制备了叔胺改性甘草次酸[GA-N(CH3)2]修饰的海藻酸钠[ALG-GA-N(CH3)2],并在温敏性琼脂糖的辅助作用下,利用微流体技术获得了高通量、单分散且粒径可控的ALG-GA-N(CH3)2微凝胶.考察了Span 80含量、疏水配体取代度、样品浓度和水/油相流速对微液滴制备的影响.研究结果表明,叔胺基改性可显著改善甘草次酸的亲水性;在Span 80质量分数为2.0%,疏水配体取代度小于12%,样品浓度小于15mg/m L,水相流速为1.5 m L/h,油相流速为6 m L/h条件下,可获得高通量、单分散及粒径为200μm的适用于细胞包封培养的微凝胶球.同时提供了一种三维培养肝细胞的新方法,为其在组织工程中的应用奠定了基础.
For the requirement of preliminary vascularization, the scaffolds for thick tissue engineering should have not only good cell affinity, but also anticoagulant ability. In this paper, enzymatically cross-linked hydrogel scaffolds based on sulfated chitosan （SCTS） were prepared. Firstly, sulfated chitosan-hydroxyphenylpionic acid （SCTS-HPA） conjugate was synthesized, and the structure of SCTS-HPA was identified by FITR and ~H NMR. And then the enzymatically cross-linked hydrogels were pre- pared in presence of horseradish peroxidase （HRP） and hydrogen peroxide （H202）. The gelation time, mechanical property, morphology and cytotoxicity to human umbilical vein endothelial cells （HUVECs） of the hydrogel were evaluated in vitro, the tissue compatibility of SCTS-HPA scaffold was studied in vivo. The results showed that the gelation time, mechanical property, morphology of the dehydrated hydrogel could be controlled by the the concentration of HRP and H202. The cytotoxicity test showed that the hydrogel extracts have no cytotoxicity to HUVECs. The in vivo assay indicated that SCTS-HPA scaffold have good tissue compatibility with no thrombus formation. All these results indicated that the SCTS-HPA scaffold could be used as a thick tissue engineering scaffold.
A series of drug delivery systems based on a sodium alginate derivative were prepared by mixing glycyrrhetinic acid （GA） and doxorubicin （DOX） conjugates at different ratios. GA （a liver-targeting ligand） and DOX （an antitumor drug） were both conjugated to oligomeric glycol monomethyl ether-modified sodium alginate （ALG-mOEG） for prolonged duration of action. These NP-based delivery systems exhibited active cell uptake and cytotoxicity in vitro and liver-targeted distribution and anti-tumor activity in vivo. In addition, nanoparticles with a 1：1 （W：W） ratio of GA-ALG-mOEG and DOX-ALG-mOEG （NPs-3） showed the highest cellular uptake and cytotoxicity in vitro and liver-targeted distribution and anti-tumor activity in vivo. Specifically, when mixed nanoparticles defined as NPs-3 were injected in mice, liver DOX concentration reached 61.9 μg/g 3 h after injection, and AUC0-∞ and t1/2 of DOX in liver reached 4744.9 μg·h/g and 49.5 h, respectively. In addition, mice receiving a single injection of NPs-3 exhibited much slower tumor growth （88.37% reduction in tumor weight） 16 days after injection compared with placebo. These results indicate that effective cancer treatment may be developed using mixed NP delivery systems with appropriate ratio of targeted ligand and drug.
