Chitosan

A potentiometric biosensor based on urease was developed for the quantitative determination of urea concentration in aqueous solutions for biomedical applications. The urease was either physisorbed onto an electrodeposited polyaniline film (PANI), or immobilized on a layer-by-layer film (LbL) assembled over the PANI film, that was obtained by the alternate deposition of charged polysaccharides (carboxymethylpullulan (CMP) and chitosan (CHI)). In the latter case, the urease (Urs) enzyme was either physically adsorbed or covalently grafted to the LbL film using carbodiimide coupling reaction. Potentiometric responses of the enzymatic biosensors were measured as a function of the urea concentration in aqueous solutions (from 10 −6 to 10 −1 mol L −1 urea). Very high sensitivity and short response time were observed for the present biosensor. Moreover, a stability study showed a higher stability over time for the potentiometric response of the sensor with the enzyme-grafted LbL film, testifying for the protective nature of the polysaccharide coating and the interest of covalent grafting.

We evaluated the potential of chitosan both to stimulate plant development and to induce protection from Botrytis cinerea in Vitis vinifera L. plantlets. The presence of 1.75% (v/v) chitogel in the culture medium was the optimal concentration for in vitro grapevine plantlet growth, as determined by measurements on enhancement of root and shoot biomass. Photosynthesis and related parameters were also stimulated in chitogel-treated plantlets. Chitogel reduced the development of Botrytis cinerea and induced cytological alterations to the pathogen. When challenged with the fungus, a significant decrease in disease incidence was observed in plants growing on medium supplemented with chitogel. Furthermore, exogenous foliar applications of chitogel to plantlets growing on chitogel-free medium sensitized them so as to be protected against Botrytis cinerea attack. Our results indicate that chitogel can be used in the vineyard as a means to attain protection against Botrytis cinerea and that its application may counteract the wide use of chemical pesticides.

The aim of the present study was to prepare, optimize and characterize ketoprofen proniosomes. The niosomes were prepared using a slurry method followed by in vitro evaluation after embedding the proniosomes-derived niosomes into a carbopol matrix. A central, composite Box-Wilson design was used for the optimization with the total lipid concentration (X 1 ), surfactant loading (X 2 ) and amount of drug (X 3 ) as the independent variables. Prepared proniosomes were characterized for percentage drug entrapment (PDE) and mean volume diameter (MVD). Multiple regression analysis and contour plots were used to relate the dependent and independent variables. Checkpoint batches were also prepared to prove the validity of the evolved mathematical model and contour plots. The optimization model predicted the levels of X 1 , X 2 and X 3 (-1, -0.3 and 0.92, respectively), for a maximized response of PDE with constraints of ≤ 5 μm on MVD. Optimized batch was used to prepare a niosomal gel, which showed significantly higher cumulative amount of drug permeated and steady state transdermal flux compared to plain gel. This work has demonstrated the use of the central composite Box-Wilson design, regression analysis, and contour plots in optimizing ketoprofen proniosomes. Developed niosomal gel formulation has also demonstrated permeation enhancement of ketoprofen compared to plain gel.

The aim of this study was to investigate the antimicrobial effect of an experimental adhesive system containing chitosan (0.2% and 0.5%) against Streptococcus mutans and Lactobacillus casei. Twenty-four extracted human third molars were used, and 4 cavities were prepared in each tooth. The teeth were contaminated with either S mutans (n = 12 teeth, 48 cavities) or L casei (n = 12 teeth, 48 cavities) microorganisms. One cavity in each tooth received 1 of the following treatments: negative control (no treatment [NC]), positive control (Adper Single Bond 2 [SB]), an experimental adhesive containing chitosan 0.2% (CHI2), or an experimental adhesive containing chitosan 0.5% (CHI5). After sealing of the cavities and an incubation period, dentin scrapings were collected from each cavity for microbiological evaluation. Analysis of variance and Tukey tests revealed no statistically significant differences among the SB, CHI2, and CHI5 groups (P > 0.05), but all 3 differed significantly fro...

Meeting consumer concerns and preferences for fresh and safely processed fisheries products free of chemical and synthetic preservatives is a challenge for the aqua-food industry. As such, natural preservatives from plant and animal origin including chitosan, essential oils (EOs), plant extracts and lactic acid bacteria have attracted considerable interest recently. These preservatives have antimicrobial and antioxidant properties that can retard spoilage, uphold product quality and safety as well as extend the storage shelf-life of fish and seafood. Chitosan and EOs have been successfully used in edible coatings, film wrapping and dipping solutions. The present review focuses on the effectiveness of chitosan, EOs and other natural preservatives intended for prolonging the shelf-life of fisheries products, and maintaining their freshness and quality. Moreover, the mechanisms of action of natural additives, harmful impacts of chemical preservatives and status of aquatic food preserva...

Extracting high-quality RNA from hydrogels containing polysaccharide components is challenging, as traditional RNA isolation techniques designed for cells and tissues can have limited yields and purity due to physiochemical interactions between the nucleic acids and the biomaterials. In this study, a comparative analysis of several different RNA isolation methods was performed on human adipose-derived stem cells photoencapsulated within methacrylated glycol chitosan hydrogels. The results demonstrated that RNA isolation methods with cetyl trimethylammonium bromide (CTAB) buffer followed by purification with an RNeasy Ò mini kit resulted in low yields of RNA, except when the samples were preminced directly within the buffer. In addition, genomic DNA contamination during reverse transcriptase-polymerase chain reaction (RT-PCR) analysis was observed in the hydrogels processed with the CTAB-based methods. Isolation methods using TRIzol Ò in combination with one of a Qiaex Ò gel extraction kit, an RNeasy Ò mini kit, or an extended solvent purification method extracted RNA suitable for gene amplification, with no evidence of genomic contamination. The latter two methods yielded the best results in terms of yield and amplification efficiency. Predigestion of the scaffolds with lysozyme was investigated as a possible means of enhancing RNA extraction from the polysaccharide gels, with no improvements observed in terms of the purity, yield, or amplification efficiency. Overall, this work highlights the application of a TRIzol Ò + extended solvent purification method for optimizing RNA extraction that can be applied to obtain reliable and accurate gene expression data in studies investigating cells seeded in chitosan-based scaffolds.

The investigation of adsorption of nitrate onto chitosan beads modified by cross-linking with epichlorohydrin (ECH) and surface conditioning with sodium bisulfate was performed. The results indicated that both cross-linking and conditioning increased adsorption capacity compared to normal chitosan beads. The maximum adsorption capacity was found at a cross-linking ratio of 0.4 and conditioning concentration of 0.1 mM NaHSO 4 . The maximum adsorption capacity was 104.0 mg g −1 for the conditioned cross-linked chitosan beads at pH 5, while it was 90.7 mg g −1 for normal chitosan beads. The Langmuir isotherm model fit the equilibrium data better than the Freundlich model. The mean adsorption energies obtained from the Dubinin-Radushkevich isotherm model for all adsorption systems were in the range of 9.55-9.71 kJ mol −1 , indicating that physical electrostatic force was potentially involved in the adsorption process.

Apple juice and apple cider were inoculated with Escherichia coli K-12 and processed using a highpressure homogenizer to study bacterial inactivation. Seven levels of pressure ranging from 50 to 350 MPa were used in the high-pressure homogenizer. Two types of chitosan (regular and water soluble) with 2 levels of concentration 0.01% and 0.1% were investigated for synergistic effect with high-pressure homogenization for the bacterial inactivation. E. coli K-12 inactivation was evaluated as a function of homogenizing pressure at different concentration of 2 types of chitosan in apple juice and cider. High-pressure homogenization (HPH) induced significant inactivation in the range of 100 to 200 MPa, while thermal inactivation was the primary factor for the bacterial inactivation above 250 MPa. Significant (P < 0.05) 2-way interactions involving pressure and type of substrate or pressure and chitosan concentration were observed during the study. The homogenization pressure and the incremental quantity of chitosan (both types) acted synergistically with the pressure to give higher inactivation. Significantly (P < 0.05) higher inactivation was observed in apple juice than apple cider at same homogenizing pressure. No effect of type of chitosan was observed on the bacterial inactivation.

This work investigates the polyanion initiated gelation process in fabricating chitosan-TPP (tripolyphosphate) nanoparticles in the size range of 100-250 nm intended to be used as carriers for the delivery of gene or protein macromolecules. It demonstrates that ionic gelation of cationic chitosan molecules offers a flexible and easily controllable process for systematically and predictably manipulating particle size and surface charge which are important properties in determining gene transfection efficacy if the nanoparticles are used as non-viral vectors for gene delivery, or as delivery carriers for protein molecules. Variations in chitosan molecular weight, chitosan concentration, chitosan to TPP weight ratio and solution pH value were examined systematically for their effects on nanoparticle size, intensity of surface charge, and tendency of particle aggregation so as to enable speedy fabrication of chitosan nanoparticles with predetermined properties. The chitosan-TPP nanoparticles exhibited a high positive surface charge across a wide pH range, and the isoelectric point (IEP) of the nanoparticles was found to be at pH 9.0. Detailed imaging analysis of the particle morphology revealed that the nanoparticles possess typical shapes of polyhedrons (e.g., pentagon and hexagon), indicating a similar crystallisation mechanism during the particle formation and growth process. This study demonstrates that systematic design and modulation of the surface charge and particle size of chitosan-TPP nanoparticles can be readily achieved with the right control of critical processing parameters, especially the chitosan to TPP weight ratio.

A novel biocompatible chitosan passivated manganese doped zinc sulfide (Mn doped ZnS) nanophosphor has been synthesized through a simple aqueous precipitation reaction. Upon excitation with ultraviolet light, the quantum dots (QDs) emit an orange luminescence peaking at 590 nm, which is visible to the naked eye. These chitosan coated Mn doped ZnS QDs can have potential applications in bio-labeling, particularly in fluorescence-based imaging. One of the envisioned applications of these QDs is in improving the conventional, organic dye-reliant Fluorescence in situ Hybridization (FISH) technique, a widely used method for microbial detection. Here we demonstrate that the chitosan-capped Mn doped ZnS QDs are suitable for this purpose.

In view of the increasing littering of the river banks by shells of crustaceans, a study was carried out to investigate the extraction and characterization of chitin and chitosan from mussel shell. Chitin and chitosan was extracted and characterized from mussel shell found in banks of the Gubi Dam in Bauchi, Nigeria using the conventional methods of pretreatment, demineralization, deprotienization and deacetylation. The results obtained revealed that carbon nitrogen ratio of the chitosan extracted was 5.9 with a degree of deacetylation of 60.69% and 60.66% calculated from the elemental analysis and the FTIR spectra of chitosan respectively. The FTIR spectra for chitosan gave a characteristic-NH 2 band of 3447 cm-1 and a carbonyl group band of 1477 cm-1. The mussel shell was discovered to contain a mineral content of 51.62% and a chitin composition was found to be 21.32%.

A cross-linking reagent is required to improve mechanical strength and degradation properties of biopolymers for tissue engineering. To find the optimal preparative method, we prepared diverse genipin-cross-linked chitosan/collagen scaffolds using different genipin concentrations and various cross-linking temperatures and cross-linking times. The compressive strength increased with the increasing of genipin concentration from 0.1 to 1.0%, but when concentration exceeded 1.0%, the compressive strength decreased. Similarly, the compressive strength increased with the increasing of temperature from 4 to 20°C, but when temperature reached 37°C, the compressive strength decreased. Showing a different trend from the above two factors, the effect of cross-linking time on the compressive strength had a single increasing tendency. The other results also demonstrated that the pore size, degradation rate and swelling ratio changed significantly with different cross-linking conditions. Based on our study, 1.0% genipin concentration, 20°C cross-linking temperature and longer cross-linking time are recommended. Long Bi and Zheng Cao contributed equally to this work.

Cucumber (Cucumis sativus L.), which belongs to the gourd family Cucurbitaceae, is an economically important vegetable crop worldwide. They have a short shelf-life that is mainly related to firmness loss, discoloration, desiccation and fungal rot.The reduction of losses resulting from bacterial and fungal rot is a major objective of postharvest technology for cucumbers, which tries to utilize safe and efficacious methods to control contamination and the growth of spoiling fungi and bacteria.

A few studies have shown an interesting inhibitory effect of essential oils (EOs) and their constituents on food-related spoiling and pathogenic microorganisms. Although most essential oils are classified as Generally Recognized as Safe (GRAS) food flavoring, their use in foods as preservatives is limited due to flavor considerations, since effective antimicrobial doses may exceed organoleptically acceptable levels. Besides, it is difficult to formulate solutions with EOs and their derivatives because they are volatile compound which can easily suffer degradation under the action of heat, pressure, light and oxygen. Furthermore, they are insoluble in water, and for certain applications a controlled release is required.

In this perspective, encapsulation procedures represent a viable and efficient approach to increase the physical stability of antimicrobial compounds and enhance their bioactivity during food processing and storage. Additionally, the encapsulation of bioactive compounds improve water solubility, controls delivery, improves absorption, reduced toxicity and the cost of using them because a less amount of the active is required. While microencapsulation systems may guarantee protection of antimicrobial compounds against evaporation or degradation, nanoencapsulation systems due to high surface area to volume ratio has a versatile advantage for targeted site-specific delivery and efficient absorption through cells that could lead to higher antimicrobial activity. Also, the nanoencapsulation methods are useful to consolidate antimicrobial agents in material used for food packaging.

In  recent  years, chitosan (CS) is receiving a lot of interest in the encapsulation of bioactive compounds owing to its general recognition as safe (GRAS), biocompatibility and excellent biodegradability, as well as ability to form films, membranes, gels, beads, fibers and particles. Among variety of methods developed to load bioactive compounds into CS nanoparticles (CSNPs), ionotropic gelation has attracted considerable attention due to this process is non-toxic, organic solvent free, convenient and controllable. The CS–TPP nanoparticles has shown its capacity for the loading and delivery of sensitive bioactive compounds such as lipophilic drugs, polyphenolic compounds, proteins, genes and vitamins.

This study was performed with the following objectives: i) to encapsulate and optimize two EOs in CS tripolyphosphate (TPP) nanoparticles; ii) to characterize several physicochemical properties of the obtained nanoparticles by ultraviolet and visible (UV–Vis) spectrophotometry, transmission electron microscopy (TEM), and dynamic light scattering (DLS); iii) to evaluate the efficacy of the CSNPs obtained under optimized conditions to inhibit phytopathogenic cucumber bacteria and fungi  in laboratory media and as a coating on the cucumbers; iv) to assess the effect of two EOs@CSNPs coating on some physical, physicochemical and microbial characteristics of the cucumbers during storage; and to extend cucumber shelf-life.

Zataria multiflora (ZEO) essential oil was encapsulated by ionic gelation technique into CSNPs with an average size of 125–180 nm, as observed by transmission electron microscopy (TEM). Meanwhile, the encapsulation efficiency (EE) and loading capacity (LC) of ZEO decreased upon increasing initial ZEO concentration with a decrease in particle size. In addition, we have prepared Cinnamomum zeylanicum (CEO) essential oil-loaded CSNPs (CEO@CSNPs) with size range of 140–200 nm, loading capacity of 3-4%, and encapsulation efficiency of 2-17% ,in the initial CEO content of 0.25–1 g/g chitosan. The optimal weight ratio of CS to ZEO or CEO was found 1:0.25. In vitro release studies also demonstrated a controlled and sustained release of ZEO and CEO.

For coating analyze, cucumbers obtained in commercial maturation stage from organic farming, were transported at low temperature to the laboratory and coating experiments were carried out on the same day. Cucumbers were selected for uniform size, shape and color, and without any signs of mechanical damage or deterioration. Then, fruits washed in sodium hypochlorite solution (1% v/v) and left for 2 h in a safe cabinet to dry. A total of 1000 fruit was used for conducting all experiments.

The superior performance of ZEO or CEO when encapsulated by CSNPs under both in vitro and in vivo conditions in comparison with unmodified ZEO against P. drechsleri was revealed. The in vivo experiment showed that the encapsulated oils significantly decreased both disease severity and incidence of infected cucumbers by P. drechsleri, after 1 or 2 days shelf-life at 20°C following removal from storage at 4°C. The in vivo experiment also showed that the ZEO@CSNPs or CEO@CSNPs coating extended the shelf life of cucumber up to 21 days at 8±1°C while uncoated fruits could not reach this far (<15days). Furthermore, it was capable of improving the microbiological and physicochemical quality and preserving the quality of the fruit during the storage period. Coated fruits were firmer, maintained color, water content, and showed lower microbial counts (P <0.05) throughout storage. According  to  these  results,  ZEO@CSNPs or CEO@CSNPs coatings can  be  an  alternative  method  with  which  to  extend  cucumber shelf-life.

Results indicated that the potential application of nanoencapsulated EOs at sub-inhibitory concentrations as an alternative to the sensory impact, particularly flavor and odor, resulting from the application of EOs alone at higher concentrations on fruits.

Chitosan has been shown to promote initial wound closure events to prevent blood loss. Platelet adhesion and activation are crucial early events in these processes after traumatic bleeding leading to thrombus formation. Platelet adhesion to chitosan was found to be enhanced in the presence of adsorbed plasma and extracellular matrix proteins and was found to be primarily mediated by a IIb b 3 integrins, while a 2 b 1 integrins were found to be involved in platelet adhesion to collagen and perlecan. Platelets were found to be activated by chitosan, as shown by an increase in the expression of a IIb b 3 integrins and P-selectin, while the extent of activation was modulated by the presence of proteins including perlecan and fibrinogen. Collagen-coated chitosan was found to activate platelets to the same extent as either chitosan or collagen alone. These data support the role of plasma and extracellular matrix proteins in promoting chitosan mediated platelet adhesion and activation supporting the hypothesis that chitosan promotes wound healing via these interactions.

The aim of this work was to study the effect of the degree of substitution (DS) and the purity of sodium carboxymethyl cellulose (CMCNa) prepared from Tunisian vine stem on the absorption and retention of water. Vine stem was first delignified using souda-anthraquione, then bleached and finally chemically modified, in order to synthesize different CMCNa derivatives. The carboxymethylation reaction was carried out in presence of NaOH (40 %) and monochloroacetic acid (ClCH 2 COOH), in n-butanol as a reaction solvent. The obtained CMCNa derivatives were characterized using different tools such as the DS, Fourier transforms IR techniques, CP-MAS 13 C-NMR, the exchange capacity as well as the determination of modification reaction yield. The performance of the prepared derivatives in term of absorption capacities and retention capacities was established. The performance of CMCNa derivatives was compared with that achieved by commercial counterparts and it was concluded that the prepared ones exerted higher efficiency.

The purpose of this research was to formulate and systematically evaluate in vitro and in vivo performances of mucoadhesive amoxicillin microspheres for the potential use of treating gastric and duodenal ulcers, which were associated with Helicobacter pylori. Amoxicillin mucoadhesive microspheres containing chitosan as mucoadhesive polymer were prepared by simple emulsification phase separation technique using glutaraldehyde as a cross-linking agent. Results of preliminary trials indicate that volume of cross-linking agent, time for cross-linking, polymer-to-drug ratio, and speed of rotation affected characteristics of microspheres. Microspheres were discrete, spherical, free flowing and also showed high percentage drug entrapment efficiency. In vitro mucoadhesive test showed that amoxicillin mucoadhesive microspheres adhered more strongly to gastric mucous layer and could retain in gastrointestinal tract for an extended period of time. A 3 2 full factorial design was employed to study the effect of independent variables, polymer-to-drug ratio (X 1 ), and stirring speed (X 2 ) on dependent variables i.e. percentage mucoadhesion, t 80 , drug entrapment efficiency, particle size and swelling index. The best batch exhibited a high drug entrapment efficiency of 70 % and a swelling index of 1.39; percentage mucoadhesion after 1 h was 79 %. The drug release was also sustained for more than 12 h. The polymer-to-drug ratio had a more significant effect on the dependent variables. The morphological characteristics of the mucoadhesive microspheres were studied using scanning electron microscopy. In vitro release test showed that amoxicillin released slightly faster in pH 1.0 hydrochloric acid than in pH 7.8 phosphate buffer. In vivo H. pylori clearance tests were also carried out by administering amoxicillin mucoadhesive microspheres and powder, to H. pylori infectious Wistar rats under fed conditions at single dose or multiple dose(s) in oral administration. The results showed that amoxicillin mucoadhesive microspheres had a better clearance effect than amoxicillin powder. In conclusion, the prolonged gastrointestinal residence time and enhanced amoxicillin stability resulting from the mucoadhesive microspheres of amoxicillin might make contribution complete eradication of H. pylori.

IntroductionObtaining hemostasis in the surgical crypt during periradicular surgery is essential. It allows for improved visibility and contributes to a dry environment suitable for the placement of moisture-sensitive root-end filling material. Although current materials may not be moisture sensitive during setting, hemostasis is important for proper placement of root-end filling materials during apical surgery. A new hemostatic agent, HemCon dental

La peau et la cornée sont deux tissus de revêtement constitués d'un épithélium fermement ancré à un tissu conjonctif, le derme pour la peau et le stroma pour la cornée. Les cellules souches de la peau ont pu être amplifiées grâce à la technique de Rheinwald et Green en 1975 et utilisées dès 1981 sous forme de feuillets épidermiques pour le traitement des grands brûlés. Plus tard, cette technique de culture a été reprise pour amplifier les cellules épithéliales limbiques. La couche basale de l'épithélium limbique se situe dans la zone transitionnelle entre la cornée et la conjonctive et contient les cellules souches de l'épithélium cornéen [J Cell Biol 1 (1986) 49-52 et Cell 57 (1989) 201-209] appelées cellules souches limbiques (CSL). Elles assurent le renouvellement de l'épithélium cornéen en générant des cellules d'amplifications transitoires qui migrent de façon centripète à partir de la couche basale limbique vers la couche basale de la cornée. Le génie tissulaire permet de reconstruire des tissus en trois dimensions (3D), associant l'épithélium à son tissu conjonctif sous-jacent. Pour reconstruire le tissu conjonctif, notre modèle associe des cellules et un polymère biodégradable et naturel à base de collagène. Ce substrat poreux sert d'échafaudage à la culture de fibroblastes pour donner un derme/ stroma équivalent vivant, qui secondairement épithélialisé aboutit à une peau/hémicornée reconstruite. Nous présentons ici : la reconstruction des épithélia dans les pathologies de surface de la peau et de la cornée et le développement de nos modèles tridimensionnels de peau et de cornées à base de collagène-GAG-chitosane et leurs applications.

Bioactive implants intended for rapid, robust, and durable bone tissue regeneration are presented. The implants are based on nanofibrous 3D-scaffolds of bioresorbable polye-caprolactone mimicking the fibrillar architecture of bone matrix. Layer-by-layer nanoimmobilization of the growth factor BMP-2 in association with chitosan (CHI) or poly-L-lysine over the nanofibers is described. The osteogenetic potential of the scaffolds coated with layers of CHI and BMP-2 is demonstrated in vitro, and in vivo in mouse calvaria, through enhanced osteopontin gene expression and calcium phosphate biomineralization. The therapeutic strategy described here contributes to the field of regenerative medicine, as it proposes a route toward efficient repair of bone defects at reduced risk and cost level.

Due to their recognised properties of biocompatibility, biodegradability and sustainability, chitosan nanocarriers have been successfully used as new delivery systems. In this work, nanoparticles combining chitosan and lignosulfonates were developed for the first time for cosmetic and biomedical applications. The ability of lignosulfonates to act as a counter polyion for stabilisation of chitosan particles, generated using high intensity ultrasound, was investigated. Several conditions for particles preparation were tested and optimised and the resulting nanoparticles were comprehensively characterised by measuring particle size, zeta potential and polydispersity index. The pH of chitosan solution, sonication time and the presence of an adequate surfactant, poloxamer 407, were determinant factors on the development of smaller particles with low polydispersity index (an average particle size of 230 nm was obtained at pH 5 after 8 min of sonication). The beneficial effects of lignosulfonates complex on chitosan nanoparticles were further characterised. Greater stability to lysozyme degradation, biocompatibility with human cells and antimicrobial activity was found upon lignosulfonates incorporation into chitosan nanoparticles. Furthermore, these particles were able to incorporate a hydrophilic model protein -RNase A. A burst release was observed when nanoparticles were loaded with low amount of protein while with high protein content, a sustained release was found, suggesting that the protein cargo maybe loaded both at the surface as in the bulk of the particle, depending on the concentration of drug incorporated.

Biodegradable blend films from rice starchechitosan were developed by casting film-solution on leveled trays. The influence of the ratio of starch and chitosan (2:1, 1.5:1, 1:1, and 0.5:1) on the mechanical properties, water barrier properties, and miscibility of biodegradable blend films was investigated. The biodegradable blend film from rice starchechitosan showed an increase in tensile strength (TS), water vapor permeability (WVP), lighter color and yellowness and a decreasing elongation at the break (E ), and film solubility (FS) after incorporation of chitosan. The introduction of chitosan increased the crystalline peak structure of starch film; however, too high chitosan concentration yielded phase separation between starch and chitosan. The amino group band of the chitosan molecule in the FTIR spectrum shifted from 1541.15 cm À1 in the chitosan film to 1621.96 cm À1 in the biodegradable blend films. These results pointed out that there was a molecular miscibility between these two components. The properties of rice starchechitosan biodegradable blend film and selected biopolymer and synthetic polymer films were compared; the results demonstrated that rice starchechitosan biodegradable blend film had mechanical properties similar to the other chitosan films. However, the water vapor permeability of rice starchechitosan biodegradable blend film was characterized by relatively lower water vapor permeability than chitosan films but higher than polyolefin.

Reparative processes are reconstructive phenomena in which cellular elements and extracellular matrix glycoproteins interact to build the injured tissue. Biomaterials can be used to improve or stimulate reconstruction. In the present experimental investigation, tissue repair induced by chitosan. an 86.8% deacetylated poly(GlcNAc), was monitored by morphological analysis. To evaluate its biological role, chitosan was positioned in contact with dura mater or was used as a dura mater substitute. This polysaccharide, having structural characteristics similar to glycosaminoglycans, seems to mimic their functional behaviour. The inductive and stimulatory activity of chitosan on connective tissue-rebuilding is clearly demonstrated, and it is suggested that chitosan could be considered a primer on which a normal tissue architecture is organized.

Wound healing is a complex process involving an integrated response by many different cell types and growth factors in order to achieve rapid restoration of skin architecture and function. The present study evaluated the applicability of a chitosan hydrogel (CH) as a wound dressing. Scanning electron microscopy analysis was used to characterize CH morphology. Fibroblast cells isolated from rat skin were used to assess the cytotoxicity of the hydrogel. CH was able to promote cell adhesion and proliferation. Cell viability studies showed that the hydrogel and its degradation by-products are noncytotoxic. The evaluation of the applicability of CH in the treatment of dermal burns in Wistar rats was performed by induction of full-thickness transcutaneous dermal wounds. Wound healing was monitored through macroscopic and histological analysis. From macroscopic analysis, the wound beds of the animals treated with CH were considerably smaller than those of the controls. Histological analysis revealed lack of a reactive or a granulomatous inflammatory reaction in skin lesions with CH and the absence of pathological abnormalities in the organs obtained by necropsy, which supported the local and systemic histocompatibility of the biomaterial. The present results suggest that this biomaterial may aid the re-establishment of skin architecture.

In this study, we describe a green and simple procedure for the synthesis of steroidal 2Hpyrans 4-6 using chitosan as an eco-friendly heterogeneous catalyst. The synthesized compounds were characterized by IR, 1 H NMR, 13 C NMR, MS and analytical data. These compounds were tested in vitro against two cancer cell lines [HeLa (cervical) and Jurkat (leukemia)] and one normal cell line (PBMC). The compounds exhibited moderate to good activity against the two human cancer cell lines and were less toxic against the non-cancer cell line. In addition, the synthesized compounds were tested for their in vitro antioxidant activity by 1,1-diphenylpicrylhydrazyl method in which compounds 4 and 6 exhibited good antioxidant activity. This study provided a new molecular scaffold for the further development of anticancer as well as antioxidant agents.

Oral mucositis is a frequent and potentially severe complication of radiation or chemotherapy for cancer. Associated with atrophy and ulceration of the oral mucosa is an increased risk of infection, and the most common pathogenic agent is Candida. Chitosan is an excellent candidate for the treatment of oral mucositis. Its bioadhesive and antimicrobial properties offer the palliative effects of an occlusive dressing and the potential for delivering drugs, including anti-candidal agents.

abstrak Biopolimer kitosan memiliki kemampuan adsorpsi terhadap zat warna dikarenakan adanya gugus fungsi amino dan hidroksil. Penelitian ini bertujuan untuk mensintesis kitosan dan beads kitosan kulit udang jerbung, dan diuji kemampuan adsorpsinya terhadap zat warna rhodamin B. Karakterisasi kitosan dan kitosan beads hasil sintesis dilakukan menggunakan Fourier Transform Infra-Red Spectrophotometer (FTIR) dan ditentukan kadar air, kadar abu, serta swelling effect. Uji kemampuan adsorpsi kitosan dan kitosan beads terhadap rhodamin B menggunakan parameter: panjang gelombang maksimum, pengaruh pH dan variasi waktu kontak. Hasil penelitian menunjukkan bahwa hasil sintesis merupakan kitosan dan beads kitosan dengan kadar air sebesar 4,45% dan 6,84%, kadar abu sebesar 0,1% dan 2,83%, dan swelling effect 143,43% dan 94,05%. Kitosan dan beads kitosan dapat mengadsorpsi rhodamin B secara optimum masing-masing pada pH 4 dan 3 dengan waktu kontak 120 menit dan 180 menit dengan panjang gelomba...

The purpose of this study was to develop thiolated nanoparticles to enhance the bioavailability for the nasal application of leuprolide. Thiolated chitosan-thioglycolic acid (chitosan-TGA) and unmodified chitosan nanoparticles (NPs) were developed via ionic gelation with tripolyphosphate (TPP). Leuprolide was incorporated during the formulation process of NPs. The thiolated (chitosan-TGA) NPs had a mean size of 252 ± 82 nm, a zeta potential of +10.9 ± 4 mV, and payload of leuprolide was 12 ± 2.8. Sustained release of leuprolide from thiolated NPs was demonstrated over 6h, which might be attributed to inter- and/or intramolecular disulfide formation within the NPs network. Ciliary beat frequency (CBF) study demonstrated that thiolated NPs can be considered as suitable additives for nasal drug delivery systems. Compared to leuprolide solution, unmodified NPs and thiolated NPs provoked increased leuprolide transport through porcine nasal mucosa by 2.0 and 5.2 folds, respectively. The r...

Poly(N-vinyl-2-pyrrolidone) (PVP) is widely used in medicine due to its high biocompatibility. In this study, itaconic acid (IA) was co-polymerized with N-vinyl-2-pyrrolidone (NVP) monomer to prepare the pH sensitive hydrogels. These copolymer hydrogels were prepared using ultra-violet (UV) induced methods at ambient temperature. Monomer and cross-linking agent (N,N -methylene-bisacrylamide (MBAAm)) concentration effects on preparation of this copolymer hydrogel were investigated using swelling, FT-IR, and SEM. The prepared copolymer hydrogel is highly pH sensitive. The percentage swell of the copolymer hydrogels was found to increase from 150 to 3011% as the pH value of the swelling solution varied from 4 to 10. These pH sensitive copolymer hydrogels present a promising approach for drug delivery applications.

An injectable blend composed of a water soluble chitosan (WSC) derivative, egg phosphatidylcholine (ePC), and fatty acid chlorides (FACl) was explored for localized delivery of anticancer agents. The composition-property relationships of the injectable WSC-FACl-ePC blend were determined by investigating the physico-chemical and performance properties of the blend as a function of the ratio of the components, as well as the acyl chain length of the FACl (C10-C16) employed. Thermal and rheological measurements revealed that the melting transitions and viscosities of the blends increased as a function of FACl acyl chain length. FTIR analysis demonstrated that the stability of the blends was attributed to the specific interactions among the molecules. In addition, confocal laser scanning microscopy revealed that the incorporation of C10-C16 FACl altered the molecular organization of ePC and WSC within the blends, which resulted in distinct physico-chemical properties. Specifically, the formation of micro-domains within the blends increased the stability, as well as delayed the release of paclitaxel from the formulation under physiologically relevant conditions. Overall, the interactions identified among the components, and the relationships established between the composition and properties of the blend can be used as a tool to develop advanced injectable drug delivery systems for pharmaceutical applications.

In this study, the potential of N-Trimethyl chitosan (TMC, degree of quaternization 50%) and dextran microparticles for pulmonary delivery of diphtheria toxoid (DT) was investigated. The antigen-containing microparticles were prepared by drying of an aqueous solution of polymer and DT through a supercritical fluid (SCF) spraying process. The median volume diameter of the dry particles, as determined by laser diffraction analysis, was between 2 and 3 m and the fine particle mass fractions smaller than 5 m, as determined by cascade impactor analysis, were 35 and 56% for the dextran and TMC formulations, respectively. The water content of the particles as measured by Karl-Fischer titration was 2-3% (w/w). Pulmonary immunization with DT-TMC microparticles containing 2 or 10 Lf of DT resulted in a strong immunological response as reflected by the induction of IgM, IgG, IgG subclasses (IgG1 and IgG2) antibodies as well as neutralizing antibody titers comparable to or significantly higher than those achieved after subcutaneous (SC) administration of alum-adsorbed DT (2 Lf). Moreover, the IgG2/IgG1 ratio after pulmonary immunization with DT-TMC microparticles was substantially higher as compared to SC administered alum-adsorbed DT. In contrast, pulmonarily administered DT-dextran particles were poorly immunogenic. Among the tested formulations only pulmonarily administered DT-containing TMC microparticles induced detectable pulmonary secretory IgA levels. In conclusion, in this paper it is demonstrated that TMC microparticles are a potent new delivery system for pulmonary administered DT antigen.

A physico-chemical investigation of the adsorption of nitrate by chitosan hydrobeads was conducted. The adsorption of nitrate by chitosan hydrobeads was increased with a decrease in the pH of the solution. The adsorption process was found to be temperature dependant with an optimum activity at 30 • C. Adsorption capacity was found to decrease with increases in temperature after 30 • C, indicating the exothermic nature of this process. Theoretical correlation of the experimental equilibrium adsorption data for the nitrate-chitosan hydrobeads system was properly explained by the Langmuir isotherm model. This was supported by the fact that homogeneity index was close to unity (0.98-1.08) from Langmuir-Freundlich isotherm model. The maximum adsorption capacity was 92.1 mg/g at 30 • C. The kinetic results corresponded well with the pseudo-second-order rate equation. Intra-particle diffusion also played a significant role at the initial stage of the adsorption process. Thermodynamic parameters such as the Gibbs free energy ( G 0 ), enthalpy ( H 0 ), and entropy ( S 0 ) for the nitrate adsorption were estimated. Results suggest that the adsorption process is a spontaneous, exothermic process that has positive entropy. Desorption of nitrate from the loaded beads was accomplished by increasing the pH of the solution to the alkaline range, and a desorption ratio of 87% was achieved around pH 12.0.

Urea modified TiO 2 nanoparticles were synthesized at different TiO 2 : urea ratios (10, 30 and 60 (%wt) named UTiO 2-10, 30 and 60) by sol-gel method and annealing at 400 °C during 1 h. Characterization revealed the presence of TiO 2 nanoparticles with visible light absorption (between 400 and 500 nm) probably due by the formation of thermolysis urea byproducts such as melon, which may induce a TiO 2 /melon heterojunction. Then, modified nanoparticles were immobilized on chitosan films by adding 30% (70QS/30UTiO 2) and 50% 50QS/ 50UTiO 2) of UTiO 2 nanoparticles. Functionalized films were characterized by SEM-EDS, DRS and AFM. Photo-induced degradation of malachite green stains was evaluated on these films under different wavelengths. Upon UV-A + visible light irradiation, films showed good activity even slightly better than those containing Evonik P-25 (70QS/30P-25). Upon visible light between 450 and 800 nm, films evidenced a satisfactory performance but slower than under UV-A + visible light irradiation whereas the photobleaching activity of 70QS/30P-25 was very poor. When visible light irradiation with wavelengths higher than 590 nm was used, a slight photobleaching was also observed. DRS spectra taken at different irradiation times showed that dye underwent N-demethylated oxidative reactions either upon UV–vis or visible light irradiation. ATR-FTIR measurements revealed the generation of benzophenones after 6 h of irradiation probably suggesting the formation of singlet oxygen under visible light. 70QS/30UTiO 2-10 films showed a good photo-bleaching activity after 18 h of continuous UV-A + visible light irradiation.

HemCon s bandage is an engineered chitosan acetate preparation used as a hemostatic control dressing, and its chemical structure suggests that it should also be antimicrobial. We tested its ability to rapidly kill bacteria in vitro and in mouse models of infected wounds. We used the Gram-negative species Pseudomonas aeruginosa and Proteus mirabilis and the Gram-positive Staphylococcus aureus that had all been stably transduced with the entire bacterial lux operon to allow in vivo bioluminescence imaging. An excisional wound in Balb/c mice was inoculated with 50-250 million cells followed after 30 min by application of HemCon bandage, alginate sponge bandage, silver sulfadiazine cream or no treatment. HemCon was more adhesive to the wound and conformed well to the injury compared to alginate. Animal survival was followed over 15 days with observations of bioluminescence emission and animal activity daily. Chitosan acetate treated mice infected with P. aeruginosa and P. mirabilis all survived while those receiving no treatment, alginate and silver sulfadiazine demonstrated 25-100% mortality. Chitosan acetate was much more effective than other treatments in rapidly reducing bioluminescence in the wound consistent with its rapid bactericidal activity in vitro as well as its light-scattering properties. S. aureus formed only nonlethal localized infections after temporary immunosuppression of the mice but HemCon was again more effective in reducing bioluminescence. The data suggest that chitosan acetate rapidly kills bacteria in the wound before systemic invasion can take place, and is superior to alginate bandage and silver sulfadiazine that may both encourage bacterial growth in the short term. r

The major aim of this study was to model the effect of two causal factors, i.e. coating weight gain and amount of pectin-chitosan in the coating solution on the in vitro release profile of theophylline for bimodal drug delivery. Artificial neural network (ANN) as a multilayer perceptron feedforward network was incorporated for developing a predictive model of the formulations. Five different training algorithms belonging to three classes: gradient descent, quasi-Newton (Levenberg-Marquardt, LM) and genetic algorithm (GA) were used to train ANN containing a single hidden layer of four nodes. The next objective of the current study was to compare the performance of aforementioned algorithms with regard to predicting ability. The ANNs were trained with those algorithms using the available experimental data as the training set. The divergence of the RMSE between the output and target values of test set was monitored and used as a criterion to stop training. Two versions of gradient descent backpropagation algorithms, i.e. incremental backpropagation (IBP) and batch backpropagation (BBP) outperformed the others. No significant differences were found between the predictive abilities of IBP and BBP, although, the convergence speed of BBP is three-to four-fold higher than IBP. Although, both gradient descent backpropagation and LM methodologies gave comparable results for the data modeling, training of ANNs with genetic algorithm was erratic. The precision of predictive ability was measured for each training algorithm and their performances were in the order of: IBP, BBP > LM > QP (quick propagation) > GA. According to BBP-ANN implementation, an increase in coating levels and a decrease in the amount of pectin-chitosan generally retarded the drug release. Moreover, the latter causal factor namely the amount of pectin-chitosan played slightly more dominant role in determination of the dissolution profiles.

In the present work crosslinked hydrogels based on chitosan (CS) and acrylic acid (AA) were prepared by free radical polymerization with various feed compositions using N,N methylenebisacrylamide (MBA) as crosslinking agent. Benzoyl peroxide was used as catalyst. Fourier transform infrared spectra (FTIR) confirmed the formation of the crosslinked hydrogels. This hydrogel is formed due to electrostatic interaction between cationic groups in CS and anionic groups in AA. Prepared hydrogels were used for dynamic and equilibrium swelling studies. For swelling behavior, effect of pH, polymeric and monomeric compositions and degree of crosslinking were investigated. Swelling studies were performed in USP phosphate buffer solutions of varying pH 1.2, 5.5, 6.5 and 7.5. Results showed that swelling increased by increasing AA contents in structure of hydrogels in solutions of higher pH values. This is due to the presence of more carboxylic groups available for ionization. On the other hand by increasing the chitosan content swelling increased in a solution of acidic pH, but this swelling was not significant and it is due to ionization of amine groups present in the structure of hydrogel. Swelling decreased with increase in crosslinking ratio owing to tighter hydrogel structure. Porosity and sol-gel fraction were also measured. With increase in CS and AA contents porosity and gel fraction increased, whereas by increasing MBA content porosity decreased and gel fraction increased. Furthermore, diffusion coefficient (D) and the network parameters i.e., the average molecular weight between crosslinks (M c ), polymer volume fraction in swollen state (V 2s ), number of repeating units between crosslinks (M r ) and crosslinking density (q) were calculated using Flory-Rehner theory. Selected samples were loaded with a model drug verapamil. Release of verapamil depends on the ratios of CS/AA, degree of crosslinking and pH of the medium. The release mechanisms were studied by fitting experimental data to model equations and calculating the corresponding parameters. The result showed that the kinetics of drug release from the hydrogels in both pH 1.2 and 7.5 buffer solutions was mainly non-Fickian diffusion.

Temperature-sensitive hydrogels composed of poly(N-isopropylacrylamide) (PNIPAAm) with chitosan (CPN) and chitosan+hyaluronic acid (CPNHA) were grafted in order to examine their physicochemical characteristics, in vitro drug release, and in vivo pharmacodynamics. The sol-gel transition behavior was investigated by UV/visible spectrophotometry, differential scanning calorimetry, and viscometry. A slight difference in the transition temperatures was observed among these polymer systems, with CPN and CPNHA exhibiting higher temperatures compared with PNIPAAm. A zeta potential determination revealed a positive charge for the CPN hydrogel, whereas no or only a negligible charge was observed for PNIPAAm and CPNHA. The entanglement of CPN hydrogels observed using scanning electronic microscopy showed the densest cross-linkage structure, followed by CPNHA and PNIPAAm. Both hydrophilic and lipophilic drugs, including nalbuphine, indomethacin, and the nalbuphine prodrug, were used as model drugs in an in vitro drug release experiment. All 3 hydrogels significantly prolonged drug release. The release rate of hydrophilic nalbuphine increased in the order CPN&amp;amp;amp;amp;amp;amp;amp;lt;CPNHA&amp;amp;amp;amp;amp;amp;amp;lt;PNIPAAm. The drug release of these hydrogels exhibited a trend opposite to that of lipophilic drugs. A cold ethanol tail-flick study was utilized in order to examine the antinociceptive activity of intravenous nalbuphine. CPN and CPNHA prolonged the analgesic duration of nalbuphine with no influence on the onset time. The loading of nalbuphine in the CPNHA hydrogel exhibited the longest analgesic duration (4h) among the 3 hydrogels tested.

A potentiometric biosensor based on urease was developed for the quantitative determination of urea concentration in aqueous solutions for biomedical applications. The urease was either physisorbed onto an electrodeposited polyaniline film (PANI), or immobilized on a layer-by-layer film (LbL) assembled over the PANI film, that was obtained by the alternate deposition of charged polysaccharides (carboxymethylpullulan (CMP) and chitosan (CHI)). In the latter case, the urease (Urs) enzyme was either physically adsorbed or covalently grafted to the LbL film using carbodiimide coupling reaction. Potentiometric responses of the enzymatic biosensors were measured as a function of the urea concentration in aqueous solutions (from 10 −6 to 10 −1 mol L −1 urea). Very high sensitivity and short response time were observed for the present biosensor. Moreover, a stability study showed a higher stability over time for the potentiometric response of the sensor with the enzyme-grafted LbL film, testifying for the protective nature of the polysaccharide coating and the interest of covalent grafting.

Chitosan is functionalized with poly(ethylene glycol) methyl ether (mPEG) at the amino and hydroxyl groups via a single step reaction in a homogeneous aqueous system. A chitosan aqueous solution obtained from the mixture of chitosan and hydroxybenzotriazole (HOBt) in water is a key factor in providing mild conditions to conjugate mPEG by using a carbodiimide conjugating agent. The reaction at ambient temperature for 24 h gives chitosan-g-mPEG with water solubility with mPEG content as high as 42%. This work demonstrates that a water-soluble chitosan-HOBt complex is an effective system for the preparation of chitosan derivatives via the aqueous system without the use of acids or organic solvents. #

This research work deals with the preparation of a series of hydrogels using renewable resources, in order to decrease the adverse impact on the environment, and understand their swelling behavior. Hydrogels were synthesized using guar gum and chitosan with glutaraldehyde as the cross-linking agent, protonated with 98% conc. sulphuric acid. Concentration of chitosan was varied as 0, 12.5, 25, 37.5 and 50% (w/w) in guar gum, while that of glutaraldehyde was varied as 0, 1.5, 3 and 6% (w/w) of the total quantity of guar gum and chitosan. Prepared hydrogels were characterized for moisture content, equilibrium water absorbency, re-swelling capacity, swelling ability in acidic (pH = 3) and basic (pH = 11) pH distilled water, equilibrium saline water absorbency and Fourier transform infrared spectroscopy. It was determined that moisture content, equilibrium water absorbency and equilibrium saline water absorbency decreased with increased concentration of chitosan and glutaraldehyde, but they still had water swelling to be classified as hydrogel. Re-swelling capacity of the hydrogels decreased with increased cycles of reswelling. Prepared hydrogels maintained high water swelling in acidic pH distilled water as compared to basic pH distilled water. This hydrogels can be utilized as eco-friendly water manageable materials.

Optimization of mechanical properties is required in applications of tissue-engineered scaffolds. In this study, a polyelectrolyte complexation approach is proposed to improve the mechanical properties of the nanofibrous scaffolds. Through an electrospun chitosan/gelatin (CG) model system, it is demonstrated that the storage modulus of CG nanofiber-based complex membranes is over 10 3 -fold higher than that of neat chitosan or gelatin membranes. Further, an annealing process was found to promote the conjugation of the oppositely charged polymers and thus the tensile modulus of CG membranes is 1.9-fold elevated. When the molar ratio of aminoglucoside units in chitosan to carboxyl units in gelatin is 1:1, the complex nanofiber-based membranes (CG2) display the highest mechanical strength. In addition, the complex membranes reveal an excellent swelling capacity. By comparing the CG membranes electrospun with cast, it is deduced that the complexation is one of the main contributing factors to the improvement in mechanical properties. FTIR and DSC analyses confirm that more molecular interactions took place in the complexation. SEM observation clearly displays the electrospinnability of the complex. Therefore, polyelectrolyte complexation is an effective strategy for enhancing mechanical properties of nanofibrous scaffolds. These mechanically enhanced chitosan/gelatin nanofibrous membranes have wider applications than wound dressing.

FXai, a direct inhibitor of the clotting factor Xa, provides high water solubility but poor membrane permeability due to multiple sites of ionization and a molecular weight exceeding 500 Da, making it a Class III drug according to the Biopharmaceutics Classification System. To overcome the ionization problem and increase the transcellular permeability, various ester and hydroxyamidine prodrugs exhibiting a reduced number of ionization sites were studied in the Caco-2 monolayer model for intestinal permeation. Alternatively, the potential transcellular permeation enhancement of Imwitor Ò 742 and the potential paracellular enhancement of three chitosan formulations were investigated in the same model. FXai has an apparent permeability (P app ) of about 1 nm/s, which is generally regarded as very low. The butylester-hydroxyamidine double-prodrug was found to provide a markedly increased permeability (40.4 nm/s) as did the co-application of chitosan (43.3 nm/s). Other prodrugs slightly increased permeability (1.3-9.2 nm/s) but were inferior to the previous attempts to enhance permeability while the Imwitor Ò admixture showed no effect (1.1 nm/s). Moreover, a bioactivating metabolism towards the hydroxyamidine mono-prodrug was detected in the Caco-2 cell permeation model. Although esterases were overexpressed and mainly located apically, an acceptable permeation was reached. In addition, the prodrugs triggered an efflux system that is not inhibited by verapamil but by quinidine, suggesting the involvement of an organic cation transporter.

The capability of mushroom tyrosinase to catalyze the oxidation of tyrosine residues of Bombyx mori silk fibroin was studied under heterogeneous reaction conditions, by using a series of silk substrates differing in surface and bulk morphology and structure, i.e. hydrated and insoluble gels, mechanically generated powder and fibre. Tyrosinase was able to oxidize 10-11% of the tyrosine residues of silk gels. The yield of the reaction was very low for the powder and undetectable for fibres. FT-Raman spectroscopy gave evidence of the oxidation reaction. New bands attributable to vibrations of oxidized tyrosine species (o-quinone) appeared, and the value of the I853/I829 intensity ratio of the tyrosine doublet changed following oxidation of tyrosine. The thermal behaviour of SF substrates was not affected by enzymatic oxidation. o-Quinones formed by tyrosinase onto gels and powder were able to undergo non-enzymatic coupling with chitosan. FT-IR and FT-Raman spectroscopy provided clear e...