Highly biocompatible superparamagnetic Fe3O4 nanoparticles were synthesized by amide of folic acid （FA） ligands and the NH2-group onto the surface of Fe3O4 nanoparticles. The as-synthesized folate-conjugated Fe3O4 nanoparticles were characterized by X-ray diffraction diffractometer, transmission electron microscope, FT-IR spectrometer, vibrating sample magnetometer, and dynamic light scattering instrument. The in vivo labeling effect of folate-conjugated Fe3O4 nanoparticles on the hepatoma cells was investigated in tumor-bearing rat. The results demonstrate that the as-prepared nanoparticles have cubic structure of Fe3O4 with a particle size of about 8 nm and hydrated diameter of 25.7 nm at a saturation magnetization of 51 A·m2/kg. These nanoparticles possess good physiological stability, low cytotoxicity on human skin fibroblasts and negligible effect on Wistar rats at the concentration as high as 3 mg/kg body mass. The folate-conjugated Fe3O4 nanoparticles could be effectively mediated into the human hepatoma Bel 7402 cells through the binding of folate and folic acid receptor, enhancing the signal contrast of tumor tissue and surrounding normal tissue in MRI imaging. It is in favor of the tumor cells labeling, tracing, magnetic resonance imaging （MRI） target detection and magnetic hyperthermia.
目的初步探讨热休克蛋白70（heat shock protein 70，HSP70）抑制脓毒症血清所致心肌细胞凋亡及其机制。方法将原代培养心肌细胞分组：正常对照组、正常大鼠血清组、脓毒症血清组、转空载体对照组和转HSP70基因组，转HSP70基因组以重组质粒pcDNA3．1-HSP70转染后36h后验证基因和蛋白表达；各组以相应血清混合培养2h；分别行Hoechst33258染色后计数以及DNA“梯状”条带检测心肌细胞凋亡，再应用Western—blot分析HSP70过表达对Caspase-3，8，9活化和Bid裂解的影响情况。结果处理后12、24、36h凋亡率，转HSP70基因组心肌细胞为（12．48±2．39）％、（23．96±3．12）％、（25．40±3．96）％，明显低于脓毒症血清组[（28．66±2．24）％、（55．76±5．69）％、（46．89±8．74）％，t=5．851、5．932、6．027，P〈0．01]，亦明显低于转空载体组[（34．25±3．42）％、（50．71±6．38）％、（47．62±5．74）％，t=5．876、5．903、6．122，P〈0．01]，但明显高于正常对照组和正常血清组（3．13％-6．75％，t=6．324、6．578、6．137、5．987、6．032、6．871，P〈0．01）；在Caspase-3、8、9活化表达中，P11、P20和P10条带比值，转HSP70基因组分别为（12．5276±2．1247、9．3481±4．5423、16．1349±6．0641），低于脓毒症血清组（27．13244-2．1564、25．5643±4．3018、36．5647±6．7135，t=5．856、5．902、5．891，P〈0．01），低于转空载体组（28．0314±2．0367、25．6413±4．1356、34．5648±5．9473，t=3．861、3．933、4．281，P〈0．05），高于正常对照组（8．0324±1．5234、5．1246±1．3274、2．0314±0．6423，￡=3．286、3．867、4．031，P〈0．05）和正常血清组（8．5649±1．2136、6．0324±1．0214、3．2146±0．1325，t=5．898、5．969、6．879，P〈0．01）；tBid条带比值，转HSPT0基因组（12．0316±2．3641）低于脓毒症血清组（27．0536±5．3214，t=3．274
