PDLLA/HA/FK506复合神经导管的制备及体外降解性能

以聚乳酸（PDLLA）为基材、纳米羟基磷灰石（HA）为添加剂、加入免疫抑制剂FK506，用溶剂挥发法制备PDLLA／HA/FK506复合神经导管。通过观察复合导管在磷酸缓冲溶液中降解时pH值变化、质量损耗及材料微观形貌，研究了该复合导管的体外降解性能。结果表明：加入适量纳米羟基磷灰石可以改善聚乳酸降解的酸性问题并提高其力学强度。免疫抑制剂FK506的加入对导管材料的降解性能有一定的影响。PDLLA/HA／FK506复合神经导管具有良好的降解性能。     

模拟体液中纳米羟基磷灰石/壳聚糖的制备及表征

从仿生合成的思路出发,分别以模拟体液和含有壳聚糖的模拟体液为反应介质,通过磷酸和硝酸钙反应合成了羟基磷灰石(HAp)和HAp/壳聚糖复合粉体,利用TG-DTA、XRD、FT-IR和TEM等对HAp和HAp/壳聚糖的形成过程、结构及其微观形貌进行了研究.结果表明,在模拟体液中合成的HAp粉体呈现出球状和短棒状形态;HAp/壳聚糖复合粉体呈现出不规则形状,粒度<100 nm,主要晶相为羟基磷灰石.体外生物活性实验结果表明,HAp/壳聚糖复合材料比纯HAp具有更好的生物活性,具有较强的诱导磷灰石沉积能力.     

Preparation and Degradation Characteristics of Poly （d,l-lactide） Composite Films

PDLLA/CHI/β-TCP/NGF composite films were prepared by a solvent evaporation method. The degradation characteristics of the poly （d, l-lactide） composite films were studied in vitro and in vivo. The acidity produced by poly （d, l-lactide） materials was not obvious. Adding chitosan and β-TCP can relieve the acidity problem and improve strength performance of films. The NGF has influences on the degradation characteristics of films. It is verified that PDLLA/CHI/β-TCP/NGF composite films prepared by solvent evaporation method have excellent degradation characteristics. It can be used as a perfect biomaterial for repairing nerve injuries.     

Preparation and Swelling Behavior of Physically Crosslinked Hydrogels Composed of Poly（vinyl alcohol） and Chitosan

The physically crosslinked poly（vinyl alcohol）/chitosan （CS） composite hydrogels were prepared by cyclic freezing/thawing techniques, and the microstructure and swelling behavior of the hydrogels in the simulated gastric （pH 1.0） and intestinal （pH 7.4） media were investigated. The experimental results of infrared spectra （IR）, scanning electron microscope （SEM） and differential scanning calorimetry （DSC） demonstrated that poly（vinyl alcohol） and chitosan had good miscibility in the composite hydrogels, and the addition of chitosan perturbed the formation of poly（vinyl alcohol） crystallites. The swelling kinetics results indicated that the composite hydrogels had good pH sensitive properties to the acidic environments, and with the increase of chitosan content in the blend, the maximum swelling degreed and the swelling rate both increased, but it led to more dissolution at pH 1.0. And the composite hydrogels also exhibited good reversible swelling behavior with pH value of the swelling medium altering between 1.0 and 7.4. In addition, the higher freezing/thawing cycle times resulted in the lower swelling rate. Therefore, the swelling behavior of the composite hydrogels could be adjusted by changing the chitosan contents and the freezing/thawing cycle times.     

可吸收 HA/PDLLA 内固定材料组织相容性观察

可吸收骨折内固定材料要求具有很好的组织相容性。本文将自行研制的可吸收羟基磷灰石／聚ＤＬ乳酸（ＨＡ／ＰＤＬＬＡ）内固定材料植入兔肌肉和骨组织中,于３、６、１２、２４、３６、５２周取材,作ｘ线摄片和组织学观察。结果：骨折在６周内正常愈合,５２周内组织反应较轻,无大量炎性细胞集聚。结论：ＨＡ／ＰＤＬＬＡ复合材料具有很好的组织相容性。     

In vitro characterization of PBLG-g-HA/ PLLA nanocomposite scaffolds

The purpose of the present study was to synthesize a new composites scaffold containing poly(γ-benzyl-L-glutamate) modified hydroxyapatite/(poly(L-lactic acid))(PBLG-g-HA/PLLA) and to investigate their in vitro behaviour on bone mesenchymal stromal cells(BMSCs). The results demonstrated that BMSC proliferation was signifi cantly increased on PBLG-g-HA/PLLA scaffolds after 3 and 7 days post seeding when compared to PLLA and HA/PLLA scaffolds. The in vitro osteogenic differentiation also favoured the composite PBLG-g-HA/PLLA scaffolds when compared to controls by signifi cantly increasing Runx2, ALP or osteocalcin mRNA expression as assessed by real-time PCR. The results illustrate the potential of PBLG-g-HA/PLLA scaffolds for bone tissue engineering applications. And the in vivo testing further confi rms the PBLG-gHA/PLLA scaffolds' potentioal for healing critical bone defects.     

Preparation and Evaluation of an Injectable Chitosan-Hyaluronic Acid hydrogel for Peripheral Nerve Regeneration

The aim of this study was to obtain the fillers in the lumen of hollow nerve conduits(NCs) to improve the microenvironment of nerve regeneration. A p H-induced injectable chitosan(CS)-hyaluronic acid(HA) hydrogel for nerve growth factor(NGF) sustained release was developed. Its properties were characterized by gelation time, FT-IR, SEM, in vitro swelling and degradation. Furthermore, the in vitro NGF release profiles and cell biocompatibility were also investigated. The experimental results show that the CS-HA aqueous solution can undergo a rapid gelation 3 minutes after its environmental p H is changed to 7.4. The CSHA hydrogel has interconnected channels with a controllable pore diameter and with a porosity of about 80%. It has a favorable swelling behavior and can be degraded by about 70% within 8 weeks in vitro and is suitable for NGF release. The CS-HA/NGF hydrogel exhibits a lower cytotoxicity and is in favor of the adhesion and proliferation of the BMMSCs cells. It is indicated that the CS-HA/NGF will be a promising candidate for neural tissue engineering.     

In vitro biomineralization of glutaraldehyde crosslinked chitosan/glutamic acid films

In vitro biomineralization of glutaraldehyde crosslinked chitosan/glutamic acid films were studied. IR and ESCA (electron spectroscopy for chemical analysis) determinations confirm that chitosan and glutamic acid are successfully crosslinked by glutaraldehyde to form chitosan-glutamic acid surfaces. Composite films were soaked in saturated Ca(OH)₂ solution for 8 d and then immersed in simulated body fluid (SBF) for more than 20 d. Morphological characterizations and structure of calcium phosphate coatings deposited on the films were studied by SEM, XRD, and EDAX (energy dispersive X-ray analysis). Initially, the treatment in SBF results in the formation of single-layer calcium phosphate particles over the film surface. As immersion time increases, further nucleation and growth produce the simulated calcium-carbonate hydroxyapatite coating. ICP results show Ca/P ratio of calcium phosphate coating is a function of SBF immersion time. The inducing of glutamic acid improves the biomineralization property of chitosan films. Funded by the Natural Science Foundation of Shanghai (No. 04ZR14087)     

Synthesis and Characterization of Core-shell Hydroxyapatite/chitosan Biocomposite Nanospheres

Novel core-shell hydroxyapatite/chitosan biocomposite nanospheres were synthesized in a multiple emulsion. The multiple emulsion was a w/o/w emulsion, made of diammonium phosphate solution as an inner aqueous phase, cyclohexane as an oil phase, and calcium nitrate solution and chitosan solution as an outer aqueous. The forming mechanism of core-shell spheres and the influence of temperature on the morphology of the nanospheres were investigated. The diameter of the resulting core-shell nanospheres was 100-2...     

Preparation of a Novel Calcium Phosphate Cement Using N-methylene Phosphonic Chitosan as a Gelling Agent

1Introduction Self hardeningcalciumphosphatecements(CPC)consistingoftetracalciumphosphate(TTCP)anddicalci umphosphate(DCPAorDCPD)havebeendeveloped since1986.ThereactionbetweenDCPAandTTCPis[1]:2CaHPO4 2Ca4(PO4)2OH2OCa10(PO4)6(OH)2.CPC isreadilyosseointegra…     

Biodegradation of Absorbable Hydroxyapatite／Poly—DL—lactide COmposites in Different Environment

To develop a new generation of absorbable fracture fixation devices with enhanced biocompatibility,the biodegradation mechanism and its influence on the cellular response at the tissue/implant interfoce of hydroxyapatite/poly-DL-lactide(HA/PDLLA) composites were investigated in vitro and in vivo.HA/PDLLA rods were immersed in phosphate-buffered saline,or implanted in muscle and bony tissue for 52 weeks.Scanning electron microscopic and histological studies were done.The degradation rate was the slowest in vitro,slower in muscle tissue and fast in bone.In vitro,the composites degraded heterogeneously and a hollow structure was formed.In bone,the limited clearing capacity leads to the accumulation of oligomeric debris,which contribute totally to the autocatalytic effect.So,the fastest degradation and intense tissue response were seen.In muscle tissue,oligomeric debris migratred into vicinal fibers over a long distance from the original implant cavity and the tissue reactions were,however,quite moderate.For the same size organic/inorganic composite,the environment where it was placed is the major factor in determining its biodegradation process and cellular reaction.In living tissue,tactors such as cells,enzymes and mechanical stress have an obvious influentce on the biodegradation and biological process at the tissue/implant interface,The biocompatibility of the HA/PDLLA composistes is enhanced with the incorporating of the resorbable HA microparticles.     

In vitro and in vivo characterization of homogeneous chitosan-based composite scaffolds

With a homogeneous distribution of hydroxyapatite (HAP) crystals in polymer matrix, composite scaffolds chitosan/ HAP and chitosan/collagen/HAP were fabricated in the study. XRD, SEM and EDX were used to characterize their components and structure, in vitro cell culture and in vivo animal tests were used to evaluate their biocompatibility. HAP crystals with rod-like shape embeded in chitosan scaffold, while HAP fine-granules bond with collagen/chitosan scaffold compactly. A homogenous distribution of Ca and P elements both in chitosan/HAP scaffold and chitosan/collagen/HAP scaffold was defined by EDX pattern. The presence of collagen brought a more homogenous distribution of HAP due to its higher ability to induce HAP precipitation. The results of in vitro cell culture showed that the composite’s biocompatibility was enhanced by the homogenous distribution of HAP. In vivo animal studies showed that the in vivo biodegradation was effectively improved by the addition of HAP and collagen, and was less influenced by the homogeneous distribution of HAP when compared with a concentrated distribution one. The composite scaffolds with a homogeneous HAP distribution would be excellent alternative scaffolds for bone tissue engineering.     

Protein adsorption behaviors on chitosan/poly(ɛ-caprolactone) blend films studied by quartz crystal microbalance with dissipation monitoring (QCM-D)

Chitosan/poly(ɛ-caprolactone) (PCL) blend films in different mass ratios were prepared using the chitosan/PCL mixture solutions in 80 vol.-% acetic acid by spin coating. Their surface micromorphologies were assessed by atomic force microscopy (AFM). It was found that the micromorphology of chitosan/PCL blend films was in large extent related to the mass ratio of chitosan. 25 wt% chitosan/PCL blend film presented microphase separation. The protein adsorption of bovine serum albumin (BSA) onto chitosan/PCL blend films was investigated by using quartz crystal microbalance with dissipation monitoring (QCM-D) in real time. The results suggested that the amount of adsorbed BSA on the chitosan/PCL blend films decreased with the addition of chitosan, but the structure and viscoelastic properties of the adsorbed BSA layers were greatly affected by the surface micromorphology of chitosan/PCL blend films. BSA absorbed on the 25 wt% chitosan/PCL blend film with microphase separation showed larger adsorption reversibility, and preferred to form a loose, dissipative layer in comparison with those on other chitosan/PCL blend films without microphase separation. Supported by the National Natural Science Foundation of China (Grant No. 20504018) and the National High Technology Research and Development Program of China (863 Program) (Grant No. 2007AA09Z440)     

BIODEGRADATION AND MECHANICAL PROPERTIES OF HYDROXYAPATITE/POLY-DL-LACTIDE COMPOSITES FOR FRACTURE FIXATION

The biodegradation and mechanical properties of self-designed hydroxyapatite/poly-DL-lactide (HA/PDLLA) compositites -were investigated in vitro and invio. In vitro, the specimens of HA/PDLLA and unfilled PDLLA -with similar molecular weights were immersed in phosphate-buffered saline. Ageing of the various devices were monitored by measuring molecular weight,water absorption, weight loss, PH, mechanical strengths and mi-crostructural changes. The follow-up times were 2, 4 , 6 , 8, 10 and 12 weeks. In vivo, a transverse transcondylar osteotomy of the distal femur was fixed with a HA/PDLLA rod (diameter, 4. 5mm;length, 30-40mm). The follow-up times were 3. 6 and 12 weeks. Roentgenographic, histologic, and biomechanical studies were carried out. The results show that the HA/PDLLA composities have higher mechanical strength and slower degradation than that of the unfilled PDLLA and that of all osteotomies unite within six weeks without delay. Consequently, the HA/PDLLA composites possess sufficient mechani     

聚乳酸/羟基磷灰石复合材料微球的制备及表征

以聚乳酸（PLA）为基体,羟基磷灰石（HA）作为无机填料,制备含HA质量分数分别为0%、10%和25%的聚乳酸/羟基磷灰石（PLA/HA）复合材料,采用喷雾干燥技术制备复合材料微球。并对其进行微观形貌和结构表征,进一步研究HA质量分数对热稳定性能的影响。傅里叶红外光谱、X射线衍射和X射线光电子能谱测试表明,已成功制备了PLA/HA复合材料微球,其粒径分布在5~11 μm范围内,且随着HA质量分数的增加,复合材料的玻璃化转变温度呈现先降低后升高的趋势,同时其分解温度升高,热稳定性能增加。     

Periodontal ligament cells cultured on the tricalcium phosphate/chitosan scaffolds in vivo and in vitro

To search suitable scaffolds for periodontal tissue regeneration, different ratios of tricalcium phosphate/chitosan(TCP/chitosan) scaffolds were prepared through a freeze-drying process. Human periodontal ligament cells(HPLCs) were incubated on the scaffolds in vitro. Cells were cultured on the scaffolds, detected by scanning electron microscopy (SEM). HPLCs were analyzed by MTT assay and alkaline phosphatase(ALP) activity detection. HPLCs were seeded onto the scaffolds. Then these scaffolds with HPLCs were implanted subcutaneously into athymic mice. The state of periodontal tissue regeneration was detected after 4 weeks. As the ratio of TCP increased, TCP/chitosan scaffolds accelerated HPLCs proliferation significantly higher than the pure chitosan scaffold. HPLCs produced the cementoid tissue in vivo. The periodontal tissue regeneration engineering is able to be applied with TCP/chitosan scaffolds.     

壳聚糖/羧甲基壳聚糖止血膜的制备与表征

针对壳聚糖止血膜柔韧性差的问题,以丙三醇和酚磺乙胺作为改性剂,采用溶液浇膜的方法制备了不同组成配比的壳聚糖(CS)/羧甲基壳聚糖(CMCS)止血膜,并评价了CS/CMCS止血膜拉伸性能和止血效果.丙三醇的引入可使CS/CMCS止血膜的断裂伸长率提高4~7倍,尽管其拉伸强度也降低了70%.丙三醇改性的CS/CMCS=8/2载药止血膜具有较好的拉伸强度(10.4±0.9 MPa)和断裂伸长率(50.4±4.5%);与未加入酚磺乙胺的CS/CMCS止血膜相比,酚磺乙胺的离子交联作用使CS/CMCS载药止血膜的拉伸强度提高55%,而断裂伸长率仅降低24%.止血评价结果表明经丙三醇改性的CS/CMCS=8/2止血膜均能使血液发生分离的时间明显缩短,并具有促使血液凝结形成黑色血块的能力.     

Preparation of new tissue engineering bone-CPC/PLGA composite and its application in animal bone defects

To investigate the feasibility of implanting the biocomposite of calcium phosphate cement (CPC)/polylactic acid-polyglycolic acid (PLGA) into animals for bone defects repairing, the biocomposite of CPC/PLGA was prepared and its setting time, compressive strength, elastic modulus, pH values, phase composition of the samples, degradability and biocompatibility in vitro were tested. The above-mentioned composite implanted with bone marrow stromal cells was used to repair defects of the radius in rabbits. Osteogenesis was histomorphologically observed by using an electron-microscope. The results show that compared with the CPC, the physical and chemical properties of CPC/PLGA composite have some differences in which CPC/PLGA composite has better biological properties. The CPC/PLGA composite combined with seed cells is superior to the control in terms of the amount of new bones formed after CPC/PLGA composite is implanted into the rabbits, as well as the speed of repairing bone defects. The results suggest that the constructed CPC/PLGA composite basically meets the requirements of tissue engineering scaffold materials and that the CPC/PLGA composite implanted with bone marrow stromal cells may be a new artificial bone material for repairing bone defects because it can promote the growth of bone tissues.     

Preparation and characterization of PDLLA/chondroitin sulfate /chitosan scaffold for peripheral nerve regeneration

A novel bioactive and bioresorbable PDLLA/chondroitin sulfate/chitosan scaffold was prepared via layer-by-layer（LBL） electrostatic-self-assembly （ESA） and the thermally induced phase separation （TIPS） technique. Chondroitin sulfate and chitosan were alternately deposited on the activated PDLLA substrate. The deposition process was monitored by UV-Vis absorbance spectroscopy. After frozen and lyophilized, the scaffold was characterized by attenuated total reflection （ATR）-FT-IR, XPS, SEM and AFM. The results showed that the scaffold was modified uniformly with a dense inner layer with few detectable pores and a porous sponge outer layer with the pore size about 5 μm, there was an obvious across section and the average thickness of each layer was about 9.4 nm.     

镁合金表面HA/CNTs涂层的制备及电化学性能研究

为了提高生物镁合金羟基磷灰石(HA)涂层的耐蚀性能,在微弧氧化电解液中加入羟基磷灰石/碳纳米管(HA/CNTs)复合粉体添加剂,制备HA/CNTs复合涂层。分别对制备的HA/CNTs复合粉体和HA/CNTs复合涂层进行表面形貌和物相组成分析,并对HA/CNTs复合涂层在模拟体液(SBF)中的耐腐蚀性能进行了研究。结果表明,HA/CNTs复合粉体在微弧氧化过程中能均匀地沉积在镁合金表面,结晶良好且无任何杂质;与HA涂层相比,HA/CNTs涂层具有较小的腐蚀电流密度值和较大的阻抗值。此外,在SBF中浸泡4d后,HA/CNTs复合涂层表面出现大量的亚微米级颗粒产物且没有任何腐蚀裂纹。