Calorimetric and kinetic analysis of thermal behaviors of chrome-tanned collagen fibers using isoconversional and multivariate non-linear regression methods / Wentao Liu in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXII, N° 12 (12/2017)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXII, N° 12 (12/2017) . - p. 399-409 Titre : Calorimetric and kinetic analysis of thermal behaviors of chrome-tanned collagen fibers using isoconversional and multivariate non-linear regression methods Type de document : texte imprimé Auteurs : Wentao Liu, Auteur ; Yuanzhi Zhang, Auteur ; Li Guoying, Auteur Année de publication : 2017 Article en page(s) : p. 399-409 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Calorimétrie Cinétique chimique Collagène Cuirs et peaux -- Analyse Tannage au chrome Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : To further understand the thermal stability of collagen in hide and leather, the thermal denaturation behaviors of chrome-tanned collagen fibers were studied by non-isothermal differential scanning calorimetry (DSC) using isoconversional and multivariate non-linear regression (Multivar-NLR) methods. The differential (Friedman) and the integral (Ozawa-Flynn-Wall) isoconversional methods as well as the Multivar-NLR method showed that the denaturation (or shrinkage) process could be best described by a three-step model, in which a reversible reaction was followed by a rate-limited irreversible step. The simulation of thermal behaviors of collagen at different temperature conditions indicated that the denaturation kinetics could be approximated to a one-step irreversible reaction at low heating rates or temperatures. For the design of new chrome-free tanning systems, which can endow collagen with high enough thermostability, the decrease in the rate of the irreversible denaturation of collagen might be an important criterion as well, besides the increases in the denaturation (or shrinkage) temperature, enthalpy and effective activation energy. Note de contenu : - EXPERIMENTAL : Materials - Preparation of chrome-tanned collagen fibers - Differential scanning calorimetry (DSC)- Kinetic analysis - Isoconversional analysis - Multivar-NLR analysis - Simulation of thermal behaviors of chrome-tanned collagen fibers - RESULTS AND DISCUSSION : Effects of heating rate and chrome-tanning on the thermal denaturation of collagen fibers - Isoconversional kinetic analysis - Multivar-NLR kinetic analysis - Simulation of thermal behaviors of chrome-tanned collagen fibers En ligne : https://drive.google.com/file/d/1PSnXKXyQNIXY8P96zXT0rFmPNHCAYsO4/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=29586 [article]

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Effect of ionic liquids pretreatment on the extraction of collagen from calf skin / Sicong Liu in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXIV, N° 10 (10/2019)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXIV, N° 10 (10/2019) . - p. 391-399 Titre : Effect of ionic liquids pretreatment on the extraction of collagen from calf skin Type de document : texte imprimé Auteurs : Sicong Liu, Auteur ; Wentao Liu, Auteur ; Li Guoying, Auteur Année de publication : 2019 Article en page(s) : p. 391-399 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Chimie analytique Collagène Cuirs et peaux de veaux Extraction (chimie) Liquides ioniques Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : The use of ionic liquids (ILs) for collagen extraction should be premised of not destroying the triple helix structure of collagen. Herein, the effects of pretreatments by two imidazolium based ILs with different anions, 1-ethyl-methylimidazolium dicyanamide ([EMIM][N(CN)2]) and 1-ethyl-methylimidazolium tetrafluoroborate ([EMIM][BF4]), on the extraction of collagen from calf skins were studied. The dependences of ILs pretreatments on ILs species and concentrations (30%, 50%, and 70% (w/w)) were examined, in terms of the fiber morphology of skins as well as the extraction rate, structural integrity, thermal stability, and aggregation behaviors of collagens. The results of histological analysis and scanning electron microscopy showed that the skin fibers were effectively loosened by the IL s pretreatments. The extraction rate of collagen was improved as the increase of ILs concentration and polarity with the highest value of 28.79%. Moreover, sodium dodecyl sulphatepolyacrylamide gel electrophoresis and Fourier transform infrared spectroscopy confirmed that the structural integrity of collagen was maintained after ILs pretreatments, although the thermal stability of collagen was determined to be slightly decreased by ultra-sensitive differential scanning calorimeter. Finally, pyrene fluorescence analysis and atomic force microscope indicated that the aggregation behavior of collagen was weakened when increasing the ILs concentration and polarity. The green ILs pretreatment of calf skins might be used as an effective approach for the extraction of bioactive collagen with improved yield and purity. Note de contenu : - EXPERIMENTAL : Materials - Ionic liquids pretreatment on NS - Histological analysis - SEM - Extraction of collagen - Extraction rate of collagen - SDS-PAGE - FTIR - Thermal analysis - Fluorescence measurements - AFM - RESULTS AND DISCUSSION : Effect of ILs on calf skin - Extraction rate anaysis - Structural integrity of collagen - Thermal stability of collagen - Aggregation behavior of collagen En ligne : https://drive.google.com/file/d/1IYTryFmWwzS6xJRTho0fxBzDFkzmgrxa/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=33035 [article]

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Investigation of the interaction between epoxides and collagen in epoxy tanning based on BDDGE cross-linked collagen solution / Yuanzhi Zhang in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXV, N° 8 (08/2020)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXV, N° 8 (08/2020) . - p. 279-287 Titre : Investigation of the interaction between epoxides and collagen in epoxy tanning based on BDDGE cross-linked collagen solution Type de document : texte imprimé Auteurs : Yuanzhi Zhang, Auteur ; Li Guoying, Auteur Année de publication : 2020 Article en page(s) : p. 279-287 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Analyse thermique Collagène Dodécyl sulfate de sodium Le laurylsulfate de sodium (LSS) ou dodécylsulfate de sodium (SDS) est un détergent et tensioactif ionique fort, couramment utilisé en biochimie et biologie moléculaire. C'est un composé à ne pas confondre avec le laureth sulfate de sodium. La concentration micellaire critique du SDS varie de 0,007 à 0,01 mol/L dans l'eau à 25°C. Le dodécylsulfate de sodium (en anglais, Sodium Dodecyl Sulfate ou SDS ou/ NaDS), de formule C12H25NaO4S, aussi connu sous le nom de laurylsulfate de sodium (en anglais, sodium lauryl sulfate ou SLS), est un tensioactif ionique qui est utilisé dans les produits ménagers tels que les dentifrices, shampooings, mousses à raser ou encore bains moussants pour ses effets épaississants et sa capacité à créer une mousse, il est également repris comme additif alimentaire par le codex alimentarius (E487). La molécule est composée d’une chaîne de 12 atomes de carbone, rattachée à un groupement sulfate conférant à la molécule les propriétés amphiphiles requises pour un détergent. Le SDS est préparé par sulfonation du dodécanol (alcool de lauryl, C12H25OH), suivie par une neutralisation par du carbonate de sodium. Le SDS est utilisé aussi bien dans les procédés industriels que pour les produits cosmétiques destinés au grand public. Dynamique moléculaire Epoxydes Extraction (chimie) Fourier, Spectroscopie infrarouge à transformée de Microscopie à force atomique Rhéologie Stabilité thermique Tannage organique Thermogravimétrie Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : To investigate further the interaction between epoxides and collagen in epoxy tanning, collagen solutions (3 mg/ml) cross-linked with various concentrations (0.5–4-wt%) of 1,4-butanediol diglycidyl ether (BDDGE) at low temperature (4ºC), alkaline conditions (pH = 10) were prepared. The sodium dodecyl sulfate–polyacrylamide gel electrophoresis and Fourier transform infrared spectroscopy confirmed the intact triple-helix structure of the cross-linked collagen. With the increasing concentration of BDDGE, the denaturation temperature measured using VP-DSC increased from 42.56 ºC to 44.25ºC and thermogravimetric analysis showed that the decomposition temperature increased from 333.0ºC to 351.8ºC. In addition, the rheology properties such as G¢, G² and η* were measured with a rotary rheometer using dynamic frequency scanning. The trinitrobenzensulfonic acid method and atomic force microscopy were used to investigate the interaction between collagen and BDDGE. The results indicated that the changes in cross-linked collagen performance were attributed to the transition of collagen aggregation caused by cross-linking. In addition, the transition point of 2-wt% BDDGE was the key node for the formation of a mature cross-linked network and the cross-linking barely increased above that. It is hoped that these findings deepen the understanding of epoxy tanning and provide guidance for the practical use of epoxides in tanning and biomaterials. Note de contenu : - MATERIALS AND METHODS : Extraction of the bovine skin collagen - Preparation of the cross-linked collagen solutions - Sodium dodecyl sulfate-polyacrylamide gel electrophoresis - Fourier Transform Infrared (FTIR) spectra - VP-DSC - TG measurements - Dynamic rheological measurements - Determination of the reacted amino group content - Atomic force microscopy - RESULTS : The integrity of cross-linked collagen - Thermal stability - Rheological properties - The content of reacted amino groups - Atomic force microscope images DOI : https://doi.org/10.34314/jalca.v115i8.3843 En ligne : https://drive.google.com/file/d/1q2Gv1tbaFa87ldb6ZUfosbdXuFLwypvh/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=34434 [article]

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Investigation of the solubility and dispersion degree of calf skin collagen in ionic liquids / Sicong Liu in JOURNAL OF LEATHER SCIENCE AND ENGINEERING, Vol. 1 (Année 2019)  

[article]  inJOURNAL OF LEATHER SCIENCE AND ENGINEERING > Vol. 1 (Année 2019) . - 12 p. Titre : Investigation of the solubility and dispersion degree of calf skin collagen in ionic liquids Type de document : texte imprimé Auteurs : Sicong Liu, Auteur ; Qian Li, Auteur ; Li Guoying, Auteur Année de publication : 2019 Article en page(s) : 12 p. Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Bovins -- Races Chimie analytique Collagène Collagène -- Analyse Collagène -- Solubilité Dispersions et suspensions Liquides ioniques Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : The dissolution of collagen in ionic liquids (ILs) was highly dependent on the polarity of ILs, which was influenced by their sorts and concentrations. Herein, the solubility and dispersion degree of collagen in two sorts of ILs, namely 1-ethyl-methylimidazolium tetrafluoroborate ([EMIM][BF4]) with low polarity and 1-ethyl-3-methylimidazolium acetate ([EMIM][Ac]) with high polarity in a concentration range from 10% to 70% at 10 °C were investigated. When 150 mg of collagen was added to 30 mg of ILs, the minimum soluble collagen concentration was 0.02 mg/mL in 70% [EMIM][BF4] with lowest polarity and the maximum was 3.57 mg/mL in 70% [EMIM][Ac] with highest polarity, which indicates that soluble collagen and insoluble collagen fibers were both present. For insoluble collagens, differential scanning calorimetry showed that the thermal-stability was weakened when increasing the ILs concentration and polarity, and the fiber arrangement was looser with a more uniform lyophilized structure, observed by atomic force microscopy and scanning electron microscopy. For soluble collagens, electrophoresis patterns and Fourier transform infrared spectroscopy showed that no polypeptide chain degradation occurred during dissolution, but the thermal denaturation temperature decreased by 0.26 °C~ 7.63 °C with the increase of ILs concentrations, measured by ultra-sensitive differential scanning calorimetry. Moreover, the aggregation of collagen molecules was reduced when ILs polarity was increased as determined by fluorescence measurements and dynamic light scattering, which resulted in an increased loose fiber arrangement observed by atomic force microscopy. If the structural integrity of collagen needs to be retained, then the ILs sorts and concentrations should be considered. Note de contenu : - EXPERIMENTAL : Materials - Processing collagen with ILs - Collagen solubility in ILs - DSC of insoluble collagen fibrils - SEM of insoluble collagen fibrils - AFM measurements of insoluble and soluble collagen - SDS–PAGE patterns of soluble collagen - FTIR of soluble collagen - Fluorescence measurements of soluble collagen - DLS measurements of soluble collagen - RESULTS AND DISCUSSION : Solubility of collagen in ILs - Thermal analysis of insoluble collagen fibrils - SEM images of insoluble collagen fibrils - AFM images of insoluble collagen fibrils - SDS-PAGE patterns of soluble collagen - FTIR spectra analysis of soluble collagen - Thermal analysis of soluble collagen - Fluorescence analysis of soluble collagen - DLS analysis of soluble collagen - AFM images of soluble collagen - Table 1 The concentration of soluble collagen in different ILs and concentrations - Table 2 Thermodynamic parameters of Col and collagen samples dissolved in different concentrations of [EMIM][Ac]a DOI : https://doi.org/10.1186/s42825-019-0013-9 En ligne : https://link.springer.com/content/pdf/10.1186/s42825-019-0013-9.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36945 [article]

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Preparation and characterization of alkali-soluble collagen from pigskin shavings / Shuai Shao in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CIV, N° 10 (10/2009)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CIV, N° 10 (10/2009) . - p. 344-351 Titre : Preparation and characterization of alkali-soluble collagen from pigskin shavings Type de document : texte imprimé Auteurs : Shuai Shao, Auteur ; Min Zhang, Auteur ; Li Guoying, Auteur ; Wentao Liu, Auteur Année de publication : 2009 Article en page(s) : p. 344-351 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : The leather industry discharges large quantities of solid wastes containing high-value native collagen. In this study, the pigskin shavings generated from the shaving of pelts which had been dehydrated with anhydrous sodium sulfate after deliming were pretreated to remove most of salt and fat. Then alkaline treatment method was used to extract collagen from the pigskin shavings. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and circular dichroism (CD) spectra revealed that the alkali-soluble pigskin collagen (ASPC) retained the polypeptide chains and triple helix conformation. The amino acid profiles showed no major deviation from the characteristic collagen composition. Both of the denaturation temperature and the isoelectric point (pI) of ASPC were lower than those of pepsin-solubilized pigskin collagen (PSPC). Scanning electron microscopy showed that ASPC sponges had porous fibrillar network structures, and the pore sizes became larger with the decrease of collagen concentrations and as the pH of the collagen solution approached the pI of ASPC. En ligne : https://drive.google.com/file/d/1oxrpfE-DAUNzUkC1P-_gIBBVEs02RTLj/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=6371 [article]

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