壳聚糖辐射裂解制备基因载体及其体外转染性能研究

Chitosan (CS) is expected to be an ideal gene carrier for its high biosafety. In this work, CS with low molecular weight were prepared through the γ-ray radiation on the acetic acid solution of CS. The CS chains were scissioned under the γ-ray radiation, and the molecular weight (MW) of CS decreased with the absorbed dose. When the absorbed dose was above 30 kGy, the molecular weight of CS decreased about an order of magnitude. The γ-ray-radiation-scissioned CS can e ectively bind with plasmid (pEGFP) through complex coacervation method, forming pEGFP/ γ-ray-radiation-scissioned CS complex particles with a size of 200-300 nm. The complex particles have good stability and little cytotoxicity. The in uitro gene transfection efficiencies of the pEGFP/ γ-ray-radiation-scissioned CS complex particles were investigated by fluorescence microscope and flow cytometry. The results showed that the gene vectors using γ-ray-radiation-scissioned CS as the carrier will possess better gene transfection efficiency than those using natural high-MW CS as the carrier. The higher the absorbed dose, the smaller the MW of CS and the better transfection efficiency of the corresponding gene vector. This work provides a green and simple method on the preparation of CS-based gene vectors with high efficiency and biosafety.     

具有双重治疗机制的磁性纳米无定型氧化铁基药物递送系统

合成一种具有pH响应性的聚乙二醇(PEG)修饰无定形介孔氧化铁纳米粒子(AFe-PEG). 这种纳米粒子可以高效负载药物分子如阿霉素(DOX)，构成新型多功能AFe-PEG/DOX药物递送体系. DOX的负载率高达948 mg/g-纳米粒子. 在酸性溶液中，AFe-PEG/DOX纳米粒子不仅可以有效释放DOX，同时可以释放Fe离子进行Fenton反应，将H₂O₂转变成·OH自由基. 体外实验结果表明，AFe-PEG/DOX纳米粒子对HeLa细胞同时具有化疗和化学动力学疗法的疗效. 同时，由于AFe-PEG/DOX 纳米粒子本身的磁性，使其在外部磁场中的细胞内化效率也得到了提高.