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肿瘤的治疗是人类一直追求的目标,其中放射治疗是治疗肿瘤的主要手段。据统计,每年有60%以上的肿瘤患者要接受放射治疗。因此,提高肿瘤的放射治疗效果,降低正常组织的辐射剂量,对于肿瘤的放射治疗具有重要的科学意义和实用价值。
高能的γ射线和X射线与物质的主要作用方式包括康普顿散射和光电吸收,而物质的光电吸收与重金属原子的原子序数密切相关。也就是说,原子序数越高,其放射增敏效果越明显。Au的原子序数为79,明显高于临床常使用的I(原子序数为53)及其化合物。然而,离子状态的Au具有较强的活性,其表面容易与体内的各种蛋白相互结合,最终导致较强的毒性。与Au离子相比,Au纳米颗粒具有明显的优势,首先,Au纳米颗粒具有较强的高通透性和滞留效应[(enhanced permeability and retention,EPR)效应],有利于放射治疗;其次,相对于Au离子,Au纳米颗粒的毒性较低;最后,Au纳米颗粒的表面容易修饰,具有更为广泛的医学用途。Au纳米颗粒由于其独特的光学[1-3]和表面化学特性[4-6],以及在光热治疗[7-8]、放射治疗[9-10]和X射线造影剂[11-13]等方面的潜在应用,引起了人们广泛的兴趣。Hainfeld等[11]使用尺寸为1.9 nm的裸Au颗粒,发现小鼠连续照射后其肿瘤体积明显变小,直至消失,而没有辐照的小鼠全部死亡。此后,多个团队也研究发现Au纳米颗粒具有明显的放射增敏作用[11-14]。
然而,纳米材料在生理环境中的形成是个极其复杂的过程。大量研究表明,Au纳米材料的生物学反应与其表面化学[14-16]、尺寸[17-19]和给药方式[20]有关。一方面,我们研究发现,表面化学可以影响Au纳米颗粒在生理环境中的稳定性,从而影响其毒性;裸的Au纳米颗粒在血液中与蛋白作用形成100 nm的聚集体,然后被内皮网状系统吸收到达肝脏和脾脏[21-23]。聚乙二醇(polyethylene glycols,PEG)包裹层通过降低表面电势来提高Au纳米颗粒的稳定性[24]。另一方面,我们发现,小尺寸的Au纳米颗粒具有更强的EPR效应,可以在肿瘤组织中更好地富集,从而达到治疗的效果。
本研究以15 nm的PEG包裹的Au纳米颗粒为材料,从物理学性质、血浆稳定性、体外的细胞活性、体外放射增敏作用等几个方面来研究其生物学反应。
15 nm聚乙二醇保护的Au纳米颗粒对HepG2细胞的放射增敏作用
Radiosensitivity enhancement of typical 15 nm polyethylene-glycol-coated Au nanoparticles on HepG2 cell
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摘要:
目的 研究Au纳米颗粒对HepG2细胞的放射增敏作用。 方法 首先制备典型的15 nm聚乙二醇(PEG)包裹的Au纳米颗粒,然后使用紫外可见分光光度计实时定量检测纳米颗粒的血浆稳定性,同时使用噻唑蓝法研究给药后24 h和48 h的细胞活性,最后,通过克隆形成实验研究不同浓度的Au纳米颗粒对HepG2细胞的放射增敏作用。 结果 PEG包裹的Au纳米颗粒具有较好的血浆稳定性,在24 h及以后未见表面等离子共振吸收峰有明显的偏移。细胞活性实验表明,24 h后,细胞的活性有所降低,但是48 h后细胞的活性迅速恢复到90%。进一步研究克隆形成发现,Au纳米颗粒具有明显的放射增敏作用。 结论 15 nm PEG包裹的Au纳米颗粒具有较高的血浆稳定性、较低的细胞毒性和较好的放射增敏作用。 Abstract:Objective To investigate the radiosensitivity enhancement of Au nanoparticles to HepG2 cell. Methods 15 nm polyethylene-glycol-coated(PEG) Au nanoparticles were synthesized, and then blood stability were tested by using the UV-vis optical absorption. Meanwhile, 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide methods were used to investigate the cell viability after 24 and 48 hours treatments, and cloning formation were used to investigate the radiosensitivity enhancement. Results It was found that PEG-coated Au nanoparticles presented a high blood stability, and surface plasmon response has not shown significant changes after 24 hours. Cell viability was decreased after 24 hours treatment, but it was recovered to 90% after 48 hours. Cloning formation showed Au nanoparticles presented a significant radiosensitivity enhancement. Conclusions 15 nm PEG-coated Au nanoparticles presented a good blood stability, low cytotoxicity and high radiosensitivity enhancement. -
Key words:
- Polyethylene glycols /
- Gold nanoparticles /
- Radiation sensitizing
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