scholarly journals THE FORMATION OF HYDROGELS BASED ON CHITOSAN AND ITS WATER-SOLUBLE DERIVATIVES

2020 ◽  
Vol XXV ◽  
pp. 5-15
Keyword(s):  
Noncovalent Interactions ◽  
Water Soluble ◽  
Production Costs ◽  
Medical Applications ◽  
Covalent Bonds ◽  
Chitosan Derivatives ◽  
Ph Values ◽  
Extended Range ◽  
Low Toxicity ◽  
Physically Crosslinked

This review considers articles on the formation of hydrogels based on chitosan as well as succinylated and quaternized chitosan derivatives. They are synthesized using low toxicity reagents, under ordinary conditions (low production costs). Chitosan derivatives are soluble in an extended range of pH values and characterized by mucoadhesiveness, bioavailability and biodegradability, which extends the potential of their medical applications. One of the most important properties of chitosan and its derivatives is the ability to form hydrogels. Depending on the nature of the bonds that occur during formation, hydrogels are divided into chemically or physically crosslinked, or a mixture of the two. Chemically crosslinked gels have covalent bonds, while physically crosslinked gels are formed by noncovalent interactions, for example, ionic. Mixed hydrogels have both types of crosslinking.

scholarly journals Antioxidant Network Based on Sulfonated Polyhydroxyalkanoate and Tannic Acid Derivative

2021 ◽  
Vol 8 (1) ◽  
pp. 9
Author(s):  
Laura Brelle ◽  
Estelle Renard ◽  
Valerie Langlois
Keyword(s):  
Gallic Acid ◽  
Tannic Acid ◽  
Water Soluble ◽  
Gel Formation ◽  
Ene Reaction ◽  
Inorganic Cations ◽  
Medium Chain Length ◽  
Physically Crosslinked ◽  
The Stability ◽  
Derivatives Of

A novel generation of gels based on medium chain length poly(3-hydroxyalkanoate)s, mcl-PHAs, were developed by using ionic interactions. First, water soluble mcl-PHAs containing sulfonate groups were obtained by thiol-ene reaction in the presence of sodium-3-mercapto-1-ethanesulfonate. Anionic PHAs were physically crosslinked by divalent inorganic cations Ca2+, Ba2+, Mg2+ or by ammonium derivatives of gallic acid GA-N(CH3)3+ or tannic acid TA-N(CH3)3+. The ammonium derivatives were designed through the chemical modification of gallic acid GA or tannic acid TA with glycidyl trimethyl ammonium chloride (GTMA). The results clearly demonstrated that the formation of the networks depends on the nature of the cations. A low viscoelastic network having an elastic around 40 Pa is formed in the presence of Ca2+. Although the gel formation is not possible in the presence of GA-N(CH3)3+, the mechanical properties increased in the presence of TA-N(CH3)3+ with an elastic modulus G’ around 4200 Pa. The PHOSO3−/TA-N(CH3)3+ gels having antioxidant activity, due to the presence of tannic acid, remained stable for at least 5 months. Thus, the stability of these novel networks based on PHA encourage their use in the development of active biomaterials.

scholarly journals Genipin as An Emergent Tool in the Design of Biocatalysts: Mechanism of Reaction and Applications

Catalysts ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1035 ◽  
Author(s):  
Veymar G. Tacias-Pascacio ◽  
Esmeralda García-Parra ◽  
Gilber Vela-Gutiérrez ◽  
Jose J. Virgen-Ortiz ◽  
Ángel Berenguer-Murcia ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Controlled Drug Delivery ◽  
Medical Applications ◽  
Fruit Extract ◽  
Biological Scaffolds ◽  
Gardenia Jasminoides ◽  
Mechanism Of Reaction ◽  
Low Toxicity ◽  
Activating Agent ◽  
The Stability

Genipin is a reagent isolated from the Gardenia jasminoides fruit extract, and whose low toxicity and good crosslinking properties have converted it into a reactive whose popularity is increasing by the day. These properties have made it widely used in many medical applications, mainly in the production of chitosan materials (crosslinked by this reactive), biological scaffolds for tissue engineering, and nanoparticles of chitosan and nanogels of proteins for controlled drug delivery, the genipin crosslinking being a key point to strengthen the stability of these materials. This review is focused on the mechanism of reaction of this reagent and its use in the design of biocatalysts, where genipin plays a double role, as a support activating agent and as inter- or intramolecular crosslinker. Its low toxicity makes this compound an ideal alterative to glutaraldehyde in these processes. Moreover, in some cases the features of the biocatalysts prepared using genipin surpassed those of the biocatalysts prepared using other standard crosslinkers, even disregarding toxicity. In this way, genipin is a very promising reagent in the design of biocatalysts.

Water-soluble chitosan derivatives as a BACE1 inhibitor

2005 ◽  
Vol 13 (23) ◽  
pp. 6551-6555 ◽  
Author(s):  
Jae-Young Je ◽  
Se-Kwon Kim
Keyword(s):  
Water Soluble ◽  
Chitosan Derivatives ◽  
Bace1 Inhibitor

scholarly journals Synthesis of the Microbial Polysaccharide Gellan from Dairy and Plant-Based Processing Coproducts

2021 ◽  
Vol 2 (2) ◽  
pp. 234-244
Author(s):  
Thomas P. West
Keyword(s):  
Corn Steep Liquor ◽  
Nitrogen Sources ◽  
Soluble Starch ◽  
Culture Conditions ◽  
Water Soluble ◽  
Production Costs ◽  
Microbial Polysaccharide ◽  
Steep Liquor ◽  
The Cost ◽  
Condensed Distillers Solubles

This review examines the production of the microbial polysaccharide gellan, synthesized by Sphingomonas elodea, on dairy and plant-based processing coproducts. Gellan is a water-soluble gum that structurally exists as a tetrasaccharide comprised of 20% glucuronic acid, 60% glucose and 20% rhamnose, for which various food, non-food and biomedical applications have been reported. A number of carbon and nitrogen sources have been tested to determine whether they can support bacterial gellan production, with several studies attempting to optimize gellan production by varying the culture conditions. The genetics of the biosynthesis of gellan has been explored in a number of investigations and specific genes have been identified that encode the enzymes responsible for the synthesis of this polysaccharide. Genetic mutants exhibiting overproduction of gellan have also been identified and characterized. Several dairy and plant-based processing coproducts have been screened to learn whether they can support the production of gellan in an attempt to lower the cost of synthesizing the microbial polysaccharide. Of the processing coproducts explored, soluble starch as a carbon source supported the highest gellan production by S. elodea grown at 30 °C. The corn processing coproducts corn steep liquor or condensed distillers solubles appear to be effective nitrogen sources for gellan production. It was concluded that further research on producing gellan using a combination of processing coproducts could be an effective solution in lowering its overall production costs.

Graphene: Insights on Biological, Radiochemical and Ecotoxicological Aspects

2021 ◽  
Vol 17 (1) ◽  
pp. 131-148
Author(s):  
Xing Haixia ◽  
Aline Oliveira da Silva de Barros ◽  
Francisco do Vale Chaves e Mello ◽  
Fan Sozzi-Guo ◽  
Cristina Müller ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Graphene Quantum Dots ◽  
Covalent Bonds ◽  
Cell Internalization ◽  
Functional Density Theory ◽  
Ecotoxicological Evaluation ◽  
Plasmatic Membrane ◽  
Low Toxicity ◽  
The Impact

Graphene, including graphene quantum dots, its oxide and unoxidized forms (pure graphene) have several properties, like fluorescence, electrical conductivity, theoretical surface area, low toxicity, and high biocompatibility. In this study, we evaluated genotoxicity (in silico analysis using the functional density theory-FDT), cytotoxicity (human glioblastoma cell line), in vivo pharmacokinetics, in vivo impact on microcirculation and cell internalization assay. It was also radiolabeled with lutetium 177 (177Lu), a beta emitter radioisotope to explore its therapeutic use as nanodrug. Finally, the impact of its disposal in the environment was analyzed using ecotoxicological evaluation. FDT analysis demonstrated that graphene can construct covalent and non-covalent bonds with different nucleobases, and graphene oxide is responsible for generation of reactive oxygen species (ROS), corroborating its genotoxicity. On the other hand, non-cytotoxic effect on glioblastoma cells could be demonstrated. The pharmacokinetics analysis showed high plasmatic concentration and clearance. Topical application of 0.1 and 1 mg/kg of graphene nanoparticles on the hamster skinfold preparation did not show inflammatory effect. The cell internalization assay showed that 1-hour post contact with cells, graphene can cross the plasmatic membrane and accumulate in the cytoplasm. Radio labeling with 177Lu is possible and its use as therapeutic nanosystem is viable. Finally, the ecotoxicity analysis showed that A. silina exposed to graphene showed pronounced uptake and absorption in the nauplii gut and formation of ROS. The data obtained showed that although being formed exclusively of carbon and carbon-oxygen, graphene and graphene oxide respectively generate somewhat contradictory results and more studies should be performed to certify the safety use of this nanoplatform.

A STUDY OF A WATER-SOLUBLE COMPLEX OF PRODIGIOSIN PRODUCED BY A STRAIN OF SERRATIA MARCESCENS

1962 ◽  
Vol 40 (1) ◽  
pp. 1019-1024 ◽  
Author(s):  
Seiichi Yoshida
Keyword(s):  
Molecular Weight ◽  
Light Scattering ◽  
Serratia Marcescens ◽  
Average Molecular Weight ◽  
Electrophoretic Analysis ◽  
Water Soluble ◽  
Soluble Complex ◽  
Ph Values ◽  
Scattering Measurements ◽  
Water Soluble Complex

A water-soluble pigment excreted from Serratia marcescens has been purified by precipitation with ammonium sulphate, dialysis, and ultracentrifugation at different pH values. The purified pigment showed a single band in the ultracentrifuge and by electrophoretic analysis at several pH values. An average molecular weight of 5 × 106 was calculated from light-scattering measurements. This pigment is composed of carbohydrate and protein combined with prodigiosin, and several properties of the complex are described.

scholarly journals Concepts for Developing Physical Gels of Chitosan and of Chitosan Derivatives

Gels ◽  
2018 ◽  
Vol 4 (3) ◽  
pp. 67 ◽  
Author(s):  
Pasquale Sacco ◽  
Franco Furlani ◽  
Gaia de Marzo ◽  
Eleonora Marsich ◽  
Sergio Paoletti ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Electrostatic Interactions ◽  
Chitosan Derivatives ◽  
Modified Chitosan ◽  
Physical Chemical ◽  
Degree Of Acetylation ◽  
Potential Applications ◽  
Low Toxicity ◽  
Physical Interactions ◽  
Biomedical Field

Chitosan macro- and micro/nano-gels have gained increasing attention in recent years, especially in the biomedical field, given the well-documented low toxicity, degradability, and non-immunogenicity of this unique biopolymer. In this review we aim at recapitulating the recent gelling concepts for developing chitosan-based physical gels. Specifically, we describe how nowadays it is relatively simple to prepare networks endowed with different sizes and shapes simply by exploiting physical interactions, namely (i) hydrophobic effects and hydrogen bonds—mostly governed by chitosan chemical composition—and (ii) electrostatic interactions, mainly ensured by physical/chemical chitosan features, such as the degree of acetylation and molecular weight, and external parameters, such as pH and ionic strength. Particular emphasis is dedicated to potential applications of this set of materials, especially in tissue engineering and drug delivery sectors. Lastly, we report on chitosan derivatives and their ability to form gels. Additionally, we discuss the recent findings on a lactose-modified chitosan named Chitlac, which has proved to form attractive gels both at the macro- and at the nano-scale.

scholarly journals Postharvest quality of essential oil treated roses

2017 ◽  
Vol 23 (2) ◽  
pp. 192 ◽  
Author(s):  
Guilherme Mariano Manfredini ◽  
Patrícia Duarte de Oliveira Paiva ◽  
Elka Fabiana Aparecida Almeida ◽  
Ângela Maria Pereira Do Nascimento ◽  
Thaís Silva Sales ◽  
...  
Keyword(s):  
Essential Oil ◽  
Essential Oils ◽  
Cold Storage ◽  
Production Costs ◽  
Postharvest Quality ◽  
Vase Life ◽  
Pot Life ◽  
Low Toxicity ◽  
Flower Quality ◽  
Cold Chamber

The loss of commercial quality during storage and transportation of roses is one of the factors that reflect on production costs, leading producers to preventively apply harmful chemicals, mainly to hamper Botrytis cinerea development and reduce further losses. An alternative to increase flower longevity without contaminating the environment with harmful chemicals is the use of natural products, such as essential oils, which have fungistatic and insecticide properties, as well as low toxicity. The objective of this study was to evaluate the effect of essential oils on the vase life of Rosa cv. Avalanche: 12 treatments were tested, resulting from the combination of 5 types of essential oils plus the control in two cold storage periods (2 to 6 days) at 1 °C, 90-95% RH. The essential oils tested were eucalyptus, cinnamon, lemongrass and peppermint (1%), clove (0.1%), plus a control with distilled water. Application was made by spraying the flower buds. After storage at low temperatures, the flower stems were kept in a room (16 °C, 70% RH) during 10 days for evaluation. Flower stems stored for 2 days in a cold chamber showed better means for darkening, turgor and bent neck, as well as a lower weight loss by the stems. The application of lemongrass essential oil at 1% caused burns on the petals, compromising quality and pot life. The essential oils of peppermint and eucalyptus allowed flower quality maintenance until the 10th day of evaluation. It is possible to conclude that post-harvest spraying with peppermint or eucalyptus essential oil at 1%, combined with cold storage for 2 days, provided greater longevity and quality for cv. Avalanche roses.

On the transfer of theoretical multipole parameters for restoring static electron density and revealing and treating atomic anharmonic motion. Features of chemical bonding in crystals of an isocyanuric acid derivative

2021 ◽  
Vol 77 (6) ◽  
Author(s):  
Sergey A. Shteingolts ◽  
Julia K. Voronina ◽  
Liliya F. Saifina ◽  
Marina M. Shulaeva ◽  
Vyacheslav E. Semenov ◽  
...  
Keyword(s):  
Electron Density ◽  
Acid Derivative ◽  
Noncovalent Interactions ◽  
Initial Guess ◽  
Atomic Motion ◽  
Total Probability ◽  
Electronic Temperature ◽  
Covalent Bonds ◽  
Isocyanuric Acid ◽  
Static Electron

The crystal and electronic structure of an isocyanuric acid derivative was studied by high-resolution single-crystal X-ray diffraction within the Hansen–Coppens multipole formalism. The observed deformation electron density shows signs of thermal smearing. The experimental picture meaningfully assigned to the consequences of unmodelled anharmonic atomic motion. Straightforward simultaneous refinement of all parameters, including Gram–Charlier coefficients, resulted in more significant distortion of apparent static electron density, even though the residual density became significantly flatter and more featureless. Further, the method of transferring multipole parameters from the model refined against theoretical structure factors as an initial guess was employed, followed by the subsequent block refinement of Gram–Charlier coefficients and the other parameters. This procedure allowed us to appropriately distinguish static electron density from the contaminant smearing effects of insufficiently accounted atomic motion. In particular, some covalent bonds and the weak π...π interaction between isocyanurate moieties were studied via the mutual penetration of atomic-like kinetic and electrostatic potential φ-basins with complementary atomic ρ-basins. Further, local electronic temperature was applied as an advanced descriptor for both covalent bonds and noncovalent interactions. Total probability density function (PDF) of nuclear displacement showed virtually no negative regions close to and around the atomic nuclei. The distribution of anharmonic PDF to a certain extent matched the residual electron density from the multipole model before anharmonic refinement. No signs of disordering of the sulfonyl group hidden in the modelled anharmonic motion were found in the PDF.

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