High Molecular Weight Chitosan Research Articles

Effect of chitosan molecular weight and protein to polysaccharide ratio on the rheological and physicochemical properties of milk proteins–chitosan complex coacervate

The small amplitude oscillatory shear (SAOS) rheological properties of complex coacervate of milk proteins with high (HMC), medium (MMC), and low (LMC) molecular weight chitosan in the optimal ratios of milk proteins to chitosan (15:1, 10:1, and 5:1, respectively) were measured. In addition, the morphological (SEM), structural (XRD), and thermal (DSC) properties of the complex coacervates were investigated in comparison with the milk protein concentrate. Complex coacervates showed the shear-thinning behavior due to a linear decrease of complex viscosity with increasing frequency. Furthermore, the highest complex modulus and the more compact structure under optimal conditions, in terms of the ratio of protein to chitosan and pH, revealed strong electrostatic bonding between proteins and chitosan. All coacervates showed a G′ > G″ (Tanδ<1), indicating the formation of an interconnected gel-like structure that was described by the power law model. The maximum fracture stress was obtained at optimum conditions (R = 15:1, pH =6.7 for HMC; R = 10:1, pH =5.5 for MMC and R = 5:1, pH =4.6 for LMC), indicating the highest intermolecular interaction between milk proteins and chitosan. The coacervates had a completely amorphous structure similar to MPC, and according to DSC results, the ionic bonds between milk proteins and chitosan were not destroyed up to 300 °C. Coacervation leads to purified milk proteins at a low cost. In addition, the coacervates can be used for the encapsulation of heat-sensitive compounds, and also as a stabilizer to improve the texture of food.

Design and in vitro Evaluation of Cocoa Butter-based Amlodipine Besylate Fast Melt Tablets

Background: Oral fast-melting tablets (FMTs) have been gaining popularity due to their advantages in resolving swallowing issues of conventional oral tablets. Cocoa butter is an excipient of choice to develop FMT with an acceptable taste and faster onset of action of the drug. Purpose: The present study aimed to prepare and characterize the amlodipine besylate-loaded cocoa butter FMTs. objective: To prepare and characterise the formulation of cocoa butter tablet as fast melt buccal delivery system of amlodipine besylate. Method: Amlodipine besylate FMTs were prepared using a simple freezing (refrigeration) method. Cocoa butter (Form V) was used as the base to achieve a final tablet weight of 500 mg with drug and other functional excipients. The designed prototype tablet formulations were subjected to disintegration tests to determine the robust selected batch. The formulation F4, containing 7% high-molecular-weight chitosan, exhibited the quickest disintegration time of 1.45 ± 0.10 min. Afterwards, the selected formulation, F4, was subjected to quality evaluation parameters. Results: Fourier transform infrared spectroscopy (FTIR) studies revealed that there was no incompatibility between amlodipine besylate, cocoa butter, and other excipients. The average hardness of the F4 formulation tablet batch was found to be 2.69 ± 0.21 kg/cm2 and a friability of less than 1%. The drug content in F4 tablets was found to be 102.38 ± 5.29% and showed an in-vitro drug release of 94.30 ± 2.63% within 30 min. Over a six-month stability testing period, the chosen F4 formulation did not significantly change in terms of tablet average weight, disintegration time, drug content, and in-vitro dissolution rate. Conclusions: Selected formulation F4 with 7% of high molecular weight chitosan exhibited good physical properties, indicating the suitability of cocoa butter as a base to produce FMTs with the aid of a natural super-disintegrant.

Chitosan and its derivatives regulate lactic acid synthesis during milk fermentation.

The influence of chitosan's physicochemical characteristics on the functionality of lactic acid bacteria and the production of lactic acid remains very obscure and contradictory to date. While some studies have shown a stimulatory effect of oligochitosans on the growth of Lactobacillus spp, other studies declare a bactericidal effect of chitosan. The lack and contradiction of knowledge prompted us to study the effect of chitosan on the growth and productivity of L. bulgaricus in the presence of chitosan and its derivatives. We used high molecular weight chitosan (350 kDa) and oligochitosans (25.4 and 45.3 kDa). The experiment was carried out with commercial strain of L. bulgaricus and the low fat skim cow milk powder reconstituted with sterile distilled water. After fermentation, dynamic viscosity, titratable acidity, pH, content of lactic acid, colony forming units, chitosan and oligochitosans radii were measured in the samples. Fermented dairy products were also examined using sodium dodecyl sulfate electrophoretic analysis, gas chromatography-mass spectrometry and light microscopy. The results of the study showed that when L. bulgaricus was cultured in the presence of 25.4 kDa oligochitosans at concentrations of 0.0025%, 0.005%, 0.0075% and 0.01%, the average rate of LA synthesis over 24 hours was 11.0 × 10-3 mol/L/h, 8.7 × 10-3 mol/L/h, 6.8 × 10-3 mol/L/h, 5.8 × 10-3 mol/L/h, respectively. The 45.3 kDa oligochitosans had a similar effect, while the average rate of lactic acid synthesis in the control sample was only 3.5 × 10-3 mol/L/h. Notably, 350 kDa chitosan did not affect the rate of lactic acid synthesis compared with the control sample. Interestingly, interaction of chitosan with L. bulgaricus led to a slowdown in the synthesis of propanol, an increase in the content of unsaturated and saturated fatty acids, and a change in the composition and content of other secondary metabolites. The quantity of L. bulgaricus in a sample with 0.01% chitosan exceeded their content in the control sample by more than 1,700 times. At the same chitosan concentration, the fermentation process was slowed down, increasing the shelf life of the fermented milk product from 5 to 17 days while maintaining a high content of L. bulgaricus (6.34 × 106 CFU/g).

Effects of chitosan hydrolysate on control of postharvest infection caused by Botrytis cinerea and physiological responses of wounded tomato fruit

Chitosan is considered an eco-friendly plant protection agent. Chitosan hydrolysate (CH) with an average molecular weight (MW) of the main fraction of 135 × 103 Da, with a deacetylation degree (DD) of 93 % is an unfractionated product of nitric acid hydrolysis of high molecular weight chitosan. The effect of the CH on gray mold caused by Botrytis cinerea in tomato fruit stored at 25 °C was investigated. Chitosan provided effective control of B. cinerea on tomato fruit. The CH treatment of wounded tomato fruit had a protective effect, reducing the percentage of infected fruit on the 7 d after treatment to 50 %, compared with untreated wounded fruit (69 %) and water-treated fruit (88 %). The protective effect of the CH in tomato fruit may be due to a direct fungitoxic action against the pathogen. It was found that the CH induced an immune response in tomato fruit via the accumulation of phenolic compounds. The level of phenolic compounds in the CH group was higher than in the untreated wound group from day 1 to 5, with a maximum reached on day 3 (113 mg-eq GA kg-1). No significant differences were found in the activities of peroxidase, phenylalanine ammonia lyase, polyphenol oxidase, β-1,3-glucanase and chitinase. Thus, the CH affects the processes occurring during fruit damage and contributes to the preservation of the consumer qualities of fruit.

Chitosan-graft-poly(vinyl acetate) for wood-adhesive applications

Poly(vinyl acetate), PVAc, adhesives are commonly used for wood bonding; however, they are fossil-based and the final products usually do not have a sufficient water resistance for more durable applications. In this study we prepared an adhesive formulation by grafting VAc from chitosan using emulsion polymerization, chitosan-graft-PVAc. Thereby, we could decrease the fossil-based content of the adhesive and at the same time significantly improve the water resistance. Chitosan by itself has very good bonding properties as a wood adhesive, especially regarding water resistance; however, very low solid contents of the adhesive formulation can be achieved due to a very high viscosity of chitosan adhesives. In our chitosan-graft-PVAc adhesives, we explored two chitosan samples with different molecular weights, by using as-received chitosan and hydrolyzing it to a lower molecular weight. The chitosan fractions in the adhesives prepared with a higher molecular weight chitosan were 15, 20 and 25 wt%. However, due to the high viscosity, a solid content higher than 17 wt% could not be achieved for these adhesives. Sufficient bond strengths were achieved when the adhesive was applied in 122 g/m2 solid spread rate. In order to decrease the viscosity, we used hydrolyzed chitosan, with a lower molecular weight, to allow for a higher adhesive solid content, 34 wt%, and for a higher chitosan fraction, 40 wt%. In the adhesive with 40 wt% chitosan and 17 wt% solid content, all VAc was grafted from chitosan. This decreased the molecular mobility of the chains, leading to a lower susceptibility to plastic creep in the adhesive which contributes to the final bond strength. The dry and wet strengths of the specimens bonded with adhesives containing chitosan were higher than the strength of the specimens bonded with the reference PVAc adhesive.

Preparation and Characterization of Hydrogels Fabricated From Chitosan and Poly(vinyl alcohol) for Tissue Engineering Applications.

In this study, we report on the preparation, characterization, and cytocompatibility of hydrogels for biomedical applications made from two different molecular weights of chitosan (CS) blended with poly(vinyl alcohol) (PVA) and chemically cross-linked with tetraethyl orthosilicate (TEOS) followed by freeze-drying. A series of CS-PVA hydrogels were synthesized with different amounts of chitosan (1%, 2%, and 3% by weight). The structure of these CS-PVA hydrogels was characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The hydrogel samples were also characterized for tensile strength, contact angle, swelling behavior, and degradation at physiological body temperature. Their physicochemical properties, biocompatibility, and cell viability when cultured with human dermal fibroblasts were assessed using alamarBlue and live/dead assays and compared to optimize their functionality. SEM analysis showed that the concentration and molecular weight of the chitosan component affected the pore size. Furthermore, the contact angle decreased with increasing chitosan content, indicating that chitosan increased its hydrophilic properties. The in vitro degradation study revealed a nonlinear time-dependent relationship between chitosan concentration or molecular weight, and the rate of degradation was affected by the pore size of the hydrogel. All of the CS-PVA hydrogels exhibited good cell proliferation, particularly with the high molecular weight chitosan samples.

A Novel Phytotherapy Application: Preparation, Characterization, Antioxidant Activities and Determination of Anti-inflammatory Effects by In vivo HET-CAM Assay of Chitosan-based DDSs Containing Endemic Helichrysum pamphylicum P.H. Davis & Kupicha Methanolic Extract.

Numerous pharmaceutical applications for chitosan, a polysaccharide made from the shells of crustaceans by deacetylating chitin that occurs naturally, are currently being researched. Chitosan, a natural polymer, is successfully used to prepare many drug-carrier systems, such as gel, film, nanoparticle, and wound dressing. Preparing chitosan gels without external crosslinkers is less toxic and environmentally friendly. Chitosan-based gels containing Helichrysum pamphylicum P.H. Davis & Kupicha methanolic extract (HP) were produced successfully. The F9-HP coded gel prepared with high molecular weight chitosan was chosen as the optimum formulation in terms of pH and rheological properties. The amount of HP was found to be 98.83% ± 0.19 in the F9-HP coded formulation. The HP release from the F9-HP coded formula was determined to be slower and 9 hours prolonged release compared to pure HP. It was determined that HP release from F9-HP coded formulation with the DDSolver program was by anomalous (non-fickian) diffusion mechanism. The F9-HP coded formulation significantly showed DPPH free radical scavenger, ABTS•+ cation decolorizing and metal chelating antioxidant activity while weakly reducing antioxidant potential. According to the HET-CAM scores, strong anti-inflammatory activity was obtained by the F9-HP coded gel at a dose of 20 μg.embryo-1 (p<0.05 compared with SDS). In conclusion, it can be said that chitosan-based gels containing HP, which can be used in both antioxidant and anti-inflammatory treatment, were successfully formulated and characterized.

Design and Characterization of Chitosan-Based Smart Injectable Hydrogel for Improved Sustained Release of Antinarcotics.

The treatment adherence of narcotics-addicted individuals with reduced incidences of relapse can be enhanced by a sustained drug release formulation of antinarcotics. So far, different drug formulations have been reported with sustained drug release periods of 28 and 35 days. To further enhance this duration, different formulations of injectable hydrogels (IHs) have been developed by combining low molecular weight (LMW) and high molecular weight (HMW) chitosan (CS) with guar gum (GG) and crosslinking them by sodium bi phosphate dibasic. The structural, morphological, and physicochemical properties of LMW-CS IH, and HMW-CS IH were evaluated using Fourier transform infrared spectroscopy (FT-IR), thermo-gravimetric analysis (TGA), scanning electron microscopy (SEM), and rheological, swelling, and biodegradation analysis. The HMW-CS IH showed high crosslinking, increased thermal stability, high mechanical strength, elevated swelling, and low biodegradation. The antinarcotic drugs naltrexone (NTX) and disulfiram (DSF) were loaded separately into the HMW-CS IH and LMW-CS IH. The release of NTX and DSF was investigated in phosphate buffer saline (PBS) and ethanol (0.3%, 0.4%, and 0.5%) over a 56-day period using an UV spectrophotometer. The drug release data were tested in zero-order, first-order, and Korsemeyer-Peppas mathematical models. In PBS, all prepared formulations followed non-Fickian drug release, while in ethanol, only NTX HMW-CS IH followed non-Fickian release in all three different concentrations of ethanol.

Synthesis, properties and applications of new hybrid material based on native/magnetically modified sepiolite and chitosans

The study introduces novel hybrid materials containing native and magnetite-containing sepiolite (Sep, SepM respectively) and chitosans (Ch) of different molecular weights. The main objective of this work was to determine the properties of these materials, including the different types of stability (colloidal, gravitational and thermal) in systems containing sepiolite, in order to obtain effective, stable and easily producible hybrid materials with great potential for water and wastewater treatment. The following measurements and methods were performed to characterize the investigated system: low-temperature nitrogen adsorption–desorption, zeta potential analysis, UV–Vis, FT-IR, XRD, XRF, SEM-EDS, TGA, DSC and DTG. It was found that the complexes with high molecular weight chitosan exhibited the best stability of the systems. The same tendency was observed for the concentration dependence: the higher the chitosan concentration, the better the stabilization of the composites. Overall, this study shows that chitosan effectively improves the colloidal and gravitational stability of the composites. Due to its unique structure, the synthesized magnetic hybrid material has shown great advantages in the adsorptive removal of textile dyes such as anionic acid red 88 (AR88) and cationic methylene blue (MB) which can be easily removed from the dye solutions after its use using an external magnetic field.

Physicochemical and kinetic properties of collagenase, native and adsorbed on chitosan

One of the modern research areas in biotechnology and medicine is the development of highly stable biopreparations based on immobilized enzymes. Using the method of sorption immobilization, heterogeneous biocatalysts were obtained based on collagenase (EC 3.4.24.3) from Clostridium histolyticum and from medium molecular weight (200 kDa) and high molecular weight (350 kDa) chitosans. The goal of the work was to study the physicochemical and kinetic properties of free and immobilized collagenase from Clostridium histolyticum on a chitosan matrix. The physicochemical and kinetic properties of the enzyme were studied in soluble and immobilized states using classical biophysical and biochemical methods. It was shown that the maximum activity of native collagenase was observed at 37ºС, while in case of the enzyme immobilized on medium and high molecular weight chitosan it was observed at 40ºС. Sorption immobilization of the biocatalyst on a chitosan matrix allowed increasing its stability during incubation within the temperature range of 40-70°C. After incubation at 80 and 90°C, no significant differences in the activity of soluble and immobilized collagenase were found. When studying the dependence of the protease activity of the enzyme on the medium acidity in the pH range from 5.0 to 9.0, it was established that the maximum catalytic ability of soluble collagenase was observed at a pH value of 7.5. The biocatalyst immobilized on medium and high molecular weight chitosans was highly active at pH 6.0-7.5. The catalytic ability of the enzyme in free and in adsorbed states noticeably decreased at pH 8.0, while at pH 9.0 soluble collagenase immobilized on medium and high molecular weight chitosans was completely inactive. The maximum rate of the enzymatic reaction of native and chitosan-immobilized biocatalysts was observed at a substrate concentration of 0.04 mM. Apparent values of V´max и K´m were calculated. The immobilization of collagenase on medium and high molecular weight chitosans did not result in a decrease of the maximum reaction rate or a change in the degree of affinity of the enzyme to the substrate. Using dynamic light scattering, we confirmed that the structure of collagenase in solution was most stable at pH 7.0-8.0, as exactly in this range of [H+] values we discovered the highest content of particles corresponding to the size of native collagenase and the lowest content of its aggregates. The optimal temperature for the best stability value of collagenase (no autolysis processes and minimal particle aggregation) can be considered as being 46°C.

Analysis of molecular structure and topological properties of chitosan isolated from crab shell and mushroom

This investigation aimed to scrutinize the chemical and structural analogies between chitosan extracted from crab exoskeleton (High Molecular Weight Chitosan, HMWC) and chitosan obtained from mushrooms (Mushroom-derived Chitosan, MRC), and to assess their biological functionalities. The resulting hydrolysates from the hydrolysis of HMWC by chitosanase were categorized as chitosan oligosaccharides (csCOS), while those from MRC were denoted as mrCOS. The molecular weights (MW) of csCOS and mrCOS were determined using Matrix-Assisted Laser Desorption Ionization Time-of-Flight (MALDI-TOF) mass spectrometry. Furthermore, structural resemblances of csCOS and mrCOS were assessed utilizing X-ray powder diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy. Intriguingly, no apparent structural disparity between csCOS and mrCOS was noted in terms of the glucosamine (GlcN) and N-acetylglucosamine (GlcNAc) composition ratios. Consequently, the enzymatic activities of chitosanase for HMWC and MRC exhibited remarkable similarity. A topological examination was performed between the enzyme and the substrate to deduce the alteration in MW of COSs following enzymatic hydrolysis. Moreover, the evaluation of antioxidant activity for each COS revealed insignificance in the structural disparity between HMWC and MRC. In summary, grounded on the chemical structural similarity of HMWC and MRC, we propose the potential substitution of HMWC with MRC, incorporating diverse biological functionalities.

Chitosan-(poly)acrylic acid polyelectrolyte complexes: Enhanced mucoadhesion and sustained drug release in vaginal tablets

Polyelectrolyte complexes (PECs) have emerged as promising vehicles for medical applications, attributable to their non-toxicity, non-immunogenicity, and ability for controlled drug release. Notably, their inherent mucoadhesive properties are being leveraged for sustained drug delivery across mucosal barriers, including vaginal, ocular, nasal, and buccal membranes. This study delves into the formulation and effects of chitosan-(poly)acrylic acid-based PEC for vaginal tablet applications. A comparative analysis of various polymer combinations was conducted, emphasizing the differential impacts of low versus high-molecular weight chitosan. Results highlighted that PECs augmented the flowability of powder mixtures and bolstered the tablets' physical properties. Moreover, PEC-enhanced formulations exhibited a pronounced increase in swelling efficiency, with swelling index values reaching up to 92.67 % ± 1.90, ensuring structural integrity during dissolution. In ex vivo mucoadhesion tests, tablets from PEC mixes demonstrated extended adhesion, surpassing 48 h for certain formulations. The optimized PEC formulation successfully achieved sustained drug release while retaining tablet adhesion for the duration of the release period.

3D-Printed Chitosan-Based Scaffolds with Scutellariae baicalensis Extract for Dental Applications.

The plant material Scutellariae baicalensis radix, which is rich in flavones (baicalin), possesses antibacterial, antifungal, antioxidant, and anti-inflammatory properties. This work aimed to develop a 3D-printed chitosan-based hydrogel rich in Scutellariae baicalensis extract as an innovative approach for the personalized treatment of periodontal diseases. Chitosan-based hydrogels were prepared, and the printability of the prepared hydrogels was determined. The hydrogel with 2.5% w/v of high molecular-weight chitosan (CS), 2% w/v gelatin (Gel), and 10% w/w of extract (Ex) presented the best printability, producing smooth and uniform scaffolds. It was proved that the CS/Gel/Ex hydrogel was stabilized by hydrogen bonds and remained in amorphous dispersion in the 3D-printed structures (confirmed by ATR-FTIR and XRPD). Due to the amorphization of the active substance, a significant increase in the release of baicalin in vitro was observed. It was demonstrated that there was an initial burst release and a continuous release profile (n = 3). Higuchi kinetic was the most likely baicalin release kinetic. The second fit, the Korsmeyer-Peppas kinetics model, showed coupled diffusion of the active ingredient in the hydrated matrix and polymer relaxation regulated release, with n values ranging from 0.45 to 0.89. The anti-inflammatory properties of 3D-printed scaffolds were assessed as the ability to inhibit the activity of the hyaluronidase enzyme. Activity was assessed as IC50 = 63.57 ± 4.98 mg hydrogel/mL (n = 6). Cytotoxicity tests demonstrated the biocompatibility of the material. After 24 h of exposure to the 2.5CS/2Gel/10Ex scaffold, fibroblasts migrated toward the scratch, closed the "wound" by 97.1%, and significantly accelerated the wound healing process. The results render the 3D-printed CS/Gel/extract scaffolds as potential candidates for treating periodontal diseases.

Reinforced hydrogel building via formation of alginate-chitosan double network with pH & salt-responsiveness and electric conductivity for soft actuators

Aiming at green and friendly environmental protection, polyvinyl alcohol/sodium alginate/chitosan (PSCS) double network hydrogel was successfully prepared through diffusing the high molecular weight chitosan into PVA/sodium alginate (PS) hydrogel without any other toxic reagents. The polyanion hydrogels could be significantly enhanced by immersing the polyanion hydrogel in high molecular weight chitosan solution without requiring specific structure. The PSCS hydrogel had a compact and rough surface structure with the smaller porosities and larger crystallization degree compared with polyvinyl alcohol/sodium alginate hydrogels and polyvinyl alcohol/sodium alginate/Ca2+ (PSCa) hydrogels. The PSCS hydrogel possessed excellent hydrolysis resistance, the significant pH-sensitive and salt-sensitive swelling. In addition, the flexibility, Young's modulus and mechanical properties of PSCS hydrogel can be adjusted through the changing the content of sodium alginate. Moreover, PS, PSCa and PSCS had electric conductivity, and PSCS showed twice the conductivity compared to PS hydrogel. Based on differences of swelling ratio, a PSCS bilayer hydrogel was designed and showed excellent pH-driven deformation ability. The PSCS hydrogel is expected to expand the application of hydrogels in conditions involving stimulus response, and might serve as a promising intelligent actuators or soft robots.

Synthesis and comprehensive characterization with anticancer activity assessment of salicylaldehyde and 2-acetylphenol based chitosan thiosemicarbazones and their copper(II) complexes

Functionalization of chitosan as salicylaldehyde and 2-acetylphenol-based chitosan thiosemicarbazone involving amino group at C2 position of pyranose ring was confirmed by comprehensive characterization by spectroscopic and analytical ways. Both the low molecular weight (Mw) chitosan oligosaccharide (CS) (Mw < 3000 Da, degree of deacetylation (DDA) = 87 %) and the crab shell chitosan (CCS) (Mw = 350 kDa, DDA = 67 %) functionalized thiosemicarbazones behaved as ONS tridentate ligand to form the square planar copper(II) complexes with a chloride ion as an additional ligand to satisfy the co-ordination sphere. All the derivatives were found thermally stable till the commencement of chitosan backbone disruption at 200 °C. The MTT assay profiles showed a conspicuous enhancement in the in vitro antitumorigenic and anticancer activity of native chitosan upon its functionalization as phenolic carbaldehyde chitosan thiosemicarbazones. Further, the assays more often revealed a further lowering of cell viability with chitosan oligosaccharide derivatives in comparison to high molecular weight chitosan derivatives, and a lower viability of the MCF-7 cancer cells than the tumorigenic MDCK cells. Both the low Mw chitosan with high DDA and high Mw chitosan with low DDA, the chitosan-functionalized salicylaldehyde based thiosemicarbazones, and their copper(II) chitosan thiosemicarbazone complexes were found to have minimal toxicity with IC50 >600 μgmL−1 against the mouse embryonic normal fibroblast NIH3T3 cells. These results were indicatives of more protonation and enhanced anticancer activity of chitosan oligosaccharide derivatives, and preferential cytotoxicity of chitosan biomaterials against the tumorigenic and cancer cells with more negatively charged cell surfaces.

Improvement of Osteogenic Differentiation of Mouse Pre-Osteoblastic MC3T3-E1 Cells on Core-Shell Polylactic Acid/Chitosan Electrospun Scaffolds for Bone Defect Repair.

Electrospun hybrid scaffolds composed of synthetic and natural polymers have gained increasing interest in tissue engineering applications over the last decade. In this work, scaffolds composed of polylactic acid electrospun fibers, either treated (P-PLA) or non-treated (PLA) with air-plasma, were coated with high molecular weight chitosan to create a core-shell microfibrous structure. The effective thickness control of the chitosan layer was confirmed by gravimetric, spectroscopic (FTIR-ATR) and morphological (SEM) investigations. The chitosan coating increased the fiber diameter of the microfibrous scaffolds while the tensile mechanical tests, conducted in dry and wet environments, showed a reinforcing action of the coating layer on the scaffolds, in particular when deposited on P-PLA samples. The stability of the Chi coating on both PLA and P-PLA substrates was confirmed by gravimetric analysis, while their mineralization capacity was evaluated though scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) after immersing the scaffolds in simulated body fluids (SBF) at 37 °C for 1 week. Sample biocompatibility was investigated through cell viability assay and SEM analysis on mouse pre-osteoblastic MC3T3-E1 cells grown on scaffolds at different times (1, 7, 14 and 21 days). Finally, Alizarin Red assay and qPCR analysis suggested that the combination of plasma treatment and chitosan coating on PLA electrospun scaffolds influences the osteoblastic differentiation of MC3T3-E1 cells, thus demonstrating the great potential of P-PLA/chitosan hybrid scaffolds for bone tissue engineering applications.

The effects of ketogenic and chitosan-based diets on submandibular salivary gland in rat model: a comparative histological study

ObjectiveThis study was carried out in the submandibular salivary glands (SSGs) of rats to demonstrate the effect of a ketogenic diet (KD) in comparison with dietary chitosan supplementation.MethodEighteen albino rats were randomly divided into three equal groups of six animals each. Rats in Group I were fed a balanced diet and considered controls. Meanwhile, those of Groups II and III were fed a KD, a balanced diet with high molecular weight chitosan, respectively. After 45 days, rats were euthanized, and the SSGs were dissected carefully for staining with hematoxylin and eosin (H&E), alpha-smooth muscle actin (α-SMA) immunohistochemical staining, and Congo red special stain. Quantitative data from α-SMA staining and Congo red staining were statistically analyzed using one-way ANOVA followed by Tukey’s multiple comparisons post hoc test.ResultsRegarding Congo red and α-SMA staining, one-way ANOVA revealed a significant difference between the three groups. For α-SMA staining and Congo red staining, Group II had the highest mean values of 91.41 ± 3.30 and 68.10 ± 5.04, respectively, while Group I had the lowest values of 56.13 ± 3.96 and 16.87 ± 2.19, respectively. Group III had mean values of 60.70 ± 3.55 for α-SMA and 19.50 ± 1.78 for Congo red. Tukey’s multiple comparisons post hoc test revealed significant differences between groups I & II and between groups II & III (P < 0.05). Meanwhile, there was a nonsignificant difference between groups I and III (P > 0.05).ConclusionA KD has a deleterious effect on rats’ SSG whatever the test we used, and dietary chitosan supplementation ameliorates these damaging effects.

Evaluation of fungicidal efficacy of free and nano-encapsulated chitosan against &lt;i&gt;Aspergillus flavus&lt;/i&gt; isolated from rice (&lt;i&gt;Oryza sativa&lt;/i&gt;) seed

Grains are exposed to contamination by mycotoxins, both in the field and during storage. Aflatoxins produced by Aspergillus species are the most harmful and carcinogenic mycotoxins in grains. Synthetic fungicides are widely used for the control of mycotoxigenic fungi in grains. However, rising public awareness about the toxicological effects of fungicides on human health necessitates the development of non-toxic bio-fungicides. In this connection, reports have shown that chitosan synthesized from shell waste has the potential to serve as an alternative fungicide. Therefore, this study investigated the fungicidal efficacy of free and nano-encapsulated chitosan against aflatoxigenic fungus (Aspergillus flavus). High molecular weight chitosan was purchased, and the in-vitro antifungal efficacy of chitosan against A. flavus was tested using the food poisoning method. Nano-encapsulated chitosan was synthesized using the ionic gelation method, the particle size was determined, and invitro inhibition against A. flavus was investigated. The results revealed that nano-encapsulated chitosan with particle sizes of 525.4 nm, 468.3 nm, and 711.7 nm were obtained. In-vitro mycelial A. flavus growth inhibition of 100% was recorded at 1.5% and 2.0% of free chitosan, while at 0.5% and 1.0% of free chitosan, 45% and 75% inhibition were observed, respectively. Nano-encapsulated chitosan with particle size (nm) of 525.4, 468.3, and 711.7 at 0.50% recorded 61%, 84% and 87% inhibition, respectively. However, at 0.25%, the rate of inhibition was 64%, 78% and 67%, respectively. This study showed that free chitosan and nano-encapsulated chitosan are potential antifungal agents for the control of A. flavus.

Ocular Mucoadhesive and Biodegradable Sponge-Like Inserts for the Sustained and Controlled Delivery of Voriconazole; Preparation, D-optimal Factorial Optimization and in-vivo Evaluation

The aim of this study was to formulate and optimize by statistical means mucoadhesive and biodegradable sponge-like inserts loaded with voriconazole (VCZ) which increases the contact time of the drug with the eye and sustain its release from the formula in a controlled manner. This avoids the pulsed effect reported for the drug suspension and results in reducing the number of drug instillations in the eye with the result of enhancing the patient compliance. Also, the sponge like nature of the insert reduces the foreign body sensation caused by other ocular solid dosage forms. They were prepared using casting/freeze-drying technique using five polymers namely high molecular weight chitosan (CH), sodium alginate (AL), sodium carboxy methyl cellulose (CMC), gellan gum (GG) and xanthan gum (XG). The prepared inserts were subjected to evaluations of their visual appearance, weight variation, drug content, surface pH, in-vitro release (percent drug released after 1h (Q1 (%)), mean dissolution time (MDT) and dissolution efficiency (DE)) in addition to kinetic analysis of the release data, water uptake, mucoadhesion and rheology of the forming plain polymer solution at the maximum rate of shear. The independent variables of the D-optimal factorial design were the polymer type and concentration while Q1 (%), MDT, DE, % water uptake after 15 minutes and rheology at the maximum rate of shear were chosen as dependant variables. The performed optimization process using design expert software showed an optimum formula consisting of 2 % GG. It showed slow release behavior compared to the drug suspension. FTIR and DSC studies showed that there is no interaction between VCZ and GG. The optimum formula has good in-vitro mucoadhesive properties and pH in the safe ocular range. Moreover, it showed promising in-vivo results of rapid hydration and gelling in addition to good mucoadhesive behavior when instilled in the eye, high ocular safety and biocompatibility, sustained antifungal activity in comparison to the drug suspension and finally biodegradation. So, it may be taken into consideration as an outstanding carrier for the ocular delivery of VCZ.

Effects of chitosan with different molecular weights on storage quality and fungi inhibition of mini-cucumber

The effect of low (LWC, 30 kD), medium (MWC, 150 kD) and high molecular weight chitosan (HWC, 300 kD) coatings on storage quality and fungi inhibition of mini-cucumber was evaluated. Chitosan coatings significantly reduced the weight loss, and delayed the color change and sensory score of mini-cucumber when compared with the control. Chitosan coatings significantly retarded the decrease of DPPH free radical scavenging rate and total phenol content, and inhibited the total number of bacterial colonies and the viable numbers of yeast and molds in mini-cucumber. Chitosan coatings also significantly reduced the disease incidence and disease severity of mini-cucumber artificial inoculated with Botrytis cinerea. LWC coating showed superior preservation effectiveness and antifungal activity to MWC and HWC coating. Compared with the control, LWC coating prolonged the shelf life by 6 days which was evaluated by sensory score, and reduced the total number of bacterial colonies and viable numbers of yeast and molds in mini-cucumber by 4.20 log10 CFU/g and 2.72 log10 CFU/g, respectively. These results suggested that chitosan molecular weights affected preservation effectiveness and antifungal activity against B. cinerea and LWC could be used to prolong the shelf life of mini-cucumber and maintain its quality after harvest.