【作者】 张利；

【导师】 冯亚凯；

【作者基本信息】 天津大学 ， 材料化学工程， 2013， 博士

【摘要】 性能稳定、结构可调的双亲可生物降解嵌段共聚物能自组装形成疏水核-亲水壳的纳米微球，因此其在药物缓释领域得到研究者的极大关注。本文以吗啉-2,5-二酮衍生物为研究对象，采用开环聚合(ROP)及原子转移自由基聚合(ATRP)技术构建一系列新型缩肽两亲嵌段共聚物，并对其进行药物缓控释研究。主要成果概括如下:1.在成功制备吗啉-2,5-二酮衍生物即3(S)-甲基-吗啉-2,5-二酮(MMD)、3(S)-正丁基-吗啉-2,5-二酮(SBMD)、3(S)-异丁基-吗啉-2,5-二酮(IBMD)以及脂肪族聚酯聚对二氧环己酮PPDO(以备后期嵌段共聚物的表征)后，首先分别以MMD及SBMD为单体，结合PDO及聚乙二醇(PEG)采用ROP技术合成双亲三嵌段共聚物，即P(MMD-co-PDO)-b-PEG-b-P(MMD-co-PDO)(PMMD-PPDO-PEG)及P(SBMD-co-PDO)-b-PEG-b-P(SBMD-co-PDO)(PSBMD-PPDO-PEG)。通过核磁共振氢谱碳谱(1H NMR，13C NMR)，傅里叶红外光谱(FT-IR)，凝胶渗透光谱(GPC)，差热扫描热力学(DSC)测试及热重分析(TGA)等对以上双亲三嵌段共聚物的结构成功表征。2.基于IBMD， PDO及PEG开环聚合合成P(IBMD-co-PDO)-b-PEG-b-P(IBMD-co-PDO)(PIBMD-PPDO-PEG)，将其与溴代异丁酰溴反应合成大分子引发剂，然后与亲水性的甲基丙烯酸二甲氨基乙酯(DMAEMA)通过原子转移自由基聚合即ATRP反应构建以聚缩肽为基础的新型双亲五嵌段共聚物PDMAEMA-b-P(IBMD-co-PDO)-b-PEG-b-P(IBMD-co-PDO)-b-PDMAEMA(PDMAEMA-PIBMD-PPDO-PEG)。对以上双亲五嵌段共聚物的结构进行1H NMR，13C NMR，FT-IR，GPC，DSC及TGA表征。3.分别以合成的双亲三嵌段共聚物PMMD-PPDO-PEG及PSBMD-PPDO-PEG为载体，阿霉素(DOX)为模型药物，采用乳化溶剂挥发扩散法(O/W)制备空白及载药微球(药物DOX与嵌段共聚物之间通过氢键作用及疏水效应结合)。对空白共聚物微球进行体外降解实验分析,临界胶束浓度CMC(芘荧光探针法)及Zeta电位测试。实验研究表明两种共聚物很容易在PBS内形成均匀统一的纳米微球，其共聚物微球的数均分子量(Mn)均随降解时间的增加而逐渐减小。基于MMD的两亲三嵌段共聚物的CMC测试结果表明共聚物PMMD-PPDO-PEG微球较稳定，CMC值在0.41-0.66μg/mL之间并且其值基本随进料中PDO含量的升高而增大。基于SBMD的三嵌段共聚物微球的Zeta电位测试表明共聚物微球具有较好的稳定性。空白及载DOX聚合物(PMMD-PDO-PEG及PSBMD-PPDO-PEG)微球的动态光散射仪(DLS)与透射电镜(TEM)测试结果表明，两系列共聚物在PBS中自组装形成的胶束粒子呈椭圆形单分布，颗粒分散较均匀，其平均粒径分别为100和200nm。除此，两系列共聚物均具有良好的载药量(LC)，包封率(EE)及药物缓释行为。4.制备双亲五嵌段ATRP共聚物纳米微球，分别以布洛芬(IBU)及IBU-DOX组合作为模型药物对共聚物微球的LC，EE及体外释放行为进行考察。测试结果均表明，载药时随模型药物投入量的增加，聚合物LC及EE相应增加，但药物(IBU,IBU-DOX)与共聚物投入质量到达一定比例(即16/44,8-8/44)后LC及EE降低，载IBU的共聚物微球,其LC和EE稍高于载IBU-DOX的共聚物微球。而且制备的聚合物微球LC和EE均与PBS浓度有关。同时，本实验选取不同pH值(5.0,7.4)的PBS溶液作为释放介质进一步考察载药微球的体外释放特征，结果表明载IBU-DOX的共聚物微球具有很好的pH响应性，低pH下IBU-DOX释放速度较快，可能由于PDMAEMA和DOX上氨基的质子化以及微球核心的快速降解所致。此外实验结合DLS及TEM探究了该系列共聚物在PBS中自组装情况、载药聚合物微球的形态及粒径分布。聚合物PDMAEMA-PIBMD-PPDO-PEG微球的DLS测试结果表明载有IBU及IBU-DOX的纳米颗粒呈圆形均匀分布，其粒径在100nm左右，而且所有载药后的共聚物微球粒径均稍有增加。由以上表征结果可以设想其共聚物系统将是很有潜力的药物控释载体。更多还原

【Abstract】 Biodegradable amphiphilic block copolymers with stable performance andadjustable structure can self-assemble into hydrophobic core and hydrophilic shellnanomicrospheres, thus they have aroused the great concern of researchers in drugdelivery field. In this paper, morpholine-2,5-dione derivatives containing depsipeptidestructure were deemed as the research objects, a series of novel amphiphilicdepsipeptide block copolymers were constructed by using the ring-openingpolymerization (ROP) and atom transfer radical polymerization (ATRP) technology,meanwhile, the drug release behavior was also studied. The main results aresummarized as follows:1. After successfully preparing morpholine-2,5-dione derivatives, i.e.3(S)-methyl-morpholine-2,5-dione(MMD),3(S)-butyl-morpholine-2,5-monomers,3(S)-isobutyl-morpholino-2,5-dione (IBMD) and aliphatic polyesters poly(p-dioxanone)(PPDO)(Mentioned here, in order to characterize the latter block copolymers). Twokinds of amphiphilic triblock copolymers {i.e.poly(3(S)-methyl-morpholine-2,5-dione-co-p-dioxanone)-block-poly(ethylene glycol)6000-block-poly(3(S)-methyl-morpholine-2,5-dione-co-p-dioxanone)[P(MMD-co-PDO)-b-PEG-b-P(MMD-co-PDO)](PMMD-PPDO-PEG) andpoly(3(S)-butyl-morpholine-2,5-dione-co-p-dioxanone)-block-poly(ethylene glycol)6000-block-poly(3(S)-butyl-morpholine-2,5-dione-co-p-dioxanone)[P(SBMD-co-PDO)-b-PEG-b-P(SBMD-co-PDO)](PSBMD-PPDO-PEG)} which werebased on morpholine-2,5-dione derivatives (MMD and SBMD, respectively), andcombined with PDO and polyethylene glycol (PEG), were synthesized by utilizing thering-opening polymerization (ROP) technique. The structural characteristics of theabove amphiphilic block copolymers were identified by using1H NMR, FT-IR, GPC,DSC and TGA analysis.2. Another ABA triblock copolymers ofpoly(3(S)-isobutyl-morpholine-2,5-dione-co-p-dioxanone)-block-poly(ethylene glycol)6000-block-poly(3(S)-isobutyl-morpholine-2,5-dione-co-p-dioxanone)[P(IBMD-co-PDO)-b-PEG-b-P(IBMD-co-PDO)] were successfully prepared by ROP of3(S)-isobutyl-morpholine-2,5-dione (IBMD) and p-dioxanone (PDO) using PEG6000asinitiator. And then the macroinitiatorsBr-P(IBMD-co-PDO)-b-PEG-b-P(IBMD-co-PDO)-Br were prepared from them by the bromination with2-bromoisobutyryl bromide (BiBB). Finally, hydrophilicpoly(2-(dimethylamino)ethyl methacrylate)(PDMAEMA) blocks were attached to thesehydrophobic triblock copolymers by ATRP, and the amphiphilic multiblock copolymerswere defined asPDMAEMA-b-P(IBMD-co-PDO)-b-PEG-b-P(IBMD-co-PDO)-b-PDMAEMA(PDMAEMA-PIBMD-PPDO-PEG). The structures of the above copolymers were characterizedby using1H NMR,13C NMR, FT-IR, GPC, DSC and TGA analysis.3. Taking the synthetic triblock copolymers PMMD-PPDO-PEG andPSBMD-PPDO-PEG as carriers, doxorubicin (DOX) as model drugs, the blank anddrug-loaded microspheres were prepared by an oil-in water (o/w) emulsion solventevaporation method (through the combination of hydrogen bond and hydrophobic effectbetween DOX and block copolymers), those blank copolymer microspheres werecharacterized by hydrolytic degradation analysis, the critical micellar concentration(CMC)(fluorescene probe method of pyrene)and Zeta potential. Experiments studiesshowed that the copolymers could easily form uniform microspheres in phosphatebuffered solution (PBS), and the number-average molecular weight (Mn) of those blockcopolymers decreased along with degradation time. Copolymer PMMD-PPDO-PEGself-assembled into stable nanosized microspheres with CMC of0.41-0.66μg/mL.Basically, the CMC of microspheres increased slightly with the increase of PDO in feed.Zeta potential measurement of the copolymer microspheres based on SBMD and IBMDindicated that the copolymer microspheres had good stability. The dynamic lightscattering (DLS) and transmission electron microscopy (TEM) results of blank andDOX-loaded copolymers (PMMD-PPDO-PEG and PSBMD-PPDO-PEG) microspheresshowed that the two series of copolymers in PBS self-assembled uniform, dispersed,ellipsoidal and single distribution nanoparticles. The average diameter of the particleswere100and200nm, respectively. In addition, they exhibited high drug loadingcapacity (LC), the encapsulation efficiency (EE) and sustained drug release behavior inPBS.4. Preparing amphiphilic multiblock ATRP copolymers nanomicrospheres,Ibuprofen (IBU) and the combination of IBU-DOX were chosen as model drugs, the LC,EE and the drug release behavior of the multiblock copolymers microspheres wereinvestigated. The tests showed that LC and EE increased with increasing the initialweight ratios of drug to copolymer, but LC and EE decreased after the ratio increased toa certain percentage (16/44and8-8/44, respectively). The LC and EE of the IBU-loadedcopolymer microspheres are slightly higher than that of IBU-DOX-loaded copolymer microspheres. Moreover, LC and EE of the prepared copolymer microspheres arecorrelated with PBS concentration. Meanwhile, we selected PBS of different pH (5.0,7.4) as the release media to further investigate the characteristics of drug-loadedmicrospheres. The results showed that IBU-DOX-loaded copolymer microspheres hadgood pH-responsiveness. The drug release rate of copolymer microspheres in low pH(5.0) was faster than that in pH (7.4), which is likely due to the protonation of the aminogroups of PDMAEMA and DOX, and fast degradation of microsphere core. In addition,experiments explored the self-assembly conditions of the copolymers, the microspheresmorphology of drug-loaded copolymers and particle size distribution through DLS andTEM measurements. The DLS results of PDMAEMA-PIBMD-PPDO-PEGmicrospheres showed that the IBU-and IBU-DOX-loaded nanoparticles werewell-defined uniform spherical particles with diameter about100nm. All copolymermicrospheres size increased slightly after drug loading. From the above results, it can beenvisaged that these copolymer systems are promising candidates for controlled releaseapplication.更多还原