Swelling Of Chitosan Research Articles

Chitosan-based promising scaffolds for the construction of tailored nanosystems against osteoporosis: Current status and future prospects.

Despite advancements in therapeutic techniques, restoring bone tissue after damage remains a challenging task. Tissue engineering or targeted drug delivery solutions aim to meet the pressing clinical demand for treatment alternatives by creating substitute materials that imitate the structural and biological characteristics of healthy tissue. Polymers derived from natural sources typically exhibit enhanced biological compatibility and bioactivity when compared to manufactured polymers. Chitosan is a unique polysaccharide derived from chitin through deacetylation, offering biodegradability, biocompatibility, and antibacterial activity. Its cationic charge sets it apart from other polymers, making it a valuable resource for various applications. Modifications such as thiolation, alkylation, acetylation, or hydrophilic group incorporation can enhance chitosan's swelling behavior, cross-linking, adhesion, permeation, controllable drug release, enzyme inhibition, and antioxidative properties. Chitosan scaffolds possess considerable potential for utilization in several biological applications. An intriguing application is its use in the areas of drug distribution and bone tissue engineering. Due to their excellent biocompatibility and lack of toxicity, they are an optimal material for this particular usage. This article provides a comprehensive analysis of osteoporosis, including its pathophysiology, current treatment options, the utilization of natural polymers in disease management, and the potential use of chitosan scaffolds for drug delivery systems aimed at treating the condition.

Modeling of Association Properties of Cetylpyridinium Halides (Cl, Br) and their Influence on Liberation and Rheological and pH Balances of Hydrogels with Ibuprofen

Abstract The paper studies the influences of two cationic surfactants - cetylpyridinium chloride (CPCl) and cetylpyridinium bromide (CPBr) - at concentrations 10-times below and 10-times above the CMC - at 258C-408C on the release of ibuprofen from hydrogels, rheological properties and pH. The association of surfactants in the water solutions was studied by conductometry. It was found that the temperature dependences of the surfactants’ CMCs are not linear and the CMCs of CPCl are higher than that of CPBr. The concentrations of the polymer (chitosan) and the drug were kept constant. Amounts of the released drug increased with the increasing temperature. From the hydrogels with CPBr and CPCl, whose surfactant concentration was below the respective CMC, higher amounts of the active ingredient were released than from the hydrogels with surfactant concentrations above the respective CMC. It is shown that for increasing temperature the hydrogels exhibit gradual transition for pseudo plastic to thixotropic system, what is advantageous for their practical application. The hydrogels’ pH values were in the interval 5.10-5.46, which is ideal for their application on the skin and for the chitosan swelling. The presented topic is a precondition of synthesis of the on-line and off-line control algorithms of an optimal release kinetics, elaborated by the authors.

Study on a quartz crystal microbalance sensor based on chitosan-functionalized mesoporous silica for humidity detection

Chitosan-functionalized mesoporous silica MCM-41 (Chi/M41) was prepared by a mild method. In the composite materials, the spherical MCM-41 particles were regarded as supporting skeletons, which reduced the effect of chitosan swelling on the repeatability and reliability of quartz crystal microbalance (QCM) sensors at high relative humidity (RH), and chitosan provided good film-forming properties of the final composite. The composite structure effectively improved the sensitivity of the QCM sensors compared to that of chitosan and MCM-41 sensors. The QCM sensor based on the Chi/M41 composites showed excellent sensitivity (58.4 ± 0.3 Hz/% RH). In addition, the optimal sensor exhibited excellent reliability, such as negligible humidity hysteresis (0.8 ± 0.1% RH), a small variation coefficient (1.1 ± 0.1), short response and recovery times (18 s/15 s) and good long-term stability. Furthermore, the Langmuir adsorption isotherm model and the Gibbs free energy were used to investigate the adsorption mechanism of water molecules on the sensitive films in this work.

Luminescent Sensing via Photonic Nanojets

A new optical sensor system based on an array of dielectric aluminum oxide microspheres covered with a layer of chitosan polymer with molecules of a luminescent chemosensitive receptor was developed for determination of ammonia ion concentration in air. The photonic nanojet effect, i.e. strong electromagnetic field local enhancement, was implemented for most effective excitation of the sensitive layer. By using of chitosan swelling polymer the effect of refractive index variation on photonic nanojets excited sensor response was demonstrated. It was shown that under certain conditions such as microsphere diameter and refractive index contrast a detection limit of chemosensitive receptor increases in three times.

Effect of Water on the Chitosan Impregnation in SC–CO2 with Hydrophobic Diaryl Imidazoles and on the Kinetics of Their Subsequent Release in a Model Biological Medium

Abstract—Sustained-release compositions based on chitosan and substituted diaryl imidazoles (DAIs) possessing antitumor activity were obtained in supercritical carbon dioxide (SC–CO2). It has been found that the use of water (0.17 vol %) as a co-solvent during SCF impregnation of chitosan with DAIs leads to an increase in the DAI content in the polymer matrix. Obviously, this is due to an increase in the degree of chitosan swelling in the SC–CO2 medium in the presence of water. It is interesting to note that the effect of water on the rate of release of the SCF-introduced DAIs from the matrix into a model medium with pH 1.6 is determined by the DAI structure. For the first time, it is shown that the solubilization of DAI molecules by Pluronic F-127 before their SCF introduction into the chitosan matrix can be used as an additional efficient way to prolong the action of matrix medicinal compositions.

Engineering and Development of Chitosan-Based Nanocoatings for Ocular Contact Lenses

This article reports on electrohydrodynamic atomization to engineer on-demand novel coatings for ocular contact lenses. A formulation approach was adopted to modulate the release of timolol maleate (TM) using chitosan and borneol. Polymers polyvinylpyrrolidone and poly (N-isopropylacrylamide) were utilized to encapsulate TM and were electrically atomized to produce optimized, stationary contact lens coatings. The particle and fiber diameter, thermal stability, material compatibility of the formed coatings, their in vitro release-modulating effect, and ocular tolerability were investigated. Results demonstrated highly stable nanomatrices with advantageous morphology and size. All formulations yielded coatings with high TM encapsulation (>88%) and excellent ocular biocompatibility. Coatings yielded biphasic and triphasic release, depending on composition. Kinetic modeling revealed a noticeable effect of chitosan; the higher the concentration, the more the release of TM because of chitosan swelling, with the mechanism changing from Fickian diffusion (1% w/v; n = 0.5) to non-Fickian (5% w/v, 0.45 <n < 0.89). The use of electrohydrodynamic atomization has not yet been explored in depth within the ocular research remit, engineering on-demand lens coatings capable of sustaining TM release. This is likely to offer an alternative dosage form for management of glaucoma with particular emphasis on improving poor patient compliance.

ATORVASTATIN ADSORPTION STUDIES ON CHITOSANS IN AN in vitro PHARMACEUTICAL MODEL

During the pharmacological therapy of specific diseases, drugs are used which, with other preparations or foods, can create connections, in many cases changing or even blocking their action. On the other hand, the use of unsuitable polymers as excipients may result in drug-polymer incompatibilities. Interactions consisting mainly of the occurrence of the adsorption phenomenon and on the formation of complex bonds that reduce the effect of the drugs are of particular importance. The aim of the study was to investigate whether the active substance atorvastatin is incompatible with dietary supplements containing chitosan. The phenomenon of the adsorption of the drug was examined using a static model of a pharmaceutical gastrointestinal tract, in the concentration range generally ingested in a single dose. Measurement results of the amount of bound drug were used to determine the average percentage of adsorbed drug dose. The results of the study prove that the anticholinesterase drug is adsorbed on chitosan in the pH ranges used, and that the binding capacity depends on the chitosan variety, which indirectly affects the reaction of the environment. It was observed that the average size of sorption depending on the chitosan variety ranged from 38% to 86%. The fact that the lowest value of adsorption was at pH 6.4 can be explained by the chemical properties of chitosan, which shows a charge only at pH &gt;6.7. Under such conditions, the phenomenon of electrostatic adsorption may occur in relation to the healing substances of weak acids. At a pH above 7.6, corresponding to the intestinal fluid-filled intestine, the mean sorption for the highest dose of chitosan was from 38–86%. The increase in the adsorbed amount of anticholinesterase drugs on the polymer along with the increase in pH from 7.6 to 8.0 can be explained by the chitosan swelling properties, which increase with an increase in the pH. As a result, the specific surface area of the polymer and its sorption capacity increase. Based on the above considerations, it can be concluded that there is an antagonistic interaction between the drug and the polymer studied, which involves the adsorption of a drug from this group on the polymer (chitosan) and a decrease in its bioavailability.

Black chokeberry (Aronia melanocarpa) pomace extract immobilized in chitosan for colorimetric pH indicator film application

During this study, different amounts of black chokeberry (Aronia Melanocarpa) pomace extract were mixed with chitosan to prepare colorimetric pH indicator films. The monomeric anthocyanin and total phenol content of ultrasonically extracted chokeberry pomace solution were determined by pH differential method and Folin-Ciocaltau assay. ATR-FTIR spectroscopy, CIELab method, solubility, swelling ability, dye migration and tensile strength measurements were used to characterize the films. The pomace extract contained enough active components to highly reduce the solubility and swelling of chitosan. The indicator films maintained their integrity even at acidic pH which was attributed to the interactions between the polymer chains and the phenolic components of the extract. With higher extract content, a higher resistance to water was observed, which also resulted in reduced dye migration. The immobilized dye in chitosan films responded well to the pH change and showed a high color difference from pH 1 to pH 10.

On the possibility of regulating the rate of enzymatic destruction of chitosan in an acetic acid solution

The enzymatic destruction of chitosan in an acetic acid solution in the presence of sodium chloride and sulfate was considered. It was shown that the addition of these low-molecular electrolytes is accompanied by a tightening of the macromolecular coil, as indicated by a decrease in the α constant in the Mark–Kuhn–Houwink equation and the intrinsic viscosity of chitosan. As a consequence, the chitosan units become less accessible for interaction with the enzyme, and the kinetic parameters of the process (Michaelis constant K M and the maximum rate of enzymatic destruction V max) change accordingly. This suggests that the resistance of this polymer to the enzyme action can be enhanced by introducing low-molecular electrolyte salts in the solution or film coating to suppress the polyelectrolyte swelling of chitosan.

Influence of Chitosan Swelling Behaviour on Controlled Release of Tenofovir from Mucoadhesive Vaginal Systems for Prevention of Sexual Transmission of HIV.

The main challenges facing efforts to prevent the transmission of human immunodeficiency virus (HIV) are the lack of access to sexual education services and sexual violence against young women and girls. Vaginal formulations for the prevention of sexually transmitted infections are currently gaining importance in drug development. Vaginal mucoadhesive tablets can be developed by including natural polymers that have good binding capacity with mucosal tissues, such as chitosan or guar gum, semisynthetic polymers such as hydroxypropylmethyl cellulose, or synthetic polymers such as Eudragit® RS. This paper assesses the potential of chitosan for the development of sustained-release vaginal tablets of Tenofovir and compares it with different polymers. The parameters assessed were the permanence time of the bioadhesion—determined ex vivo using bovine vaginal mucosa as substrate—the drug release profiles from the formulation to the medium (simulated vaginal fluid), and swelling profiles in the same medium. Chitosan can be said to allow the manufacture of tablets that remain adhered to the vaginal mucosa and release the drug in a sustained way, with low toxicity and moderate swelling that ensures the comfort of the patient and may be useful for the prevention of sexual transmission of HIV.

Swelling induced regeneration of TiO2-impregnated chitosan adsorbents under visible light

Since only the molecules that are in direct contact with the TiO2 surface undergo photosensitization, it is challenging to regenerate the TiO2-impregnated chitosan (TIC) adsorbent beads under visible light. This study focused on the role of chitosan swelling properties. It was found that dye-loaded TIC adsorbent exhibited a pH-dependent swelling owing to protonation/deprotonation of free amino groups on chitosan chains. In the acidic medium (pH<6.0), the adsorbent underwent a ‘smart’ phase transition from a dry contracted state to a hydrated swollen state, and its physicochemical properties were also significantly changed, which eventually enabled the photosensitized oxidation of dye. This swelling induced regeneration was further confirmed by Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The involvement of oxygen radical species (O2−/HOO and OH) was also confirmed with electron spin resonance (ESR) spectroscopy. Moreover, the adsorption effectiveness of TIC adsorbent was mostly recovered after six regeneration cycles.

Chemical Modification of Chitosan in order to Inverse Swelling Behavior: Comparison between Crosslinking, Michael Addition and Graft Copolymerization Reactions

In the present work, three methods were used to inverse chitosan swelling behavior including, conjugation of p-amino benzoic acid (PABA) on cross-linked chitosan in different condition, Michael addition reaction of acrylic acid (AA) on chitosan and finally graft copolymerization of methacrylic acid (MMA) on chitosan. We couldn’t inverse chitosan swelling behavior by the Michael addition reaction of acrylic acid, but conjugation of PABA on cross-linked chitosan inversed the chitosan swelling behavior. In addition, the graft copolymerization of MMA on chitosan was also successful. In general, the third method, among the above-mentioned modifications provided the best results.Bangladesh Pharmaceutical Journal 18(2): 110-117, 2015

Chitosan reinforced alginate controlled release beads of losartan potassium: design, formulation and in vitro evaluation

The work investigates the development and optimization of chitosan-alginate beads containing Losartan potassium (LP) through ionotropic/external gelation technique using 32 factorial design. The effect of polymer-blend concentrations i.e. chitosan and sodium alginate on the drug encapsulation efficiency (DEE%), and cumulative drug release after 20 h (R20h %) was optimized. The DEE% of all these beads was within the range of 67.12 ± 1.97–89.81 ± 1.52 % with sustained in vitro drug release of 80.98–97.13 % over 20 h. The in vitro drug release from these beads was followed first order kinetic model. The beads were also characterized by FE-SEM, FTIR and XRD analysis. The swelling of chitosan–alginate beads containing LP were influenced by the pH of the test medium. Chitosan coated alginate beads were developed as oral sustained delivery carriers for LP in order to improve patient compliance, to reduce side effects associated with it and also to reduce the dose/dosing frequency in the management of hypertension.

Novel Chitosan-Functionalized Spherical Nanosilica Matrix As an Oral Sustained Drug Delivery System for Poorly Water-Soluble Drug Carvedilol

A novel spherical nanosilica matrix (SNM) together with chitosan (CTS) encapsulated SNM (CTS-SNM) was developed in order to investigate the feasibility of using chitosan to regulate drug release rate from porous silica and obtain an oral sustained drug delivery system. To achieve this goal, we synthesized a spherical nanosilica matrix (SNM) and incorporated chitosan chains on the SNM surface. Solvent evaporation method was adopted to load the model drug carvedilol into SNM and CTS-SNM. The physicochemical properties of the drug carriers and drug-loaded composites were systematically studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption, X-ray diffraction (XRD), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The structural changes in CTS-SNM in simulated gastrointestinal fluid as well as the relationships between swelling effect of chitosan and in vitro drug release behaviors were investigated. Pharmacokinetic and bioavailability aspects were also discussed. The results showed that the powerful dispersing effect of SNM and the blocking action due to the swelling of chitosan were the two main factors contributing to the sustained drug release behavior. The swelling effect of chitosan in an acidic environment together with the shrinking effect in a relatively alkaline environment allowed regulation of drug release behavior in simulated gastrointestinal fluid. An in vivo study showed that the bioavailability of CAR was improved 182% compared with that of the commercial capsule when SNM was used as the drug carrier. As for CAR-CTS-SNM, the T(max) of CAR was delayed by about 3.4 h and the bioavailability was slightly increased in comparison with the commercial capsule. We believe that SNM and CTS-SNM developed in this study will help increase the use of polymers and inorganic materials in pharmaceutical applications and stimulate the design of oral drug delivery systems for immediate or sustained release of poorly water-soluble drugs.

Production of 3D scaffolds applied to tissue engineering using chitosan swelling as a porogenic agent

AbstractThe preparation of 3D scaffolds using poly(3‐hydroxybutyrate) (PHB) and chitosan (CTS) has been proposed because of the favorable interactions of these materials with mammalian cells in particular osteoblasts (HOB). In this work, a new method of producing porous 3D scaffolds based on the swelling of a dense matrix of PHB and CTS was developed. Scanning electron microscopy images showed the formation of an interconnected porous CTS structure inside a PHB structure. The pore formation was attributed to the swelling of CTS. The scaffolds presented 70% porosity, heterogeneous pore‐size distribution, and a compressive modulus equal to (13.07 ± 0.014) MPa, which is close to that of cancellous bone. In vitro cytotoxicity assays indicate that the scaffold was not cytotoxic. Its morphology, chemical, and physical properties indicate that the scaffold produced by this new methodology has potential applications in bone‐tissue engineering, with drug‐delivery capabilities. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Reversible Swelling of Chitosan and Quaternary Ammonium Modified Chitosan Brush Layers: Effect of pH and Counter Anion Size and Functionality.

This study investigates the swelling of grafted polycationic brushes as a function of pH and anion type. The brushes are chitosan (CH) and chitosans with 27% and 51% degree of substitution (DS) of quaternary ammonium salt, denoted as CH-Q(25) and CH-Q(50), respectively. The water content and swelling behaviors are monitored using in situ quartz-crystal microbalance with dissipation (QCM-D). The pH varies from ~3.5 to 8.5, and the counter anion types include chloride, acetate, and citrate. At fixed pH, the water content and brush swelling increase as the DS increases. Whereas the CH-Q(50) brush layer shows symmetric swelling with a minimum near pH = 4.5, the swelling of CH and CH-Q(25) is relatively constant as pH decreases from 8.2 to 5.5, and then begins to increase near pH 4. These studies indicate that the symmetric swelling of CH-Q(50) is likely attributed to increasing protonation of primary amines for pH values below pH 6.5 and the quaternary ammonium salts above pH 6.5. At pH 4, the swelling of the CH brush increases upon exchanging the smaller chloridewith a bulkier acetate anion, which is less effective at screening intra/inter molecular repulsion. In contrast, upon exchanging the acetate with trifunctional citrate, CH and CH-Q(25) brushes collapse by 53 and 42%, respectively, because the citrate forms ionic cross-links. To test antibacterial properties, silicon oxide, CH and CH-Q(50) brush layers are exposed to 10(7)-10(8) cfu/ml of S. aureus for two days at 37 °C and exposed to stepped shear stresses in 2 min intervals. Whereas an S. aureus biofilm adheres strongly to silicon oxide and CH for stresses up to 12 dyne/cm(2), biofilms on CH-Q(50) detach at a relatively low shear stress, 1.5 dyne/cm(2). Due to their high degree of swelling that can be tuned via pH, counterion size and type, chitosan and quaternary modified chitosans have potential as responsive coatings for applications including MEMS/NEMS devices and drug eluting implants.

Polyaniline–chitosan nanocomposite: High performance hydrogen sensor from new principle

A high selectivity and response towards hydrogen gas is realized with a composite of polyaniline nanofibers embedded in chitosan matrix. The enhanced response originated from the new sensing mechanism related with the composite nature of chitosan and polyaniline. Based on the high gas sensing performance through nanostructured resistive polyaniline nanofibers, the swelling of chitosan as the matrix distributing among the resistor network controls the hopping conduction between the nanofibers. This gate control of chitosan on the polyaniline conduction claims a new type of sensor mechanism resulting in a reverse polarity in conductivity change with respect to the conductivity change of polyaniline. The response-reversal can enhance the sensing response. Furthermore, the highly enhanced selectivity for hydrogen was also achieved through filtration action of chitosan for large size and polar molecules. We thus demonstrate a new material and structural design of solid state sensor for improvement in selectivity and response.

NMR imaging of chitosan and carboxymethyl starch tablets: Swelling and hydration of the polyelectrolyte complex

The hydration and swelling properties of the tablets made of chitosan, carboxymethyl starch, and a polyelectrolyte complex of these two polysaccharides have been studied by NMR imaging. We studied the effect of pH and ionic strength on the swelling of the tablets and on the diffusion of fluid into the tablets in water and simulated physiological fluids. The pH value of the fluids exerts a more significant effect than their ionic strengths on the swelling of the tablets. The tablets are compared also with those made of cross-linked high amylose starch. The formation of complex helps to keep the integrity of the tablets in various media and render a slow and restricted swelling similar to that of the tablets of the cross-linked high amylase starch, which is significantly lower than the swelling of chitosan and of carboxymethyl starch. The capacities to modulate the release rate of drugs in different media are discussed by comparing the matrices and evaluating the preparation process of the complex. A sustained release of less soluble drugs such as aspirin in gastrointestinal fluids can be provided by the complex, due to the ionic interaction and hydrogen bonding between the drug and the biopolymer complex.

Preparation and Structure of Chitosan Swellable in Alkali Solution by Ultrasonic Treatment

By treating chitin with ultrasonic in hot concentrated NaOH solution for about 30-120min, chitosan swellable highly in alkali was prepared. The swelling behavior and the structure of the prepared chitosan were invested. It was shown that the prepared chitosan can swell highly in NaOH solution by freeze-thawing treatment, with the particles turns into hydrogel. The swelling behavior showed that with the increase of NaOH concentration, the swelling degree of chitosan increases, until a concentration of 8.0 wt%, and ultrasonic treatment time has less significant influence on the swelling behavior. SEM showed that ultrasonic treatment makes the structure of chitin enough looser for the permeation of NaOH and H2O, resulting in the swelling of chitosan in alkali solution.

Nonlinear effects in mass transfer of liquid media through polymeric materials

Transport properties of several aromatic polyamides among which there exist fairly subtle structural differences were examined in perva-poration of water-isopropanol solutions. The dependences of the flux density on the membrane area and the oscillatory kinetics of permeability were established, and an unstable steady state arising via predominant permeation of an organic solvent through a highly hydrophilic polymeric membrane was revealed. Conductometric examination of the swelling kinetics showed that chitosan swelling in water gives rise to instabilities in the form of macrofluctuations of local sorbate concentration distribution in the polymer. The wavelet analysis of the time series of the stochastic oscillations was carried out.