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Controlling the fibril-formation process of collagen in vitro to fabricate novel biomaterials is a new area in the field of collagen research. This study aimed to determine the effect of ultrasonication on collagen fibril formation and the properties of the resulting collagen gels. Native collagen, extracted from the skin of grass carp, self-assembled under ultrasonic conditions (at different ultrasonic power and duration). The self-assembly kinetics, fibrillar morphology, and physical and cell growth-promoting properties of the collagen gels were analyzed and compared. The results showed that the self-assembly rate of collagen was increased by ultrasonication at the nucleation stage. The resulting fibrils exhibited smaller diameters and D-periodicity lengths than that of the untreated collagen samples (p<0.05). The viscoelasticity and textural properties of collagen gels also changed after ultrasonication at the nucleation stage. Texture profile analysis and cell proliferation assays showed that ultrasonication produced softer collagen gel colloids, which were more suitable for cell proliferation than the untreated collagen gels., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Background: The molecular configuration, molecular weight distribution and thermal transition enthalpy (ΔH) of grass carp skin (GCS) collagens after heat treatment under different conditions were measured using circular dichroism, gel filtration chromatography and differential scanning calorimetry (DSC). The enzymatic stability of collagen was evaluated using different enzymes, while the ability to form fibrils in vitro was assessed by morphological observation of collagen fibrils and turbidity testing., Results: The ΔH values, in-solution molecular aggregation and the stability to enzymatic hydrolysis of GCS collagen decreased irreversibly and progressively with the duration of heat treatment at 33 °C, which was the onset endothermic temperature obtained from the DSC curve. A strong positive linear correlation between the enzymatic sensitivity of collagen and the degree of thermal denaturation was found. A decrease in fibril diameter and D-periodicity length with denaturation could also be observed in the SEM and TEM images., Conclusion: The onset endothermic temperature (To ) rather than the denaturation temperature (Td ) is the threshold temperature for configurational stability of GCS collagen in acidic solution, and the biological properties would obviously change if the collagen was heat treated at this temperature., (© 2014 Society of Chemical Industry.)

In order to study the similarities and differences of physical-chemical properties of collagens from different parts of the fish body, acid-soluble collagens and pepsin-soluble collagens were isolated from skin, scale, and bone of grass carp (Ctenopharyngodon idellus), with yields ranging from 0.7 to 25.5% on the basis of dry weight. The content of acid-soluble collagen in skin and scale was much higher than that in bone according to the data of extraction yield. Collagens from grass carp have similar amino acid composition, protein patterns, and sequences of primary structure. Thermal transition temperatures of collagens from different parts of grass carp body decreased in the order of bone > skin > scale. The pepsin-soluble collagens showed more resistance to collagenase, compared to acid-soluble collagens extracted from the same part of the grass carp body. All grass carp collagens did not induce a significant cytotoxic effect according to the results ofin vitrocytotoxicity test. [ABSTRACT FROM PUBLISHER]

In this study, fibrillogenesis and thermal dissociation of pepsin-soluble collagen ( PSC ), extracted from snakehead ( Channa argus ) skin, were monitored by fluorescence method based on thioflavin T (Th-T), where the accuracy and sensitivity were evaluated and compared with those of turbidity assay. The fluorescence method revealed the fibrillogenesis dynamics of collagen with better sensitivity, especially at nucleation and plateau stages. The melting temperature ( T m ) of PSC was estimated to be 47 °C by circular dichroism spectroscopy; below this temperature, the triple-helical structure should be intact. After that, the dynamic process of collagen dissociation was explored by the fluorescence method, and verified by morphological analysis of the fibrils and the proportion of retained fibrils. The thermal dissociation critical temperature (TDCT) of PSC fibrils was confirmed to be 39 °C. The fluorescence intensity of fibril-incorporated Th-T gradually decreases in the dissociation process, and the decrease rate can be accelerated by increasing temperature. Finally, the thermal stability of triple-helical structures of free-, assembled- and dissociated- PSC was compared. Thus, we demonstrated the formation and thermal dissociation of collagen fibrils in vitro by a fluorescence method based on Th-T. This approach may advance the understanding of fibril formation and inverse dissociation of fish-sourced collagen in vitro . [ABSTRACT FROM AUTHOR]