国家重大科学研究计划项目“生物医学纳米材料对血细胞作用的研究”工作进展与讨论

结合多模态纳米探针进行淋巴癌等血液恶性肿瘤的在体分子成像与疗效评价研究

东南大学 顾宁 教授


一、紫杉醇修饰的氧化铁纳米颗粒用于肿瘤成像与治疗

本文利用我们前期工作中制备的聚乙二醇修饰的氧化铁纳米颗粒作为药物载体,共价负载抗肿瘤药物紫杉醇,体外实验表明,该载药体系具有与市售紫杉醇注射液相当的肿瘤细胞毒性,体内实验表明,该载药体系能够有效的聚集在肿瘤组织,且其肿瘤抑制效果优于市售紫杉醇注射液。
Dongfang Liu, Wei Wu, Xi Chen, Song Wen, Xizhi Zhang, Qi Ding, Gaojun Teng,Ning Gu*.Conjugation of paclitaxel to iron oxide nanoparticles for tumor imaging and therapy, Nanoscale, 2012, 4, 2306-2310.


Schematic chemical structures of PTX-COOH, SPION-PEG, SPION-PTX and their synthetic routes.


T2*-weighted images (TR/TE of 408 ms/3.5 ms) at pre-injection (a) and 4 h post-injection (b) of 8 mg kg-1 of SPION-PTX at the level of the tumor on the proximal thigh of the mice. The white arrow indicates the tumor region. (c) In vivo antitumor effect obtained from each treated group, expressed as the average values of the relative tumor volume v/v0 (where v denotes the tumor volume at test time points and v0 denotes the corresponding initial tumor volume at the beginning of treatment). *P < 0.05 (versus PTX injection group at the equivalent dose from the 5th day). Inset shows the typical photographs of excised tumors from mice on the 7th day after treatments with SPION-PTX (5 mg kg-1 equiv), PTX (Taxol) injection (5 mg kg-1 equiv), SPION-PEG and saline. (d) Evolutionof body weight of each group during the experiments. Data in (c) and (d) are presented as mean - SD (n ¼ 3–5).

二、形貌及表面替换反应对单分散Fe3O4纳米颗粒磁性的影响

采用高温热解法制备两种形貌不同(准方形和球形)、尺寸及分布基本相同(约10nm)的油溶性Fe3O4纳米颗粒,并以配体交换的表面修饰方法将其替换到水相,在此过程中,研究了配体替换时间对颗粒形貌和尺寸的影响,之后以VSM测量、MRI造影效果、交变磁场下升温效果作为评价手段,研究了纳米颗粒形貌对其磁学性质的影响,为改善纳米颗粒性能、优化应用效果提供了一个思路。研究表明,延长替换时间,所得样品单分散性不变,但样品形貌受到破坏,进而导致磁学性质变弱。此外,准方形纳米颗粒具有较球形颗粒高的磁学性质,表现为相同条件下准方形纳米颗粒具有高的饱和磁化强度、MRI弛豫率、SAR值等。
Mengjie Song, Yu Zhang, Sunling Hu, Lina Song, Jinlai Dong, Zhongping Chen, Ning Gu. Influence of morphology and surface exchange reaction on magnetic properties of monodisperse magnetite nanoparticles. Colloids and Surf. A. 2012. 5(39):1-8


TEM images of (a) quasi-cubical and (b) spherical Fe3O4@OA samples and their relevant size distribution histograms. Their average diameters were 9.5nm and 9.6nm, respectively


TEM images (a-d) of Fe3O4@DMSA samples and their respective size distribution histograms (A-D): (a) q-cubical-30min; (b) spherical-30min; (c) q-cubical-4h; (d) spherical-4h; (e, f) HRTEM images of sample a and b.


Hysteresis loops of Fe3O4@DMSA samples Samples tested were of identical concentration of 0.6mg [Fe]/ml, and the results were obtained through converting the unit to emu/g. (a) quasi-cubical-30min; (b) spherical-30min; (c) quasi-cubical-4h; (d) spherical-4h;


T2-weighted images of Fe3O4@DMSA samples in MR experiment and their relaxivities obtained with linear fitting (inverse of the relaxation times as a function of the iron concentration)


Time-temperature curves for Fe3O4@DMSA samples under alternating magnetic field (samples were measured in aqueous phase with the concentration of 0.5mg [Fe]/ml)


三、氧化铁纳米颗粒的双酶活性及其对降低细胞毒性的意义

氧化铁纳米颗粒具有广泛的生物医学应用,但它们的潜在生物安全性问题仍然受到极大关注。尽管大量文献报道细胞在接触氧化铁纳米材料以后,会产生细胞凋亡/死亡、增殖/分化抑制,氧化应激水平升高等后果,但很少有研究直接关注纳米材料表面发生的化学反应,从而明确其毒性来源。

本文中我们发现氧化铁纳米颗粒具有pH依赖的类过氧化物酶和类过氧化氢酶双酶活性,并将其与细胞毒性联系起来。研究结果表明,在酸性条件下,氧化铁纳米颗粒能够催化H2O2产生羟自由基(•OH),进而氧化多种有机分子,即具有类过氧化物酶活性;而在中性条件下,氧化铁纳米颗粒直接催化双氧水分解为H2O和O2,即具有类过氧化氢酶活性。当被吞噬进入细胞以后,氧化铁纳米颗粒主要定位于酸性环境的溶酶体中,因而能通过类过氧化物酶活性增强H2O2诱导的细胞损伤。Fe3O4催化H2O2产生比Fe2O3更多的•OH,因而能够导致更强的细胞毒性。如果氧化铁纳米颗粒没有被困在溶酶体中,则可能不仅不会升高细胞内活性氧水平,反而能通过类过氧化氢酶活性达到抗氧化的目的。本文结果说明不同细胞内微环境对于氧化铁纳米颗粒的毒性可能具有相反的影响。考虑到细胞内源源不断产生的H2O2,逃避溶酶体的纳米颗粒运送方式可能是降低其长期细胞毒性的一种有效手段。
Zhongwen Chen, Jun-Jie Yin, Yu-Ting Zhou, Yu Zhang*, Lina Song, Mengjie Song, Sunling Hu, and Ning Gu*.Dual Enzyme-like Activities of Iron Oxide Nanoparticles and Their Implication for Diminishing Cytotoxicity. ACS Nano, 2012. DOI: 10.1021/nn300291r.


氧化铁纳米颗粒的双酶活性与其细胞毒性关系的示意图


氧化铁纳米颗粒的双酶活性


氧化铁纳米颗粒吞噬进入细胞后定位于内吞体或溶酶体中


氧化铁纳米颗粒增强H2O2诱导的细胞损伤


电子顺磁共振结合自旋标记技术验证氧化铁纳米颗粒在酸性环境中催化H2O2产生羟自由基,在中性环境中催化H2O2分解为水和氧气