High-efficiency bio-degreasing technology for leather making - Characterization of catalytic hydrolysis properties of lipases towards fats based on greasy skin powder substrate / Yongkang Luo in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXIV, N° 11 (11/2019)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXIV, N° 11 (11/2019) . - p. 429-439 Titre : High-efficiency bio-degreasing technology for leather making - Characterization of catalytic hydrolysis properties of lipases towards fats based on greasy skin powder substrate Type de document : texte imprimé Auteurs : Yongkang Luo, Auteur ; Shan Li, Auteur ; Shencai Pan, Auteur ; Chunxian Zhang, Auteur ; Cai Huang, Auteur ; Biyu Peng, Auteur Année de publication : 2019 Article en page(s) : p. 429-439 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Catalyse Cuirs et peaux -- Dégraissage Cuirs et peaux de porcs Hydrolyse Lipases Les lipases sont des enzymes hydrosolubles capables d'effectuer l'hydrolyse de fonctions esters et sont spécialisées dans la transformation de triglycéride en glycérol et en acides gras (lipolyse). À ce titre, elles constituent une sous-classe des estérases. Poudre de peaux Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Bio-degreasing technology based on the use of lipases has attracted more attention in the leather industry. Although lipases have been applied in leather making in the past, the previously reported lipase degreasing ratio is still not very high, i.e. less than 60%. In order to correctly understand the mechanism of lipase degreasing and to choose lipases and optimize the degreasing process for achieving efficient degreasing, a novel method of evaluating the catalytic hydrolysis properties of lipases towards skin fats based on a greasy skin powder substrate in an aqueous medium was established. This simulated the actual leather degreasing process and detected the amount of fatty acids produced. The special substrate was prepared; the determination conditions were optimized; then the performances of several typical lipases were evaluated. The results revealed that the lipase performances determined by the novel method were quite different from the standard method using emulsified olive oil substrate. There was a strong product-inhibition characteristic in the catalytic hydrolysis reaction of lipase, and the inhibition concentration of fatty acids varied with the lipase type, thus the maximum hydrolysis ratio of fats was only 67%. The lipases exhibited “super-activity” at pH around 9.5. This occurred because the fatty acids produced transformed into soluble soaps, thus the product-inhibition was weakened. According to the above results, a two-step lipase processing was made, i.e., beginning at pH 7.5 then 9.5. The hydrolysis ratio of fats rose to 82.57% from 46.23%, and the degreasing ratio increased from 50.78% to 89.68%. The new method with better repeatability can be used as a tool to correctly select lipases and optimize process parameters for lipase degreasing. Note de contenu : - EXPERIMENTAL : Materials - Preparation of the pigskin powder substrate rich in grease - Determination of lipase activity based on the prepared greasy skin powder substrate - Optimization of the method to terminate enzyme reaction - Water washing method - Hot drying method - Ethanol termination method - Acidification method - Acidification and water washing method - Absorption of fatty acids by pigskin powder after acidification - Extraction ratio of absorbed fatty acids by dichloromethane - Determination of lipase activity with the standard method - Evaluation of catalytic hydrolysis properties of some lipases towards fats in greasy skin powder - High-efficiency catalytic hydrolysis of fats by lipase and degreasing effect - RESULTS AND DISCUSSION : Main parameters of the prepared greasy pigskin powder substrate - Optimization of the method to terminate lipase reaction - Impact of acidification on the absorption of fatty acids by pigskin powder - Extraction ratio of fatty acid by dichloromethane - Comparison of the measuring result of lipase activity between the novel and standard methods - Impact of lipase concentration on lipolytic activities of lipases - Impact of reaction time on lipolytic activity of lipases - Effect of temperature on lipolytic hydrolysis of lipase En ligne : https://drive.google.com/file/d/1Db6VxRnqj3vXDlsp1w3HSE05ySOJRZs3/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=33255 [article]

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Polycaprolactone strengthening keratin/bioactive glass composite scaffolds with double cross-linking networks for potential application in bone repair / Liying Sun in JOURNAL OF LEATHER SCIENCE AND ENGINEERING, Vol. 4 (Année 2022)  

[article]  inJOURNAL OF LEATHER SCIENCE AND ENGINEERING > Vol. 4 (Année 2022) . - 13 p. Titre : Polycaprolactone strengthening keratin/bioactive glass composite scaffolds with double cross-linking networks for potential application in bone repair Type de document : texte imprimé Auteurs : Liying Sun, Auteur ; Shan Li, Auteur ; Kaifeng Yang, Auteur ; Junchao Wang, Auteur ; Zhengjun Li, Auteur ; Nianhua Dan, Auteur Année de publication : 2022 Article en page(s) : 13 p. Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Composites Ingénierie tissulaire kératines La kératine est une protéine, synthétisée et utilisée par de nombreux êtres vivants comme élément de structure, et également l'exemple-type de protéine fibreuse. La kératine est insoluble, et peut être retrouvée sur l'épiderme de certains animaux, notamment les mammifères, ce qui leur garantit une peau imperméable. Parfois, lors d'une friction trop importante, la kératine se développe à la surface de la peau formant une callosité. Les cellules qui produisent la kératine meurent et sont remplacées continuellement. Les morceaux de kératine qui restent emprisonnés dans les cheveux sont couramment appelés des pellicules. La molécule de kératine est hélicoïdale et fibreuse, elle s'enroule autour d'autres molécules de kératine pour former des filaments intermédiaires. Ces protéines contiennent un haut taux d'acides aminés à base de soufre, principalement la cystéine, qui forment un pont disulfure entre les molécules, conférant sa rigidité à l'ensemble. La chevelure humaine est constituée à 14 % de cystéine. Il y a deux principales formes de kératines : l'alpha-kératine, ou α-keratin, présente chez les mammifères notamment, dont l'humain, et la bêta-kératine, ou β-keratin, que l'on retrouve chez les reptiles et les oiseaux. Ces deux types de kératines ne présentent clairement pas d'homologie de séquence. Chez l'être humain, la kératine est fabriquée par les kératinocytes, cellules se trouvant dans la couche profonde de l'épiderme. Les kératinocytes absorbent la mélanine (pigment fabriqué par les mélanocytes), se colorent et ainsi cette pigmentation de l'épiderme permet de protéger les kératinocytes des rayons ultraviolets du Soleil. (Wikipedia) Poly-e-caprolactone Polymères en médecine Régénération (biologie) Réticulation (polymérisation) Tissu osseux Verre Index. décimale : 668.9 Polymères Résumé : In this study, we aimed at constructing polycaprolactone (PCL) reinforced keratin/bioactive glass composite scaffolds with a double cross-linking network structure for potential bone repair application. Thus, the PCL-keratin-BG composite scaffold was prepared by using keratin extracted from wool as main organic component and bioactive glass (BG) as main inorganic component, through both cross-linking systems, such as the thiol-ene click reaction between abundant sulfhydryl groups of keratin and the unsaturated double bond of 3-methacryloxy propyltrimethoxy silane (MPTS), and the amino-epoxy reaction between amino groups of keratin and the epoxy group in (3-glycidoxymethyl) methyldiethoxysilane (GPTMS) molecule, along with introduction of PCL as a reinforcing agent. The success of the thiol-ene reaction was verified by the FTIR and 1H-NMR analyses. And the structure of keratin-BG and PCL-keratin-BG composite scaffolds were studied and compared by the FTIR and XRD characterization, which indicated the successful preparation of the PCL-keratin-BG composite scaffold. In addition, the SEM observation, and contact angle and water absorption rate measurements demonstrated that the PCL-keratin-BG composite scaffold has interconnected porous structure, appropriate pore size and good hydrophilicity, which is helpful to cell adhesion, differentiation and proliferation. Importantly, compression experiments showed that, when compared with the keratin-BG composite scaffold, the PCL-keratin-BG composite scaffold increased greatly from 0.91 ± 0.06 MPa and 7.25 ± 1.7 MPa to 1.58 ± 0.21 MPa and 14.14 ± 1.95 MPa, respectively, which suggesting the strong reinforcement of polycaprolactone. In addition, the biomineralization experiment and MTT assay indicated that the PCL-keratin-BG scaffold has good mineralization ability and no-cytotoxicity, which can promote cell adhesion, proliferation and growth. Therefore, the results suggested that the PCL-keratin-BG composite scaffold has the potential as a candidate for application in bone regeneration field. Note de contenu : - MATERIALS AND METHODS : Materials - Fabrication of keratin-BG and PCL-keratin-BG composite scaffolds CHARACTERIZATION : Analyses of chemical structure - Morphology observation and porosity detection of scaffolds - Hydrophilicity testing - Mechanical properties - In vitro biological activity evaluation - Statistical analysis - RESULTS AND DISCUSSION : Characterization of chemical structure - Porous morphology of keratin-BG and PCL-keratin-BG scaffolds - Hydrophilicity of scaffolds - Mechanical properties - In vitro mineralization characterization - Biocompatibility–cell viability assay - Table 1 : The radio of calcium to phosphorus (Ca/P) of HA after mineralization in keratin-BG and PCL-keratin-BG scaffolds DOI : https://doi.org/10.1186/s42825-021-00077-w En ligne : https://link.springer.com/content/pdf/10.1186/s42825-021-00077-w.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=37565 [article]

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