两种不同复合唑来膦酸骨水泥的体外浸提对比实验研究

目的对比观察不同唑来膦酸含量的两种骨水泥在体外的药物释放情况,为临床应用其治疗骨巨细胞瘤奠定体外药物释放动力学基础。方法将唑来膦酸分别与聚甲基丙烯酸甲酯骨水泥及磷酸钙骨水泥以0.2%、0.4%、0.6%的质量比混合制备复合唑来膦酸骨水泥的测试标本,并同时设立空白对照,所制两种不同骨水泥标本均分成a(空白对照)、b(含0.2%的唑来膦酸)、c(含0.4%的唑来膦酸)、d(含0.6%的唑来膦酸)4组,每组1个标本。将4组标本分别放于5m L生理盐水中,并最终置于智能溶出仪中持续浸提42天,于特定时间点取样待测,用高效液相色谱仪测定浸提液中唑来膦酸的浓度,计算各时点的药物释放浓度和释放总量百分比,并绘制相应曲线。结果复合唑来膦酸聚甲基丙烯酸甲酯骨水泥的各实验组浸提液色谱图中未发现唑来膦酸吸收峰的出现,而复合唑来膦酸磷酸钙骨水泥的各实验组浸提液色谱图中均可见唑来膦酸吸收峰的出现且各实验组在第42天实验结束时的唑来膦酸累计溶出量百分比:b组d组c组。结论唑来膦酸不能从聚甲基丙烯酸甲酯骨水泥中释放,但可以从磷酸钙骨水泥中释放并最终可以以一稳定药物浓度缓慢、持久释放。     

利福平-异烟肼-控释型载药人工骨的实验研究

开发研究一种能承载多药并有控释特性的载药人工骨。利用三维打印技术,制备具有多层同心圆柱体结构的载药人工骨,并将利福平和异烟肼由内到外按特定顺序加载,观察微观结构、孔隙率、体外药物释放特性和体外细胞生物相容性。所制备的载药人工骨呈多孔结构,孔隙率(61.76±2.53)%、微孔孔径50~100μm,体外药物呈现序贯释放,双药释放峰值依次交替出现,持续释放时间超过50 d,MTT检测示细胞毒性0级,电镜观察细胞生长分化良好,并有大量细胞黏附于载药人工骨表面;三维打印技术可以精确地制备具有复杂结构的载药人工骨,制备的多药控释型载药人工骨具有药物缓释和序贯控释的特性,同时具有良好的孔隙率和细胞相容性,为骨结核治疗提供一种新型有效的手段。     

载药型磷酸钙骨水泥的制备及体外释放性能

背景：磷酸钙骨水泥具有良好的生物相容性,可作为骨修复材料与药物载体。 目的：制备载药磷酸三钙骨水泥,并分析其体外释放性能。 方法：采用共沉淀法制备磷酸三钙前躯体,经高温煅烧研磨获得α-磷酸三钙粉体,测试含不同浓度(1.25%,2.5%,3.75%,5%)抗生素(头孢拉定或头孢氨苄或环丙沙星)骨水泥,浸泡不同时间后(6 h、12 h、24 h、2 d、3 d、4 d、 5 d、6 d、7 d、8 d)的药物体外释放浓度。 结果与结论：制备的磷酸三钙粉体粒度约2 μm,结晶度良好。载不同抗生素的骨水泥体外释放都受自身物理性质的影响。载药骨水泥中环丙沙星能够满足长时间缓释,并能达到一个比较理想的缓释浓度,头孢类药物由于自身稳定性等原因,缓释效果并不理想。头孢氨苄的水解速率较低,环丙沙星的光降解条件比较苛刻,因此两者释放未受太大影响,与Higuchi模型基本吻合;头孢拉定的水解速率相对较高,对体系的释放驱动力产生较大影响,使得释放不再遵循Higuchi模型。     

SrHA/PMMA复合骨水泥的制备、理化性能及细胞相容性研究

目的结合PMMA和锶羟基磷灰石(Sr HA)各自的优势,制备出兼具高的力学强度、合适的固化时间、较低的热释放、生物活性和骨整合性能的Sr HA/PMMA复合骨水泥,并系统性地研究Sr HA的引入对复合骨水泥的体外固化性能、力学强度和生物学性能的影响。方法将水热合成法制备的锶羟基磷灰石引入PMMA基体,制备Sr HA/PMMA复合骨水泥。系统性地对Sr HA/PMMA复合骨水泥的力学强度、固化时间、热释放、生物活性进行研究。将复合骨水泥和细胞共培养,利用MTT法、扫描电镜等研究Sr HA/PMMA复合骨水泥的细胞毒性,粘附和增殖。结果结果表明,与纯的PMMA骨水泥(对照组)相比,Sr HA/PMMA复合骨水泥的固化热释放明显降低(约80~84℃),同时又维持了合适的固化时间(8~11分钟)和较好的力学性能(抗压强度为90MPa左右)。Sr HA的引入,不仅赋予了复合骨水泥生物活性,也显著地改善了其细胞/材料的相互作用。浸泡在SBF后,Sr HA/PMMA复合骨水泥显示出更好的体外矿化性能。与成骨细胞MC3T3-E1共培养后,表面沉积的羟基磷灰石能够更好的促进细胞的粘附和爬行。结论兼具优异的理化性能和生物活性的Sr HA/PMMA复合骨水泥,有着广阔的骨科微创修复应用前景。     

复合唑来膦酸磷酸钙骨水泥的力学性能测定

目的研究加入不同浓度的唑来膦酸对磷酸钙骨水泥体外凝结时间、抗压强度的影响。方法将唑来膦酸与磷酸钙骨水泥以不同质量比混合,制备力学性能测试标本,并分为A(空白对照)、B(含0.2%唑来膦酸)、C(含0.4%唑来膦酸)、D(含0.6%唑来膦酸)4组,每组6个标本。测定其凝结时间及抗压强度。结果随载药浓度的增加,复合磷酸钙骨水泥凝结时间逐渐延长,但各实验组凝结时间与空白对照组均无明显统计学差异(0.05)。B、C组抗压强度与A组之间无明显统计学差异(0.05),而D组与A组之间有统计学差异(=0.000)。结论三组中唑来膦酸的添加量对磷酸钙骨水泥凝结时间无明显影响,且各组凝结时间均满足临床应用标准。含0.2%和0.4%唑来膦酸对磷酸钙骨水泥抗压强度无明显影响,而含0.6%唑来膦酸可使磷酸钙骨水泥抗压强度明显降低。但三含量组的抗压强度均满足临床应用标准。     

用复合诱导型骨修复材料修复兔桡骨缺损的实验研究

以不同的载药方式构建4种壳聚糖/聚羟基丁酸酯-羟基戊酸酯(PHBV)复合诱导型骨修复材料,检测并比较4种支架材料对兔桡骨缺损的修复效果,筛选出最佳骨修复材料并确定最佳药物控释方式。以淫羊藿苷为诱导因子,采用两相混合冷冻干燥技术以微球载药、改性药物微球(W/O法制得并表征)、改性药物与材料共价结合等药物添加方式及不加药制得4种支架材料,并对其进行显微结构以及载药支架药物缓释表征,后将4种材料分别植入兔桡骨缺损处,于1、3、6个月进行X射线及三维CT观察支架材料对兔桡骨缺损的修复情况,HE,Masson染色观察其诱导成骨效果。结果表明,支架材料呈网络状串珠状的显微结构,载药微球粒径分布在3～11 μm,载药支架材料有着良好的药物缓释,其中共价结合组药物释放峰值时间较其他组推迟,为72 h,且峰值后药物缓释量迅速平稳为75 μg左右。X射线及三维CT观察显示,最终共价结合组支架材料骨缺损处连通,且骨密度高于其他3组。HE、Masson染色结果显示,共价结合组成骨效果优于其他组。共价结合的药物添加方式能使支架具有良好的药物缓释效果,进而对兔桡骨缺损表现出良好的修复效果。     

载药硼酸盐骨水泥的制备及其体外生物活性和抗菌性能的研究

目的以硼酸盐生物活性玻璃和改性壳聚糖液相制备了新型的硼酸盐骨水泥,同时负载骨髓炎治疗药物硫酸庆大霉素,考察其体外抗菌性能,以探讨其治疗骨髓炎的可能性。方法以硼酸盐骨水泥为载体,制备了负载硫酸庆大霉素(GS)的骨水泥。探究负载GS对骨水泥的可注射性能、初凝时间的影响;将负载GS且预固化的硼酸盐骨水泥浸泡于磷酸盐缓冲溶液(PBS)中,考察其体外生物活性、生物降解性和药物释放;利用抑菌圈实验评估了负载GS的硼酸盐骨水泥的体外抗菌性能。结果制备的载药硼酸盐骨水泥能够被完全注射,初凝时间约6 min;在体外的磷酸盐缓冲溶液(PBS)中浸泡时,GS能够持续稳定的释放,药物释放长达26天;负载GS的硼酸盐骨水泥能够很好地抑制金黄色葡萄球菌(S.aureus)和大肠杆菌(E.coli)的生长。结论制备的负载GS的硼酸盐骨水泥具有优异的可注射性,合适的原位自固化时间,长期持续的药物释放和抗菌性能,可以用于骨髓炎治疗的进一步研究。     

5-氟尿嘧啶缓释剂制备及体外释药性能比较*

背景：5-氟尿嘧啶-聚乳酸-乙醇酸共聚物缓释微球在青光眼滤过术后抑制滤过泡的瘢痕化具有潜在应用价值,但微球制备程序复杂,微球载药量一般较低,且药物突释现象明显。 目的：比较乳化溶剂挥发法制备的5-氟尿嘧啶-聚乳酸-乙醇酸共聚物微球和喷雾成膜法制备的5-氟尿嘧啶-聚乳酸-乙醇酸共聚物缓释膜两种缓释剂的形态、载药量、体外释放规律,以探讨获得缓释效果较佳的5-氟尿嘧啶缓释剂制备方法。 方法：以聚乳酸-乙醇酸共聚物为载体,采用乳化溶剂挥发法制备5-氟尿嘧啶-聚乳酸-乙醇酸共聚物微球;用喷雾成膜法制备5-氟尿嘧啶-聚乳酸-乙醇酸共聚物缓释膜。 结果与结论：用乳化溶剂挥发法制备的微球外观圆整,粒径为(4 447.4±359.8) nm,载药量(8.67±0.37)%,包封率为(86.68± 1.92)%;用喷雾成膜法制备的缓释膜表面光滑平整,质量为(13.76±0.26) mg ,直径为6 mm ,厚度为(0.24±0.005) mm,载药量(23.76±0.37)%,包封率为(95.04±1.36)%。缓释剂制备过程未影响5-氟尿嘧啶的药物性能。微球体外释放突释明显,缓释膜的体外释放平稳持久,释放曲线符合Higuchi方程。结果表明缓释膜制备方法更简单易行,且能明显提高缓释剂的载药量,降低突释现象,同时延长药物的缓释时间。 关键词：聚乳酸-聚乙醇酸;5-氟尿嘧啶;微球;缓释膜;体外释放 doi:10.3969/j.issn.1673-8225.2012.08.022     

盐酸四环素/α-TCP骨水泥载药体系的体外释放研究

对盐酸四环素/磷酸钙骨水泥药物释放体系进行了体外释放研究。XRD分析结果表明，一定含量的盐酸四环素的存在不会影响α-TCP的水化。在体外释放实验中，各种药物含量的载药体系均表现出了良好的缓释性能，持续释放时间超过1200h；由于盐酸四环素同磷酸钙的吸附与结合，当药物在体系中的含量发生改变时，释放控制机理发生改变。当抗生素在固相中含量较大时，药物释放速率以扩散控制为主。药物释放量满足时间平方根关系；当药物含量较低时，在释放前期，药物释放速率仍然以扩散控制为主；释放后期、药物分子从磷酸钙表面的解脱溶出与扩散对药物释放形成混合控制。     

新型介孔二氧化硅纳米微球/羟基磷灰石/生物玻璃复合生物涂层的体外理化特性

目的本实验设计制备了介孔硅纳米微球(mesoporous silica nanoparticulate,MSN)/羟基磷灰石(hydroxyapatite,HA)/生物玻璃(bioactive glass,BG)复合生物涂层。并对其加载唑来膦酸(Zoledronic acid,ZOL)后的体外药物释放特性进行了研究。方法通过扫描电镜、透射电镜及能谱仪等方法观察H/M涂层表征。通过高效液相色谱法进行HA/MSN/BG、HA/MSN及HA生物涂层体外ZOL加载及释放的比较。结果通过扫描电镜观察HA/MSN涂层,发现其具有二氧化硅微球组成的多孔结构。体外药物实验中H/M比HA载药量大更且与初始药物浓度相关,并具有药物缓释的特性,涂布BG后缓释效应更加明显。结论 H/M/B因其具有载药量大及药物缓释特性,为生物涂层内固定物在骨折愈合上的应用提供了新技术。     

Controlled release of gentamicin from calcium phosphate-poly(lactic acid-co-glycolic acid) composite bone cement

Modification of a self setting bone cement with biodegradable microspheres to achieve controlled local release of antibiotics without compromising mechanical properties was investigated. Different biodegradable microsphere batches were prepared from poly(lactic-co-glycolic acid) (PLGA) using a spray-drying technique to encapsulate gentamicin crobefate varying PLGA composition and drug loading. Microsphere properties such as surface morphology, particle size and antibiotic drug release profiles were characterized. Microspheres were mixed with an apatitic calcium phosphate bone cement to generate an antibiotic drug delivery system for treatment of bone defects. All batches of cement/microsphere composites showed an unchanged compressive strength of 60 MPa and no increase in setting time. Antibiotic release increased with increasing drug loading of the microspheres up to 30% (w/w). Drug burst of gentamicin crobefate in the microspheres was abolished in cement/microsphere composites yielding nearly zero order release profiles. Modification of calcium phosphate cements using biodegradable microspheres proved to be an efficient drug delivery system allowing a broad range of 10-30% drug loading with uncompromised mechanical properties.     

Antibiotic delivery system using nano-hydroxyapatite/chitosan bone cement consisting of berberine

Different concentrations of berberine were mixed with nano-hydroxyapatite/chitosan (n-HA/CS) bone cement to generate an antibiotic drug delivery system for treatment of bone defects. Properties of the system such as setting time, compressive strength, surface morphology, phase compositions, drug release profiles and antimicrobial activity were also characterized. It was shown that the setting time of the cement ranged from 17.03 +/- 0.50 min to 28.47 +/- 0.96 min and the compressive strength changed from 184.00 +/- 7.94 MPa to 120.33 +/- 9.02 MPa with the increase of berberine. The XRD, IR, and SEM analyses suggested that berberine powders were stable in the bone cement in simulated body fluid (SBF). In vitro release of berberine from the bioactive bone cement pellets in SBF could last more than 4 weeks. The release profiles of 1.0 wt % berberine loaded bone cement followed the Higuchi equation at the infusion stage. The drug loaded pellets can inhibit bacterial growth (Staphylococcus aureus) at the standardized berberine minimum inhibitory concentration of 0.02 mg/mL during berberine release from 1 to 28 days. The n-HA/CS bone cement only with 1.0 wt % berberine proved to be an efficient antibiotic drug delivery system.     

Newly developed Sr-substituted α-TCP bone cements

New bone cements made of Sr-substituted brushite-forming α-tricalcium phosphate (α-TCP) were prepared and characterized in the present work. The quantitative phase analysis and structural refinement of the starting powders and of hardened cements were performed by X-ray powder diffraction and the Rietveld refinement technique. Isothermal calorimetry along with setting time analysis allowed a precise tracing of the setting process of the pastes. The pastes showed exothermic reactions within the first 10–15 min after mixing and further release of heat after about 1 h. An apatitic phase formed upon immersion of the hardened cements in simulated body fluid for 15 and 30 days due to the conversion of brushite into apatite confirming their in vitro mineralization capability. The compressive strength of the wet cement specimens decreased with increasing curing time, being higher in the case of Sr-substituted CPC.The results suggest that the newly developed Sr-substituted brushite-forming α-TCP cements show promise for uses in orthopaedic and trauma surgery such as in filling bone defects.     

Preparation and characterization of electrospun PLGA/gelatin nanofibers as a drug delivery system by emulsion electrospinning

Novel biocompatible poly(lactide-co-glycolide) (PLGA) nanofiber mats with favorable biocompatibility and good mechanical strength were prepared, which could serve as an innovative type of tissue engineering scaffold or an ideal controllable drug delivery system. Both hydrophobic and hydrophilic drugs, Cefradine and 5-fluorouracil were successfully loaded into PLGA nanofiber mats by emulsion electrospinning. The natural bioactive protein gelatin (GE) was incorporated into the nanofiber mats to improve the surface properties of the materials for cell adhesion. Nanofibrous scaffolds were characterized by scanning electron microscopy, X-ray diffraction, differential scanning calorimetry, contact angle and tensile measurements. Emulsion electrospun fibers with GE had perfect hydrophilic and good mechanical property. The in vitro release test showed thedrugs released from emulsion electrospun fibers, which achieved lower burst release. The cells cytotoxicity experiment indicated that emulsion electrospun fibers were less toxic and tended to promote fibroblasts cells attachment and proliferation, which implied that the electrospun fibers had promising potential application in tissue engineering or drug delivery.     

Three-dimensional printing of strontium-containing mesoporous bioactive glass scaffolds for bone regeneration

In this study, we fabricated strontium-containing mesoporous bioactive glass (Sr-MBG) scaffolds with controlled architecture and enhanced mechanical strength using a three-dimensional (3-D) printing technique. The study showed that Sr-MBG scaffolds had uniform interconnected macropores and high porosity, and their compressive strength was ∼170 times that of polyurethane foam templated MBG scaffolds. The physicochemical and biological properties of Sr-MBG scaffolds were evaluated by ion dissolution, apatite-forming ability and proliferation, alkaline phosphatase activity, osteogenic expression and extracelluar matrix mineralization of osteoblast-like cells MC3T3-E1. The results showed that Sr-MBG scaffolds exhibited a slower ion dissolution rate and more significant potential to stabilize the pH environment with increasing Sr substitution. Importantly, Sr-MBG scaffolds possessed good apatite-forming ability, and stimulated osteoblast cells’ proliferation and differentiation. Using dexamethasone as a model drug, Sr-MBG scaffolds also showed a sustained drug delivery property for use in local drug delivery therapy, due to their mesoporous structure. Therefore, the 3-D printed Sr-MBG scaffolds combined the advantages of Sr-MBG such as good bone-forming bioactivity, controlled ion release and drug delivery and enhanced mechanical strength, and had potential application in bone regeneration.     

Adsorption and release studies of sodium ampicillin from hydroxyapatite and glass-reinforced hydroxyapatite composites

As a potential therapy for periodontitis, sodium ampicillin, a broad spectrum antibiotic, was adsorbed onto hydroxyapatite (HA) and glass-reinforced hydroxyaptite (GR-HA) composites, and was subsequently released in vitro. The sodium ampicillin, was adsorbed more on HA compared to the GR-HA composites. X-ray diffraction (XRD) and Rietveld analysis were used to identify and quantify the levels of HA and beta-tricalcium phosphate (beta-TCP) in the microstructure of the GR-HA composites. Lattice parameters changes were observed for the beta-TCP phase dependant on the amount of glass added. The release kinetics were shown to be divided into three stages, the first of which where a large amount of sodium ampicillin is released, followed by a slower release rate and then a final stage where the release amount approaches zero, until no more sodium ampicillin was present. X-ray photoeletron spectroscopy (XPS) studies were carried out in order to ensure that the entire antibiotic adsorbed onto the materials had been released. These kinetics studies have indicated the possibility of using these materials as possible carriers for drug delivery.     

Synthesis and characterization of hydroxyapatite with different crystallinity: effects on protein adsorption and release

Increasing demand exists for the development of a tissue-engineered alternative in the repair of nonunion and critical-sized bone defects. The delivery of osteoinductive proteins, such as bone morphogenetic proteins (BMPs), to replicate physiological bone-healing process appears a logical and promising option, but is currently limited in its clinical application due to lack of a suitable drug carrier. The study aimed to investigate the effects of the crystallinity of hydroxyapatite (HA) drug carrier on adsorption of proteins onto and their release from the carrier. HA samples with different crystallinities were synthesized under controlled conditions, that is, pH, temperature, and maturation time, and characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and surface area analyzer. Results demonstrated that both bovine serum albumin (BSA) and cytochrome C had a greater tendency to bind onto amorphous calcium phosphate (ACP) than crystalline HA, and the adsorption rate was correlated oppositely with the HA crystallinity. For both BSA and cytochrome C, the release kinetics of protein from HA depended on the crystallinity of HA, in which ACP had the highest release rate at 74%, whereas only 15% of proteins were released from the highly crystalline HA over a 14-day period. Burst release within 12 h of incubation was observed for all groups.     

Control of crystallinity of hydrated products in a calcium phosphate bone cement

In this study, a calcium phosphate cement (CPC), consisting of partially crystallized calcium phosphate (PCCP), was synthesized. X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR) and scanning electronic microscope (SEM) were used to characterize the cement. The results showed that by changing the ratio of amorphous calcium phosphate (ACP) to PCCP in the cement, hydrated products of controllable crystallinity were obtained. With increase in the relative amount of PCCP, the hydrated products changed gradually from very poor crystallinity with little needle-like hydroxyapatite (Hap) crystallites to relatively high crystallinity with more needle-like Hap crystallites; the compressive strength of the cement increased, and the degradation of the cement decreased. The cement was implanted into the tibia tubercle of healthy mature Zelanian white rabbits and the histological specimens were obtained after 4 and 16 weeks of implantation. The result revealed that this bone cement was biocompatible and showed very early osteoconductive properties. Thus, the CPC has potential for use in orthopedic surgery for filling non- load-bearing bone defects.     

医用磷酸钙骨水泥的制备及性能的实验研究

探索了磷酸四钙（Ca4（PO4）2O，TTCP）的制备，并合成了磷酸钙骨水泥（CPC），对CPC固化时间、引起浸泡液pH值的变化、抗压强度、产物物相组成及微观结构进行了研究。结果表明：在真空条件下、1500℃下煅烧6h可制得TTCP，并含有少量CaO。CPC初凝时间为4min、终凝时间为15min，浸泡1d和7d后的抗压强度分别为20MPa和35MPa，浸泡液的pH值在6．4～8．9之间变化，这些性能均符合临床用CPC的性能要求。CPC水化产物为片状或针状羟基磷灰石（Ca5（PO4）3OH，HA），相互交错呈连续分布的网状结构，这种结构有利于材料强度的提高。实验研制的CPC材料可用于骨缺损的修复治疗。     

三种多孔磷酸钙骨水泥体外研究比较

目的：探讨以不同方法制备的三种多孔磷酸钙骨水泥（Calcium phosphate cement, CPC）的理化特性、生物相容性及强度的差异.方法：将20wt%甘露醇（A组）、5wt%碳酸氢钠（B组）及5wt%明胶微球（C组）分别与CPC粉末混合固化制备多孔CPC.生理盐水浸泡1周、4周后,测定材料孔径率及抗压强度,电镜观察材料断面,X线衍射法检测CPC的转化情况.成骨细胞接种于各组CPC支架上,扫描电镜观察细胞形态;三组材料浸提液分别与成骨细胞共培养3 d,MTT法测定细胞增殖率,试剂盒检测碱性磷酸酶水平.结果：浸泡1周后C组孔径率稍低,4周后各组无明显差异;但两个时间点C组强度均最高.材料断面扫描A组孔径较大、连通性欠佳,B组孔径极不规则且分布不均匀,C组孔径规则、连通性好.1周后X线衍射显示三组均出现羟基磷灰石衍射峰;4周后C组羟基磷灰石衍射峰最强,磷酸四钙衍射峰最弱.成骨细胞在各组材料上生长良好,但C组细胞量最多,细胞增殖及碱性磷酸酶水平明显高于其他两组.结论：以明胶微球制备的多孔CPC具有较高的初始强度及较好的生物相容性,可作为非负重部位骨替代材料.