载微球纳米羟基磷灰石/壳聚糖复合多孔支架的制备与表征

首先通过乳化法合成海藻酸钠/壳聚糖(ALG/CS)复合微球,然后将其与纳米羟基磷灰石/壳聚糖H(n-HA/CS)复合材料混合均匀,用气体发泡法制备了载微球复合组织工程支架.并用扫描电子显微镜(SEM)、傅立叶变换红外光谱仪(IR)以及转靶X射线仪(XRD)等方法对该载微球多孔支架进行分析和表征.结果表明:n-HA/CS复合材料中无机相均匀分散在连续有机基质中,复合前后两组分均未发生明显变化;制备的载微球多孔支架中孔隙分布均匀,孔间贯通性良好,孔隙率较高;而其中的微球均呈球状,直径分布在150～350μm之间;微球表面粗糙且有大量微孔,载药后将利于药物的释放;微球在整个支架中分布均匀,而且与n-HA/CS基体材料间亲和性较高.本研究将为骨或软骨缺损提供一种性能优良且具有药物缓释功能的组织工程支架.     

碳纤维/聚乳酸/壳聚糖三元多孔复合支架材料的制备及评价

利用溶液共混法以及冷冻干燥法制备了多孔碳纤维/聚乳酸/壳聚糖(CF/PLA/CS)三元复合生物材料,通过扫描电子显微镜(SEM)观察了其表面形貌特征,并对其细胞相容性进行了评价.实验结果表明,利用上述复合方法制备的三维多孔材料的孔径为20～500μm,孔分布均匀,孔与孔之间相互连通;碳纤维的分散、冷冻干燥温度对材料结构影响较大,随冷冻温度的降低,支架的孔隙变小、变规则,内部结构趋向均一,孔隙率有所降低;该材料与细胞具有较好的相容性,符合组织支架材料的基本要求.     

PDGF/BMP-2-CMs/nHA/PLGA复合支架的制备及性能

将壳聚糖缓释微球与可降解多孔支架复合,构建可次第释放不同生长因子的骨组织工程支架,并进行表征和性能研究。首先,制备载骨形态发生蛋白-2的壳聚糖微球(BMP-2-CMs),然后将微球与纳米羟基磷灰石/羟基乙酸(nHA/PLGA)及血小板衍生生长因子(PDGF)按照一定的比例混合,通过粒子沥虑-冷冻干燥复合工艺制备PDGF/BMP-2-CMs/nHA/PLGA复合支架。BMP-2-CMs呈规则球形,粒径分布在4~10μm之间,BMP-2包封率为65.9%,载药量为0.134%。PDGF/BMP-2-CMs/nHA/PLGA复合支架孔径为100~200μm,孔隙率为51.2%,抗压强度为7.7MPa,8周降解率为20.1%。7d时,PDGF和BMP-2累计释放率分别为75.0%和42.2%;14d时,PDGF和BMP-2累计释放率分别为79.9%和53.5%。分析可知,复合支架中释放的PDGF和BMP-2能够持续有效地促进人脐静脉血管内皮细胞(HUVEC)和成骨细胞(MG63)的增殖和分化,具有良好的生物活性。由此可得,PDGF/BMP-2-CMs/nHA/PLGA复合支架能够次第释放PDGF和BMP-2,且能够显著促进HUVEC和MG63的增殖和分化。     

胶原/壳聚糖/羟基磷灰石复合微球的制备及表征

首先探讨了实验参数对胶原/壳聚糖复合微球的影响,确定了胶原/壳聚糖的最佳理论质量配比以及戊二醛和氢氧化钠的最佳加入量。随后,在上述最佳条件的基础上,采用分散乳化法制备了具有不同羟基磷灰石(HA)含量的胶原/壳聚糖/HA三组分复合微球。采用傅里叶变换红外光谱(FT-IR)和扫描电子显微镜(SEM)对微球进行了表征,并探讨了HA的含量对微球组成、形态和分散性的影响。结果表明,复合微球的分散性随着HA含量的增加而逐渐提高。当HA含量为30%时,可以获得球形规则、分散性高且粒径分布均匀的复合微球,所得微球的平均粒径约为5μm。然而,当HA含量超过30%时会导致微球的球形呈现不规则的特征。     

静电喷雾法制备壳聚糖/康普瑞丁载药微球

本研究采用静电喷雾法,以壳聚糖为基质材料,康普瑞丁为模型药物制备微球。实验中采用AcOH/H2O和AcOH/H2O/EtOH两种溶剂,分析了微球形貌和粒径分布的影响因素,并且对CS-CA4微球的缓释性能进行了测定。结果表明,壳聚糖浓度、溶剂配比及乙醇和康普瑞丁的加入会使壳聚糖微球呈球状、中间塌陷的类球状、棒状等不同形貌,微球粒径存在较大差异;通过AcOH/H2O/EtOH复合溶剂将疏水性药物康普瑞丁载入壳聚糖微球,制备出的壳聚糖/康普瑞丁载药微球分散性好,粒径分布均匀,平均粒径仅为0.27μm;使用戊二醛蒸汽交联48h的微球缓释效果明显。     

壳聚糖/明胶复合微球的制备及对铬离子的吸附性能

壳聚糖具有较高的吸附性能,明胶高分子链上有氨基、羟基、羧基等活性基团,对六价铬Cr(Ⅵ)具有一定的吸附螯合作用。本工作采用乳化交联法制备壳聚糖/明胶复合微球,以微球对Cr(Ⅵ)的去除率为指标,通过正交实验优化微球制备条件,并利用扫描电镜对微粒形貌进行表征。在研究复合微球对水体中Cr(Ⅵ)的吸附性能时,考察了吸附剂用量、pH值、吸附时间、温度等因素对吸附容量的影响。结果表明,壳聚糖/明胶微球的最佳制备条件为壳聚糖/明胶质量比1∶2,乳化时间40 min,乳化剂span80用量6 mL,水油比1∶7(体积比),乳化温度60℃;最佳吸附条件为:吸附剂用量2 g/L,pH值4,温度35℃,吸附时间120 min,在该条件下微球对Cr(Ⅵ)的去除率为95.5%。     

载药壳聚糖缓释微球的制备及其释放研究

实验采用乳化交联法,使用复合交联剂(先用甲醛交联,再用戊二醛交联),制得盐酸四环素壳聚糖缓释微球,并考察不同分子量的壳聚糖、原料质量比、交联剂用量、复合交联剂用量、搅拌速度对微球的影响,筛选出最佳条件制备出戢药微球,并研究了该微球在扫描电镜和倒置式研究型显微镜下的形态及其在pH=7.4,温度为37℃时的释放规律.结果表明,采用复合交联剂的乳化交联法所制得的微球球形好,粒径分布为5～50μm之间,载药量为26.9%,包封率为56.3%,并且具有良好的缓释效果.     

纳米羟基磷灰石/壳聚糖复合微球的原位仿生制备及表征

为解决纳米羟基磷灰石/壳聚糖(nHA/CS)复合微球中nHA团聚及分散不均的问题, 本研究在油包水的乳液体系中, 原位仿生制备了nHA/CS复合微球, 并与共混法制备的nHA/CS复合微球进行了对比研究。利用扫描电镜(SEM)、X射线能谱(EDS)、X射线衍射(XRD)、红外(FTIR)和激光粒度仪等手段对不同微球的理化性能进行表征。结果表明: 相比共混法, 原位仿生制备的nHA/CS复合微球形态圆整均匀, 分散性好, 粒径分布较窄, 平均粒径为8.62 μm, nHA晶体均匀分布在微球内部及表面, 并与CS基质以化学键结合。该复合微球有望用于骨组织工程及药物控制释放。     

壳聚糖/羟基磷灰石复合微球的原位合成及体外释药性能

采用原位合成法在乳液体系中制备了壳聚糖/羟基磷灰石(HA)复合微球,并探讨了实验条件对复合微球制备的影响。结果表明,当壳聚糖/HA质量比为4/1时,可以获得球形规则,分散性好,平均粒径为9μm的复合微球。此外,NaOH溶液(1mol/L)的加入量应不少于3mL;交联剂(1mL)的最佳加入浓度为8%;向油相中先加入钙盐比先加入磷酸盐时的成球效果好。以盐酸四环素为模型药物,对复合微球的体外载药和释药性能进行了研究。结果显示,HA的引入大大提高了药物的包封率和载药量,而且使得复合微球比纯壳聚糖微球具有更显著的药物缓释效果。     

纳米缺钙羟基磷灰石/壳聚糖复合微球的原位均匀制备

针对纳米缺钙羟基磷灰石/壳聚糖(nCDHA/CS)复合微球中,nCDHA在微球中分布不均和含量不足的问题,在油包水(W/O)体系中,运用均匀沉淀法原位制备了nCDHA/CS复合微球。利用扫描电镜(SEM)、粒度分析仪、X射线衍射(XRD)、傅里叶红外光谱仪(FT-IR)、热重分析(TG)、X射线光电子能谱仪(XPS)等对复合微球的理化性能进行了表征。结果显示,所制得的nCDHA/CS复合微球中,nCDHA均匀分布于复合微球中,其含量高达43%;复合微球粒径分布较窄,球形度良好,分散性指数(PDI)为0.291,平均粒径18.6μm。仿生矿化结果显示,复合微球表面矿化是从nCDHA生成nHA的过程,仿生矿化14 d后,微球表面形成大量均匀的片状类骨磷灰石,表明该复合微球具有较好的生物学性能,对骨组织再生修复具有较大的潜力。     

Sustained release of Semaphorin 3A from α-tricalcium phosphate based cement composite contributes to osteoblastic differentiation of MC3T3-E1 cells

The reinforcement of calcium phosphate materials with silk fibroin (SF) has been one of the strategies to overcome the brittleness. However, the lack of osteoinductivity may still restrict their further use. This study aimed to investigate the biocompatibility and osteogenesis capacity of a novel Semaphorin 3A-loaded chitosan microspheres/SF/α-tricalcium phosphate composite (Sema3A CMs/SF/α-TCP) in vitro. Sema3A was first incorporated into CMs, and the Sema3A CMs/SF/α-TCP composite was then prepared. The morphology of the CMs was observed using SEM. The in vitro release kinetics, cytotoxicity, and cell compatibility were evaluated, and the real-time quantitative polymerase chain reaction (RT-qPCR) and activity of alkaline phosphatase (ALP) were used to evaluate the osteogenesis capacity of the composite. The in vitro release of Sema3A from the Sema3A CMs/SF/α-TCP composite showed a temporally controlled manner. The extract of the Sema3A CMs/SF/α-TCP composite presented no obvious side effect on the MC3T3-E1 cell proliferation, nor promote cell proliferation. The MC3T3-E1 cells were well-spread and presented an elongated shape on the Sema3A CMs/SF/α-TCP composite surface; the ALP activity and the osteogenic-related gene expression were higher than those seeded on the surface of the CMs/SF/α-TCP and SF/α-TCP composites. In conclusion, Sema3A CMs/SF/α-TCP has excellent biocompatibility and contributes to the osteoblastic differentiation of MC3T3-E1 cells.     

A study on the in vitro degradation of poly(L-lactide)/chitosan microspheres scaffolds

Recent research shows that the addition of chitosan microspheres (CMs) to poly(L-lactide) (PLLA) can result in a composite scaffold material with improved biocompatibility and mechanical properties for tissue engineering applications. However, research regarding the influence of CMs on scaffold degradation is absent in the literature. This paper presents a study on the in vitro degradation of scaffolds made from PLLA with CMs. In this study, the PLLA/CMs scaffolds with a 25% ratio of CMs to PLLA were immersed in phosphate-buffered saline (PBS) solution at 37°C for 8 weeks. The in vitro degradation of the scaffolds was investigated using micro-computed tomography (μCT), weight loss analysis, Raman spectroscopy, and differential scanning calorimetry (DSC). Microstructure changes during degradation were monitored using μCT. The μCT results were consistent with the results obtained from Raman spectra and DSC analysis, which reflected that adding CMs into PLLA can decrease the degradation rate compared with pure PLLA scaffolds. The results suggest that PLLA/CMs scaffold degradation can be regulated and controlled to meet requirements imposed a given tissue engineering application.     

The effect of boron nitride on electrical conductivity of nanocarbon-polymer composites

The electrical conductivity concentration and temperature dependences of polymer composite materials (CMs) with nanocarbon fillers [graphite nanoplatelets and multi-walled carbon nanotubes (MWCNTs)] were investigated. Epoxy resin modified with organosilicon compound was used as polymer matrix. The content of nanocarbon filler in varied from 1 to 10 wt%. To study of the synergetic properties the additional dispersed dielectric filler—boron nitride (BN) was added to given systems in content of 27 wt%. The electrical resistivity of CMs was investigated in the temperature range of 77–300 K. In the studied CMs the percolation transition at sufficient low filler content (0.01–0.022 vol. fr.) was observed. The values of critical index varied from 3.0 to 5.2. The electrical conductivity of investigated CMs was analyzed in the framework of proposed model that takes into consideration the morphology of filler particles. It was shown that the increase of electrical conductivity of GNP-polymer CM in the presence of BN is attributed to the decrease of contact resistance between filler particles, while for MWCNT-polymer CM is due to the increase of the number of conductive chains in this particular system.     

Sustained release effects of berberine-loaded chitosan microspheres on in vitro chondrocyte culture

The low bioavailability and short biological half-life of berberine chloride (BBR) negatively affect the protective role of this compound against osteoarthritis (OA). The present study was performed to evaluate the effectiveness of sustained BBR release system. Novel BBR-loaded chitosan microspheres (BBR-loaded CMs) were successfully synthesized using an ionic cross-linking method for sustained release. The basic characteristics of the prepared microspheres were subsequently evaluated by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) techniques, encapsulation efficiency (EE), and in vitro release experiments. BBR-loaded CMs displayed spherical forms to encapsulate a considerable quantity of BBR (100.8?±?2.7?mg/g); these microspheres also exhibited an ideal releasing profile. The FT-IR spectra and XRD results revealed that BBR-loaded CMs were successfully synthesized via electrostatic interaction. In vitro experiments further showed that BBR-loaded CMs significantly inhibited sodium nitroprusside (SNP)-stimulated chondrocyte apoptosis as well as cytoskeletal remodeling, and led to increasing mitochondrial membrane potential and maintaining the nuclear morphology. BBR-loaded CMs exerted markedly higher anti-apoptotic activity in the treatment of OA, and markedly inhibited the protein expression levels of caspase-3, a disintegrin, and metalloproteinase with thrombospondin motifs (ADAMTS)-5 and matrix metalloproteinase (MMP)-13 induced by SNP in rat articular chondrocytes, compared with free BBR at equivalent concentration. Therefore, novel BBR-loaded CMs may offer potential for application in the treatment of OA.     

Preparation and antibacterial activity of chitosan microshperes in a solid dispersing system

In this study, we investigated the interface contacting inhibition behaviors of chitosan against bacterial in the dispersing state. For that purpose, chitosan microspheres (CMs) in the dispersing state was prepared by the emulsification cross-linking method. The CMs had smooth surface and spherical shape with the diameter of about 124 μm. They were stable after sterilization at 121°C and 150 kPa for 20 min. The CMs had similar antibacterial activity to that of chitosan in the solution form. Their antibacterial activities increased with the increase of the CM concentration, while decreased with the increase of pH of the system. It was found that the CMs with the degree of deacetylation (DD) of 63.6% exhibited the highest antibacterial activity, while the CMs with the DD of 83.7% exerted the lowest antibacterial activity among the three tested samples.     

Preparation and antibacterial activity of chitosan microshperes in a solid dispersing system

In this study, we investigated the interface contacting inhibition behaviors of chitosan against bacterial in the dispersing state. For that purpose, chitosan microspheres (CMs) in the dispersing state was prepared by the emulsification cross-linking method. The CMs had smooth surface and spherical shape with the diameter of about 124 ?m. They were stable after sterilization at 121°C and 150 kPa for 20 min. The CMs had similar antibacterial activity to that of chitosan in the solution form. Their antibacterial activities increased with the increase of the CM concentration, while decreased with the increase of pH of the system. It was found that the CMs with the degree of deacetylation (DD) of 63.6% exhibited the highest antibacterial activity, while the CMs with the DD of 83.7% exerted the lowest antibacterial activity among the three tested samples.     

Structure and high temperature frictional behavior of a coal pitch-derived carbonaceous mesophase (CM) treated by high-energy ball milling

A coal tar pitch-derived carbonaceous mesophase (CM) was treated in a high-energy ball mill apparatus. The structures for the raw and the as-milled CMs were characterized by X-ray diffraction and laser-Raman spectroscopic techniques, and the frictional behaviors for the CMs were investigated by using a SRV high temperature friction and wear tester. The results have shown that, high-energy ball milling leads to a drop in the crystallinity of the CMs and a decrease in the size of graphite planar micro-crystals, implying a higher structural amorphism caused by the high-energy ball milling. In addition, the CMs display a high temperature lubrication effect. High-energy ball milling is supposed to be beneficial to the graphitization of the CMs induced by friction mechanical action, and, therefore, facilitate the high temperature lubrication effect to some extent.     

Boron-doped carbon microspheres as the catalyst for rechargeable Al-air batteries

Three-dimensional mesoporous boron-doped carbon microspheres (B-CMs) were synthesized through a facile impregnation-calcination method. The B atoms introduced plentiful defects into the surfaces of CMs and were mainly presented in the form of boron carbide, which increases the specific surface area of the composite material and endows it with enhanced catalytic activity. A rechargeable aluminum (Al-)-air battery with B-CMs catalysts exhibited low overpotentials and its effective discharge capacity reached 300 mAh g^?1 at the current density of 50?mA g^?1. The capacity of Al-air battery was maintained at 584 mAh g^?1 after 30 cycles.     

羰基铁粉/聚甲基丙烯酸甲酯/聚苯胺复合吸波剂的制备与性能

以苯胺(ANI)、羰基铁粉(CIP)和甲基丙烯酸甲脂(MMA)等为原料,采用化学氧化法和原位复合技术制备了掺杂态聚苯胺(PANI)、羰基铁粉/聚甲基丙烯酸甲脂(CIP/PMMA)和羰基铁粉/聚甲基丙烯酸甲脂/聚苯胺(CIP/PMMA/PANI)吸波剂,用XRD、SEM、TEM表征了吸波剂的结构与形貌,通过矢量网络分析仪测定吸波剂的电磁参数表明CIP/PMMA/PANI复合吸波剂既有电损耗又有磁损耗。在2～18 GHz频段内,材料厚度为1.0 mm时,计算出其最小反射率达-11.26 dB,反射率小于-10 dB的带宽为9.2 GHz、小于-8 dB的带宽达14 GHz,计算结果表明该复合吸波剂具有良好的宽频吸波性能。      

乙酰化壳聚糖微球作为潜在动脉栓塞剂的研究

利用优化后的乳化交联法制备的壳聚糖微球(CMs)及其乙酰化微球(ACMs)表面光滑、球形完整、粒径均匀。微球溶胀率试验、体外降解试验和细胞毒性试验显示,ACMs多种特性较CM更优。采用ACMs对兔耳栓塞15d后,栓塞部位小动脉萎缩消失,周围组织坏死,部分发生脱落,与坏死组织交界的边缘表皮萎缩增厚。结果表明,ACMs可以作为潜在的动脉栓塞剂。