Visual targeted therapy of hepatic cancer using homing peptide modified calcium phosphate nanoparticles loading doxorubicin guided by T1 weighted MRI

Effective treatment and real-time monitoring of hepatic cancer are essential. A multifunctional calcium phosphate nanoparticles loading chemotherapeutic agent doxorubicin and magnetic resonance imaging contrast agent diethylenetriaminepentaacetic acid gadolinium (A54-CaP/Gd-DTPA/DOX) was developed for visual targeted therapy of hepatic cancer via T1-weighted MRI in real-time. A54-CaP/Gd-DTPA/DOX exhibited a higher longitudinal relaxivity (6.02?mM^?1?s^?1) than commercial MR contrast agent Gd-DTPA (3.3765?mM^?1?s^?1). The DOX release from the nanoparticles exhibited a pH dependent behavior. The cellular uptake results showed that the internalization of A54-CaP/Gd-DTPA/DOX into BEL-7402 cells was1.9-fold faster than that of HepG2 cells via A54 binding. In vivo experiments presented that A54-CaP/Gd-DTPA/DOX had higher distribution and longer retention time in tumor tissue than CaP/Gd-DTPA/DOX and free DOX, and also displayed great antitumor efficacy (95.38% tumor inhibition rate) and lower toxicity. Furthermore, the Gd-DTPA entrapped in the nanoparticles could provide T1-weighted MRI for real-time monitoring the progress of tumor treatment.     

微波等离子体引发合成P(AMPS/NIPA)新型智能凝胶及其性能

以2-丙烯酰胺-2-甲基丙磺@（AMPS）和异丙基丙烯酰胺（NIPA）为单体，通过微波等离子体引发聚合制备了新型二元智能凝胶P（AMPS／NIPA），并对其性能进行了研究。探讨了等离子体功率及处理时间对聚合反应的影响；研究了该凝胶的温度敏感性、吸水／失水动力学和pH敏感性及其影响因素；对凝胶的组成及三维交联网络结构进行了表征。结果表明，P（AMPS／NIPA）二元智能凝胶具有高的溶胀比、很好的温度敏感性和pH敏感性以及快的智能响应速率。     

聚(2-乙基-2-噁唑啉)-胆固醇碳酸甲酯修饰的多西紫杉醇pH-敏感胶束的构建与性质考察

目的 利用聚(2-乙基-2-噁唑啉)-胆固醇碳酸甲酯[poly(2-ethyl-2-oxazoline)-cholesteryl methyl carbonate,PEOz-CHMC,简称PC]构建多西紫杉醇(docetaxel,DOC)纳米胶束,并对其进行性质考察。方法 利用芘荧光探针法测定PC的临界胶束浓度。利用薄膜分散法制备DOC-PC胶束(DOC-PC micelles,DOC-M),对DOC-M的粒径、形态、包封率等进行表征。采用透析法考察DOC-M的药物释放,并模拟肿瘤微环境考察DOC-M的稳定性和pH敏感性。通过MTT法评价DOC-M对体外HeLa细胞的抑制作用。利用流式细胞仪定量观察胶束对HeLa细胞的摄取情况。结果 PC的临界胶束质量浓度为9.26 μg·mL^-1(4.63×10^-6mol·L^-1)。DOC-M的粒径小于130 nm,外观呈类球形,分布均匀,Zeta电位为(-7.32±0.98)mV。X-射线粉末衍射(XRD)和红外光谱(IR)结果表明,DOC被成功包封于胶束中,DOC-M的包封率为(80.55±2.44)%。体外药物释放和胎牛血清稳定性结果实验表明,DOC-M的pH敏感性和稳定性良好。细胞抑制实验结果表明,在微酸条件下DOC-M的细胞抑制作用更强。细胞摄取实验分析,DOC-M具有较低的毒性,显著地促进药物的细胞摄取。结论 DOC-M表现出良好的稳定性和pH敏感性,以及较低毒性和较好的载药能力,有望成为药物递送的良好载体。     

载氟尿嘧啶pH敏感树枝状聚合物纳米载体的体外释药及对人肝癌细胞药效学评价

目的 考察pH值对氟尿嘧啶（5-FU）从pH敏感树枝状聚合物纳米载体（mPEG-pDEA-PAMAM,PDP）中释放的影响,以及该载体制剂在不同pH值条件下对人肝癌HepG2细胞的作用。 方法 用HPLC分析方法测定释放介质中5-FU浓度,考察不同pH值条件下5-FU从PDP释放的特征。用不同pH值培养基体外培养人肝癌细胞株HepG2细胞,建立模拟体内肿瘤组织微环境的细胞模型,MTT法研究PDP制剂对HepG2细胞的抑制率及细胞毒性。结果 PDP在弱酸性环境（pH 6.5）中迅速释放5-FU,而在中性环境（pH 7.4）中释放很缓慢。在pH 6.5条件下,5-FU-PDP与5-FU水溶液同样对HepG2细胞生长有明显抑制作用,单用PDP没有明显细胞毒性。结论 5-FU-PDP纳米制剂具有明显pH值敏感释药的特点,能在肿瘤弱酸性环境下快速释药并发挥药效,可能成为理想的抗肿瘤药物靶向载体。     

基于肿瘤微环境pH-redox智能响应多功能纳米靶向载体的制备及表征

利用透明质酸有效靶向肿瘤细胞CD44受体的功能,在寡聚透明质酸的结构基础上,引入对pH敏感的缩酮键和对还原环境敏感的二硫键,构建一种新型基于肿瘤微环境的pH-redox智能响应多功能纳米靶向载体——两亲性寡聚透明质酸-巯基薄荷缩酮(oHMST),利用¹H NMR、IR和 ESI-MS技术对其结构进行表征确证。通过透析法制备了载姜黄素胶束,并初步考察了制剂的粒径、电位、电镜形貌特征以及 pH、还原敏感特性。结果表明,成功合成了两亲性寡聚透明质酸-巯基薄荷缩酮载体,制备了载药胶束,制剂形态为球形,粒径在100 nm 左右,Zeta电位为-(21.97±1.08)mV,体外考察证明具有pH及还原敏感性。     

口服双氯芬酸钠pH敏感性水凝胶球研究

目的：以N-琥珀酰壳聚糖、海藻酸钠为载体,制备口服双氯芬酸钠pH敏感性水凝胶小球,并考察该水凝胶小球在不同pH环境中的释放行为。方法：通过正交试验优选口服双氯芬酸钠pH敏感性水凝胶小球最佳制备工艺。采用红外光谱和电子显微镜扫描对其进行结构表征,并考察该水凝胶小球在体外不同pH环境、人工胃液及人工肠液中的释放行为,揭示其在体外不同环境中的pH敏感性释放机制。结果：该水凝胶小球最佳处方组成为：N-琥珀酰壳聚糖浓度为1％(w/v),海藻酸钠浓度为1％(w/v),氯化钙浓度为1.5％(w/v),药物与海藻酸钠质量比为3∶5(g/g);口服双氯芬酸钠pH敏感性水凝胶小球具有明显的pH敏感性,在人工胃液中3 h的累积释放度小于22%,在人工肠液中11 h的累积释放度可达98%。结论：口服双氯芬酸钠pH敏感性水凝胶小球可望成为具有时辰药理学特性的pH敏感性肠道释药系统。     

A boronate-linked linear-hyperbranched polymeric nanovehicle for pH-dependent tumor-targeted drug delivery

Advanced drug delivery systems, which possess post-functionalization feasibility to achieve targetability and traceability, favorable pharmacokinetics with dynamic but controllable stability, and preferable tumor accumulation with prolonged drug residence in disease sites, represent ideal nanomedicine paradigm for tumor therapy. To address this challenge, here we reported a dynamic module-assembly strategy based on reversible boronic acid/1,3-diol bioorthogonality. As a prototype, metastable hybrid nanoself-assembly between hydrophobic hyperbranched diol-enriched polycarbonate (HP-OH) and hydrophilic linear PEG terminated with phenylboronic acid (mPEG-PBA) is demonstrated in vitro and in vivo. The nanoconstruction maintained excellent stability with little leakage of loaded drugs under the simulated physiological conditions. Such a stable nanostructure enabled the effective in vivo tumor accumulation in tumor site as revealed by NIR imaging technique. More importantly, this nanoconstruction presented a pH-labile destruction profile in response to acidic microenvironment and simultaneously the fast liberation of loaded drugs. Accordingly at the cellular level, the intracellular structural dissociation was also proved in terms of the strong acidity in late endosome/lysosome, thus favoring the prolonged retention of remaining drug-loaded HP-OH aggregates within tumor cells. Hence, our delicate design open up a dynamical module-assembly path to develop site and time dual-controlled nanotherapeutics for tumor chemotherapy, allowing enhanced tumor selectivity through prolonged retention of delivery system in tumor cells followed by a timely drug release pattern.     

pH-Induced solubility transition of sulfonamide-based polymers

As an approach to designing new pH-sensitive polymers for bio-related application, we have modified selected sulfonamides, with various pK_a, to polymerizable monomers. The pK_a of the monomers, homopolymers, and copolymers with N,N-dimethylacrylamide were examined, and pH-induced phase transition behavior, particularly in solubility, was investigated. The pK_a of sulfonamide monomers and polymers at 25 °C was slightly higher than those of corresponding sulfonamides but the enthalpy of the ionization was influenced due to interfering resonance structures that are present in the mother compounds. The solubility transition of each homopolymer in aqueous solutions occurred at a degree of ionization of 85–90%. For the copolymers, the solubility transition observed by light transmittance completed in a narrow pH range (0.2–0.3 pH units) and this transition pH shifted to a higher pH region with the increasing sulfonamide unit in the copolymer, though the pK_a was not considerably changed. This polymer precipitation occurs because of the relative balance of overall hydrophilicity/hydrophobicity along the polymer chain. Because the unionized form of sulfonamide units is considered to be hydrophobic, the copolymer with higher content of sulfonamide unit requires a higher degree of ionization for solubilization and thus solubility transition occurred at higher pH.     

Lysine-based surfactants in nanovesicle formulations: the role of cationic charge position and hydrophobicity in in vitro cytotoxicity and intracellular delivery

Understanding nanomaterial interactions within cells is of increasing importance for assessing their toxicity and cellular transport. Here, the authors developed nanovesicles containing bioactive cationic lysine-based amphiphiles and assessed whether these cationic compounds increase the likelihood of intracellular delivery and modulate toxicity. Different cytotoxic responses were found among the formulations, depending on surfactant, cell line and endpoint assayed. The induction of mitochondrial dysfunction, oxidative stress and apoptosis were the general mechanisms underlying cytotoxicity. Fluorescence microscopy analysis demonstrated that nanovesicles were internalised by HeLa cells and evidenced that their ability to release endocytosed materials into cell cytoplasm depends on the structural parameters of amphiphiles. The cationic charge position and hydrophobicity of surfactants determine the nanovesicle interactions within the cell and, thus, the resulting toxicity and intracellular behaviour after cell uptake of the nanomaterial. The insights into some toxicity mechanisms of these new nanomaterials contribute in reducing the uncertainty surrounding their potential health hazards.     

pH敏感性叶酸修饰羧甲基壳聚糖纳米粒子作为紫杉醇载体的研究

将活化的叶酸分子连接到O-羧甲基壳聚糖(O-CMCS)上。以CaCl2为交联剂,通过离子交联法制备叶酸修饰的O-CMCS纳米粒子(FCC NPs),并开展了从FCC NPs作为抗癌药物紫杉醇(PTX)载体的研究。结果表明：FCC NPs呈球形,粒子大小约190 nm,对PTX的载药量和包封率均受PTX加入量的影响。该纳米粒子对药物的释放具有较好的pH敏感性,能够增强PTX在癌细胞处的富集。同时,该纳米粒子无细胞毒性,纳米粒子表面由于叶酸的存在使其具有较好的细胞靶向性,且载药纳米粒子对癌细胞生长具有良好的抑制作用。