Chitosan Composites Research Articles

Investigation of the antimicrobial properties of nanoclay and chitosan based nanocomposite on the microbial characteristics of Gouda cheese

In recent years, active packaging has been introduced as a new method to better preserve food. Chitosan and nanoclay have been used for preparation of an active nanocomposite with respect to their antimicrobial properties to investigate its effects on the microbial limitation in Gouda cheese. Nanoclay film, chitosan film, chitosan-based nanocomposites and nanoclay-based nanocomposites were prepared and their antimicrobial properties were evaluated to the microbial limitations of Gouda cheese consist of coliforms, Escherichia coli, Salmonella spp., coagulase-positive Staphylococcus, mold and yeast by agar diffusion method. The results indicated, the best antimicrobial effect belonged to nanocomposite film with the composition of chitosan 3 wt% by adding nanoclay 1 wt%, which can prevent microbial characteristics of Gouda cheese. The chitosan and nanoclay nanocomposite had excellent antibacterial activity and performed well against microbial limitations (coliforms, E. coli, Salmonella spp., coagulase-positive Staphylococcus, mold and yeast) of Gouda cheese. Therefore, the nanocomposite may be possibly used as a surface coating in addition to Gouda cheese as well as similar cheeses and other food to enhance microbial characteristics and extend shelf life.

Spectroscopic studies of plasma-modified silver-exchanged zeolite and chitosan composites

Composite biomaterials can be formed by combining natural or synthetic, organic or inorganic materials which are exactly or partially compatible when in contact with a living organism. To greatly improve the utilization of these biomaterials, understanding its interaction with its environment or host is essential. In this work, naturally-occurring and locally-abundant materials such as zeolite (Z) and chitosan (Ch), were fabricated as a silver-exchanged zeolite/chitosan (AgZ-Ch) composite using a solvent casting approach. The composites were subsequently exposed to argon (Ar) plasma excited by a 13.56 MHz radio frequency (RF) power source. Fourier-transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS) techniques were utilized to investigate the surface and subsurface properties of the AgZ-Ch composites. Results revealed different interactions within the bulk and on the surface of the composite. The interactions for the composite formation are dominated by the attraction of the AgZ species with the –OH and –NH2 functional groups of Ch. On the other hand, the surface composition of Ch was influenced by the etching effect of Ar with the –COCH3 termination from the Ch. This study showed that the surface layer prefers to be terminated with amine and hydroxyl groups instead of amide functional groups. The present work also demonstrated the use of plasma irradiation to tune AgZ-Ch composite surface and tailor the reactivity of the functional groups on the surface.

Amorphous carbon dot and chitosan based composites as fluorescent inks and luminescent films

A composite of self-passivated amorphous carbon dots (CDs) and chitosan has been developed and utilized to form fluorescent inks and luminescent films. The ink is invisible under visible light but glows brightly under external excitation. Cross-linking between the numerous surface groups present in the highly disordered CDs and chitosan, endow the inks and films with enhanced optical and mechanical properties. The amorphous CD based ink is capable of writing on nearly all types of surfaces and exhibits excellent anti-clogging and anti-smearing properties. The luminescent films on the other hand are characterized by good mechanical strength (σUTS ≈ 61.3 MPa) along with high luminescence efficiency. The luminescence yield, ultimate tensile stress, hydrophobicity and glass transition temperature of the films were found to scale similarly with the concentration of CDs in chitosan. All the parameters initially improved with increasing CD concentration but then deteriorated beyond some optimal CD loading due to agglomeration effect. We demonstrate that the amorphous carbon dot-based inks and films outperform all other carbon-based fluorescent inks and films prepared from the more expensive crystalline structures.

ANTI-MICROBIAL ACTIVITY OF SILVER NANO PARTICLES (AG-NPS) ON BACTERIA ISOLATED FROM DIABETIC FEET

Background: Silver nanoparticles (Ag NPS) have long been known to have powerful antimicrobial activities. The aim of this study: to synthesize of silver nanoparticles (Ag NPS) in chitosan composite for possible use in biological application. Objective: Chitosan – silver nanoparticles composite materials was synthesized by adding AgNo3 0.5 gm and NaOH solution to chitosan solution at 120 c. Different concentrations of chitosan 0.05 % - 0.125 % - 0.25 % - 0.5 % were used for synthesis. Chitosan – silver nanoparticle composite materials were characterized by Ultraviolet visible spectroscopy (UV), particles size and zeta potential (NCS) and transmission electron microscopy (TEM). Bacteria isolated from diabetic feet were used to test the bactericidal efficiency of synthesized chitosan – silver nanoparticles composite materials. Results: The bacteriological tests showed either bacterial growth inhibition or cell death occurred depending on the concentration of chitosan used. Antibacterial effect of chitosan – silver nanoparticles composite materials increased by increasing chitosan concentration. Conclusion: The presence of Ag- nanoparticles in different concentrations of chitosan composite was enough to significantly enhance antibacterial activity.

Study of physicochemical properties of nanohydroxyapatite–chitosan composites

Hydroxyapatite nanoparticles were synthesized using modified sol–gel approach. Its biocompatibility was proved by in vitro experiments with diploid fibroblasts. The experiment showed that the presence of hydroxyapatite in the environment of cells does not reduce their viability. The observed phase transition of hydroxyapatite was explained as order/disorder transition, saving the crystal structure symmetry. Organo–inorganic composites of chitosan and hydroxyapatite were obtained by preparing a joint solution and pouring onto a glass substrate. According to XRD and DTA data, addition of hydroxyapatite reduces the softening and decomposition temperature of chitosan. This information is necessary to optimize the manufacturing processes of organo–inorganic scaffolds.

Nanocomposite Films of Chitosan-Grafted Carbon Nano-Onions for Biomedical Applications.

The design of scaffolding from biocompatible and resistant materials such as carbon nanomaterials and biopolymers has become very important, given the high rate of injured patients. Graphene and carbon nanotubes, for example, have been used to improve the physical, mechanical, and biological properties of different materials and devices. In this work, we report the grafting of carbon nano-onions with chitosan (CS-g-CNO) through an amide-type bond. These compounds were blended with chitosan and polyvinyl alcohol composites to produce films for subdermal implantation in Wistar rats. Films with physical mixture between chitosan, polyvinyl alcohol, and carbon nano-onions were also prepared for comparison purposes. Film characterization was performed with Fourier Transformation Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), Tensile strength, X-ray Diffraction Spectroscopy (XRD), and Scanning Electron Microscopy (SEM). The degradation of films into simulated body fluid (SBF) showed losses between 14% and 16% of the initial weight after 25 days of treatment. Still, a faster degradation (weight loss and pH changes) was obtained with composites of CS-g-CNO due to a higher SBF interaction by hydrogen bonding. On the other hand, in vivo evaluation of nanocomposites during 30 days in Wistar rats, subdermal tissue demonstrated normal resorption of the materials with lower inflammation processes as compared with the physical blends of ox-CNO formulations. SBF hydrolytic results agreed with the in vivo degradation for all samples, demonstrating that with a higher ox-CNO content increased the stability of the material and decreased its degradation capacity; however, we observed greater reabsorption with the formulations including CS-g-CNO. With this research, we demonstrated the future impact of CS/PVA/CS-g-CNO nanocomposite films for biomedical applications.

Study on the Adsorption of Methyl Red by Bentonite / Chitosan Composites

A composite material is formed by using chitosan and bentonite under the condition of dissolution with acetic acid. The material was characterized by scanning electron microscope thermogravimetric analysis and infrared spectroscopy. The effects of initial concentration of methyl red, adsorption time, pH, and amount of adsorbent on adsorption were investigated. Then, the adsorption process was analyzed from kinetics, and related parameters were calculated. The results showed that the composite material has a wider pH range than using chitosan as an adsorbent to adsorb methyl red; The mass ratio of chitosan to bentonite is 0.08:1, the removal rate of methyl red is the best; The amount of adsorbent used is 0.7mg to reach saturation for a volume of 25mL of methyl red solution with a concentration of 20ug/l; the adsorption of methyl red by the material conforms to the pseudo-second-order kinetic model.

Novel hybrid multifunctional composite of chitosan and altered basalt for barium adsorption: Experimental and theoretical studies

Herein, the starting low‒cost and eco‒friendly weathered basalt (WB) was found to be rich in zeolite and clay minerals, which have wide applications in water purification. WB was chemically activated by hydrogen peroxide (H2O2) followed by the interaction with chitosan (Ch) to fabricate a new hybrid composite (WB/Ch) with multifunctional groups. The resulted WB/Ch composite was characterized by XRD, FTIR, SEM, and applied for Ba (II) adsorption at pH 5.0 and different temperatures (i.e., 25, 35 and 45 °C). The adsorption data were fitted to kinetics, classical (Langmuir, Freundlich and Dubinin–Radushkevich) as well as advanced statistical (multilayer) models. The adsorption data of Ba(II) onto WB/Ch were described well by the pseudo-second-order and the applied traditional equilibrium models. The monolayer adsorption capacity (qmax = 45.78 mg g−1) reflected the high removal efficiency of WB/Ch for Ba(II) uptake as compared to varied natural and synthetic adsorbents. Steric and energetic parameters of the multilayer model were interpreted to understand the interaction mechanism between the Ba(II) ions and WB/Ch active sites. Theoretical number of receptor sites (n) was less than unity at all temperatures revealing multi–docking adsorption mechanisms. Interaction between Ba(II) and WB/Ch of the first layer played the principle role in increasing the adsorption capacities (Qsat) from 115.06–128.86 mg g‒1 within the temperature range of 25–45 °C. The total adsorbed Ba(II) layers (the Nt parameter) decreased from 2.79 to 2.02 with temperature thus reflecting its insignificant role to determine the Qsat values. The calculated adsorption energies varied from 22.35 to 28.56 kJ mol‒1 indicated that the Ba(II) adsorption onto the WB/Ch composite was endothermic and related to physical forces. Thermodynamic parameters including Gibbs free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) reflected the endothermic and spontaneous nature of Ba(II) adsorption process.

Valorisation of shrimp and rice straw waste into food packaging applications

The potential use of chitosan films as a replacement to synthetic polymers in food packaging applications is receiving remarkable attention due to their biodegradability and antimicrobial properties. This study presents the preparation of composite films from chitosan as polymeric matrices, and rice straw and nano rice straw fibres as reinforcements. The films were produced via wet mixing and casting techniques with various reinforcement contents (25–35 wt%). The aim of this research is to investigate the physical, mechanical, chemical, and thermal properties of the synthesized composite films and determine their feasibility for use in food packaging. The synthesized composite films will degrade by the time food is consumed leaving zero waste. Experimental results showed that rice straw fibres and nano-rice straw fibres enhanced the yield strength, fracture strength, and Young‘s modulus in comparison to the unreinforced material, and with reference to Egyptian plastic bags material. Thermal degradation temperature of the chitosan was improved by adding rice straw and nano rice straw compared to chitosan composites, which indicates that the composite thin films can perhaps compete with current thermoplastic synthetic polymers fabricated by melting techniques and serve as an alternative for synthetic plastics. The use of a local (shrimp and rice straw) waste as the source for biodegradable bags, turns food waste problem to being part of the solution of synthetic plastic waste.

Chitosan Composites in Packaging Industry-Current Trends and Future Challenges.

Chitosan-based composites play an important role in food packaging applications and can be used either as films or as edible coatings. Due to their high costs and lower performance (i.e., lower barrier against water vapor, thermal, and mechanical properties) when compared to the traditional petroleum-based plastics, the use of such biopolymers in large-scale is still limited. Several approaches of chitosan composites in the packaging industry are emerging to overcome some of the disadvantages of pristine polymers. Thus, this work intends to present the current trends and the future challenges towards production and application of chitosan composites in the food packaging industry.

Preparation of Multicomponent Biocomposites and Characterization of Their Physicochemical and Mechanical Properties

This work focused on a mutual comparison and characterization of the physicochemical properties of three-component polymer composites. Binary polyaniline–chitosan (PANI–CHT) composites were synthesized by in situ polymerization of PANI onto CHT. Ternary composites were prepared by blending with a third component, polyvinyl alcohol (PVA). Composites with variable PANI:CHT (25:75, 50:50 and 75:25) weight ratios were prepared whilst fixing the composition of PVA. The structure and physicochemical properties of the composites were evaluated using thermal analysis (thermogravimetric analysis (TGA), differential scanning calorimetry (DSC)) and spectroscopic methods (infrared (IR), nuclear magnetic resonance (NMR)). The equilibrium and dynamic adsorption properties of composites were evaluated by solvent swelling in water, water vapour adsorption and dye adsorption isotherms. The electrical conductivity was estimated using current–voltage curves. The mechanical properties of the samples were evaluated using dynamic mechanical analysis (DMA) and correlated with the structural parameters of the composites. The adsorption and swelling properties paralleled the change in the electrical and mechanical properties of the materials. In most cases, samples with higher content of chitosan exhibit higher adsorption and mechanical properties, and lower conductivity. Acid-doped samples showed much higher adsorption, swelling, and electrical conductivity than their undoped analogues.

Polyurethane-Based Composites: Effects of Antibacterial Fillers on the Physical-Mechanical Behavior of Thermoplastic Polyurethanes.

The challenge to manufacture medical devices with specific antibacterial functions, and the growing demand for systems able to limit bacterial resistance growth, necessitates the development of new technologies which can be easily produced at an industrial level. The object of this work was the study and the development of silver, titanium dioxide, and chitosan composites for the realization and/or implementation of biomedical devices. Thermoplastic elastomeric polyurethane was selected and used as matrix for the various antibacterial functions introduced during the processing phase (melt compounding). This strategy was employed to directly incorporate antimicrobial agents into the main constituent material of the devices themselves. With the exception of the composite filled with titanium dioxide, all of the other tested composites were shown to possess satisfactory mechanical properties. The best antibacterial effects were obtained with all the composites against Staphylococcus aureus: viability was efficiently inhibited by the prepared materials in four different bacterial culture concentrations.

Melanin deposition in two Cryptococcus species depends on cell-wall composition and flexibility

Cryptococcus neoformans and Cryptococcus gattii are two species complexes in the large fungal genus Cryptococcus and are responsible for potentially lethal disseminated infections. These two complexes share several phenotypic traits, such as production of the protective compound melanin. In C. neoformans, the pigment associates with key cellular constituents that are essential for melanin deposition within the cell wall. Consequently, melanization is modulated by changes in cell-wall composition or ultrastructure. However, whether similar factors influence melanization in C. gattii is unknown. Herein, we used transmission EM, biochemical assays, and solid-state NMR spectroscopy of representative isolates and "leaky melanin" mutant strains from each species complex to examine the compositional and structural factors governing cell-wall pigment deposition in C. neoformans and C. gattii. The principal findings were the following. 1) C. gattii R265 had an exceptionally high chitosan content compared with C. neoformans H99; a rich chitosan composition promoted homogeneous melanin distribution throughout the cell wall but did not increase the propensity of pigment deposition. 2) Strains from both species manifesting the leaky melanin phenotype had reduced chitosan content, which was compensated for by the production of lipids and other nonpolysaccharide constituents that depended on the species or mutation. 3) Changes in the relative rigidity of cell-wall chitin were associated with aberrant pigment retention, implicating cell-wall flexibility as an independent variable in cryptococcal melanin assembly. Overall, our results indicate that cell-wall composition and molecular architecture are critical factors for the anchoring and arrangement of melanin pigments in both C. neoformans and C. gattii species complexes.

Research on WPU‐RGO/ATP‐Fe3O4/chitosan composites with excellent electrical and magnetic properties

First, attapulgite‐Fe3O4 magnetic filler (ATP‐Fe3O4) was prepared by using a chemical precipitation method. Subsequently, graphite oxide (GO) was prepared through Hummer method, and then reduced GO (RGO) was prepared through GO reduced by chitosan (CS). Finally, a series of WPU‐RGO/ATP‐Fe3O4/CS composites were prepared by introduced RGO/ATP‐Fe3O4/CS to waterborne polyurethane. The structure and properties were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR), X‐ray diffraction (XRD), vibrating sample magnetometry (VSM), thermogravimetric analysis TGA, conductivity test, and tensile test. The experimental results indicated that thermal stability and tensile strength of nanocomposites were improved with the increase of the content of RGO/ATP‐Fe3O4/CS. Meanwhile, with the increase of the RGO/ATP‐Fe3O4/CS content, the electrical and magnetic properties of WPU‐RGO/ATP‐Fe3O4/CS composites were improved. When the content of RGO/ATP‐Fe3O4/CS was 8 wt%, the electrical conductivity and the saturation magnetic strength of WPU‐RGO/ATP‐Fe3O4/CS composites were 3.1 × 10−7 S·cm−1 and 1.38 emu/g, respectively. WPU‐RGO/ATP‐Fe3O4/CS composites have excellent electrical and magnetic properties.

Methylene Blue Adsorption onto Neem Leave/Chitosan Aggregates: Isotherm, Kinetics and Thermodynamics Studies

Abstract The work was aimed at evaluating the adsorptive properties of neem leave/chitosan aggregates for methylene blue removal. The adsorbent was screened to form coarse (CCANL, 600 µm), medium (MCANL, 300 µm) and fine (FCANL, 150 µm) neem leave/chitosan particles. The samples were characterized for pH, water binding capacity (WBC), surface chemistry by Fourier transform infrared spectroscopy, surface morphology by scanning electron microscope and textural properties by Brunauer-Emmett-Teller method. CCANL, MCANL and FCANL possessed specific surface area of 255, 258 and 242 m2/g, respectively. The effects of initial concentration, adsorbent dosage, contact time, pH and temperature were studied. CCANL, MCANL and FCANL demonstrated adsorption capacity of 102, 92.5 and 105 mg/g, respectively, in which ionic interaction and mesopore filling were the possible adsorption mechanisms. The equilibrium data were well fitted by Redlich-Peterson model, suggesting a monolayer adsorption onto a heterogeneous surface of adsorbent. The kinetics data were best described by pseudo-second-order and intraparticle diffusion models, for which the film diffusion, intraparticle diffusion and surface adsorption could co-exist as the controlling steps in adsorption. Adsorption of methylene blue onto chitosan composites was spontaneous, endothermic and demonstrated increased randomness at solid-solution interface.

Green Route for the Removal of Pb from Aquatic Environment.

Wastewater treatment/remediation is a very important process that has a great environmental and economic impact. Therefore, it is crucial to innovate different methods to remove pollutants of different sources from wastewater. This work was conducted in order to study the removal of lead (Pb+2) from wastewater using microspheres of composites of sodium alginate, cellulose and chitosan, as well as using a cost-effective green route through composites of sodium alginate and dried water hyacinth. Molecular modeling at B3LYP/6-31g(d,p) was utilized to study sodium alginate, cellulose and chitosan. Sodium alginate was cross-linked with calcium chloride to form microspheres, then both sodium alginate/cellulose and sodium alginate/chitosan were also crosslinked as 50/50 to form microspheres. The roots of the aquatic plant water hyacinth in dry form were added to the cross-linked sodium alginate for up to 70%. SEM and FTIR were employed to study the surface of the prepared microspheres and their structures respectively. Atomic absorption spectroscopy was used to study the levels of Pb. Molecular modeling indicated that the blending of such structures enhances their ability to bind with surrounding molecules owing to their ability to form hydrogen bonds. SEM results indicated that homogeneous structures of cellulose and chitosan are deformed when blended with sodium alginate, and FTIR confirmed the proper formation of the desired blends. Microspheres from sodium alginate showed the ability to remove Pb+2 from wastewater. SEM indicated further deformation in the morphology with the roughness of sodium alginate/water hyacinth microspheres, while FTIR confirmed the uniform matrices of the microspheres. The removal of Pb+2 was enhanced because of the addition of dried water hyacinth's roots. Modeling, experimental and kinetic data highlight sodium alginate/water hyacinth root as a green route to remediate Pb+2 from wastewater.

Integration of collagen into chitosan blend film composites: physicochemical property aspects for pharmaceutical materials

Chitosan and collagen-based hydrogel composites were successfully prepared at chitosan:collagen volume ratio of 1:1, 1:3, 1:5, and 1:10. The structural, thermal, morphological, swelling, mechanical characteristics were investigated, and in vitro degradation testing was conducted. Tetraethyl orthosilicate (TEOS) was used as a crosslinking agent between the chitosan and collagen chains. The NH group of both chitosan and collagen can form crosslinks with the OH groups of TEOS. XRD reported that no significant peak of crystallinity was observed during the integration of collagen into the chitosan film. The surface of the composite was rougher than that of the collagen. The composites were thermally stable up to 200 °C. The glass transition temperature slightly decreased in the presence of collagen. The tensile strength significantly decreased, while the elongation at break significantly increased, when collagen was integrated into the chitosan film. The collagen conferred strong swelling and rapid degradation on the composite. The chitosan/collagen composite films developed in this study have potential applications as pharmaceutical materials.

Pillared graphene oxide composite as an adsorbent of soluble hydrocarbons in water: pH and organic matter effects

Graphene oxide (GO) is a single-atom-thick sheet of carbon with oxygen-containing functional groups decorating its basal plane and edge sites. Most of its high surface area can be lost due to restacking of individual layers during the synthesis and drying of GO-based bulk sorbents. There is great interest to increase the specific surface area of graphene-based sorbents by introducing organic molecules as “pillaring agents” between GO sheets to hinder the stacking process and create sorbents with elevated surface area. This work synthesizes pillared GO by introducing chitosan (CS), a linear polysaccharide with various molecular weights. A composite of low molecular weight CS at a CS/GO ratio of 0.1 is shown to have the highest specific surface area (up to 70.5 m2/g) in comparison to the medium and high CS molecular weight, pristine GO, and the CS/GO composite materials. The affinity of the optimized GO/CS composites towards benzene, toluene, and naphthalene was evaluated at 19.3 mg/L of organic matter content while altering pH. Sips and Langmuir adsorption isotherm models well described the adsorption behavior, and benzene adsorption performance was reduced at low pH. Related to the presence of dissolved organic matter (DOM) in solution, lower diffusivity constants (k1) in hydrocarbon systems were recorded. Our results demonstrate the feasibility of CS as a potential pillaring agent in CS/GO composites to increase specific surface area and enhance the capture of soluble hydrocarbons from aqueous solutions.

Influence of the Preparation Method on Some Characteristics of Alginate/Chitosan/Lovastatin Composites

This study investigates the effects of direct and indirect dispersion methods for lovastatin solid dispersion (LSD) in alginate (AG)/chitosan (CS) composites on the characteristics and properties of the AG/CS/LSD composites. The preparation method significantly influences the structure, morphology, and LSD size distribution of the composites as well as the drug release of LSD from the samples. The differences in dispersion methods for LSD lead to differences in the interaction between the components, the structure, and the control drug release of LSD. Lovastatin was released from the samples containing LSD in two stages (a fast release stage and a slow release stage), and the drug release content prepared using the indirect method is lower than that prepared using the direct method in the same buffer solution. After 32 h of testing, the released LSD content from the indirect and direct LSD dispersion methods in pH 2 and pH 7.4 buffer solutions was 87–94% and 41–61%, respectively. Drug release kinetics from the above samples in solutions with different pH values was also set up.

Antibacterial activity of polypyrrole-based nanocomposites: a mini-review

Abstract The development of polypyrrole-based nanocomposites as alternative antibacterial agents represents a promising strategy to be applied against the prevailing multi-resistant bacteria. Herein, it is reported the most recent development of antibacterial materials based on the combination of polypyrrole and different fillers (metal nanoparticles, carbon nanotubes, and polysaccharides) and strategies to improve their action (such as light and electrical stimulus). The synergistic interaction of electrostatic forces provided by charged polypyrrole combined with the permeation of nanoparticles through the cell wall favors the leakage of cytoplasmic components and reinforces the antibacterial activity of the resulting material, observed in all-organic composites of polypyrrole and chitosan that reached superior performance against Escherichia coli (108 CFU) or metal-polymer composites (polypyrrole-palladium) with an outstanding performance against different types of bacteria. The development of binary and ternary composites is explored to potentialize the antibacterial synergy of components.