Fumarate Copolymer–Chitosan Cross‐Linked Scaffold Directed to Osteochondrogenic Tissue Engineering

Natural and synthetic cross‐linked polymers allow the improvement of cytocompatibility and mechanical properties of the individual polymers. In osteochondral lesions of big size it will be required the use of scaffolds to repair the lesion. In this work a borax cross‐linked scaffold based on fumarate‐vinyl acetate copolymer and chitosan directed to osteochondrondral tissue engineering is developed. The cross‐linked scaffolds and physical blends of the polymers are analyzed in based on their morphology, glass transition temperature, and mechanical properties. In addition, the stability, degradation behavior, and the swelling kinetics are studied. The results demonstrate that the borax cross‐linked scaffold exhibits hydrogel behavior with appropriated mechanical properties for bone and cartilage tissue regeneration. Bone marrow progenitor cells and primary chondrocytes are used to demonstrate its osteo‐ and chondrogenic properties, respectively, assessing the osteo‐ and chondroblastic growth and maturation, without evident signs of cytotoxicity as it is evaluated in an in vitro system.

     

Modification of acrylic bone cements by poly(ethylene glycol) with different molecular weight

The high polymerization temperature of acrylic bone cements can cause arthroplasty failure because of the thermal necrosis of surrounding bone tissue. To reduce this undesired effect we have developed novel acrylic bone cement composites containing a phase change material (PCM). As PCM poly(ethylene glycol) (PEG) of different molecular weight was applied and the effect of its incorporation on curing parameters, mechanical and morphological properties of acrylic bone cement was investigated. A significant decrease in maximum temperature from 65.8°C to 47.4°C and slight increase of setting time were observed. PEG introduction also contributed to the thermal stability of acrylic bone cement increase. SEM investigation of modified bone cement confirmed that the microstructure does not alter considerably because of PEG content. It was found that both PEG addition and incubation test contribute to an inconsiderable decrease in mechanical strength of bone cement. However, the mechanical strength increase can be caused by the fresh bone tissue incorporation into the pores appearing in bone cement. Copyright © 2016 John Wiley & Sons, Ltd.     

Decomposition of in vivo spatially offset Raman spectroscopy data using multivariate analysis techniques

The decomposition of spatially offset Raman spectra for complex multilayer systems, such as biological tissues, requires advanced techniques such as multivariate analyses. Often, in such situations, the decomposition methods can reach their limits of accuracy well before the limits imposed by signal‐to‐noise ratios. Consequently, more effective reconstruction methods could yield more accurate results with the same data set. In this study we process spatially offset Raman spectroscopy (SORS) data with three different multivariate techniques (band‐target entropy minimization (BTEM), multivariate curve resolution and parallel factor analysis (PARAFAC)) and compare their performance when analysing a spectrally challenging plastic model system and an even more challenging problem, the analysis of human bone transcutaneously in vivo. For the in vivo measurements, PARAFAC's requirement of multidimensional orthogonal data is addressed by recording SORS spectra both at different spatial offsets and at different anatomical points, the latter providing added dimensionality through the variation of skin/soft tissue thickness. The BTEM and PARAFAC methods performed the best on the plastic system with the BTEM more faithfully reconstructing the major Raman bands and PARAFAC the smaller more heavily overlapped features. All three methods succeeded in reconstructing the bone spectrum from the transcutaneous data and gave good figures for the phosphate‐to‐carbonate ratio (within 2% of excised human tibia bone); the PARAFAC gave the most accurate figure for the mineral‐to‐collagen ratio (20% less than excised human tibia bone). Previous studies of excised bones have shown that certain bone diseases (such as osteoarthritis, osteoporosis and osteogenesis imperfecta) are accompanied by compositional abnormalities that can be detected with Raman spectroscopy, the utility of a technique which could reconstruct bone spectra accurately is manifest. The results have relevance on the use of SORS in general. © 2014 Crown copyright. Journal of Raman Spectroscopy published by John Wiley & Sons, Ltd.     

Fabrication of Nanofiber Scaffolds With Gradations in Fiber Organization and Their Potential Applications

A new and simple method for fabrication of nanofiber scaffolds with gradations in fiber organization is reported. The nanofiber organization, achieved by deposition of random fibers on the uniaxially aligned nanofiber mat in a gradient manner, directed morphological changes of applied adipose‐derived stem cells. These morphological changes and resultant biochemical changes can help mimic the structural orientation of complex biomechanical structures like the collagen fiber structure at the tendon‐to‐bone insertion site. In addition, chemical gradients can be established through nanoencapsulation in this novel scaffold allowing for enhanced biomedical applications.

     

骨靶向抗肿瘤药物中间体N-Boc-N’-3,3-双(二乙氧膦酰基)丙基甘氨酰胺的合成

采用缩合、Michael加成、氢化还原和偶联等多步应合成了骨靶向抗肿瘤药物的关键中间体——N-Boc-N’-3,3-双(二乙氧膦酰基)丙基甘氨酰胺,其结构经1H NMR,13C NMR,IR和MS确证。     

大豆异黄酮对骨质疏松模型大鼠骨量及微观结构的影响

为研究大豆异黄酮（SI）对骨质疏松模型大鼠骨量及微观结构的影响,将46只雌性SD大鼠双侧摘除卵巢,术后一周按血清总胆固醇水平随机分为5组,分别给予雌激素,低、中、高剂量SI干预并设正常对照组,实验周期为12周,灌胃给药,每周称质量一次,分别在去卵巢、给药4、8周处死时抽取尾静脉血,实验结束后分别测定血清碱性磷酸酶（AKP）活性及骨密度等指标。结果表明,高剂量SI干预对维持大鼠骨密度的作用与雌激素相似,去卵巢后干预SI可提高碱性磷酸酶（AKP）活性并能缓解因去卵巢造成的骨丢失,全视野下骨形态学以雌激素组、高剂量SI干预组与正常组结构最为接近。提示大豆异黄酮对骨质疏松模型大鼠的骨量及微观结构存在一定影响,中、高剂量干预可使骨质疏松模型大鼠血清AKP酶活性增加、逆转因去势造成的骨密度下降,考虑到植物雌激素与哺乳动物的雌激素受体（ER）结合能力低下,采用SI在临床开展干预的剂量与远期效果尚待进一步论证。     

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.     

聚己内酯-天然骨粉生物医用复合材料的制备和性能

采用熔融共混法制备了不同天然骨粉含量的聚己内酯-天然骨粉（PCL-BP）生物医用复合材料,并通过力学实验、表面亲水性分析、差示扫描量热分析和热重分析对复合材料的性能进行了表征。结果表明：随着天然骨粉含量的增加,复合材料的拉伸和弯曲强度先增加后降低,其表面亲水性得以改善。此外,复合材料的结晶温度升高,熔融焓降低,热稳定性...