摘要：
Side chain modification of collagen provides an attractive way to enhance their structure and functions, which is highly desirable for the development of promising biomaterials. However, the impact of structural change of side chains on the intrinsic self-assembly property of collagen was always ignored. Here, a series of acrylic acid-grafted-collagen (AA-g-Col) with different grafting density were prepared to explore the impact of side chain structural variation on the self-assembly of collagen. The results showed that excessive grafting density would weaken or even disappear the self-assembly property of AA-g-Col, but only affects the triple helix to a minor extent. Compared to pristine collagen, the mechanical property and cytocompatibility of AA-g-Col based matrices also deteriorated, along with the increase of grafting density. Therefore, this work contributed a new insight into the importance of grafting density for the study of modified collagen, which would be helpful for the design of optimized formulate collagen-based hybrid materials with both additional novel functions and tissue-mimicking fibrillary structures.
关键词：
atelocollagen;collagen;fluorescein isothiocyanate;telopeptide;tropocollagen;Article;collagen fibril;extracellular matrix;grass carp;morphology;nonhuman;pig;polyacrylamide gel electrophoresis;priority journal;scanning electron microscopy;skin;viscoelasticity
摘要：
Xenogeneic collagen co-assembly (XCCA) is a novel and efficient strategy for improving and regulating the performance of collagen assembled products. However, the effect of collagen molecular structures on XCCA has long been neglected and remains unclear. Herein, we investigated the telopeptide effect of collagen on XCCA by employing grass carp skin collagen (GCSC) with two different structures (tropocollagen and atelocollagen) and porcine skin collagen (PSC). Kinetic analysis showed that the co-assembly rate of PSC and grass carp skin atelocollagen (AC-GCSC) was faster than that of PSC and grass carp skin tropocollagen (TC-GCSC). Based on this observation, we further obtained different concentration dependences of XCCA by the alteration of telopeptide. Compared with PSC/TC-GCSC co-assembly, PSC/AC-GCSC co-assembly exhibited a higher sensitivity and a lower detection limit. Furthermore, telopeptide promoted the fabrication of thicker fibrils and improved the mobility of gels.
摘要：
A sensitive and robust electrochemical aptasensor for determining dopamine (DA) was developed using a grass carp skin collagen-graphene oxide (GCSC-GO) composite as a transducer and a label-free aptamer as a biological recognition element for the first time. In order to fabricate this sensor, the GCSC-GO composite was firstly prepared by ultra-sonication method and characterized by atomic force microscope, infrared spectroscopy, Raman spectroscopy, and electrochemical impedance spectroscopy. Subsequently, a label-free DA-binding aptamer was immobilized through strong interaction between collagen and aptamer. The fabricated electrochemical aptasensor was used to determine DA by differential pulse voltammetry. The results indicated that the peak current changes of the developed aptasensor was linear relationship with the DA concentrations from 1 to 1000 nM, and the detection limit was 0.75 nM (S/N = 3). Moreover, the fabricated aptasensor showed high selectivity for DA More importantly, the obtained aptasensor exhibited satisfactory recovery toward DA in human serum specimens with excellent stability. (C) 2019 Elsevier B.V. All rights reserved.
摘要：
Ultra-high pressure technology has attracted a great deal of attention in recent years, and has been widely used in food science, medicine, and other fields. This study aimed to determine the effect of ultra-high pressure on the structure and properties of collagen. Native collagen extracted from bullfrog skin was processed under different ultra-high pressure treatment conditions (300, 400, and 500 MPa). Then systematic analysis of the molecular structures and properties of the samples after ultra-high pressure treatment were performed. It was found that the conformation of collagen molecules could be adjusted by ultra-high pressure treatment, and this regulation was closely related to the level of treatment pressure. A possible mechanism of the impact of ultra-high pressure on the collagen molecular structures was speculated according to the experimental results. At low pressure levels (300-400 MPa), the pressure perpendicular to collagen axis dominates and leads to a tightening of the triple helix structure of collagen, while the pressure parallel to collagen axis is dominant and the triple helix tends to dissociate like a zipper at high pressure levels (> 400 MPa). These structural changes would simultaneously result in various changes to thermal stability, self-assembly properties, and antigenicity of collagen. (C) 2018 Elsevier B.V. All rights reserved.
摘要：
A Hybrid collagen fibril (HCF) assembled from xenogeneic collagens is a special kind of collagen fibrils in vivo and plays an important role in living systems. Inspired by nature, can a HCF form in vitro? Herein, we fabricated a new HCF by neutralizing a mixture of type I bullfrog (Rana catesbeiana Shaw) skin collagen and porcine (Sus scrofa domesticus) skin collagen with a phosphate buffer, and investigated its physicochemical properties. Self-assembly kinetics and fluorescence-quenching experiments showed that a significant intermolecular interaction and co-assembly behavior occurred between bullfrog skin collagen and porcine skin collagen, thus confirming that xenogeneic collagens can self-assemble to form HCF. Differential scanning calorimetry revealed that the thermal stability of HCF was completely different from that of the syngeneic bullfrog skin and porcine skin collagen fibrils. This finding indicated that a new kind of collagen fibril was fabricated successfully. Scanning electron microscopy and transmission electron microscopy tests showed that the diameters and D-periodicity lengths of HCF were smaller than those of the syngeneic collagen fibrils, suggesting that the morphological features of HCF were distinguished from those of the syngeneic fibril samples. Moreover, viscoelasticity of a collagen gel also changed after the self-assembly of xenogeneic collagens. Meanwhile, the obtained hybrid gel still exhibited good biocompatibility and cell proliferation properties. Finding from this work provides a new idea for the improvement or regulation of collagen-based products performance.
摘要：
Much work has been done to understand the self-assembly properties of collagens from mammals. However, there is little information about fish-sourced collagens that are advantageous in certain applications. In this study, the self-assembly dynamics of tropocollagen (with telopeptides) and atelocollagen (without telopeptides) extracted from snakehead (Channa argus) skins was studied with turbidity, dynamic rheology, scanning electron microscopy (SEM), and quantitative percentage of self-assembly. Turbidity results indicate that the self-assembly of fish-sourced collagens followed the nucleation-growth two-step model, while rheological results unveiled two growth stages in the development of collagen gels. Based on SEM, telopeptides promoted the formation of thicker fibrils and increased the density of network that provided the structural basis of increased turbidity and strengthened storage and loss moduli. The SEM data were supported by the increased percentage of self-assembled collagens by telopeptides. Findings from this work may facilitate the understanding of structures and functions of products containing fish-sourced collagens and their application.
摘要：
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 degrees 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 degrees 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. (C) 2016 Elsevier B.V. All rights reserved.
