聚甲基丙烯酸廿二烷酯在环己烷中静态和动态溶液性质的研究

利用光散射法,测定了带有长链侧基的聚甲基丙烯酸正廿二烷基酯在环己烷中稀溶液范围内(C相似文献   

Hydrolytic Stability of Methacrylamide and Methacrylate in Gelatin Methacryloyl and Decoupling of Gelatin Methacrylamide from Gelatin Methacryloyl through Hydrolysis

Gelatin methacryloyl (GelMA; GM) is a promising nature‐derived photocurable material that can mimic the extracellular matrix because GelMA features tailorable mechanical properties, proteolytic degradation, and good cell adhesion. GelMA contains not only methacrylamide but also methacrylate. However, the hydrolytic stability of methacrylamide and methacrylate groups of GelMA in aqueous solutions has not been scrutinized. Here, the structural change of GelMA through hydrolysis is investigated for the first time. The structural change of hydrolyzed GelMA is quantitatively identified using colorimetric and ¹H NMR methods. The methacrylate groups decompose markedly at high pH solutions, but the methacrylamide groups remain stable. Further, pure gelatin methacrylamide is successfully decoupled from GelMA for a better understanding of GelMA structure and future use for biomedical applications.     

Mucoadhesive platforms for targeted delivery to the colon

A novel platform system, comprising a mucoadhesive core and a rapid release carrier, was designed for targeted drug delivery to the colon. Prednisolone pellets containing different carbomers, including Carbopol 971P, Carbopol 974P and Polycarbophil AA-1, with or without organic acids, were produced by extrusion-spheronization. Mucoadhesive pellets were coated with a new enteric double-coating system, which dissolves at pH 7. This system comprises an inner layer of partially neutralized Eudragit^® S and buffer salt and an outer coating of standard Eudragit^® S. A single layer of standard Eudragit S was also applied for comparison purposes. Dissolution of the coated pellets was assessed in USP II apparatus in 0.1 N HCl followed by Krebs bicarbonate buffer pH 7.4. Visualization of the coating dissolution process was performed by confocal laser scanning microscopy using fluorescent markers in both layers. The mucoadhesive properties of uncoated, single-coated and-double coated pellets were evaluated ex vivo on porcine colonic mucosa. Mucoadhesive pellets coated with a single layer of Eudragit^® S release its cargo after a lag time of 120 min in Krebs buffer. In contrast, drug release from the double-coated mucoadhesive pellets was significantly accelerated, starting at 75 min. In addition, the mucoadhesive properties of the core of the double coated pellets were higher than those from single-coated pellets after the core had been exposed to the buffer medium. This novel platform technology has the potential to target the colon and overcome the variability in transit and harmonize drug release and bioavailability.     

经皮中央纵向穿刺技术在治疗6例骶骨转移性肿瘤中的应用

目的探讨经皮中央纵向穿刺技术在治疗骶骨转移性肿瘤中应用的疗效。方法回顾性分析2009年9月至2011年10月,在C型臂X线引导下应用经皮中央纵向穿刺技术治疗骶骨转移性肿瘤6例的临床资料。结果 6例11个椎体均顺利完成,每椎平均手术时间21.3min。S1、S2、S3椎体平均注入骨水泥分别为4.2、2.8、2.0mL,骨水泥外漏1椎(S3),无神经损害并发症发生。术后3dVAS评分[(3.25±0.90)分]较术前[(6.25±1.09)分]明显下降(P<0.05)。结论通过中央纵向穿刺途径行经皮骶椎成形术具有安全有效、操作简单等特点。适于对骶骨转移性肿瘤的穿刺活检及强化治疗。     

异戊二烯-甲基丙烯酸甲酯的阴离子嵌段共聚合

在四氢呋喃(THF)与环己烷的混合溶剂中,以正丁基锂(n-BuLi)为引发剂,采用具有较大空间位阻和特定电荷环境的P配合物为添加剂,实现了异戊二烯(Ip)和甲基丙烯酸甲酯(MMA)的阴离子嵌段共聚。分别采用GPC、1H-NMR对聚合物的结构进行了分析表征。结果表明：随着THF与环己烷体积比的增大,单体的转化率呈现下降的趋势;同时空间位阻较大的P配合物的加入,堵塞了正、负离子对之间的部分通道,有效地抑制了MMA段聚合副反应的发生,在易于工业化的0 ℃之下成功合成了分子量分布窄(1.21)的聚异戊二烯聚甲基丙烯酸甲酯嵌段共聚物(PI-b-PMMA),并且共聚物中PI嵌段以3,4结构链节为主。     

Polyelectrolyte complex nanoparticles of amino poly(glycerol methacrylate)s and insulin

Amino poly(glycerol methacrylate)s (PGOHMAs) were synthesized from linear or star-shaped poly(glycidyl methacrylate)s (PGMA)s via ring opening reactions with 1,2-ethanediamine, 1,4-butanediamine and diethylenetriamine, respectively. The resulting cationic polymers were employed to form polyelectrolyte complexes (PECs) with insulin. Parameters influencing complex formation were investigated by dynamic light scattering (DLS). PECs in the size range of 100-200 nm were obtained under optimal conditions, i.e., the pH value of PECs was 5.58-6.27, the concentration of NaCl was 0.02 mol/L, and insulin-polymer weight ratio was 0.8. The insulin association efficiency (AE) of current system increased with zeta potentials of PECs. Circular dichroism (CD) analysis corroborated that the structure of insulin in the PEC nanoparticles was preserved after lyophilization. Fourier transform infrared (FT-IR) and X-ray diffraction (XRD) experiments demonstrated that weak physical interactions between insulin and amino PGOHMAs play an important role in the formation of PECs. The release of insulin depends on both structure and architecture of amino PGOHMAs. These PECs would be potentially useful for mucosal administration.     

A rabbit model for efficacy evaluation of endovascular coil materials

Background

To investigate biomaterials seeking for their possible use for aneurysm treatment, in vivo screening tests using a number of potential materials are required. However, there is no established animal model that is suitable for such purpose. Some models require special preparation of tested materials for transcatheter delivery and others are inappropriate in view of their cost-effectiveness. The purpose of this study is to establish an animal model that overcomes these limitations and help us select potential materials before the preclinical evaluation.

Methods

Bilateral CCAs in a rabbit were surgically ligated, and a 2-cm segment of either a bare platinum coil or a polymeric coil (a platinum coil coated with PLGA 10/90) was implanted into each blind-ended arterial segment (n = 26). They were harvested at day 1, 7, 10, 14, or 30, respectively. Angiographic and histologic evaluations as well as quantitative analysis on the development of the organized thrombus were performed.

Results

One day after the implantation, both platinum and PLGA coils were surrounded by immature thrombus that was induced by blood flow stagnation in the arterial segment. At day 7, minimal thrombus organization was observed around both types of materials. At postimplantation days 10 and 14, fibrocellular responses, the early findings of the thrombus organization process, were observed in both material groups. Such histologic findings were more prominent in the PLGA coil group as compared to the platinum coil group (day 10, P = .051; day 14, P = .011). Well-organized thrombus was observed in both material groups at day 30 without showing statistical difference (P = .12).

Conclusion

Given the cost-effectiveness, the simple material preparation process, and its feasible histologic evaluation methods, this new animal model can be useful in screening other potential biomaterials for the development of new coil devices.     

一种新型的复合生物敷料――人发角蛋白－胶原海绵－聚甲基丙烯酸羟乙酯对大鼠烧伤创面治疗作用的实验研究

背景：作者在对人发角蛋白的机制研究和临床应用中提出了一个全新的组织工程学概念--在体/原位组织工程。在该理论的指导下,拟以人发角蛋白-胶原海绵为支架,复合一种可作为药物缓释载体的聚甲基丙烯酸羟乙酯,探讨其在体内原位诱导周围组织细胞构建真皮的可行性。 目的：以人发角蛋白-胶原海绵为敷料内层,复合包裹药物虎杖的聚甲基丙烯酸羟乙酯载体,制备一种双层复合生物材料,观察其对烧伤创面的促愈合作用。 设计、时间及地点: 随机对照动物实验,于2005-03/12在南方医科大学组胚教研室完成。 材料：选用雄性SD大鼠15只制备烧伤动物模型,将模型鼠完全随机分为3组：实验组,阳性对照组及阴性对照组。 方法: ①将在体内具有慢、中、快3种吸收速度的人发角蛋白组分材料编织成网孔为 1 mm×1 mm的网格,与从牛跟腱中抽提Ⅰ型胶原溶液混合后放入模具,经真空冷冻干燥后制成海绵状膜（作复合内层敷料）。②用聚合法制备聚甲基丙烯酸羟乙酯,再与药物虎杖一同成膜,制备药物缓释载体膜（作复合外层敷料）。③用SD大鼠制备深Ⅱ度烧伤动物模型,烧伤后3 d做清创处理,清创后实验组用与创面相同大小的人发角蛋白-胶原海绵-聚甲基丙烯酸羟乙酯复合敷料覆盖创面,阳性对照组用戊二醛猪皮覆盖创面,阴性对照组为单纯无菌纱布覆盖。 主要观察指标:①术后以创面完全上皮化为标准,记录创面愈合时间并分别计算7,14,21 d愈合率。②于覆敷料后1,2,4,6,8周切取整个创面及其周围组织,光学显微镜观察肉牙组织生长情况和免疫组织化学染色观察新生组织中的胶原纤维和弹性纤维形态。 结果：①实验组创面覆盖后渗出明显减少且保持一定湿度,而阳性对照组创面较干燥;实验组及阳性对照组的创面愈合时间较阴性对照组提前（P＝0.000）;创面在7,14,21 d的愈合率均较阴性对照组高（P＝0.000）,且实验组在14 d的愈合率较阳性对照组高（P < 0.05）。②覆敷料后2周,光镜下观察可见创面肉芽组织中有较细小的胶原纤维填充创面。实验组较其他2组明显。胶原蛋白及弹性蛋白的免疫组织化学染色显示：第2周,实验组创面真皮基质中,Ⅰ型胶原呈棕黄色细密条带状;且有少量被染成棕黄色细丝状的弹性纤维,阳性对照组不明显,而阴性对照组中弹性蛋白无阳性表达。第8周,3组创面均愈合良好。实验组及阳性对照组胶原纤维束改造塑形,无瘢痕形成趋势。阴性对照组真皮层组织排列紊乱。 结论: 人发角蛋白-胶原海绵-聚甲基丙烯酸羟乙酯/虎杖复合生物敷料可促进深Ⅱ度烧伤实验大鼠创面的愈合。     

甲基丙烯酸环氧丙酯致人支气管上皮细胞恶性转化相关DNA修复基因表达改变的研究

目的：检测甲基丙烯酸环氧丙酯（glycidyl methacrylate,GMA）致人支气管上皮细胞（16HBE）恶性转化相关DNA修复基因表达改变的情况,以探讨GMA致细胞癌变的机制。方法：采用＂基因组稳定和DNA修复基因芯片＂分析检测GMA诱导16HBE细胞恶性转化过程中,经鉴定具备恶性细胞表型特征的第30代转化细胞DNA修复基因表达的改变。结果：GMA转化第30代细胞与同代龄对照细胞比较,在113个基因中有8个基因的表达有显著差异,其中7个基因表达上调（ratio〉2）,分别是NBN、RAD50、RAD51、OGG1、XAB2、TOP3A、TNKS;NEIL2基因表达下调（0〈ratio〈0.5）。结论：GMA致16HBE细胞恶性转化是一个多基因参与涉及多通路的复杂过程,DNA修复基因表达的改变可能是该过程中重要的分子事件。