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.
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.
作者机构：
[Zhang, Jian] Wuhan Polytech Univ, Sch Chem & Environm Engn, Wuhan 430023, Hubei, Peoples R China.;[Jha, Sunil Kr.] Ton Duc Thang Univ, Dept Management Sci & Technol Dev, Ho Chi Minh City, Vietnam.;[Jha, Sunil Kr.] Ton Duc Thang Univ, Fac Sci Appl, Ho Chi Minh City, Vietnam.;[Liu, Chuanjun; Hayashi, Kenshi] Kyushu Univ, Grad Sch Informat Sci & Elect Engn, Dept Elect, 744 Motooka, Fukuoka, Fukuoka 8190395, Japan.
通讯机构：
[Jha, Sunil Kr.] T;Ton Duc Thang Univ, Dept Management Sci & Technol Dev, Ho Chi Minh City, Vietnam.;Ton Duc Thang Univ, Fac Sci Appl, Ho Chi Minh City, Vietnam.
关键词：
Banana storage quality;Overripe odor;GC-MS;Volatile chemical compounds;Principal component analysis
摘要：
A promising research to evaluate the quality of ripe banana during storage period by analyzing the variability of the volatile chemical components in odor from peels and flesh based on solid-phase microextraction-GC-MS characterization and statistical analysis has been discussed. A rapid increase of ethanol concentration in peels and flesh contributes to rotting of the banana. Specifically, occurrence of some compounds, including 1,2-dimethoxybenzene, 3,4-dimethoxybenzaldehyde, and isoeugenol, is an important feature of banana rotting. The decrease of 3-hydroxy-4-methoxybenzaldehyde concentration signifies a weakening of antiseptic, bactericidal, fungicidal, and antioxidant properties of banana. Besides, the principal component analysis (PCA) has been implemented in the discrimination of banana odor at different days of storage.
摘要：
Phytic acid, containing a myoinositol ring coupled with six phosphate groups, can react with the amino groups of collagen to regulate their self-assembly behavior. The aim of this research is to evaluate the effects of phytic acid on the selfassembly behavior of collagen, the structures and properties of the resulting fibrils and hydrogels. Turbidity and chloramine T assay suggested that phytic acid could improve the self-assembly kinetics and degree of collagen, and the optimal ratio of phytic acid/collagen was 1/1 (w/w). Scanning electron microscopy (SEM) analysis indicated that co-fibrils of collagen with phytic acid are more slender than that of pure collagen, and transmission electron microscopy (TEM) reveals that the characteristic D-periodicity of collagen fibrils is not affected by phytic acid. Besides, differential scanning calorimetry (DSC) and rheology revealed that the thermal stability of collagen fibrils and the viscoelasticity of collagen hydrogels could be improved by phytic acid and the optimal ratio of phytic acid/collagen is 1/1 (w/w).
通讯机构：
[Xie, Dong] I;Indiana Univ Purdue Univ, Purdue Sch Engn & Technol, Dept Biomed Engn, Indianapolis, IN 46202 USA.
关键词：
Dimethacrylamide;photopolymerization;degree of conversion;compressive strength
摘要：
A dimethacrylamide was synthesized and used to formulate with the selected (meth)acrylates to form the in situ photocureable resins and composites. The effects of the selected comonomers with different functional groups on polymerization rate, degree of conversion, gel time, and compressive strength were investigated. The results show that in situ photopolymerization of the synthesized dimethacrylamide with comonomers having an electron-withdrawing and/or acrylate group dramatically increased the polymerization rate, degree of conversion, and compressive strength. On the other hand, an electron-donating group on either carbon-carbon double bond or ester linkage slowed down the polymerization. In contrast, the triethylene glycol dimethacrylate-based system did not show a clear pattern. The synergistic effect of the strong hydrogen-bonding between dimethacrylamide and organic acid groups may be responsible for higher compressive strengths. The formed composites showed the similar trend in compressive strength to the corresponding resins. Within the limitation of this study, it seems that in situ photopolymerization of dimethacrylamide or diacrylamide can be greatly accelerated by copolymerization with monomers having electron-withdrawing and/or acrylate groups. The monomers with methacrylate group can significantly reduce the polymerization rate and degree of conversion.
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：
Self-assembled environment of collagen is one of the important factors for improving and regulating the properties of collagen-based biomaterials. This study aimed to investigate the effect of ionic liquids (ILs) on the fibril-formation and gel properties of grass carp (Ctenopharyngodon idellus) skin collagen. Fibrillogenic kinetics analysis showed that the collagen self-assembly can be suppressed by the introduction of ILs, and the inhibitory effect is influenced by concentration and types of ILs. Scanning electron microscopy test indicated that the assembled collagen fibrils in the presence of ILs had bigger diameters than that in the conventional buffer. Differential scanning calorimetry analysis revealed that the thermal stability of collagen fibrils can be significantly increased when self-assembly is performed in the presence of ILs. Moreover, the introduction of ILs enhanced the mechanical strength of collagen gels. Finding from this work provides a new idea for improving the performance of fish-sourced collagen biomaterials.
摘要：
Several new urethane-based dimethacrylates were synthesized, characterized and used to formulate the resin composites. Compressive strength (CS) was used as a screen tool to evaluate the mechanical property of the formed composites. Flexural strength, diametral tensile strength, water sorption, degree of conversion and shrinkage of the composites were also evaluated. The results show that most of the synthesized urethane-based dimethacrylates were solid, which are not suitable to dental filling restorations. However, it was found that liquid urethane-based dimethacrylates could be derivatized using asymmetrical methacrylate synthesis. Not only the newly synthesized urethane-based dimethacrylates showed lower viscosity values but also their constructed composites exhibited higher mechanical strengths. Without triethyleneglycol dimethacrylate (TEGDMA) addition, the new urethane-constructed composites showed significantly lower water sorption and shrinkage.
摘要：
Gel matrices of mammalian collagen are routinely used as bioengineering materials and food thickening agents, for which the modulation of their mechanical properties is a key issue. However, little information is available regarding gel matrices based on fish-sourced collagen, which offer unique advantages for some applications. Here, a rheology assay, which is the most commonly used method for monitoring developing gels, was used to systematically reveal the influence of environmental parameters on the gelation dynamics and rheological properties of pepsin-soluble collagen (PSC) extracted from snakehead (Channa argus) skins. The gelation dynamics and equilibrium elastic moduli of PSC were affected by concentration, temperature, pH, buffer, and ion strength and type. SEM and TEM images of gels at different concentrations and incubation temperatures confirmed that the mechanical properties of PSC gels are directly related to the density, rather than size, of fibrils. Additionally, the relationship between the biological and mechanical properties of these collagen gels was also evaluated. The present study would facilitate a better understanding of the gelation of fish-sourced collagen and enable more precise control of the mechanical properties of these gel matrices.
