气电纺纳米羟基磷灰石/聚羟基丁酸酯复合纤维支架对大鼠骨髓基质细胞成骨分化的影响

背景:利用静电纺丝技术制备的纤维支架材料具有类似于细胞外间质的形态和结构,且其独特的生产工艺可以很便捷地将功能性纳米颗粒复合入高分子纤维内,在制备组织工程支架方面具有独特的优势.目的:创新性地将物理共混法与气流-高压静电纺丝技术相结合,仿生构建纳米羟基磷灰石/聚羟基丁酸酯复合纳米纤维支架材料,评价其作为骨组织工程支架在体外的生物活性.设计、时间及地点:细胞学体外实验,于2008-03/2009-04在四川大学口腔疾病研究国家重点实验室完成.材料:按照预定参数进行气流-高压静电纺丝,分别制备气电纺纯聚羟基丁酸酯纤维支架及含质量分数为10%纳米羟基磷灰石的纳米羟基磷灰石,聚羟基丁酸酯复合纤维支架.方法:将大鼠骨髓基质细胞接种于纳米羟基磷灰石/聚羟基丁酸酯纳米纤维支架后进行体外培养(实验组),以接种于气电纺纯聚羟基丁酸酯纳米纤维支架为对照组,接种于细胞培养板为空白对照组.主要观察指标:通过RT-PCR检测连续培养14 d后细胞成骨分化标志物碱性磷酸酶、I型胶原和骨钙素的mRNA表达.结果:各组均能检测到3种成骨标志物碱性磷酸酶、I型胶原和骨钙素的mRNA表达.通过Quantity One软件分析计算目的条带吸光度值与内参β-actin条带吸光度值的比值,可以发现3种目的基因在实验组具有最高表达水平,其次为对照组,空白对照组的表达明显最弱.结论:气电纺纳米羟基磷灰石,聚羟基丁酸酯复合纤维支架可促进大鼠骨髓基质细胞成骨分化,证实其在体外具有优良的生物活性.     

聚羟基丁酸已酯-聚乳酸材料改性应用于组织工程隆鼻充填材料的可行性

目的:观察以改性聚羟基丁酸已酯即聚羟基丁酸已酯与聚乳酸共混的组织工程软骨做为隆鼻充填材料的可行性。方法:实验于2005-07/11在解放军第四军医大学附属西京医院整形外科实验室完成。①取兔耳软骨细胞的分离、培养并鉴定。②预先将聚羟基丁酸已酯-聚乳酸制备成1.5cm×1.0cm的瓦状形态膜片,表面以聚羟基丁酸已酯-聚乳酸制成的纺丝反复缠绕,形成“三明治”样结构,进行预处理。③进行细胞-支架复合物的体外构建及培养,收集体外扩增的第3代软骨细胞,接种于聚羟基丁酸已酯-聚乳酸支架上。④取3周龄新西兰兔12只,采用随机数字法将其分成实验组和对照组,每组各6只。实验组:将细胞-支架复合物置于兔的鼻背部骨膜下,观察软骨形成情况;对照组:单纯以未接种软骨细胞的支架移植于兔背部皮下。于相同时间点进行检测。结果:经过大体、组织染色及扫描电镜检查发现:①实验组:植入4周后该复合物在兔鼻背下支架表层有软骨层形成,并可见软骨细胞突入至支架材料内部;8周后支架材料继续降解,软骨细胞及细胞基质生成明显,伴有胶原长入。②对照组:植入4周、8周支架材料外周先形成一层透明组织薄膜,周围无炎性细胞浸润,内部为聚羟基丁酸已酯-聚乳酸支架材料,随着时间延续,周围纤维组织增生,支架材料出现不同程度的降解,不能维持原有的空间结构,较实验组结构崩解明显。未见有类软骨样组织形成。结论:以改性聚羟基丁酸已酯(聚羟基丁酸已酯-聚乳酸共混物)做为支架材料构建的组织工程软骨,可用于隆鼻的充填材料。     

聚羟基丁酸已酯-聚乳酸材料改性应用于组织工程隆鼻充填材料的可行性

目的：观察以改性聚羟基丁酸已酯即聚羟基丁酸已酯与聚乳酸共混的组织工程软骨做为隆鼻充填材料的可行性。 方法：实验于2005—07／11在解放军第四军医大学附属西京医院整形外科实验室完成。①取兔耳软骨细胞的分离．培养并鉴定。②预先将聚羟基丁酸已酯-聚乳酸制备成1．5cm&;#215;1．0cm的瓦状形态膜片，表面以聚羟基丁酸已酯-聚乳酸制成的纺丝反复缠绕，形成“三明治”样结构，进行预处理。③进行细胞-支架复合物的体外构建及培养，收集体外扩增的第3代软骨细胞，接种于聚羟基丁酸已酯-聚乳酸支架上。④取3周龄新西兰兔12只，采用随机数字法将其分成实验组和对照组，每组各6只。实验组：将细胞-支架复合物置于兔的鼻背部骨膜下，观察软骨形成情况；对照组：单纯以未接种软骨细胞的支架移植于兔背部皮下。于相同时间点进行检测。 结果：经过大体．组织染色及扫描电镜检查发现：①实验组：植入4周后该复合物在免鼻背下支架表层有软骨层形成，并可见软骨细胞突入至支架材料内部；8周后支架材料继续降解，软骨细胞及细胞基质生成明显，伴有胶原长入。②对照组：植入4周、8周支架材料外周先形成一层透明组织薄膜，周围无炎性细胞浸润，内部为聚羟基丁酸已酯-聚乳酸支架材料，随着时间延续，周围纤维组织增生，支架材料出现不同程度的降解，不能维持原有的空间结构，较实验组结构崩解明显。未见有类软骨样组织形成。 结论：以改性聚羟基丁酸已酯（聚羟基丁酸已酯-聚乳酸共混物）做为支架材料构建的组织工程软骨，可用于隆鼻的充填材料。     

不同方法制备聚羟基脂肪酸酯支架材料及扫描电镜结构观察

背景：聚羟基脂肪酸酯材料是一类具有良好生物相容性和完全可降解性的生物塑料，但由于生产成本相对较高因而暂时限制了其普及应用。目的：拟采用溶剂浇铸法、热致相分离法、分子自组装法制作聚羟基脂肪酸酯支架材料，并利用扫描电镜对3种多孔材料的结构进行观察分析。设计、时间及地点：组织工程材料学体外观察，于2007—10／2008—03在汕头大学多学科研究中心完成。材料：聚3．羟基丁酸己酸酯由清华大学微生物实验室友情赠送，聚3-羟基丁酸酯为中国江苏省南天股份有限公司产品。方法：①将1．0g马来酸化的聚3-羟基丁酸己酸酯溶于50mL氯仿中，加热温度60℃持续1h，所得溶液倾倒在120mm培养皿中，室温下挥发1d，置冰干机48h，溶剂充分蒸发。同法以聚乳酸制备支架材料作为对照。②将0．5g聚3-羟基丁酸己酸酯溶于20mL 1，4-二氧六环中，加热至80℃并不断搅拌使材料充分溶解，所得澄清液倒进50mL敞口烧杯后，迅速转移至液氮（-196℃）中孵育30min，置冰干机48h，除去溶剂。同法以聚乳酸制备支架材料作为对照。③将1．0g聚3-羟基丁酸酯溶于50mL 60℃氯仿中，得到澄清液后，每10mL溶液中加入2．5mL二氧六环，所得混合液用普通超声仪超声20min，4℃冷冻20h使溶液变成凝胶，用水浸泡凝胶1d，去水后-80℃冷冻1h，再置于冰干机中48h。主要观察指标：3种样品的表面形貌和空隙度扫描电镜观察结果。结果：溶剂浇铸法制备的聚乳酸膜非常平滑，而厚度约200μm的马来酸化的聚3-羟基丁酸己酸酯膜比较粗糙，且膜表面具有很多螺纹结构。热致相分离法制备的聚3-羟基丁酸己酸酯多孔支架比聚乳酸支架具有更大的孔隙度，平均孔径约达到500μm。分子自组装法制备的聚3-羟基丁酸酯纳米纤维支架具有连续的三维网状结构，纤维平均直径为80—350nm，与胶原蛋白的纳米纤维结构类似。结论：采用溶剂浇铸法、热致相分离法、分子自组装法成功制作出3种不同类型的聚羟基脂肪酸酯支架材料，且其表面形态及孔隙结构良好。     

电纺丝技术制备生物活性复合纤维支架及其体外降解性

背景:聚乳酸/羟基磷灰石类复合材料支架常用的制备方法主要有冷压法、粒子沥滤法、热致相分离法等,但是在增强材料界面的结合、调节材料的降解速率、改善材料的强度等方面仍不能满足要求。目的:制备左旋聚乳酸/羟基磷灰石复合纳米纤维支架。方法:采用静电纺丝法制备聚乳酸/羟基磷灰石复合纳米纤维支架。以扫面电镜对纤维的结构形态进行分析,并观察其在PBS中浸泡不同时间的体外降解过程。结果与结论:羟基磷灰石纳米粒子与聚乳酸/基体间存在化学键合,纳米粒子使纤维直径增大且表面粗糙程度增加,这种结构将有利于细胞在纤维膜上的伸展和和繁殖。羟基磷灰石的引入,抑制了聚乳酸降解过程中的自催化作用,减缓了聚乳酸的降解速度。说明电纺丝技术制备的聚乳酸/羟基磷灰石复合支架在组织工程支架材料方面具有潜在的应用前景。     

壳聚糖-聚羟基丁酸酯接枝共聚物的制备与表征

背景：壳聚糖／聚羟基丁酸酯共混或共聚材料的研究因壳聚糖和聚羟基丁酸酯特殊的生物来源而倍受关注，但尚无合适的方法对二者进行有效的聚合。 目的：在均相条件下，以温和的引发剂引发获得壳聚糖／聚羟基丁酸酯接枝共聚物。 设计、时间及地点：单一样本试验，于2007—08／10在西安建筑科技大学化学实验研究中心完成。 材料：壳聚糖（DD=100％，Mη=123000，为日本Kyoto公司产品。聚-3-羟基丁酸酯由购白Aldrich chemicals的聚羟基丁酸酯树脂在醋酸中降解精制得到，Mr10000。 方法：以过氧化二苯甲酰为引发剂，在醋酸-二甲基亚砜复合体系中进行聚-3-羟基丁酸酯与壳聚糖的接枝反应。反应温度为85℃，在氮气保护下反应5h。红外分析、核磁共振分析和元素分析证实了接枝反应的发生及接枝产物的化学结构。用广角X线衍射和热重／差热分析分别表征了接枝产物的晶体形态和热稳定性。 主要观察指标：接枝产物的化学结构、晶体形态、热稳定性。 结果：产物经红外分析、核磁共振及元素分析证实了接枝反应的发生，广角X射线衍射和热重分析表明，接枝产物的结晶状态不同于壳聚糖和聚羟基丁酸酯，且具有一定的热稳定性。 结论：以过氧化二苯甲酰为引发剂，可以制备出性质稳定的壳聚糖／聚羟基丁酸酯接枝共聚物。     

电纺丝技术制备生物活性复合纤维支架及其体外降解性

背景：聚乳酸/羟基磷灰石类复合材料支架常用的制备方法主要有冷压法、粒子沥滤法、热致相分离法等,但是在增强材料界面的结合、调节材料的降解速率、改善材料的强度等方面仍不能满足要求。目的：制备左旋聚乳酸/羟基磷灰石复合纳米纤维支架。方法：采用静电纺丝法制备聚乳酸/羟基磷灰石复合纳米纤维支架。以扫面电镜对纤维的结构形态进行分析,并观察其在PBS中浸泡不同时间的体外降解过程。结果与结论：羟基磷灰石纳米粒子与聚乳酸/基体间存在化学键合,纳米粒子使纤维直径增大且表面粗糙程度增加,这种结构将有利于细胞在纤维膜上的伸展和和繁殖。羟基磷灰石的引入,抑制了聚乳酸降解过程中的自催化作用,减缓了聚乳酸的降解速度。说明电纺丝技术制备的聚乳酸/羟基磷灰石复合支架在组织工程支架材料方面具有潜在的应用前景。     

热致相分离法制备聚羟基丁酸酯-羟基戊酸酯纳米纤维支架及其表征

背景:由微生物合成的聚羟基丁酸酯-羟基戊酸酯(polyhydroxybutyrate-hydroxyvalerate,PHBV)是聚羟基脂肪酸酯的一种,具有良好的生物相容性和机械强度。目的:探讨热致相分离法制备PHBV纳米纤维支架的方法及结晶行为。方法:采用扫描电镜、广角X射线衍射、红外光谱和差示扫描量热分析分析基质的结构。结果与结论:凝胶温度对纳米纤维的结晶和热性质有很大的影响。当凝胶温度较高时,PHBV纳米纤维的结晶度和晶粒尺寸随着凝胶温度的降低而减小,而且随着凝胶温度的降低,其结晶的有序性增加。说明温度对PHBV支架形貌和结构的影响可能对PHBV支架的性质-包括生物降解性和对细胞活性的生物应答反应有一定的积极意义。     

新型生物材料改性聚碳酸亚丙酯的制备及其生物相容性研究

目的 为改善聚碳酸亚丙酯（PPC）耐热性及稳定性较差等缺点,制备了新型生物材料改性聚碳酸亚丙酯（M-PPC）,并对其进行生物相容性研究,为其临床应用提供理论基础。方法 将PPC与聚β-羟基丁酸酯（PHB）共混制备成M-PPC;应用四甲基偶氮唑盐微量酶反应比色法（MTT）检测其细胞毒性,并进行52周白兔肌肉植入试验以评价其生物相容性。结果 制备出M-PPC;M-PPC无细胞毒性,植入白兔背部肌肉后,机体无任何炎症反应。结论 成功地制备出新型生物材料M-PPC,M-PPC在体内外均具有良好的生物相容性。     

聚碳酸亚丙酯/壳聚糖纳米纤维复合三维多孔支架的构建与性能

背景:聚碳酸亚丙酯(PPC)具有良好的力学性能和生物相容性,但是也存在合成高分子的共性不足即缺乏生物活性.壳聚糖纳米纤维具有优异的生物活性,但力学性能较差,很难保持稳定的高强度三维结构.目的:将壳聚糖纳米纤维与聚碳酸亚丙酯复合,制备具有优异生物活性和良好力学性能的三维多孔组织工程支架.方法:用溶液浇铸/粒子沥滤法制备PPC多孔支架,再用相分离法原位复合三维壳聚糖纳米纤维制备聚碳酸亚丙酯,壳聚糖纳米纤维复合三维多孔支架(PPC/CSNF).用扫描电子显微镜观察PPC及PPC,CSNF多孔支架微观形态,并测定其压缩模量、孔隙率.用扫描电子显微镜观察PPC/CSNF多孔支架在新西兰大白兔大腿皮下埋植1,2个月后的细胞生长情况.结果:PPC多孔支架孔径分布为200-500 μm且孔连通性好,PPC/CSNF多孔支架中的壳聚糖纳米纤维分布均匀其直径在50～500 nm之间;各种质量浓度的支架孔隙率均为90%以上;各种支架的压缩模量随着PPC浓度的增加而增加,最高可达约15 MPa;体内埋植的实验结果表明PPC/CSNF多孔支架具有良好的生物活性,可促进骨髓基质干细胞向软骨细胞分化.结果提示溶液浇铸/粒子沥滤法与低温相分离法相结合成功制备了力学性能与生物活性优异的PPC/CSNF多孔支架.该支架可促进新西兰大白兔的骨髓基质干细胞向软骨细胞分化.     

多孔聚3-羟基丁酸-4-羟基丁酸/偏磷酸钙复合膜的制备及降解性能

背景:种子细胞能否成功黏附于支架材料表面,与支架材料的降解性能密切相关。目的:制备多孔聚3-羟基丁酸-4-羟基丁酸/偏磷酸钙复合膜,并观察其体外降解性能。方法:将聚3-羟基丁酸-4-羟基丁酸和偏磷酸钙按50∶50混合均匀,完全溶解于氯仿后,搅拌均匀,倾倒在培养皿上,干燥后即成多孔膜。将其置于循环装置中,流速为0.30m/s,管路内灌满37℃生理盐水50mL。结果与结论:流场作用多孔复合膜2,4,8,16,24h后,其失重率分别为4.5%,5.6%,6.9%,9.6%和10.6%;扫描电镜显示,降解24h后,表面偏磷酸钙微粒已降解完全或脱落,而内凹偏磷酸钙微粒仍嵌入在聚3-羟基丁酸-4-羟基丁酸复合膜内,复合膜表面直径2μm的微孔基本不见,直径30~50μm的大孔基本未变,但孔隙边缘变得圆滑;水静力称重法计算出降解实验前后复合膜吸水率、显气孔率和密度分别为降解前的40.6%,46.3%,1.14g/cm3和降解后的51.6%,54.1%1.05g/cm3。说明实验制备的多孔聚3-羟基丁酸-4-羟基丁酸/偏磷酸钙复合膜降解早期以偏磷酸钙降解为主,降解过程中孔内微丝易降解或断裂。     

改性纳米羟基磷灰石/PLGA材料同骨髓基质干细胞复合后相关生物学评价

背景:改性纳米羟基磷灰石/聚乙交酯-丙交酯复合材料(L-lactic acid oligomer/Poly(lactide-co-glycolde),PLGA/g-HA)因具有良好的稳定性及机械性能,目前备受关注。目的:观察骨髓基质干细胞和改性PLGA/g-HA体外复合后的细胞活性及生物相容性。方法:原代培养兔骨髓基质干细胞,传代培养至第3代,MTT比色法检测在不同浓度PLGA/g-HA浸提液(10%、30%、50%、80%)中骨髓基质干细胞的增殖情况,以及骨髓基质干细胞在PLGA/g-HA表面的黏附性及其细胞形态。结果与结论:于培养后1,3d测得在不同浓度浸提液下骨髓基质干细胞的A值,10%浸提液组和对照组相比无显著性差异,4种浓度浸提液的细胞毒性均为1级;扫描电镜观察到骨髓基质干细胞在PLGA/g-HA表面逐渐伸展,形成伪足,最终牢固锚定在材料表面。提示在PLGA/g-HA的浸提液中骨髓基质干细胞能够发生增殖,对细胞无毒性。骨髓基质干细胞可以黏附在PLGA/g-HA表面且形态正常,生长状态良好,证明PLGA/g-HA具有良好的相容性和黏附性,可作为修复骨缺损的复合组织工程骨。     

Release of tetracycline hydrochloride from electrospun poly(ethylene-co-vinylacetate), poly(lactic acid), and a blend.

Electrospun fiber mats are explored as drug delivery vehicles using tetracycline hydrochloride as a model drug. The mats were made either from poly(lactic acid) (PLA), poly(ethylene-co-vinyl acetate) (PEVA), or from a 50:50 blend of the two. The fibers were electrospun from chloroform solutions containing a small amount of methanol to solubilize the drug. The release of the tetracycline hydrochloride from these new drug delivery systems was followed by UV-VIS spectroscopy. Release profiles from the electrospun mats were compared to a commercially available drug delivery system, Actisite (Alza Corporation, Palo Alto, CA), as well as to cast films of the various formulations.     

Three-dimensional crimped biodegradable poly(lactic acid) fibers prepared via melt spinning and controlled structural reorganization

Biodegradable three-dimensional crimped fibers were prepared by the side-by-side composite spinning of poly(lactic acid) (PLA) and low-melting point PLA (LM-PLA). The structural variation of the PLA/LM-PLA composite fibers during dry and wet heat treatment was explored systematically. It is shown that crystallization and disorientation were two key factors for the formation of the three-dimensional crimped structure of PLA/LM-PLA side-by-side composite fibers (SSCF). The wet heat-treated fiber has better crimp performance and fluffiness, and the crimp number, crimp ratio and crimp elasticity ratio of the treated PLA/LM-PLA SSCF with good comprehensive properties are 21 per 25 mm, 31.9% and 81.6%, which are similar to those of industrialized PET/PTT three-dimensional crimped fibers. The results of this study shed light on the development of novel three-dimensional crimped fibers with biodegradability.

Biodegradable three-dimensional crimped Poly(Lactide acid)(PLA)/low-melt point poly(Lactide acid) (LM-PLA) side-by-side composite fiber was prepared by regulating the crystallization and disorientation through dry and wet heat treatment.     

Humidity sensor based on poly(lactic acid)/PANI–ZnO composite electrospun fibers

The electrospinning technique has been successfully used to prepared micro-fibers of the poly(lactic acid)/polyaniline–zinc oxide (PLA/PANI–ZnO) composite. The polyaniline–zinc oxide (PANI–ZnO) nanocomposites are synthesized by hydrothermal and in situ polymerization methods. X-ray diffraction techniques are used to study the structural properties of the PLA/PANI–ZnO composite fibers and the PANI–ZnO nanocomposite. The average crystallite size of the PANI–ZnO nanocomposite is found to be 36 nm. The morphology and diameter of the composite fibers are analyzed by scanning electron microscopy (SEM). The average fiber diameter of the pure poly(lactic acid) (PLA) fiber is around 2.5 μm and that of the PLA/PANI–ZnO composite fiber is around 1.4 μm. Differential scanning calorimetry (DSC) provides the thermal properties of the PLA/PANI–ZnO composite fibers. The melting temperature (T_m) for the pure PLA is observed at 149.3 °C, and it is shifted to 153.0 °C for the PLA/PANI–ZnO composite fibers. The enhanced thermal properties of the composite fibers are due to the interaction between the polymer and the nanoparticles. The water contact angle measurements probe the surface hydrophilicity of the PLA/PANI–ZnO composite fibers. The role of the PANI–ZnO nanocomposite on the sensing behavior of PLA fibers has also been investigated. The humidity sensing properties of the composite fiber based sensor are studied in the relative humidity (RH) range of 20–90% RH. The experimental results show that the composite fiber exhibited good response (85 s) and recovery (120 s) times. These results indicate that the one-dimensional (1D) fiber structure enhances the humidity sensing properties.

The electrospinning technique has been successfully used to prepared micro-fibers of the poly(lactic acid)/polyaniline–zinc oxide (PLA/PANI–ZnO) composite for humidity sensor application.     

纳米羟基磷灰石/聚磷酸钙纤维/聚乳酸骨组织工程复合支架的特性

背景:近年来国内外在骨与软骨组织支架复合材料方面进行了广泛的研究,取得了积极的成果,但仍存在许多问题.目的:观察纳米羟基磷灰石/聚磷酸钙纤维/聚乳酸(HAP/CPP/PLLA)骨组织工程支架复合材料的特性.方法:采用溶媒浇铸、粒子滤取技术与气体发泡相结合的方法制备出纳米HAP/CPP/PLLA 骨组织工程支架复合材料,测试该支架复合材料的物理力学性能,并用扫描电子显微镜对其微观结构进行观察.结果与结论:结果表明,纳米HAP/CPP/PLLA 支架复合材料具有三维、连通、微孔网状结构,并具有较高的孔隙率和较好的压缩模量,是理想的骨组织工程支架材料.     

Biocompatibility of poly (DL-lactic acid/glycine) copolymers

In this review the authors discuss the polymer chemical, physical and cell biological aspects of poly (DL-lactic acid/glycine) copolymers, both in vitro and in vivo. The mechanism and rate of degradation and the degree of foreign body reaction were evaluated as a function of the molecular composition of the (co)polymer, its initial molecular weight and changes in crystallinity. Data from the literature concerning poly(lactic acid), poly(glycolic acid) and poly(amino acids) are included in this review. The choice to apply the polymers mentioned was determined by their nature: all are present in the human body as natural residues. Upon degradation, biocompatibility will thus not be impaired. The authors conclude that the degradation mechanism of poly(lactic acid), poly(glycolic acid) and poly(amino acids) are similar, i.e. bulk hydrolysis of ester bonds. The initial molecular weight and the chemical composition, determine the rate of degradation and the degree of foreign body reaction.     

Stability of insulin during the erosion of poly(lactic acid) and poly(lactic-co-glycolic acid) microspheres.

In recent years, the acylation of peptides during the erosion of poly(lactic acid) and poly(lactic-co-glycolic acid) microspheres has been described in the literature. To investigate whether insulin is prone to the covalent attachment of lactic or glycolic acid, insulin-loaded PLA and PLGA microspheres containing 5% bovine insulin were manufactured using a w/o/w multiple emulsion-solvent evaporation technique. Microspheres were characterized for their insulin encapsulation efficiency and release characteristics in phosphate-buffered saline (PBS) at pH 7.4 and 37 degrees C. Moreover, the stability of the peptide during 18 days of release was evaluated using HPLC and HPLC-MS techniques. The results showed that the insulin loading efficiencies of PLA and PLGA microspheres were 75.18% and 79.63%, respectively. The microspheres were spherical with relatively porous surfaces with an average diameter of 40 and 53 mum, respectively. Insulin release from the microspheres was characterized by an initial burst, which was attributed to the amount of protein located on or close to the microsphere surface. The total ion chromatogram (TIC) of insulin samples extracted after 18 days of erosion in phosphate buffer pH 7.4 at 37 degrees C revealed that deamidation was the major mechanism of instability. Surprisingly, no acylation products were found. Control experiments in concentrated lactic acid solutions confirmed a minimal reactivity of the peptide under these conditions.     

One-pot self-assembly preparation of thiol-functionalized poly(3,4-ethylenedioxythiophene) hollow nanosphere/Au composites,and their electrocatalytic properties

In this work, we developed a thiol-functionalized poly(3,4-ethylenedioxythiophene) hollow sphere (poly(EDOT-MeSH)/Au) polymer through a simple one-pot self-assembly method using polyvinylpyrrolidone (PVP) as a soft template. The monomer was used as both a reductant and a stabilizer to decorate gold nanoparticles (Au NPs). FTIR, XRD, EDX, SEM and TEM analyses were used to characterize the composite hollow spheres. The chemical bond between S and Au was confirmed by XPS. The electrochemical performance of the composite hollow spheres was determined by cyclic voltammetry (CV) and an ampere response timing current test. The results revealed that the poly(EDOT-MeSH)/Au hollow-sphere-based electrochemical sensor possesses excellent conductivity and high redox reversibility with detection limits (S/N = 3) of 0.2, 0.02, 0.08 and 0.05 μM in the linear ranges of 0.1–650 μM, 0.05–100 μM and 0.1–600 μM for the determination of ascorbic acid (AA), dopamine (DA), uric acid (UA) and nitrate ions (NO₂⁻), respectively. The preparation method for these composites will further the development of this type of conducting polymer/gold nano-composite material modified electrochemical sensor for biological species.

In this work, we developed a thiol-functionalized poly(3,4-ethylenedioxythiophene) hollow sphere (poly(EDOT-MeSH)/Au) polymer through a simple one-pot self-assembly method using polyvinylpyrrolidone (PVP) as a soft template.