Chitosan Aqueous Solution Research Articles

Investigating the effects of chitosan solution and chitosan modified TiO2 nanotubes on the corrosion protection performance of epoxy coatings

In this research, TiO2 nanotubes (TNT) are hydrothermally synthesized and modified by chitosan (named as TCS). The structures of the prepared nanomaterials are investigated by X-ray diffraction and X-ray photoelectron spectroscopy, while transmission electron microscopy is used for characterizing the morphology of the nanopowders. Moreover, epoxy coatings loaded with different wt.% of TCS (0.1, 0.5, and 1.0 wt%), aqueous chitosan solution (1 and 2.5 wt%), and both aqueous chitosan solution (2.5 wt%) and TCS (0.1, 0.25, 0.5, and 1.0 wt% TCS) are prepared which are abbreviated as E-TCS, ECS, and ECS-TCS coating systems, respectively. The corrosion behavior of the coated samples are considered by using salt spray and electrochemical impedance spectroscopy. Pull-off test is used to evaluate the adhesion strength of the prepared coatings to the substrate, and field emission scanning electron microscopy is used for considering the fracture surface of the coated steel panels. The results clearly show that the corrosion resistance increases in the following order: pure epoxy < E-TCS0.1% < ECS2.5% < ECS-TCS0.5%, revealing that modifying the epoxy matrix with chitosan and loading the TCS in the epoxy coating increase the corrosion resistance more effectively through an eco-friendly approach and provide good anti-corrosion stability which is related to the chemical compatibility between the nanofiller and the matrix.

Colloidal nanodispersions for the topical delivery of Ibuprofen: Structure, dynamics and bioperformances

Colloidal liquid-in-liquid nanodispersions such as micro- and nanoemulsions were developed, characterized and compared as potential carriers for the topical administration of ibuprofen. Both colloidal systems were based on water as the continuous phase, limonene as the dispersed phase and a mixture of pharmaceutically acceptable surfactants (Pluronic® L-35, Labrasol®, Tween 80). To improve their properties regarding penetration efficacy, an aqueous solution of chitosan was used as continuous phase in both systems. Micro- and nanoemulsions were structurally studied applying Dynamic Light Scattering (DLS), Electron Paramagnetic Resonance (EPR) spectroscopy and viscometry. Microemulsions with mean droplet diameter of 41 nm and PdI < 0.3 were obtained in the absence and presence of either chitosan or ibuprofen. Nanoemulsions were developed by high-pressure homogenization using the same ingredients at different concentrations. Unlike thermodynamically stable microemulsions, nanoemulsions showed storage stability for 2 months, higher droplet size (174 nm) and lower PdI (<0.15). In the presence of Ibuprofen droplet size and stability of the nanoemulsions were not affected. EPR spectroscopy revealed ibuprofen’s location in the oil cores and gave information about the rigidity of the surfactants’ monolayer. In both cases an outer compact configuration of the interfacial layer and a more flexible inner one was observed. The cytotoxicity of both systems towards human melanoma cell line WM 164 was relatively low. Interestingly, ibuprofen was released more promptly from the microemulsions (prospectively, systemic exposure increase), however the ex vivo studies, regarding skin uptake and penetration, revealed that the nanoemulsions are more appropriate as nanocarriers for the topical administration of ibuprofen.

The preparation of peppermint oil/2-hydroxypropyl-β-cyclodextrin/chitosan composite microcapsule and their prolonged retaining ability

In this paper, the peppermint oil/HP-β-CD (2-hydroxypropyl-β-cyclodextrin)/chitosan composite microcapsules were prepared. The release ability of these microcapsules was improved for peppermint oil through the combination of molecular encapsulation by HP-β-CD and physical encapsulation by chitosan shell. First, stable peppermint oil/HP-β-CD pre-emulsion was prepared by stirring, based on which the optimal conditions were determined for producing the pre-emulsions with the highest encapsulation efficiency. Then, the pre-emulsion was moved into the flow-focusing microfluidic device as the inner phase and was cut into droplets by chitosan aqueous solution as the middle phase and the octanol as the outer phase to obtain templated emulsions. They were collected using a Petri dish with n-octane coagulation bath containing glutaraldehyde and 2 wt% span80 to be cured into microcapsules. The crosslinking time and the ratio of HP-β-CD in the templated emulsions were adjusted to investigate their impact on the microcapsule structures and correspondingly the capability of the microcapsules to retain peppermint. It was found out that the extended crosslinking time and the addition of HP-β-CD can improve the capability of the composite microcapsules to retain peppermint oil. It provides a straightforward method to produce composite microcapsules. Besides, the microcapsules with improved retaining ability were obtained by combing molecular and physical encapsulation, thus laying a foundation for the exquisite, efficient and polylaminate protection of the volatile perfume or other physically or chemically active components.

Structure Formation as a Method of Forming Physicomechanical Characteristics of Films Obtained from Aqueous Solutions of Certain Polysaccharides

The aqueous solutions of chitosan, succinyl chitosan sodium salt, and carboxymethylcellulose sodium salt are studied by the rheological method. An increase in the polymer concentration in solution leads to a sharp increase in viscosity due to formation of the entanglement network, the transition of the polymer solution to the gel-like state, a sharp increase in the relaxation time, and the appearance of elasticity of solutions. These systems are characterized by time anomalies characterized by a hysteresis loop, the area of which depends not only on concentration but also on the rate of increase/decrease of the shear rate. Thixotropy is observed in the intermediate concentration range, where supramolecular structures are formed and the time required for their destruction is comparable to the time of the experiment. This makes it possible to regulate a number of properties of materials formed from solutions. According to DSC studies, the glass transition temperatures and the melting temperatures of films obtained from solutions of different concentrations are different. The tensile stress and the elastic modulus of film polymeric materials pass through a maximum corresponding to the polymer concentration at which the maximum degree of structuring is implemented while maintaining the fluidity.

Environmentally-Benign Phytic Acid-Based Multilayer Coating for Flame Retardant Cotton.

Chemically bleached cotton fabric was treated with phytic acid (PA), chitosan (CH) and urea by means of layer-by-layer (LbL) deposition to impart flame retardant (FR) behavior using only benign and renewable molecules. Samples were treated with 8, 10, 12 and 15 bilayers (BL) of anionic PA and cationic CH, with urea mixed into the aqueous CH solution. Flammability was evaluated by measuring limiting oxygen index (LOI) and through vertical flame testing. LOI values are comparable to those obtained with commercial flame-retardant finishes, and applying 10 or more bilayers renders cotton self-extinguishing and able to pass the vertical flame test. Microscale combustion calorimeter (MCC) measurements show the average reduction of peak heat release rate (pHRR) of all treated fabrics of ~61% and the reduction of total heat release (THR) of ~74%, in comparison to untreated cotton. Decomposition temperatures peaks (T1max) measured by thermogravimetric analyzer (TG) decreased by approximately 62 °C, while an average residue at 650 °C is ~21% for 10 and more bilayers. Images of post-burn char indicate that PA/CH-urea treatment is intumescent. The ability to deposit such a safe and effective FR treatment, with relatively few layers, makes LbL an alternative to current commercial treatments.

ЕФЕКТИВНІСТЬ ПОПЕРЕДНЬОГО ОБРОБЛЕННЯ ЯГІД СУНИЦІ РОЗЧИНОМ ХІТОЗАНУ ЗА ХОЛОДИЛЬНОГО ЗБЕРІГАННЯ В МОДИФІКОВАНОМУ ГАЗОВОМУ СЕРЕДОВИЩІ

Strawberries (Fragaria ananassa) belong to short-term berries. Many technologies are used to extend its shelf life. One of the current technologies is the use of pretreatment of berries with polysaccharide solutions before refrigerated storage. This treatment makes it possible to reduce weight loss and improve the overall quality of berries by forming a protective barrier film on their surface. The purpose of this study was to investigate the effectiveness of chitosan strawberries pre-treatment while storing it in a refrigerated chamber using a modified gas atmosphere. To achieve the purpose, strawberries were treated with 0,05 %; 0,2 %; 0,5 % aqueous solutions of low molecular weight chitosan were stored in a refrigerator at t 0 + 2 °C using polyethylene bags of 30 microns thickness. Unprocessed berries were used as a control. All experimental studies were performed in triplicate. According to the research results it was found that the weight loss of treated berries was 1,48 – 5,11 % and in the control 11,35 %. The mass fraction of sugars at the end of storage in the treated berries was (2,2–2,6 %), which is 0,2–0,6 times higher than in the control.. The content of ethyl alcohol is fixed in all samples. In the control variant, it was 0,87 %, and in the samples the treatment was from 0,57 – 0,8 % According to the results of the tasting evaluation, the best performance was in the sample with a concentration of 0,5 % Pretreatment of strawberry berries with aqueous solutions of low molecular weight chitosan has a positive effect on the quality of strawberry berries and can be used as an effective tool in the storage of berries

A combined molecular dynamic simulation, DFT calculations, and experimental study of the eriochrome black T dye adsorption onto chitosan in aqueous solutions

This study aims to evaluate and understand the adsorption of eriochrome black T (EB) by chitosan extracted from local shrimp shells under different experimental conditions. Chitosan samples were characterized by XRD, SEM, and FTIR. Experimental results indicate that the process was pH-dependent with a high adsorption capacity in acidic medium. The adsorption was rapid and kinetic data were suitably correlated to the pseudo-second-order kinetic model. EB molecules were adsorbed on monolayer according to the Langmuir model with an adsorption capacity of 162.3 mg/g. On the other hand, it should be noted that calculated quantum chemical parameters support the experimentally obtained results. The interaction energies calculated for (molecule/chitosan) complexes were in the order of H2EB− > HEB2− (O38) > HEB2− (O48) > EB > H3EB > EB3−, which means that the best and possible adsorption process can take place with H2EB− form. The molecular dynamics (MD) approach was performed to illuminate the nature of the relationship between the EB and the chitosan (110) surface. It was found that the chitosan (110) surface adsorbs EB molecule in a nearby parallel orientation. The higher negative adsorption energy determined for the H2EB− implies that the adsorption mechanism is the typical chemisorption.

Modeling Drying Behavior of an Aqueous Chitosan Single Droplet Using the Reaction Engineering Approach.

Spray drying of Chitosan solutions to prepare microparticles either using pilot or industrial scale spray dryer is a complex process; tracking morphological changes and obtaining drying kinetics of a single droplet would be very difficult. The acoustic levitator being a non-intrusive method is a useful experimental apparatus that enables particle/droplet suspension in the gaseous medium and capable of mimicking the drying process in a spray dryer. The drying of chitosan aqueous solutions into solid particles was investigated. The prediction of the size and drying kinetics until the formation of the solid structure was performed in an acoustic levitator. Studying the drying of single droplets is crucial for revealing the influence of the drying process parameters on the formation of dried particles. Droplets with initial chitosan concentration (10, 20, and 30mg/ml) were investigated at different air-drying temperatures. A Reaction Engineering Approach (REA) model was developed and compared with the experimental drying curves, a very well agreement was found between the drying experiments and the REA model with a relative error of about 3% between the initial droplet mass and predicted droplet mass by the REA model.

The effect of multilayered chitosan–pectin–Mentha piperita and Lemon essential oil on oxidation effects and quality of rainbow trout fillet (Oncorhynchus mykiss) during refrigerator at 4±1˚C storage

This study was carried out to evaluate the lipid oxidation and quality of rainbow fish coated by multilayer aqueous solution of chitosan–pectin and extracted Mentha piperita or Lemon essential oil in different percentages (0.5 and 1%). The essential oil was extracted by hydrodistillation method. Protein, fat, moisture and ash content of rainbow fish samples were determined. The control and the coated fish samples were analyzed during 16-days periodically for lipid oxidation expressed by peroxide value and thiobarbituric acid, meat deterioration by total volatile base nitrogen, free fatty acids and sensory characteristics. The results have shown that Mentha piperita 1% was the most appropriate coverage (p <0.05) with 0.5% extracted essential oil. In all samples, Mentha piperita essential oil results were better than those of Lemon. The sensorial data results have shown that the comfortable time of storage control and covered samples was approximately less than 8 and 16-days, respectively.

Melatonin loaded lecithin-chitosan nanoparticles improved the wound healing in diabetic rats

Wound healing in diabetic patients remains a worldwide problem that can cause amputations and even lead to death. This work aimed to produce lecithin-chitosan nanoparticles loaded with melatonin (MEL-NP) incorporated in a topical formulation to be evaluated for healing in the in vivo animal model for diabetes. To produce nanoparticles, an ethanolic solution containing soybean lecithin and melatonin was added dropwise to an aqueous solution of chitosan under sonication. The nanoparticles were physicochemical characterized and evaluated in vivo for toxicity using the Galleria mellonella model and its potential for wound healing in diabetic rats. The MEL-NPs presented a particle size of 160 nm and a zeta potential of 25 mV. The melatonin entrapment efficiency was 27%. Our results indicated that treatment with MEL-NP improved wound healing demonstrated by wound closure earlier than the other treatments evaluated. A desired therapeutic effect was achieved by MEL-NP in the induction of fibroblast and angiogenic proliferation. In addition, it was accompanied by an expressive collagen deposition. Considering the observed data, the MEL-NP developed could be used as a proof of concept to develop a promising strategy for the healing of diabetic wound.

Chitosan-Based biogels: A potential approach to trap and bioremediate naphthalene

Pseudomonas sp. bacteria were incorporated into a double emulsion system (water in oil in water, W/O/W), which can be injected in the subsurface to trap and biotreat naphthalene. The outermost phase of the W/O/W emulsion was an aqueous solution of chitosan (1.65 wt.%). Naphthalene could be dispersed in the aqueous chitosan phase of W/O/W emulsions. Two separate primary water in oil (W/O) emulsions were emulsified in chitosan, using Tween 20 as emulsifier. W/O emulsions were prepared with canola oil (containing ethylcellulose and calcium stearate as emulsifiers), and aqueous solutions of either Pseudomonas sp. in minimal broth or sodium citrate (crosslinker). The formation of W/O/W double emulsions was verified with optical and confocal microscopy. Without addition of triggers able to induce gelation on demand, W/O/W emulsions were stable and mainly viscous under shear. The shear elastic modulus (G’ = 1.90 ± 0.39 Pa) and the shear viscous modulus (G” = 5.76 ± 0.06 Pa) were low, to facilitate pumping in the subsurface. With addition of the surfactant cocamidopropyl betaine, W/O/W emulsions were destabilized on demand, thereby releasing citrate (crosslinker) and Pseudomonas sp. in the chitosan phase, where naphthalene was dispersed. Mixing chitosan with citrate led to its gelation, trapping naphthalene. Mixing naphthalene with Pseudomonas sp. led to its bioremediation. Gelation was demonstrated by the increase in the viscoelastic moduli, with G’ = 111.02 ± 1.67 Pa > G” = 8.66 ± 0.10 Pa. With naphthalene, Pseudomonas sp. survival in gelled chitosan was confirmed by plating bacteria sampled from the gel. Without naphthalene, Pseudomonas sp. did not survive in chitosan.

Chitosan-coated nonwoven polyethylene terephthalate material for efficient removal of cationic and anionic dyes from aqueous solution

ABSTRACT A simple dye adsorbent based on polyethylene terephthalate – PET functionalised by chitosan‘Chit-Pet-T’ was developed to remove cationic (MG, CV) and anionic (SY, DB71, AY17) synthetic dyes from aqueous solutions. In the first part of this study, the surface of the non-woven PET material was activated by using an aqueous solution of NaOH (0.5 M), and then the surface of the alkaline activated PET was functionalised by treatment with an acidic aqueous solution of chitosan. The Chit-Pet-T was then characterised by physicochemical methods: X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), zeta potential,energy-dispersive X-ray spectroscopy (EDS), air permeability and water contact angle measurements (WCA). The physicochemical characterisation of Chit-Pet-T confirmed the successful immobilisation of the chitosan on the surface of the non-woven PET with a coating ratio of 46%. The dye adsorption studies show that the capacity of Chit-Pet-T to adsorb the studied dyes is affected significantly by the initial pH, Chit-Pet-T dose, ionic strength, temperature and initial dye concentration. The removal rate (R) reached the maximum value at pH = 11 and pH = 2 for the cationic (MG: 91%, CV: 90%) and anionic (SY: 95%, DB71: 96%, AY17: 94%) dyes, respectively, within 300 min, under a wide range of temperature, with dye solution of 0.1 M. The Langmuir isotherm model could be best adequate to describe the dye adsorption onto Chi-Pet-T and the thermodynamic parameters indicated that the adsorption was a spontaneous exothermic process. The excellent performance and regeneration capabilities demonstrate that Chi-Pet-T can be used as a potential efficient and recyclable adsorbent for removal of cationic and anionic dyes from wastewaters.

Flame-retardant and Self-healing Biomass Aerogels Based on Electrostatic Assembly

It remains a significant challenge to fabricate self-healing aerogels with excellent flame retardancy. Herein, we develop a class of biomass aerogels by electrostatically assembling chitosan (CS), phytic acid (PA), and itaconic acid (IA). The electrostatic interaction between CS and IA is weak and dynamic, so freeze-drying the solution of CS and IA enables the formation of continuous aerogel skeleton with self-healing ability and re-programmability; in comparison, the electrostatic interaction between CS and PA is strong and less dynamic, and thus mixing PA with CS in aqueous solution leads to fine precipitates of high flame retardancy due to the synergistic phosphorus-nitrogen effect. Integrating the continuous skeleton and the fine precipitates results in self-healing aerogles with UL-4 V-0 rating of flame retardancy aerogels and auto-extinguishable feature. Interestingly, the aerogels after burning in flame for 30 s form a skin-core structure, and the carbonized skin protects the integrity of the aerogels and the self-healing ability of the internal parts. Therefore, this work provides a facile strategy to develop multi-functional aerogels which hold great promise for advanced applications.

Radiation-synthesis of chitosan/poly (acrylic acid) nanogel for improving the antitumor potential of rutin in hepatocellular carcinoma.

The current study aimed to investigate the ability of chitosan/poly (acrylic acid) nanogel (CAN) to improve the bioavailability and anticancer potential of rutin. Synthesis of CAN was carried out by gamma radiation-induced polymerization of acrylic acid in an aqueous solution of chitosan. The relationship between the hydrodynamic radius of CAN and the absorbed radiation doses was also investigated. The prepared nanogels were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) techniques, and then, it was used as a nano-drug carrier for rutin. The developed formulation was evaluated for its antitumor activity against chemically induced hepatocarcinoma in rats. The following parameters were measured: aspartate and alanine aminotransferase, alkaline phosphatase, gamma glutamyltransferase, and total bilirubin as liver function test; vascular endothelial growth factor as an angiogenesis marker; α-fetoprotein as a tumor marker; and P53, caspase-3, Bax, and Bcl-2 as apoptosis markers. Histopathological examination was also confirmed. Significant enhanced anti-proliferative, anti-angiogenic, and apoptotic effects were observed for rutin-loaded CAN than free rutin, indicating that this formulation could provide a novel therapeutic approach to serve as a promising agent for treatment of hepatocellular carcinoma. Graphical abstract.

A Comparative Study on Aqueous Chitosan Solution and Various Submucosal Injection Fluids Using a Three-Dimensional Sensor.

Background/AimsChitosan, a natural polymer widely used in the biomaterials field, has been proposed as a potential submucosal injection solution. The purpose of this study was to compare the performance and efficacy of aqueous chitosan solution and commercialized submucosal injection fluids using a three-dimensional sensor and to evaluate the efficacy of the measured parameters.MethodsNormal saline (0.9% NaCl), as a control, Eleview® (Poloxamer 188), Blue EyeTM (0.4% hyaluronic acid), and aqueous chitosan solution (2.0%) were injected into the submucosa of porcine stomachs ex vivo. The mucosal elevation height, elevated surface area, and angle of the tangent of the submucosal fluid cushion were measured using a three-dimensional sensor. The rates of change for each variable were calculated, and the correlation between parameters was analyzed. Tissue specimens were stained with hematoxylin and eosin.ResultsAll variables exhibited the highest values under chitosan injection. The mucosal elevation height rate of change differed significantly between normal saline and chitosan solution (p=0.024). The elevated surface area rates of change for normal saline and Eleview® were significantly different from those for TS-905 and chitosan solution (p=0.006 and p=0.009, respectively). Further, height, area, and angle showed a positive correlation (p<0.001). A histological examination revealed an even distribution of aqueous chitosan within the submucosa without tissue damage.ConclusionsAqueous chitosan was superior to normal saline and Eleview® and was noninferior to TS-905. A three-dimensional sensor and the measured parameters were effective and useful for evaluating the performance of submucosal fluids.

Effect of carbon dots in combination with aqueous chitosan solution on shelf life and stability of soy milk

Use of carbon dots (CDs) in combination with aqueous chitosan solution to extend shelf life and improve stability of soy milk was investigated. Soy milk samples with chitosan solution (0.00%, 0.08%, 0.12%, 0.16% and 0.20%) and banana-based CDs (4%, 6% and 8%) were prepared and stored at room temperature (25–30 °C) for shelf life evaluation. Soy milk with 0.16% chitosan solution exhibited improved stability as evident by increased viscosity, stability coefficient, zeta potential and decreased centrifugation rate compared with soy milk without chitosan. The suitable amount of carbon dots could effectively inhibit the growth of Escherichia coli, Staphylococcus aureus and Bacillus subtilis. Soy milk with 0.16% chitosan and 8% CDs exhibited longer shelf life and significantly lower total bacterial count after storage at room temperature for up to 4 days. Electronic nose-based flavor characteristics of all treated soy milk samples were not far from that of the control sample.

Direct ionization and solubility of chitosan in aqueous solutions with acetic acid

A better understanding of the physicochemical phenomena underlying the direct solubilization of solid chitosan in an aqueous acetic acid medium without the addition of salt is needed. These phenomena have been studied using an inverse approach in which the chitosan is treated as a poly-acid and not as poly-base, and the macrophenomenon observed represents the aggregation of the macromolecules of chitosan instead of their solubilization. The purpose of this study is to present an overview of the physicochemical phenomena underlying this direct solubilization in an aqueous acetic acid medium without the addition of salt through a mathematical model based on equilibrium equations, mass balances, and correlations between experimental data. This model allowed us to model dilute chitosan/acetic acid/water systems without the addition of salt with an adequate fit (R2 > 0.9951) to the trend of the experimental data, enabling the calculation of the pH, degree of ionization, apparent dissociation constant, and the concentrations of the smaller molecules $$\left( {{\text{CH}}_{3} {\text{COOH}}, {\text{CH}}_{3} {\text{COO}}^{ - } ,{\text{H}}_{3} {\text{O}}^{ + } } \right)$$ , with only a priori knowledge of the initial concentration of acetic acid, initial concentration of amine groups, and the dissociation constant of acetic acid. The main finding of this study was that the diluted systems lacking salt studied here showed a tendency toward an apparent dissociation constant of $$pK_{1/2} \to 6.44$$ as the polymer concentration increased. This value is similar to the values reported in the literature for systems containing salt and a degree of deacetylation $$\left( {f_{\text{D}} \sim 0.7} \right)$$ similar to the chitosan evaluated here.

Ondansetron buccal administration for paediatric use: A comparison between films and wafers.

The objective of this study was the development of different solid formulations, such as wafers and films, for buccal administration of ondansetron, a selective and potent antagonist of 5-hydroxytryptamine 3 receptors used in children for the treatment of nausea and vomiting. Wafers and films have been prepared drying an aqueous solution of pectin, hydroxypropyl methylcellulose, sodium hyaluronate, sodium carboxymethylcellulose, chitosan or gelatin, through lyophilization or oven. Formulations were characterized in terms of morphology, drug solid state and ability to hydrate, adhere to mucosa, release and favour the permeation of the drug through porcine esophageal epithelium, used as model of human buccal epithelium. The most promising formulations were tested for in vitro biocompatibility in human pulp fibroblasts. Films showed greater hydration and mucoadhesion abilities and allowed the release and the permeation of a greater amount of ondansetron with respect to wafers. Chitosan or hyaluronate provided films with the best mucoadhesion properties and good biocompatibility profile. Moreover, chitosan based film allowed to obtain the highest amount of permeated drug and could represent a novel child-appropriate dosage form able to combine the advantages of solid dosage form with the possibility to avoid the swallowing.

Bacterial Cellulose-Chitosan Paper with Antimicrobial and Antioxidant Activities.

The production of paper-based bacterial cellulose-chitosan (BC-Ch) nanocomposites was accomplished following two different approaches. In the first, BC paper sheets were produced and then immersed in an aqueous solution of chitosan (BC-ChI); in the second, BC pulp was impregnated with chitosan prior to the production of paper sheets (BC-ChM). BC-Ch nanocomposites were investigated in terms of physical characteristics, antimicrobial and antioxidant properties, and the ability to inhibit the formation of biofilms on their surface. The two types of BC-Ch nanocomposites maintained the hydrophobic character, the air barrier properties, and the high crystallinity of the BC paper. However, BC-ChI showed a surface with a denser fiber network and with smaller pores than those of BC-ChM. Only 5% of the chitosan leached from the BC-Ch nanocomposites after 96 h of incubation in an aqueous medium, indicating that it was well retained by the BC paper matrix. BC-Ch nanocomposites displayed antimicrobial activity, inhibiting growth of and having a killing effect against bacteria Staphylococcus aureus and Pseudomonas aeruginosa and yeast Candida albicans. Moreover, BC-Ch papers showed activity against the formation of a biofilm on their surface. The incorporation of chitosan increased the antioxidant activity of the BC paper. Paper-based BC-Ch nanocomposites combined the physical properties of BC paper and the antimicrobial, antibiofilm, and antioxidant activities of chitosan.

Deposition of a Chitosan Coating on Celgard Porous Matrices in the Presence of Carbon Dioxide under Pressure

It is shown that a chitosan coating can be deposited on the pore surface of Celgard polyolefin matrices from aqueous solutions of chitosan saturated with carbon dioxide under high pressure; i.e., when carbonic acid is formed. To ensure the stability of the coating, the initially hydrophobic matrices should be pretreated in the presence of peroxycarbonic acid, which is formed when the aqueous solution of hydrogen peroxide is saturated with carbon dioxide at a high pressure. The morphology of the deposited coating is studied by high-resolution microscopy. The introduced hydrophilic properties are evaluated from a change in the nature of the wetting of the matrix surface with water. It is found that the hydrophilized matrix modified with chitosan, in spite of a lower characteristic pore size, has ~1.5 times higher permeability for water than the initial matrix.