Chitosan

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 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...

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.

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

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...

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.

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.

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.

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...