April 2018 Abstracts

Characterization and Thermal Properties of Polygenipin-crosslinked Hide Powders

by Jie Liu, Eleanor M. Brown, Cheng-Kung Liu, and Keyong Tang

Genipin is a naturally occurring iridoid compound, it is widely used as an ideal biological protein crosslinking agent due to its low toxicity compared to glutaraldehyde and formaldehyde. Under alkaline condition, genipin could undergo ring-opening polymerization via nucleophilic attack of hydroxyl ions followed by an aldol condensation. Because of the fact that polygenipin could create long-range intermolecular crosslinking between protein chains, preliminary investigations have been carried out to study effect of polygenipin crosslinking on color and thermal stability of hide powder by using colorimetry, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The results show that the peak denaturation temperature (Tp) for hide powders obtained from DSC increased to a maximum and then decreased with increasing of the molecular weight of polygenipin. Degree of crosslinking was evaluated, and the results suggest that thermal stability of hide powder is influenced not only by degree of crosslinking, but also by the type of crosslinking. Thermogravimetric analysis also confirms that long-range intermolecular crosslink bridges formed between collagen molecules results in more thermally stable hide powders. This study suggests that polygenipin can be potentially useful in producing eco-friendly leather.

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Studies on the Application of Biocolorant for Leather Dyeing Using Monascus Purpureus

by A. Tamil Selvi, G.C. Jayakumar, N. Usha Rani, A. Yasothai and Swarna V. Kanth

World-wide requirement for colorants from natural origins have been rapidly increasing in the leather sector due to environmental effluent concerns. Biocolorant obtained from Monascus purpureus, which yields red colored extract, has been studied for the dyeing process of leather. The effect of varying conditions like pH, concentration, time and temperature on the levelness of the dyeing, shade brightness, color intensity and exhaustion of the dye have been studied herein, and the conditions optimized. The change in color shade obtained has been quantified by reflectance measurements and compared with the visual assessment data. The bulk properties viz., softness and grain smoothness have been found to be marginally improved, versus control, in biocolorant treated leathers. There is no significant change in strength properties by the use of these natural colorants in the post tanning process.

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Thermally Responsive Collagen Switching from Bactericidal for Ambient Storage Condition to Biologically Inert in Vivo

by Jinming Chang, Zhou Xu, Gaofu Yang, Zhonghui Wang, Yi Chen and Haojun Fan

Incorporating preservatives is now the most commonly employed strategy to prevent microbial deterioration of collagen. However, many preservatives are non-selective; they cannot differentiate the orthologs in mammalian cells from their biological targets in pathogens, and thus their incorporation compromises the inherent biocompatibility of naturally occurring collagen. Here, we report a strategy to covalently anchor antibacterial agents to collagen via a thermally responsive poly(N-isopropylacrylamide) spacer. As the spacer suddenly collapses from an extended coil upon heating through ~30°C, bioactivity of the anchored antibacterial agents can be switched off, because their lateral mobility and, hence, target-site accessibility are restricted. Accordingly, the modified collagen can be preserved without microbial deterioration for ambient storage condition, while imposing no cytotoxic impact upon surrounding tissues in vivo. This thermally responsive collagen holds great potential in biomedical fields, where the collagen products are intended to have intimate contact with human tissues or be administered parenterally.

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Hydrolysis of Chromium Tanned Leather Waste: Turning Waste into Valuable Materials – A Review

by B. S. Scopel, C. Baldasso, A. Dettmer and R. M. C Santana

Among the reuse and/or disposal possibilities for chromium tanned leather waste (CTLW), one in particular stands out: hydrolysis. This process not only allows chromium recovery, but also the extraction of its protein, as collagen hydrolysate or as gelatin. CTLW hydrolysis has been performed for decades. However, industrial application of this important alternative has not been widespread. Thus, this review presents how CTLW alkaline hydrolysis has been evolving over the years; how the process can be adjusted to increase protein extraction yield and to produce better quality products. Finally, it reviews in which areas its products have already been tested. Here, researchers may find practical process information that might allow them to focus on the most important current issue for CTLW hydrolysis: how to upgrade this process to an industrial scale.

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