新型聚己内酯/磷酸钙支架的制备及生物相容性研究

探讨新型聚己内酯(PCL)/磷酸钙(CPC)复合材料支架的制备方法及对骨髓基质细胞(BMSCs)的生物相容性。采用溶液共混法,利用可溶盐晶体做造孔剂,制备PCL/CPC复合材料支架,以单纯PCL和CPC支架为对照组,Q800型动态力学分析仪进行动态力学性能试验(DMA),采用排水法测量孔隙率;灭菌后通过与犬BMSCs体外共同培养后细胞形态、生长曲线、碱性磷酸酶(ALP)染色和半定量及骨钙素(OC)半定量等方法检测细胞在支架材料上的黏附、增殖及成骨分化情况,动物体内异位成骨检测其成骨情况。结果显示,复合材料的储能模量在PCL/CPC比例为7:3时达到最大,制得的材料孔径为250～350μm,多孔支架的孔隙率为70%～80%;BMSCs在新型PCL/CPC组、CPC组支架表面分布均匀,生长增殖明显较PCL组活跃(P<0.05);PCL/CPC组、CPC组BMSCs成骨行为与PCL组之间有显著差异(P<0.05)。动物体内异位成骨检测提示,4周时PCL/CPC组为13.78%±1.60%、CPC组BMSCs为15.29%±1.20%,成骨显著强于PCL组BMSCs的7.56%±2.20%(P<0.05),表明PCL和CPC的复合明显改善了两种材料的缺陷,获得的PCL/CPC支架具有良好的生物相容性,可与BMSCs共同构建具有成骨能力的三维立体组织工程化骨。     

聚己内酯材料的生物相容性与毒理学研究

由本实验室自行制备的,用钛酸丁酯引发的生物可降解材料聚ε-己内酯PCL,经细胞毒性试验,全身急性毒性试验,皮内刺激试验及植入试验研究,结果表明:样品中微量有机溶剂的存在对细胞毒性有一定影响.样品植入初期有轻度炎症反应,三个月后炎症反应基本消失.结论为用钛酸丁酯引发的PCL材料具有良好的生物相容性.     

甲壳素短纤维增强聚己内酯复合材料的制备及生物学评价

用共混法制备甲壳察短纤维增强聚己内酯复合材料，并对纯聚己内酯和甲壳察短纤维增强聚己内酯复合材料进行体外细胞毒性和生物相容性评价，为临床应用提供有价值的实验依据。对该两种材料进行体外细胞毒性试验、急性全身毒性试验、溶血试验、热源试验和过敏试验。结果显示受试材料最终细胞毒性级为0级，对细胞生长和增殖无明显抑制作用，材料中不存在潜在致敏性物质，浸提液无溶血反应和急性全身毒性反应，无热源反应，表明该复合材料具有良好的细胞和组织相容性，其作为胸壁缺损修补材料应用于临床具有可行性和安全性。     

注射用聚乳酸和交联透明质酸钠凝胶的制备及性能研究

本研究对交联透明质酸钠凝胶的交联工艺以及和自制的聚乳酸微球的不同配比进行研究,成功制备了注射用美容凝胶。对不同交联度和不同配比的溶胀度、流变学、渗透压、动力粘度、稳定性等性能指标进行研究,并对本产品的灭菌稳定性进行了考察。结果表明本产品灭菌后较稳定,均匀细腻,其弹性模量、动力粘度和溶胀度均较好,具有很好的临床应用前景。     

骨植入用生物可降解材料新合成方法及生物相容性的研究

采用 Y(CF3COO) 3/AL(i- Bu) 3络合物催化合成聚己内酯 (Polycaprolactone,PCL)及其与聚乳酸(Polylactic acid,PL A)的共聚物 ,并应用生物化学、细胞毒理及细胞免疫学等实验方法对这一新型骨科生物降解可吸收材料的生物相容性进行评价。用 PCL 和 PCL/PDL L A共聚物作为骨科生物降解可吸收内置物材料 ,国内外属首次研究 ;多聚物的分子量和降解时间可以通过控制反应时间、单体与催化剂的比例来调控产物分子量 ,人为调节降解时间。实验证明该材料细胞相容性好 ,未发现明显毒性及免疫排斥反应。     

聚左乳酸己内酯-胶原蛋白静电纺人工血管的降解研究

探讨聚左旋乳酸己内酯-胶原蛋白构建的可降解人工血管材料的降解规律以及生物相容性。聚左旋乳酸己内酯-胶原蛋白混合溶液通过静电纺丝技术制成静电纺人工血管材料作为实验组(n=40),市售聚四氟乙烯人工血管材料作为对照组(n=40),分别植入兔背部脊柱两侧肌肉,于术后10、30、90、180 d取材,行形态学、组织学观察;并在400 倍光学显微镜视野下进行中性粒细胞、巨噬细胞和淋巴细胞的分类计数。结果镜下聚左旋乳酸己内酯胶原蛋白组材料周围组织炎症反应轻,术后90 d材料碎裂,纤维组织长入材料网孔间隙内,逐步取代材料部位,形成囊状纤维膜;术后180 d材料基本降解殆尽,植入区域组织重塑后形态接近正常组织。聚四氟乙烯组材料周围组织炎症反应轻,术后180 d仍基本保持原有结构,材料周围有薄层纤维组织膜包绕。细胞计数结果提示植入后不同时期两组材料引起的细胞反应类型和反应趋势相同;仅术后10 d时实验组中性粒细胞数量较对照组增多(2244±372 vs 1922±181 个/025 mm2, P<005),其余两组各期各类细胞均无明显差异(P>005)。实验材料降解时间为3～6月,具有生物相容性好、降解规律适宜的良好生物学性能,有作为血管替代物的潜在可能性。     

壳聚糖温敏性凝胶的制备及其热敏性实验研究

目的:用壳聚糖作为一种生物材料,和甘油磷酸盐(GPS)反应制备温敏性凝胶,使其在植入体内后发生形态上的变化,从而达到用于组织缺损和药物释放的目的.方法:将不同浓度的壳聚糖和GPS反应生成凝胶,测定其pH值和在不同温度下的凝固时间.结果:凝胶的pH值随壳聚糖和GPS的浓度的增加而增加,同时也随溶解壳聚糖的酸浓度增加下降;其凝固时间随pH值和随温度的增加而减少.结论:壳聚糖与GPS反应,能制备出在低温下呈流体状液体,而当温度升高到体温时则成凝固的温敏性凝胶.     

交联透明质酸凝胶膜的制备及其生物相容性的研究

制备交联透明质酸凝胶膜并评价其生物相容性.本研究采用己二酸二酰肼作为交联剂制备交联透明质酸凝胶膜,并采用GB/T16886医疗器械生物学评价标准规定的方法,对凝胶膜进行体外溶血试验、细胞毒性试验、急性毒性试验、眼刺激试验、皮内反应试验、致敏试验以及鼠伤寒沙门氏菌回复突变试验、哺乳动物培养细胞染色体畸变试验和小鼠骨髓嗜多染红细胞微核试验等三项遗传毒性试验.结果表明交联透明质酸凝胶膜无溶血性、无眼刺激作用、无皮内刺激和致敏作用,未见急性毒性反应,细胞毒性0～1级;三项遗传毒性试验均为阴性.交联透明质酸凝胶膜具有良好的生物相容性,是一种理想的医用生物材料.     

聚己内酯埋植剂的制备及药物通透性研究

目的制备聚己内酯（PCL）长效药物缓释制剂,优化药物缓释效果,并研究PCL埋植剂的药物通透性.方法 合成分子质量为（8～16）×104 u含有普朗尼克F68的PCL,用挤出法制备不同壁厚的PCL长效缓释埋植剂.将左炔诺孕酮（LNG）装入PCL管封装,制成LNG药囊.通过高效液相色谱法测定LNG的释放效果,考察PCL的分子质量及PCL管壁厚度对LNG通透性的影响.结果 当PCL分子质量为（8～16）×104u时,对LNG通透性无显著影响.PCL管壁厚在0.20～0.40 mm时,对LNG通透性亦无显著影响;当壁厚小于0.15 mm时,LNG通透性显著提高.结论 PCL埋植剂对LNG具有通透性,可通过改变PCL管壁厚度增加药物通透性.     

生物可降解材料聚己内酯微球的细胞相容性体外研究

将聚己内酯制成平均粒径 5 .0 8± 0 .2 3μm的微球 ,采用流式细胞术研究经不同纯化处理的微球其浸提液对小鼠成纤维细胞凋亡及细胞周期的影响。结果表明 ,不同的纯化条件对聚己内酯微球的细胞相容性影响巨大。经充分洗涤干燥的产品在给药剂量范围内细胞相容性良好     

PEG-g-chitosan thermosensitive hydrogel for implant drug delivery: cytotoxicity,in vivo degradation and drug release

Thermosensitive hydrogels based on chitosan are of great interests for injectable implant drug delivery. The poly(ethylene glycol)-grafted-chitosan (PEG-g-CS) hydrogel was reported as a potential thermosensitive system. The objective of the present study is to evaluate the cytotoxicity, in vivo degradation and drug release of PEG-g-CS hydrogel. Cytotoxicity was evaluated using L929 murine fibrosarcoma cell line. Degradation and drug release in vivo were investigated by subcutaneous injection of the hydrogel into Sprague-Dawley rats. PEG-g-CS polymer exhibits no significant cytotoxicity when its concentration is less than 3 mg mL^?1. After being implanted, PEG-g-CS hydrogel maintains its integrity for two weeks and collapses, merging into the tissue, in the third week. It causes moderate inflammatory response but no fibrous encapsulation around the hydrogel is found. The hydrogel presents a three-week sustained release of cyclosporine A with no significant burst release in vitro and produces the effective drug concentration in blood for more than five weeks in vivo, performing almost the same bioavailability to chitosan/glycerophosphate hydrogel. Further modifications of PEG-g-CS hydrogel might be necessary to modulate the degradation and to mitigate the fluctuations in blood drug concentration.     

Injectable alginate hydrogels for cell delivery in tissue engineering

Alginate hydrogels are extremely versatile and adaptable biomaterials, with great potential for use in biomedical applications. Their extracellular matrix-like features have been key factors for their choice as vehicles for cell delivery strategies aimed at tissue regeneration. A variety of strategies to decorate them with biofunctional moieties and to modulate their biophysical properties have been developed recently, which further allow their tailoring to the desired application. Additionally, their potential use as injectable materials offers several advantages over preformed scaffold-based approaches, namely: easy incorporation of therapeutic agents, such as cells, under mild conditions; minimally invasive local delivery; and high contourability, which is essential for filling in irregular defects. Alginate hydrogels have already been explored as cell delivery systems to enhance regeneration in different tissues and organs. Here, the in vitro and in vivo potential of injectable alginate hydrogels to deliver cells in a targeted fashion is reviewed. In each example, the selected crosslinking approach, the cell type, the target tissue and the main findings of the study are highlighted.     

肌醇为核的星形聚己内酯的制备及表征

目的制备六臂星形聚己内酯并评价其生物相容性。方法采用本体开环聚合法以ε-己内酯为单体,辛酸亚锡为催化剂,肌醇为多功能基团引发剂,合成一系列不同相对分子质量的六臂星形聚己内酯(6-s-PCLx)(其中x为单体与引发剂的摩尔比)。通过傅里叶红外光谱(FT-IR)、核磁共振氢谱(1H-NMR)、凝胶渗透色谱(GPC)、差示扫描热分析法(DSC)对其结构、相对分子质量及热力学性质进行表征。以此材料为载体,采用超声乳化/溶剂挥发法,制备空白纳米粒。采用动态光散射法(DLS)和扫描电子显微镜(SEM)对其粒径和形态进行表征,通过WST-1比色法探讨该材料的体外细胞毒性。结果 FT-IR和1H-NMR表明,该聚合物为六臂星形结构;由GPC得出其相对分子质量分别为22 822、31 459、49 533,并呈单峰分布;DSC结果表明,聚合物的熔融温度(Tm)、熔融焓(ΔH)及结晶度(Xc)随着相对分子质量的增加而升高;制备的纳米粒呈椭圆形,平均粒径在100~200 nm,粒径均一;WST-1比色法证明,该材料具有良好的生物相容性。结论成功合成六臂星形聚己内酯并制备了纳米粒,细胞实验证明该材料具有良好的生物相容性。     

Mussel-inspired protein-mediated surface functionalization of electrospun nanofibers for pH-responsive drug delivery

pH-responsive drug delivery systems could mediate drug releasing rate by changing the pH values at specific times as per the pathophysiological need of the disease. This paper demonstrates that a mussel-inspired protein polydopamine coating can tune the loading and releasing rate of charged molecules from electrospun poly(ε-caprolactone) (PCL) nanofibers in solutions with different pH values. In vitro release profiles show that the positive charged molecules release significantly faster in acidic than those in neutral and basic environments within the same incubation time. The results of fluorescein diacetate staining and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays show the viability of cancer cells after treatment with doxorubicin-released media at different pH values qualitatively and quantitatively, indicating that the media containing doxorubicin that were released in solutions at low pH values could kill a significantly higher number of cells than those released in solutions at high pH values. Together, the pH-responsive drug delivery systems based on polydopamine-coated PCL nanofibers could have potential application in the oral delivery of anticancer drugs for treating gastric cancer and in vaginal delivery of anti-viral drugs or anti-inflammatory drugs, which could raise their efficacy, deliver them to the specific target and minimize their toxic side effects.     

Three dimensionally printed pearl powder/poly-caprolactone composite scaffolds for bone regeneration**

Abstract

Pearl has great potential as a natural biomaterial for bone tissue engineering, but it suffers from low porosity, difficulty in molding, and poor anti-buckling property. In this study, we used the 3-D printing technique to fabricate original pearl powder and PCL composite scaffolds with different concentrations of pearl powder. The four groups of scaffolds were termed PCL, 30% Pearl/PCL, 50% Pearl/PCL and 80% Pearl/PCL scaffolds according to the proportion of pearl powder. The samples were systematically investigated by scanning electron microscopy (SEM), wide-angle XRD, liquid substitution, Zwick static materials testing, and energy dispersive X-ray analysis. Biological characterization included SEM, fluorescent staining using calcein-AM, cell counting kit-8 assay, alkaline phosphatase and qRT-PCR analysis. The results show that the pore size and the pore morphology of the scaffolds are closely controlled via 3-D printing. This is very beneficial for tissue growth and nutrition transmission. The regular and uniform square macropore structure ensured that the pearl powder/PCL scaffolds had favorable mechanical strength. As the concentration of pearl powder in the scaffolds increase, the compressive strength and apatite formation increase as well as cell adhesion, proliferation, and osteogenic differentiation. These results show that pearl powder/PCL scaffolds fit the requirements of bone tissue engineering. The structures as well as physicochemical and biological properties of pearl powder/PCL composite scaffolds are positively associated with pearl powder concentrations.     

Solute transport analysis in pH-responsive,complexing hydrogels of poly(methacrylic acid-g-ethylene glycol)

We report on the preparation and properties of hydrogels of poly(methacrylic acid-g-ethylene glycol) that exhibit pH-responsive swelling behavior due to the reversible formation/dissociation of interpolymer complexes. Because of their nature, these materials may be useful in drug delivery applications. In this work, we studied the diffusional behavior of three solutes of varying molecular size in the complexing hydrogels as a function of solution pH. The ability of these gels to control the solute diffusion rates was strongly dependent on the molecular size of the solute and the environmental pH. The diffusion coefficients for solutes were calculated as a function of pH and were lower in acidic than neutral or basic media due to the formation of interpolymer complexes in the gels. However, the ratio of the solute radius to the network mesh size also was a significant factor in the overall behavior of these gels. The diffusion coefficient of the smallest solute, proxyphylline, studied only changed by a factor of five between the complexed and uncomplexed state. However, for the largest solute, FITC-dextran, which has a molecular radius ten times greater than proxyphylline, the diffusion coefficients of the drugs in complexed and uncomplexed gels varied by almost two orders of magnitude. These results are explained in terms of mesh size characteristics of the gels.     

Polymeric micelles for GSH-triggered delivery of arsenic species to cancer cells

Arsenic trioxide (ATO), dissolved in water as arsenous acid or inorganic arsenite (As^III), is an effective chemotherapeutic agent against acute promyelocytic leukemia (APL). It has been under investigation as a potential treatment for a variety of solid tumors although with much poorer efficacy than for APL. The toxicity of As^III and its derivatives is a common concern that has limited its use. The objective of the current study was to develop a polymeric micelle drug delivery system for efficient and controlled delivery of trivalent arsenicals to solid tumor cells. A polymeric micelle-based drug delivery system can potentially extend the duration of drug circulation in blood, restrict access of encapsulated drug to normal tissues, achieve tumor targeted drug delivery, enhance drug accumulation in the tumor area, and trigger drug release at tumor sites if designed properly. These, in turn, can lead to an improved therapeutic index for the polymeric micellar formulation of arsenic species compared to their free form. Towards this goal, a biodegradable block copolymer with pendent thiol groups on the hydrophobic block, i.e., methoxy poly(ethylene oxide)-block-poly[α-(6-mecaptohexyl amino)carboxylate-ε-caprolactone] [PEO-b-P(CCLC₆-SH)], was synthesized and used for conjugation of a trivalent arsenical, phenylarsine oxide (PAO), to free thiol groups on the polymer backbone. PAO-loaded micelles had refined size distribution with an average diameter of 150 nm as evidenced by dynamic light scattering (DLS) in water. Prepared polymeric micelles were characterized for the level of PAO conjugation using inductively coupled plasma mass spectrometry (ICP-MS). The results showed 65% of total free thiols were conjugated to PAO providing an arsenic/polymer loading content of ∼2.5 wt%. In vitro release study suggests prolonged release of PAO from its polymeric micellar carrier, which was accelerated in the presence of glutathione (GSH). Cytotoxicity studies against MDA-MB-435 cells show that the IC₅₀ of PEO-b-P(CCLC₆-S-PAO) is not significantly different from that of free PAO. The results indicate that PEO-b-P(CCLC₆-SH) is a promising carrier for successful arsenic delivery for cancer therapy.     

Thermosensitive hydrogels based on polypeptides for localized and sustained delivery of anticancer drugs

Thermosensitive hydrogels based on poly(γ-ethyl-l-glutamate)-poly(ethylene glycol)-poly(γ-ethyl-l-glutamate) triblock copolymers (PELG-PEG-PELG) were prepared for localized and sustained delivery of anticancer drugs. The polypeptide-based hydrogels showed much lower critical gelation concentration than the traditional polyester-based hydrogels. In vivo biocompatibility studies revealed that the in situ formed gels in the subcutaneous layer last for ∼21 days, and H&E staining study suggested acceptable biocompatibility of our materials in vivo. Then the hydrogels were tried as injectable implants to encapsulate antitumor drug, paclitaxel (PTX), to assess the in situ anti-tumoral activity using liver cancer xenograft model. The results demonstrated that the PTX-incorporated hydrogels could efficiently suppress the tumor growth, and did not result in obvious damage to normal organs. Therefore, the polypeptide-based thermosensitive hydrogels designed in the present study have great potential to serve as an effective platform for localized anti-cancer drug delivery.     

Examination of fabrication conditions of acrylate-based hydrogel formulations for doxorubicin release and efficacy test for hepatocellular carcinoma cell

The objective of the present study was to develop 2-hydroxypropyl methacrylate-co-polyethylene methacrylate [p(HPMA-co-PEG–MEMA)] hydrogels that are able to efficiently entrap doxorubicin for the application of loco-regional control of the cancer disease. Systemic chemotherapy provides low clinical benefit while localized chemotherapy might provide a therapeutic advantage. In this study, effects of hydrogel properties such as PEG chains length, cross-linking density, biocompatibility, drug loading efficiency, and drug release kinetics were evaluated in vitro for targeted and controlled drug delivery. In addition, the characterization of the hydrogel formulations was conducted with swelling experiments, permeability tests, Fourier transform infrared, SEM, and contact angle studies. In these drug-hydrogel systems, doxorubicin contains amine group that can be expected a strong Lewis acid–base interaction between drug and polar groups of PEG chains, thus the drug was released in a timely fashion with an electrostatic interaction mechanism. It was observed that doxorubicin release from the hydrogel formulations decreased when the density of cross-linking, and drug/polymer ratio were increased while an increase in the PEG chains length of the macro-monomer (i.e. PEG–MEMA) in the hydrogel system was associated with an increase in water content and doxorubicin release. The biocompatibility of the hydrogel formulations has been investigated using two measures: cytotoxicity test (using lactate dehydrogenase assay) and major serum proteins adsorption studies. Antitumor activity of the released doxorubicin was assessed using a human SNU398 human hepatocellular carcinoma cell line. It was observed that doxorubicin released from all of our hydrogel formulations which remained biologically active and had the capability to kill the tested cancer cells.     

Functionalization of electrospun poly(caprolactone) fibers for pH-controlled delivery of doxorubicin hydrochloride

Functionalized electrospun polymer fibers are a promising candidate for controlled delivery of chemotherapeutic drugs to improve the therapeutic efficacy and to reduce the potential toxic effects by delivering the drug at a rate governed by the physiological need of the site of action. In this study, poly(caprolactone) (PCL) fibers were fabricated by electrospinning, followed by hydrolyzation to introduce functional groups on the fiber surface. Characterization studies were performed on these functionalized fibers using X-ray photoelectron spectroscopy, scanning electron microscopy, and Toluidine Blue O dye assay. The pH-sensitivity of the functional groups on the fiber surface and doxorubicin hydrochloride was utilized to bind the drug electrostatically to these functionalized PCL fibers. The effect of pH on drug loading and release kinetics was investigated. Results indicate successful electrostatic binding of the drug to functionalized electrospun fibers and a high drug payload. The drug delivery response can be modulated by introduction of suitable stimuli (pH).