblast (L929) cells and bone marrow‐derived mesenchymal stem cells (BMSCs). Additionally, it was found that SF/PCS hydrogel group could sustainably release TGF‐β1 and efficiently regulate cartilage‐specific and inflammatory‐related gene expressions. Finally, the cartilage‐regeneration potential of the hydrogel groups embedded with and without BMSCs were evaluated in SD rat models under histopathological analysis, which showed promising cartilage repair. Overall, we conclude that the TGF‐β1‐SF/PCS injectable hydrogel demonstrates enhanced in vitro and in vivo tissue regeneration properties, which lead to efficacious therapeutic potential in cartilage regeneration.

Preparation and characterization of a novel emphatically charged strengthened chitosan composite nanofiltration membrane

In this paper, chitosan was grafted with acrylic acid and positively charged elements, and a series of reinforced nanofiltration membranes were prepared by coating modified chitosan polymer with polysulfone ultrafiltration membrane as support. The structure of chitosan derivatives and polymers was characterized by infrared spectrum, and the membrane structure was characterized by scanning electron microscope and atomic force microscope. The performance of composite nanofiltration membrane was closely related to the structure of polymer and the electrical properties of positively charged elements. The rejection rate of 50% molar ratio composite nanofiltration membrane to CaCl2 reached 97.4%. The corresponding flux is 430.7 Lm-2h-1. The retention order was: CaCl2 > NaCl > Na2SO4. The tensile strength increased by 27.3%. Acid resistance (5%HCl)) was improved by 50.5%. Alkali resistance (5%NaOH) increased by 42.2%. The results showed that the positive charge enhanced chitosan composite nanofiltration membrane had excellent performance. The charge effect had no effect on NaCl and Na2SO4, but had significant effect on CaCl2. The membrane is a typical positive charged nanofiltration membrane suitable for separating high-valent cations from weak acids or weak bases.

Immobilization of Catalase onto Polylysine Modified Chitosan Polymer

In this study, chitosan polymer was modified in two different ways and used for the immobilization of bovine liver catalase (CAT). First, it was activated with glutaraldehyde (GAL), and then covalently immobilized covalently onto the support via lysine amino acid residue in CAT. In the second modification, GAL-activated chitosan was interacted with polylysine (pLYS), then reactivated with GAL and used in CAT immobilization. Samples of bare chitosan (Chi), GAL-activated (ChiGAL), polylysine-modified (ChiGAL-pLYS), reactivated with GAL (ChiGAL-pLYSGAL) and CAT-immobilized chitosan (ChiGAL -CAT and ChiGAL-pLYSGAL-CAT) were all characterized by FTIR. The enzymatic activities of Free CAT, ChiGAL -CAT and ChiGAL-pLYSGAL-CAT samples were investigated at different pH and temperatures and the values with the highest activity were determined. In addition, the effect of substrate concentration on activity under optimal conditions was investigated. Optimum pH values of Free CAT, ChiGAL-CAT and ChiGAL-pLYSGAL-CAT samples were 7.5, 7.0 and 7.0, respectively; temperature values were determined as 25, 30 and 35 C, respectively. After immobilization, the Vmax values of the enzymes decreased, the Km values increased, and the efficiency of catalase immobilized to the polylysine modified support was found to be higher. It was observed that after 20 repeatedly use in the column reactor, ChiGAL-CAT and ChiGAL-pLYSGAL-CAT enzymes retained 88 % and 76 % of their initial activities, respectively.

The Impact of Multiple Functional Layers in the Structure of Magnetic Nanoparticles and Their Influence on Albumin Interaction.

In nanomedicine, hybrid nanomaterials stand out for providing new insights in both the diagnosis and treatment of several diseases. Once administered, engineered nanoparticles (NPs) interact with biological molecules, and the nature of this interaction might directly interfere with the biological fate and action of the NPs. In this work, we synthesized a hybrid magnetic nanostructure, with antibacterial and antitumoral potential applications, composed of a magnetite core covered by silver NPs, and coated with a modified chitosan polymer. As magnetite NPs readily oxidize to maghemite, we investigated the structural properties of the NPs after addition of the two successive layers using Mössbauer spectroscopy. Then, the structural characteristics of the NPs were correlated to their interaction with albumin, the major blood protein, to evidence the consequences of its binding on NP properties and protein retention. Thermodynamic parameters of the NPs–albumin interaction were determined. We observed that the more stable NPs (coated with modified chitosan) present a lower affinity for albumin in comparison to pure magnetite and magnetite/silver hybrid NPs. Surface properties were key players at the NP–biological interface. To the best of our knowledge, this is the first study that demonstrates a correlation between the structural properties of complex hybrid NPs and their interaction with albumin.

Corrosion mitigation performance of disodium EDTA functionalized chitosan biomacromolecule - Experimental and theoretical approach

Disodium ethylenediaminetetraacetate salt is known for its excellent coordinating properties with the metal ions. The present study deals with the investigation of the prepared Disodium EDTA functionalized chitosan in corrosion inhibition for mild steel in 1 M HCl. The modified chitosan was characterized by spectral studies, thermal analysis, and Zeta potential studies. The corrosion inhibition efficiency (%) was evaluated using the gravimetric method and electrochemical studies. The electrochemical studies included potentiodynamic polarization, linear polarization resistance, and electrochemical impedance methods. The modified chitosan polymer showed an inhibition efficiency of 96.63% for 500 ppm at 303 K. Adsorption process obeyed Langmuir isotherm. Experimental results and theoretical calculations endorsed initial physisorption followed by a chemisorption process. Surface characterization studies supported the formation of a protective film that enabled the inhibition process. Density functional theory, Monte Carlo studies, and molecular dynamics simulation studies show a good agreement with the experimental results. Two-way Analysis of Variance was performed to test the influence of immersion period and inhibitor concentration on the corrosion rate using the statistical software IBM SPSS 20.0. A quartic model was generated as the best fit with the highest R2 value of 0.973. Design Expert software was employed for statistical modeling fit.

N-Halamine Hydantoin-Containing Chitosan: Synthesis, Characterization, Thermal and Photolytic Stability Studies

Current demand for new protective materials ensuring sterility is systematically growing. The purpose of this work was the synthesis of the biocidal N-halamine hydantoin-containing chitosan (CS-CMH-Cl) and characterization of its properties. The functionalization of the chitosan by 5-hydantoinacetic acid substitution leads to obtaining the CS-CMH polymer, which was chlorinated in next step to transform N-H into N-Cl bonds. In this study, the possibility of forming two biocidal N-Cl bonds in hydantoin ring, grafted onto chitosan chains, was proved. The structure and stability of the prepared material was confirmed by spectroscopic (FTIR, NMR, colorimetric test) and microscopic analyses (SEM, AFM). Surface properties were investigated based on contact-angle measurements. In addition, the thermal and photochemical stability of the obtained samples were determined as functional features, determining the range of potential use. It was found that both modified chitosan polymers (CS-CMH and CS-CMH-Cl) were characterized by the smaller thermal stability and more hydrophilic and rougher surface than unmodified CS. Photooxidative degradation of the obtained materials was observed mainly on the sample surface. After irradiation, the surfaces became more hydrophilic—especially in the case of the CS-CMH-Cl—which is advantageous from the point of view of the antibacterial properties. Antibacterial tests against S. aureus and E. coli confirmed the antibacterial activities of received CS-CMH-Cl material.

Efficient Removal of Methyl Orange from Wastewater by Polymeric Chitosan-iso-vanillin

Introduction: Water pollution is a serious issue in several countries. In addition, because of limited water resources, the recycling of wastewater is crucial. Consequently, new and effective sorbents are required to reduce the cost of wastewater treatment as well as to mitigate the health problems caused by water pollution. Methods: In this study, the removal of Methyl Orange (MO) dye from wastewater using a chitosan-iso-vanillin polymer was evaluated. The removal of MO from an aqueous solution was studied in a batch system, using the modified chitosan polymer. Results: The results indicate that the removal of MO by the modified chitosan was affected by the solution pH, sorbent dosage, initial MO concentration, contact time, and temperature. The experimental data were fitted to the Langmuir, Freundlich, and Temkin isotherms, and Freundlich isotherm showed the best fit. The kinetic data were fitted to the pseudo-first-order and pseudo-second-order rate equations. Thus, the removal of MO was controlled via chemisorption, and the removal rate was 97.9% after 3 h at an initial MO concentration of 100 ppm and a sorbent dose of 0.05 g. The adsorption behavior of the modified chitosan for the removal of MO was well-described using the pseudo-second-order kinetic model. Intraparticle diffusion analysis was also conducted, and the thermodynamic properties, including entropy (∆S), enthalpy (∆H), and free energy (∆G), were determined. Conclusion: The pH, initial MO concentration, sorbent dosage, adsorption temperature, and contact time had a significant effect on the adsorption of MO by chitosan-iso-vanillin.

"Study the Effect of Immobilization on Electrostatic Potential for Methyl Orange Dye "

"In the current study, the effect of the immobilization on electrostatic potential, pH and the absorbance of aqueous solutions of methyl orange that was immobilized on a modified chitosan polymer by glass wool were studied. It was found that the values of these parameters of the supported methyl orange are increased compared to unsupported samples. Furthermore, the electrostatic potential of the supported methyl orange is investigated in the presence of an aqueous solutions of NaCl, where showed the value of the electrostatic potential is raised With increasing ionic strength of the sodium chloride solution and a decrease in the value of pKa to the methyl orange dye after immobilization while the results are inversely before immobilization methyl orange on a modified chitosan polymer by glass wool.

Sulfonic Acid Functionalized Chitosan as a Sustainable Component for Proton Conductivity Management in PEMs

AbstractOne of the most fundamental assets of natural polysaccharides is their water storage capacity. Analogically, materials able to regulate water hydration in energetic systems (e.x.: fuel‐cells) are of paramount interest. In light of this key characteristic, chitosan, an aminocarbohydrate derived from shellfish waste, was structurally conjugated using sulfosuccinic acid to afford CS‐SO3H. The resulting polymeric material appears well suitable for enhancing proton conduction and tuning the hydrophilic‐hydrophobic balance of the proton exchange membranes (PEM). Consequently, Nafion membrane modified with CS‐SO3H presented σH+ values almost 2 times higher than that of pristine Nafion at every % RH level exposed (30 °C ‐ 80 °C and 30% ‐ 90%). The σH+ enhancement is in agreement with the lower activation energy indicating that the proton transport is facilitated in the presence of ‐SO3H modified chitosan. We have found indications that –SO3H modified chitosan polymer, as a sustainable additive to Nafion is able to control the proton conduction mechanism and keep the activation energy for proton conduction at lower values as compared to pristine Nafion.

Chemically modified chitosan polymers for bromate removal

Bromate is a harmful byproduct formed during drinking water disinfection processes. In this work, adsorption of bromate by natural chitosan and its chemically modified polymers has been investigated. Bromate adsorption was found between 22.73 mg/g and 43.48 mg/g. Adsorbents were analysed by Fourier transform infrared-ATR spectroscopy. It is suggested that chemical adsorption is the main bromate adsorption mechanism. By fitting theoretical results to experimental data, it is shown that the Langmuir adsorption model and the second-order kinetic model are more applicable to explain the adsorption process. Furthermore, increased bromate adsorption is found at high temperature and at low pH, while coexisting ions have little influence at low concentrations.

Capping Gold Nanoparticles with Modified Chitosan Polymers for Biomedical Applications

Capping Gold Nanoparticles with Modified Chitosan Polymers for Biomedical Applications

Metal uptake by chitosan derivatives and structure studies of the polymer metal complexes

Two modified chitosan polymers were obtained by reaction of chitosan with cinnamoyl chloride and cinnamoyl isothiocyanate to produce two new derivatives. The new modified polymers were characterized by elemental and spectral analysis to confirm their structures. Their metal up take capacity was investigated both under competitive and noncompetitive conditions. At pH 5.6, the (ChitoCin and ChitoThioCin) polymers exhibit higher capacity for Cu(II) (0.461–0.572 mmol/g) than the other metal ions used. Where the capacities of the other metal ions are: Fe(III) (0.235–0.341 mmol/g), Cr(III) (0.078–0.099 mmol/g), Co(II) (0.046–0.057 mmol/g) and Ni(II) (0.041–0.053 mmol/g). These results show that the capacity of ChitoThioCin polymer is higher than that of ChitoCin for each metal ion. However, at lower pH the capacities (for Cr(III) pH < 1.8 and Fe(III) pH < 3.1) are higher than other metal ions under investigation. It has been found that the absorption follows the Langmuir isotherm better than that of the Freundlich isotherm. The metal complexes with several metal cations were isolated and their structures with the new chitosan polymers were found to be octahedral and schematic representations of the complexes were given.

Folate mediated in vitro targeting of depolymerised trimethylated chitosan having arginine functionality

Delivery vectors having targeting ligands provide an impending impact on cancer gene therapy. Our work focuses on folate mediated targeting induced by conjugating poly(ethylene glycol)–folate (PEG–FA) with arginine modified chitosan polymer having low molecular weight of 15 kDa and high degree of quaternization (ATFP15H). The ATFP15H derivative on condensation with plasmid DNA formed nanoparticles with core shell nanostructure. It also affirmed good buffering capacity. The derivative was found to protect DNA from DNase I degradation and also from disassembly in presence of negatively charged plasma proteins. It exhibited blood compatibility in terms of percentage hemolysis, erythrocyte aggregation and also by platelet activation. At a concentration of 10 μg, the capability of the derivative to enhance cell growth at normal cell growing conditions was observed. The transfection efficiency was also found to be comparable to PEI when transfected in KB cell line, which over expressed the folate receptor (FR) in presence of 10% fetal bovine serum (FBS). On comparison with native chitosan and trimethylated chitosan, ATFP15H derivative exhibited high cellular uptake and nuclear localization due to the superior colloidal stability attained on conjugation with polyethylene glycol. This has been ascertained by flow cytometry and YOYO labeling of plasmid DNA.

Folate mediated histidine derivative of quaternised chitosan as a gene delivery vector

Folate targeted gene delivery vectors showed enhanced accumulation in folate receptor expressing tumor model. In the present work, the water solubility and transfection efficiency of chitosans were improved by modifying the depolymerised trimethylated chitosans with histidine moiety. Folate mediated targeting was induced by conjugating poly(ethylene glycol)-folate (PEG-FA) on histidine modified chitosan polymer having low molecular weight of 15 kDa and high degree of quaternisation (HTFP15-H). The zeta potential and size of the HTFP15-H/pDNA nanoparticles were determined using dynamic light scattering technique and the results were confirmed by transmission electron microscopy (TEM). The morphology of the nanoparticles was found spherical in shape having core–shell nanostructure. The HTFP15-H derivative found to buffer in the pH range from 10 to 4. The blood compatibility in terms of percentage hemolysis, erythrocyte aggregation and also by platelet activation was found to be significantly improved compared to the control vector PEI. At a concentration of 10 μg the derivative promote the cell growth up to 139% compared to control at normal cell growing conditions. The transfection efficiency in KB cell line, which over expresses the folate receptor (FR) in presence of 10% fetal bovine serum (FBS) was also found to be comparable to the control. Moreover the enhanced cellular and nuclear uptake due to the conjugation of both folic acid and histidine makes it a potential vector for gene delivery applications.

Fluorescence analysis of chemical microenvironments and their impact upon performance of immobilized enzyme

In this work the shift in fluorescence emission spectra of acrylodan, a polar sensitive fluorophore, has been used to characterize the polarity immediately surrounding cytoplasmic (cMDH) and mitochondrial malate dehydrogenase (mMDH) enzyme immobilized within three-dimensional macroporous chitosan scaffolds. The scaffolds were fabricated from solutions of fluorescently tagged enzymes mixed with deacetylated and hydrophobically modified chitosan polymer. Each solution was frozen and then freeze-dried through the process of thermally induced phase separation (TIPS). The blue shift in acrylodan's emission maxima (lambda(max)) revealed a polar shift in the chemical microenvironment surrounding the enzymes when immobilized in a modified as opposed to unmodified chitosan scaffold. These results suggest that the method of hydrophobic modification of native chitosan polymer can be used to control the amphiphilic nature of the chemical microenvironment immediately surrounding the enzyme after it has been immobilized.

Fluorescence characterization of chemical microenvironments in hydrophobically modified chitosan

In this work we use the steady state and time-resolved fluorescence of free and enzyme-bound fluorophores to characterize the binding capacity of both unmodified and hydrophobically modified chitosan polymers. Additionally, fluorescence emission is used to qualitatively characterize the extent to which hydrophobic modification of the chitosan polymer affects the relative polarity of the resultant amphiphillic micelles. In total, these results are used to describe how fluorescence techniques can be used to characterize the chemical microenvironment provided by immobilization polymers such as chitosan. Commentary is also given on how this information can be correlated to enzyme activity and spatial distribution during the immobilization processes.

Spatial Distribution of Malate Dehydrogenase in Chitosan Scaffolds

In this work, confocal laser scanning microscopy was used to study the spatial distribution of malate dehydrogenase immobilized within three-dimensional macroporous chitosan scaffolds. The scaffolds were fabricated from solutions of native and hydrophobically modified chitosan polymer through the process of thermally induced phase separation. The hydrophobically modified chitosan is proposed to possess amphiphilic micelles into which the enzyme can be encapsulated and retained. To test this theory, we applied the immobilization procedure of Klotzbach and co-workers [J. Membr. Sci. 2006, 282 (1-2), 276-283] to solutions of fluorophore-tagged malate dehydrogenase in the presence of native and hydrophobically modified chitosan polymer and then tracked the distribution of enzymes in the resulting scaffolds using fluorescent microscopy. Results suggest that the modified chitosan does encapsulate the enzyme with a significant degree of retention and with altered distribution patterns, suggesting that hydrophobic modification of the chitosan polymer backbone does create amphiphilic regions that are capable of physically encapsulating and retaining enzymes. Commentary is also given on how this information can be correlated to enzyme activity and spatial distribution during immobilization processes.

Characterization and evaluation of hydrophobically modified chitosan scaffolds: Towards design of enzyme immobilized flow-through electrodes

Chitosan scaffolds were fabricated by application of thermally induced phase separation from aqueous solutions of unmodified chitosan and hydrophobically modified chitosan polymer. The final pore structure, in terms of diameter and geometry, were correlated to freezing temperature and freezing time for both the unmodified and hydrophobically modified chitosan polymer. Results showed that the resulting pore structure is strongly dependent upon the freezing temperature and less dependant upon the freezing time. For scaffolds produced from unmodified chitosan, the pore size decreased as expected with decreasing freezing temperature from −5 °C to −10 °C. However, an inconsistency in this trend was observed as the freezing temperature was decreased to −20 °C. Combined analysis of pore size distribution and average pore diameter suggested that the freezing process was mainly mass transfer dominated at −5 °C and −10 °C, but principally heat transfer dominated at −20 °C. In comparison, the scaffolds produced from hydrophobically modified chitosan (butyl-chitosan) followed the expected trend of decreasing mean pore diameter with decreased freezing temperatures throughout the entire temperature range. The scaffolds produced from the unmodified chitosan were more stable and rigid, and possessed average pore diameters that were generally smaller than those fabricated from the hydrophobically modified chitosan. The generally larger pores in the butyl-modified chitosan scaffolds might be explained by increased phase separation rates due to the introduced hydrophobicity of the chitosan polymer. Among the scaffolds fabricated from the butyl-modified chitosan, those produced at −20 °C yielded the most uniform pore structure, the smallest average pore diameters, and the least temporal broadening of pore size distribution.

Copper sorption from diesel oil on chitin and chitosan polymers

Chitin, chitosan and modified chitosan, biopolymers which have structures similar to that of cellulose, are proposed for removal of copper ion from diesel oil. These natural polymers had been used before for recovering traces of metals from aqueous solutions and from industrial and sea waters. The present work describes the obtention and characterisation of chitin, chitosan and modified chitosan polymers. The removing ability of these polymers for copper ion has been demonstrated in diesel oil and chitosan presented the best performance. The removal percentage from kinetic studies depends on several factors as the polymer type, the temperature and the contact time and reaches values of about 92% at equilibrium.