兔皮Ⅰ型胶原的提取、改性与性能研究

采用酸溶、酶溶相结合的方法,从兔皮中提取了胶原蛋白.通过SDS-PAGE对其进行定性分析,利用FT-IR及TG/DTG表征其理化性能.结果表明,所提胶原为I型胶原,保持了完整的三股螺旋结构;热处理过程中,在100℃之前,200～450℃之间和450℃以后有3次明显失重.经戊二醛交联改性后,该胶原的含水量为(78.7±1.3)%,酶降解率从(88.65±0.11)%降为(6.03±0.38)%(p0.01).采用细胞生长抑制法测定了改性胶原对小鼠胚胎成纤维细胞(MEF-WT)的细胞毒性.结果表明,改性胶原对MEF-WT细胞无明显毒性,毒性评价为0级或1级.该胶原可用于组织工程.     

FTIR analysis of natural and synthetic collagen

Collagen is the most abundant protein in humans and animals, comprising of one third of the total proteins that accounts for three quarters of the dry weight skin in humans. Collagen containing a range of proteins has been reported for tissue engineering applications, but, only a small number of studies related to chemical structure evaluation of collagen are found in the literature. Collagen can be obtained from both the natural and synthetic sources and offers a wide range of biomedical applications due to its excellent biocompatibility and low immunogenicity. Hence, it is important to identify chemical structural properties of collagen and Fourier transform infrared (FTIR) appears to be a technique of choice to study their chemical structure. This review aims to highlight the use of FTIR to study collagen-based biomaterials, using it for characterization of collagen extracted from various sources. Characterization of collagen-based materials used in wound healing, skin substitutes, derma fillers, and aging of skin, collagen containing drug delivery agents, collagen-based materials used in tissue engineering, bone regeneration, and osteogenic differentiation is discussed in detail. FTIR analysis of collagen-containing materials used for dental applications, cleft-palate, and in alveolar-ridge preservation has also been highlighted.     

Novel Biologically Inspired Collagen Nanofibers Reconstituted by Electrospinning Method

The possibility to prepare bioinspired collagen nanofibers by electrospinning from aqueous suspension of telopeptide-free collagen molecules avoiding both organic solvents and blends with any synthetic and natural polymers has been investigated. The results have highlighted the need for a basic atmosphere between the needle and the ground collector in order to increase the environmental pH during the collagen molecules self-assembly along the electrostatic force lines. Morphological, spectroscopic and calorimetric analyses carried out on the electrospun collagen nanofibers have opened the possibility to take advantage of this new approach in order to prepare an ideal biomimetic reinforcing component of new biomedical and surgical biomaterials.     

TGase对海地瓜胶原蛋白凝胶强度的影响

为了研究海地瓜胶原蛋白的凝胶特性,提高其凝胶强度,探讨了谷氨酰胺转氨酶(TGase)对海地瓜胶原蛋白凝胶特性的影响,在单因素的基础上采用响应面设计对影响凝胶特性的3个显著因素（TGase添加量、作用时间、作用温度）进行优化.结果显示:单因素实验时,海地瓜胶原蛋白的凝胶强度在TGase添加量18.0 U/g、作用时间5.0 h、作用温度40.0 ℃时达到最大;通过响应面优化,得到海地瓜胶原蛋白凝胶强度在TGase添加量18.00 U/g、作用时间5.13 h和作用温度40.30 ℃时达到最大,为6473.98 g·mm,是未优化前凝胶强度5511.50 g·mm的1.17倍,是未添加TGase前凝胶强度1118.88 g·mm的5.79倍,即TGase能够促进蛋白质之间的交联作用,显著提高海地瓜胶原蛋白凝胶强度.经过验证性试验,得到该条件下海地瓜胶原蛋白凝胶强度为6428.36 g·mm,与理论值相比,误差仅为0.70%.     

Viscosity of Collagen Solutions: Influence of Concentration,Temperature, Adsorption,and Role of Intermolecular Interactions

An investigation of the influences of the adsorption, electrolyte, shear rate, and temperature on the viscometric behavior of collagen solutions was performed using a photoelectric viscometer. The experimental results showed an abnormal behavior of the reduced viscosity (η_sp/C) of dilute collagen solutions measured by a viscometer with or without a hydrophobic surface treatment; the reduced viscosity increased with decreasing concentration. This phenomenon can be completely eliminated by increasing the concentration of an added salt. It indicated that the abnormal viscosity resulted from a long-ranged, inter-molecular electrostatic force. The reduced viscosity decreased as the shear rate increased. The shear-thinning cavitation phenomenon resulted from the high aspect ratio of the collagen molecules. The reduced viscosity of the collagen solutions increased with an increase in temperature, which was due to the association of collagen molecules at high temperature.     

Early results of transcutaneous injection laryngoplasty with micronized acellular dermis versus type-I thyroplasty for glottic incompetence dysphonia due to unilateral vocal fold paralysis

Medialization thyroplasty (type I) has become the gold standard to improve glottic closure due to unilateral vocal fold paralysis. A newer injection method utilizing homologous collagen from cadaveric human tissue has been described as an attractive alternative as no donor site is required, there is a very low risk of hypersensitivity, and the intact, acellular collagen fibers may suffer a reduced long-term reabsorption rate. Preliminary results on eight patients comparing presurgical and postsurgical parameters (perceptual, stroboscopic, acoustic, and aerodynamic) revealed comparable results when compared with a control group of individuals, age- and sex-matched, that had undergone standard medialization thyroplasty (type I). Further study is needed to assess the long-term results with this minimally invasive method of vocal fold medialization.     

Raman spectroscopy reveals differences in collagen secondary structure which relate to the levels of mineralisation in bones that have evolved for different functions

Bone is a composite material comprising a collagen fibril scaffold surrounded by crystals of carbonated‐hydroxyapatite mineral. It is well established that the relative proportions of mineral and collagen in mature bone are not definite and are adapted in order to ‘tune’ its mechanical properties. It is not known, however, how the mineral to collagen ratio is controlled. This paper uses Raman spectroscopy (which permits the probing of both the mineral and the collagen phases of bone) to explore the hypothesis that the control mechanism is related to the nature of the collagen and that bones with different levels of mineralisation have qualitatively different collagen. Raman spectra of functionally adapted bones with varying levels of mineralisation are presented and features that indicate the differences in the collagen's secondary structure (amide I band profiles) and post‐translational modification (hydroxyproline/proline ratios) are highlighted. The study demonstrates that Raman spectroscopy can provide a means to investigate the mechanisms that control the mineral to collagen ratio of bone. Understanding these mechanisms could pave the way towards the therapeutic alteration of the mineral to collagen ratio and, thus, the control of the mechanical properties of bone. Copyright © 2012 John Wiley & Sons, Ltd.     

二维红外相关光谱法研究温度对交联胶原结构的影响

采用傅里叶红外光谱和二维相关分析研究了改性前后胶原在升温(25～115℃)过程中结构的变化。结果显示,改性前后胶原的特征吸收峰强度降低,峰值向低波数移动,其中酰胺II带的变化最明显,降低了～10cm-1,表明维系胶原三股螺旋结构稳定的氢键被破坏,结构发生改变。在1 515cm-1处自相关峰强度最强,说明温度对酰胺II带的影响最大。与未改性胶原相比,改性胶原的相关程度更弱,表明改性胶原结构受温度影响要小,交联提高了胶原的热稳定性;改性后胶原结构变化的顺序也不一样。由此可见,二维红外相关分析法能提供由温度引起的胶原结构动态变化的微观信息,对进一步研究改性胶原结构和功能之间的关系有一定的意义。     

Preparation of bow tie–type methacrylated poly(caprolactone‐co‐lactic acid) scaffolds: effect of collagen modification on cell growth

A branched methacrylated poly(caprolactone‐co‐lactic acid) and methacrylated poly(tetramethylene ether glycol) (PTMG‐IEM) resins were synthesized. ¹H‐NMR spectroscopy, attenuated total reflectance Fourier transform infrared spectroscopy (ATR‐FTIR) spectroscopy, and gel permeation chromatography confirmed the chemical structures of copolymers. The photoinitiated polymerization of formulation composed of various amounts of methacrylated poly(caprolactone‐co‐lactic acid), PTMG‐IEM, poly(ethylene glycol) diacrylate, water, and photoinitiator were performed. The curing reactions were followed by photo‐DSC (Differential scanning calorimetry). Gel fraction was calculated from the insoluble part and found as ≥93%. Swelling and contact angles were measured, and all increased with the increasing amount of PTMG‐IEM in network formulations. In vitro degradation studies were performed at 37 °C in phosphate‐buffered saline (pH 7.4). Collagen‐modified polymers were also prepared and introduced as a bioactive moiety to modify the polymer to enhance cell affinity. To compare the cell adhesion affinity to the polymer with and without collagen, cell growth experiments were performed. The results showed that collagen improves the cell adhesion onto the polymer surface. With the increasing amount of collagen, cell viability increases 86% (ECV304, p < 0.05) and 83% (3 T3, p < 0.05). Copyright © 2011 John Wiley & Sons, Ltd.