Increasing Chitosan Concentration Research Articles

In Vitro Mechanical Property Evaluation of Chitosan-Based Hydrogels Intended for Vascular Graft Development.

Vascular grafts made of synthetic polymers perform poorly in cardiac and peripheral bypass applications. In these applications, chitosan-based materials can be produced and shaped to provide a novel scaffold for vascular tissue engineering. The goal of this study was to evaluate in vitro the mechanical properties of a novel chitosan formulation to assess its potential for this scaffold. Two chitosan-based hydrogel tubes were produced by modulating chitosan concentration. Based on the standard ISO 7198:1998, the hydrogel tubes were characterized in vitro in terms of suture retention strength, tensile strength, compliance, and burst pressure. By increasing chitosan concentration, suture retention value increased to reach 1.1N; average burst strength and elastic moduli also increased significantly. The compliance seemed to exhibit a low value for chitosan tubes of high concentration. By modulating chitosan concentration, we produced scaffolds with suitable mechanical properties to be implanted in vivo and withstand physiological blood pressures.

Enhance Stability and in vitro Cell Response to a Bioinspired Coating on Zr Alloy with Increasing Chitosan Content

The aim of the present paper is to characterize bioinspired chitosan (CS) + hydroxyapatite (HA) coatings with various components ratio on a zirconium alloy with titanium. The coatings were characterized by FT-IR, SEM, hydrophilic/hydrophobic balance, adherence, roughness, electrochemical stability and in vitro cell response. Electrochemical tests, including potentiodynamic polarization curves and electrochemical impedance spectroscopy, were performed in normal saline physiological solution. Cell viability of MC3T3-E1 osteoblasts, lactate dehydrogenase, nitric oxide, and Reactive Oxygen Species (ROS) levels, as well as actin cytoskeleton morphology, were evaluated as biological in vitro tests. The results on in vitro cell response indicated good cell membrane integrity and viability for all samples, but an increased cell number, a decreased ROS level and a better cytoskeleton organization were noticed for the sample with a higher CS content. The coating with highest CS concentration indicated the best performance based on the experimental data. The highest hydrophilic character, highest resistance to corrosion and best biocompatibility as well recommend this coating for bioapplications in tissue engineering.

Biomimetic chitosan-hydroxyapatite hybrid biocoatings for enamel remineralization

Abstract Development of biomimetic ceramic-based materials is currently a challenge in dental tissue engineering. Synthetic hybrid chitosan (CS)-hydroxyapatite (HAP) layers are regarded as candidates for teeth remineralization, protection against further demineralization ensuring also antibacterial activity. Thus, the aim of this work was to obtain new biomimetic CS-HAP layers for restoration of damaged mature enamels and to pursue morphological, compositional, structural and hardness modifications of the grown layers by immersion for 4, 7 and 10 days into artificial saliva (AS) under CS-Emdogain (EMD) hydrogel action. SEM-EDX, HRTEM-SAED, FTIR and micro-Raman findings indicated formation of carbonate-substituted HAP, B-type, with c-axis orientation in the newly formed CS-HAP coatings. Prolonged immersion span of 10 days caused increasing CS content in the superficial grown layer while carbonate content diminished. Optimum Ca/P ratio (1.85 at%) and hardness of 2.48 GPa were recorded for seven days growth using CS-EMD hydrogel. Subtle changes in HAP lattice parameters were recorded for 10-day grown layer while c-axis orientation of HAP crystals at mesoscale was preserved. Mechanism of CS interaction during in situ biomimetic synthesis and self-assembly of HAP crystals under CS-EMD hydrogel presence is also discussed.

Molecular interactions in gelatin/chitosan composite films

Gelatin and chitosan were mixed at different mass ratios in solution forms, and the rheological properties of these film-forming solutions, upon cooling, were studied. The results indicate that the significant interactions between gelatin and chitosan promote the formation of multiple complexes, reflected by an increase in the storage modulus of gelatin solution. Furthermore, these molecular interactions hinder the formation of gelatin networks, consequently decreasing the storage modulus of polymer gels. Both hydrogen bonds and electrostatic interactions are formed between gelatin and chitosan, as evidenced by the shift of the amide-II bands of polymers. X-ray patterns of composite films indicate that the contents of triple helices decrease with increasing chitosan content. Only one glass transition temperature (Tg) was observed in composite films with different composition ratios, and it decreases gradually with an increase in chitosan proportion, indicating that gelatin and chitosan have good miscibility and form a wide range of blends.

Chitosan Immobilized Cotton Fibres for Antibacterial Textile Materials

This paper reports the fabrication of natural, biodegradable, disposable and low cost clothing with antibacterial activity. Chitosan has been successfully immobilized on woven cotton with the help of natural rubber latex. The water contact angle studies reveal increased hydrophilicity of the samples with increase in chitosan concentration. The as prepared materials exhibited excellent antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Due to the electrostatic interaction between chitosan and bacterial surface, the chitosan immobilized samples exhibited clear inhibition zones. This study invokes the possibility of fabrication of medical textiles with antibacterial properties by simple processing of woven cotton materials.

Survival of Lactobacillus Acidophilus as Probiotic Bacteria using Chitosan Nanoparticles

Chitosan was used for nanoencapsulation of Lactobacillus acidophilus as probiotic bacteria. In vitro experiments were done with the objective of investigating the survival of the bacteria cells in gastro-intestinal conditions. The results demonstrated that the size of chitosan nanoparticles noticeably increases by increasing chitosan concentration from 0.05 to 0.5 g/mL. Encapsulation of the cells caused a decrease at the leakage of probiotic bacteria when compared with free bacteria. However, the number of probiotic cells reduced from 3.27 to 3.23 log CFU/ml in gestural acid condition in contrast to free cells which they approximately dropped from 3.3 to 3 log CFU/ml after 120 min. Good probiotic viability and stability was also obtained by nanocapsulation of Lactobacillus acidophilus in intestinal juice. At this condition, the initial capsulated cells numbers were 3.28 log CFU/ml which after placing in biliary salt condition for 120 min, it reached to 3.23 log CFU/ml. On the other hand, the free bacteria cells reduced from 3.3 to 2.97 log CFU/ml in intestinal environment. Overall, nanocapsulation of probiotic bacteria plays a pivotal role in enhancing the viability and survival of them against gastro- intestinal environmental conditions.

Surface charge switchable and pH-responsive chitosan/polymer core-shell composite nanoparticles for drug delivery application

Abstract The mutually conflicting surface charge requirements for nanoparticles to have long circulation and good cell affinity have made the development of polymer nanoparticles for controlled drug delivery fall into a dilemma. In order to solve this problem, the first attempt has been made in this work to develop vancomycin loaded composite nanoparticles with a novel chitosan core and poly (lactide- co -glycolide) (PLGA) shell structure and with both pH-responsive and surface charge switchable properties. Spherical composite nanoparticles have been successfully fabricated through a modified emulsion-gelation method with a controllable size (316–573 nm), surface charge (−27.6–31.75 mV) and encapsulation efficiency up to 70.8%. The dilemma can be avoided by tailoring the composite nanoparticles with the specially designed core-shell structure to be negative charged in the beginning and switch to positive charge later on. The negative charge of particles can be switched to positive charge gradually as the erosion of biodegradable polymer shells and exposure of the positive charged chitosan core. The formed chitosan hydrogel exhibited multi-layer structures, which were primarily influenced by chitosan concentration. Influences of the chitosan gelation behaviors on the properties of the composite nanoparticles in response to different chitosan and NH 3 concentrations have also been studied. Release rate decreased significantly with increasing chitosan concentration. With the introduction of the chitosan, the increase in drug release rate by orders of magnitude was observed for the samples immersing in the phosphate buffer saline solution of lower pH value proving a pH responsive release property. Drug release profiles of the composite nanoparticles were divided into fast release stage and slow release stage. The fast release stage was well described by a modified first-order kinetic model; while the slow release stage was fitted well with the classical first-order release kinetic model. All the presented results make the proposed composite nanoparticles a promising system for controlled drug delivery.

Nitrate permeability of semi‐permeable membranes prepared from binary blends of cellulose triacetate and chitosan

Semi‐permeable membranes of binary polymer blends of cellulose triacetate (CTA) and chitosan (CS) were produced to harvest microalgal biomass for biofuels. Relatively thick membranes of polymer blends containing more than 70% CTA were prepared via solution blending in formic acid. Various characterization methods revealed that both polymers are immiscible at the molecular level at room temperature. However, they were macroscopically compatible and exhibited uniform physical properties due to the molecular interactions between CTA and CS with the same cellulosic backbone containing two linear polysaccharides through a β‐1,4 glycosidic bond. Careful visual inspection revealed that these membranes are transparent and their light transmittance was greater than 90% at all blend compositions. All membranes showed excellent tensile strength at all compositions and the maximum tensile strength was 52.4 MP from the membrane with a CTA/CS weight ratio of 9:1. The permeability of these blend films increased with increasing CS content and the maximum value was 44.28 mg/m2/day. To improve the permeability or transfer rate of the CTA/CS membranes, the porous CTA/CS membranes were also prepared using various amounts of silica nanoparticles. POLYM. ENG. SCI., 58:192–197, 2018. © 2017 Society of Plastics Engineers

Entrapment of protein in chitosan-tripolyphosphate beads and its release in an in vitro digestive model.

This research sought to evaluate the entrapment and in vitro release behaviour of bovine serum albumin (BSA) in chitosan-tripolyphosphate (TPP) hydrogel beads. Beads were manufactured by extruding gel forming solutions containing varying concentrations of chitosan (1-2.5%w/w) and BSA (0.25-10%w/w) into TPP solutions ranging in concentration from 0.1 to 10%w/w and in ionic strength from 0.16 to 0.67M at pH values of 4, 5 and 9.4. Beads produced at a low TPP concentration of 0.4% w/w had the highest BSA entrapment efficiency (71.6±0.7%) and inhibited BSA release in simulated gastric fluid (SGF) to a greater extent. Increasing chitosan concentration resulted in a higher protein entrapment efficiency, but lowered the overall release. Increasing TPP concentration or the BSA concentration loaded, led to early release in SGF. The results indicate that the utilization of lower concentrations of TPP is a good approach to improve the protein retention ability of chitosan-TPP beads in a simulated gastric environment.

Influence of chitosan concentration on mechanical and barrier properties of corn starch/chitosan films

The active packaging films based on corn starch and chitosan were prepared through mixing the starch solution and the chitosan solution (1:1) by casting. The aim of this work was to characterize and analyze the effects of the chitosan concentrations (0, 21, 41, 61 and 81wt% of starch) on physicochemical, mechanical and water vapor barrier properties as well as morphological characteristics of the corn starch/chitosan (CS/CH) films. Starch molecules and chitosan could interact through hydrogen bonding as confirmed from the shift of the main peaks to higher wavenumbers in FTIR and the reduction of crystallinity in XRD. Results showed that the incorporation of chitosan resulted in an increase in film solubility, total color differences, tensile strength and elongation at break and a decrease in Young’s modulus and water vapor permeability (WVP). Elongation at break of the CS/CH films increased with increasing of chitosan concentration, and reached a maximum at 41 wt%, then declined at higher chitosan concentration. The WVP of CS/CH films increased with an increase of chitosan concentration and the same tendency observed for the moisture content. The results suggest that this biodegradable CS/CH films could potentially be used as active packaging films for food and pharmaceutical applications.

Turning hydrophilic bacteria into biorenewable hydrophobic material with potential antimicrobial activity via interaction with chitosan

Alteration of a bacteriocin-producing hydrophilic bacterium, Lactococcus lactis IO-1, into a hydrophobic material with potential antimicrobial activity using chitosan was investigated and compared with five other bacterial species with industrial importance. The negatively charged bacterial cells were neutralized by positively charged chitosan, resulting in a significant increase in the hydrophobicity of the bacterial cell surface. The largest Gram-positive B. megaterium ATCC 14581 showed a moderate response to chitosan while the smaller E. coli DH5α, L. lactis IO-1 and P. putida F1 exhibited a significant response to an increase in chitosan concentration. Because L. lactis IO-1 is a good source for natural peptide lantibiotic that is highly effective against several strains of food spoilage organisms and pathogens, hydrophobic material derived from L. lactis IO-1 and chitosan is a promising novel material with antimicrobial activity for the food and pharmaceutical industries.

Effect of interactions between starch and chitosan on waxy maize starch physicochemical and digestion properties

ABSTRACTPhysicochemical and digestion properties of chitosan modified starch prepared by dry heat treatment were investigated. Starch granule aggregation occurred following the addition of chitosan and this trend was enhanced with increasing chitosan concentration. The size of chitosan modified starch particles was about six times of that of the native starch granules. Interactions between the hydroxyl groups of starch and the amino groups of chitosan was confirmed by Fourier transform infrared spectroscopy analysis. The disappearance of the trough in the Rapid Visco Analyzer profile indicated that the cross-links increased the starch shear resistance. The cross-links between starch and chitosan also reduced starch digestion rate compared to the control (p < 0.001), and this reduction was further enhanced with an increasing chitosan concentration. Additionally, the addition of chitosan altered starch digestion kinetics from one phase to two phases, implying that chitosan modification changed both starch structure and its digestion behaviors.

Enhanced electrokinetic properties and antimicrobial activities of biodegradable chitosan/organo-bentonite composites

In this study, chitosan (CS), Na+-bentonite (Na+-BNT) and chitosan/organo-bentonite (CS/O-BNT) biodegradable composites having three different compositions were investigated. Electrokinetic measurements were examined in aqueous medium by taking the effects pH, electrolytes (NaCl and BaCl2), surfactants (CTAB and SDS), and temperature into account. It was noticed that the initial ζ-potential of Na+-BNT shifted from negative (ζ=−35mV) to positive region (ζ=+13mV) with increasing polycationic CS content in the composite structure as aimed. Divalent 2:1 electrolyte (BaCl2) caused to shift the ζ-potentials of all the dispersions to more positive regions. While the most negative effect on ζ-potential of the composites was reached with SDS, which reduced the value of ζ-potential to −39mV for CS(1)/O-BNT composite, the most positive effect was monitored with CTAB (ζ=+40mV) for CS(3)/O-BNT composite. Further, the composites were tested against various bacterial (Gram-positive and Gram-negative) and fungal microorganisms at various concentrations and results obtained were compared with the reference antibiotics and fungicide. According to inhibition zone values accomplished, antibacterial and antifungal activities of the CS/O-BNT composites are increased with increasing CS content as proportional with their positive ζ-potential values.

Improvement of functionality after chitosan-modified zein biocomposites

A series of chitosan-modified zein composite films were fabricated from zein and chitosan by a process involving blending, solution casting and evaporation. Effects of chitosan content on the structure and physical properties of the composite films were investigated by Fourier transform infrared spectroscopy, differential scanning calorimetry, scanning electron microscopy, tensile testing, water absorption measurement and water contact angle measurement. The results showed that the zein/chitosan composite films were fabricated successfully due to the formation of hydrogen bonds between zein and chitosan, and the thermal stability, water absorption, hydrophilicity, tensile strength, flexibility of the composite films increased with an increase in chitosan content from 0 to 50%. The cytotoxicity and cytocompatibility of the composite films were evaluated by 3-[45-dimethyl-2-thiazoly1]-25-diphenyl-2H-tetrazolium bromide (MTT) assay and in vitro cell culture, which showed that the films have non- or low-cytotoxicity, and chitosan promoted the growth, adhesion and proliferation of the cells. These results indicated that chitosan-modified zein composite films might have potentials applications as biomaterials.

Electrospun polycaprolactone/chitosan scaffolds for nerve tissue engineering: physicochemical characterization and Schwann cell biocompatibility

Electrospun polycaprolactone (PCL)/chitosan (CH) blend scaffolds with different CH weight ratios were prepared to study the effect of scaffold composition on its physicochemical and biological properties. Scanning electron microscopy showed bead-free homogeneous randomly arranged nanofibers whose average diameter decreased from 240 to 110 nm with increasing CH content. The infrared spectra of the PCL/CH blends were very similar to the neat PCL scaffold. Energy-dispersive x-ray spectroscopy analysis confirmed the presence of carbon, oxygen and nitrogen in the scaffolds, although fluorine—from chemicals used as solvent—was also detected. The water contact angle decreased from 113° (for PCL) to 52° with increasing chitosan content. The biocompatibility was evaluated using fibroblasts and Schwann cell (SC) cultures. Cytotoxicity assays using fibroblasts demonstrated that electrospun scaffolds could be considered as non-cytotoxic material. Biocompatibility tests also revealed that the SCs adhered to scaffolds with different CH content, although the formulation containing CH at 5 wt% exhibited the highest proliferation on days 1 and 3. A better cell distribution was observed in the CH/PCL blends than in the neat PCL or CH scaffolds, where the cells were clustered. Immunochemistry analysis confirmed that SCs expressed the specific p75 cell marker on the scaffolds, suggesting that PCL/CH scaffolds would be good candidates for peripheral nerve tissue engineering.

Synthesis and Characterization of 5-Fluorouracil-Loaded Glutaraldehyde Crosslinked Chitosan Hydrogels

In this work, the characterization and drug release behavior of 5-fluorouracil-loaded glutaraldehyde-crosslinked chitosan hydrogels have been studied. The structure of the hydrogels were investigated by Fourier transform infrared spectroscopy, differential scanning calorimetry, and X-ray diffraction, also their properties were compared with those of the drug-unloaded hydrogels. The equilibrium swelling studies and drug release profiles were determined at 37°C in two different pHs (2.1 and 7.4). The results indicated that increased chitosan concentration in the hydrogel decreased the swelling and drug release values and the hydrogels released nearly the same amount of 5-fluorouracil in both acidic (~59%) and basic medium (~50%).

Reverse indentation size effects in gamma irradiated blood compatible blend films of chitosan-poly (vinyl alcohol) for possible medical applications

In the present work binary blends of polyvinyl alcohol (PVA) and chitosan (CS) were prepared by solution cast method and characterized by analytical methods like FTIR, XRD and SEM for seeking structural and morphological information. The blends were exposed to gamma radiation and evaluated for their improved mechanical strength. It was found that the tensile strength and microhardness increased after irradiation of CS-PVA films. Plastic effect due to absorption of water molecules and scissoring effect due to gamma irradiation were found to decrease the softness or increase the microhardness of the blends. Improved mechanical properties were attributed to intermolecular and intramolecular hydrogen bonds and adhesive nature of the blends also. The blends were also investigated for water intake behavior and in vitro blood compatibility property on the basis of certain in vitro tests like protein adsorption, haemolysis and blood clot formation on the un-irradiated and irradiated blend samples. The increased % swelling with time could be assigned to the fact that increasing water content facilitates the phase separation process within the blend which results in advancement in interstitial nano-void spaces which are occupied by water molecules. The blood compatibility results showed that when the amount of CS was varied from 0.5% to 2%, the amount of blood clot and percent haemolysis decreased while the protein adsorption increased with increasing CS content of the blend films.

The rheology of hydrogels based on chitosan–gelatin (bio)polyelectrolyte complexes

ABSTRACTInfluence of the chitosan concentration in the low-concentrated acidic hydrogels formed by (bio)polyelectrolyte chitosan–gelatin complexes (at a constant gelatin concentration of 1%) was studied by shearing in steady flow and linear oscillations. These complexes, including native gelatin, demonstrate clearly expressed viscoelastic properties. Viscoelastic properties correlated well with the non-Newtonian behavior of hydrogels (according to the Cox–Merz rule). Increasing the chitosan concentration (from 0.1% to 0.6%) results in exponential growth of the apparent viscosity, yield stress, and storage modulus. However, a further increase in chitosan concentration to 0.8% leads to a reduction in these rheological parameters due to the electrostatic repulsion of similarly charged polyelectrolyte complexes under the high concentration of these complexes. The macro-rheological properties of chitosan–gelatin gels are mainly determined by the colloidal structure of sol-precursors in solutions. The yield stress dependence on the radius of the dispersed particles is of square type. Electron photomicrographs showed that the introduction of even small quantities of chitosan leads to radical changes in the supramolecular structure of the gelatin gel.

Effect of chitosan on the antibacterial and physical properties of corn starch nanocomposite films

The influence of chitosan on the antibacterial and physical properties of corn starch nanocomposite films impregnated with calcium carbonate nanoparticles was investigated. With the increase of chitosan content, the nanocomposite films significantly enhanced antimicrobial activity against Escherichia coli, Staphylococcus aureus, and Bacillus cereus, and the films were more effective against gram‐negative bacteria. As chitosan content increased, the tensile strength of the nanocomposite films significantly increased from 2.24 to 10.71 MPa, and the highest elongation at break of the films was 134.31%, with the incorporation of chitosan at a 30% level. Fourier transform infrared spectra analysis revealed that hydrogen bonds were formed between the chitosan and the starch.

Ketoconazole encapsulated in chitosan-gellan gum nanocomplexes exhibits prolonged antifungal activity

The objective of the present study was to prepare ketoconazole loaded chitosan-gellan gum (CSGG) nanoparticles and to evaluate them for antifungal activity against Aspergillus niger. Ketoconazole loaded CSGG nanoparticles were prepared by electrostatic complexation technique using chitosan (CS) as cationic polymer and gellan gum (GG) as anionic polymer with ketoconazole as drug. It was observed that the effect of gellan gum on particle size was more pronounced in comparison to chitosan and increase in its concentration resulted in a significant increase in particle size but decrease in zeta potential. Whereas, increase in concentration of chitosan resulted in increase in zeta potential. The particle size and zeta potential of optimal formulation was 155.7±26.1nm and 32.1±2.8mV which obtained at concentration of chitosan (0.02% w/v) and gellan gum (0.01% w/v). On comparative evaluation, ketoconazole loaded CSGG nanoparticles showed significantly higher antifungal activity against Aspergillus niger than dummy CSGG nanoparticles (without drug) and drug individually.