Targeted charge-reversal nanoparticles for nuclear drug delivery
Targeted charge-reversal nanoparticles for nuclear drug delivery
复制标题
DOI：
10.1002/anie.200605254
复制
发表时间：
2007-01-01
影响因子：
16.6
通讯作者：
Shen, Youqing
中科院分区：
文献类型：
--
作者：
Xu, Peisheng;Van Kirk, Edward A.;Shen, Youqing
大多数癌症化疗药物，如蒽环类药物和顺铂，靶向核DNA引起DNA损伤和/或拓扑异构酶抑制，诱导细胞死亡（凋亡）。[1,2]耐药癌细胞除了在细胞膜内过度表达多重耐药机制外，[3,4]耐药癌细胞还有许多胞内耐药机制，限制胞质药物进入细胞核。[5,6]因此，只有一小部分进入细胞质溶胶的药物最终到达细胞核。例如，进入细胞的顺铂分子中，只有不到1%真正与细胞核DNA结合因此，能够定位并直接将药物释放到细胞核内的药物载体将绕过多重耐药和细胞内耐药机制，有效地将药物输送到DNA附近，从而获得较高的治疗效果。聚合物纳米颗粒[7,8]可以通过增强的渗透和保留（EPR）效应[9,10]优先将药物携带到癌组织，绕过细胞膜中的多药耐药，但迄今为止发现的纳米颗粒保留在细胞质细胞器中，包括溶酶体，而不是细胞核中核定位肽（nlp）是一种短而高正电荷的多肽，可在核膜上主动运输大蛋白，已被用于将药物分子从细胞质溶胶定位到细胞核。[13,14]阳离子聚合物聚乙烯亚胺（PEI）已广泛应用于非病毒基因传递。它可以携带DNA穿过细胞膜，利用分子马达沿着微管网络主动移动，最终进入细胞核。[15-17]然而，nlp和PEI在生理ph下是高度正电荷的。带正电荷的聚合物或胶体颗粒会引起严重的血清抑制，并迅速从血浆室中清除，[18,19]因此不能在体内使用。理想的方案是只在癌组织或其细胞内区室中激活阳离子。在此，我们报道了具有负到正电荷反转PEI外层的纳米颗粒，该外层由实体肿瘤细胞外酸度（pH< 7,[10,20]）或溶酶体（pH 4-5,[21]）触发，用于核药物递送。带负电荷的聚合物与血液成分的相互作用很小，在体内得到了广泛的应用。[22,23]邻羧酸基团的酰胺表现出ph依赖性水解测试了顺式- 1,2 -环己二羧酸酐制备的伯胺和仲胺模型酰胺在不同pH值下的水解情况（见辅助资料中的图S1）。在pH值为5时，仲胺的酰胺几乎立即水解，pH值为6时水解速度稍慢，但在pH值为7.4时，60 h后水解率仅为50%。伯胺酰胺在pH为5和6时水解速度较仲胺酰胺慢，在pH为7.4时不水解。因此，我们使用这种类型的酰胺来保存PEI的伯胺和仲胺：在中性pH下，由于β-羧酸基团，酰胺稳定且带负电荷，而在低pH下，酰胺水解再生胺基以携带阳离子电荷。
Most cancer chemotherapy drugs, such as anthracyclines and cisplatin, target nuclear DNA to cause DNA damage and/or topoisomerase inhibition to induce cell death (apoptosis).[1, 2] In addition to the overexpressed multidrug-resistance mechanism in the cell membrane,[3, 4] drug-resistant cancer cells have many intracellular drug-resistance mechanisms to limit the access of cytosolic drugs to the nucleus.[5, 6] Consequently, only a small percentage of drugs delivered into the cytosol finally reach the nucleus. For example, less than 1% of the cisplatin molecules that enter the cell actually bind the nuclear DNA.[2] Thus, a drug carrier capable of localizing and directly releasing drugs into the nucleus would circumvent the multidrug-resistance and intracellular drug-resistance mechanisms to effectively deliver drugs to the vicinity of DNA, leading to a high therapeutic efficacy. Polymer nanoparticles [7, 8] can carry drugs preferentially to cancerous tissues by means of the enhanced permeation and retention (EPR) effect [9, 10] and bypass the multidrug resistance in the cell membrane,[11] but the nanoparticles developed to date were found retained in cytoplasmic organelles including lysosomes rather than the nucleus.[12] Nuclear localization peptides (NLPs)—short highly positively charged peptides that actively transport large proteins across the nuclear membrane—have been used to localize drug molecules from the cytosol to the nucleus.[13, 14] A cationic polymer, polyethyleneimine (PEI), has been used extensively in nonviral gene delivery. It can carry DNA across the cell membrane, harness the molecular motors to actively move along the microtubule network, and finally enter the nucleus.[15–17] NLPs and PEI, however, are highly positively charged at physiological pH. Positively charged polymers or colloidal particles can cause severe serum inhibition and are rapidly cleared from the plasma compartment,[18, 19] and thus cannot be used in vivo.An ideal regime would be to activate the cationic charges only in cancerous tissues or their intracellular compartments. Herein, we report nanoparticles with a negative-to-positive charge-reversal PEI outer layer triggered by the solid tumor extracellular acidity (pH< 7,[10, 20]) or lysosomal (pH 4–5,[21]) for nuclear drug delivery. Negatively charged polymers have little interaction with the blood components and have been used extensively in vivo.[22, 23] Amides with neighboring carboxylic acid groups exhibit pH-dependent hydrolysis.[24] The hydrolysis of model amides of primary and secondary amines made from cis-1, 2-cyclohexanedicarboxylic anhydride was tested at different pH values (Figure S1 in the Supporting Information). The amide of the secondary amine almost instantly hydrolyzed at pH 5, slightly slower at pH 6, but only 50% even after 60 h at pH 7.4. The amide of the primary amine hydrolyzed more slowly at pH 5 and 6 than that of the secondary amine amide, and did not hydrolyze at pH 7.4. Thus, we used this type of amides to preserve the primary and secondary amines of PEI: At neutral pH, the amides are stable and negatively charged because of the β-carboxylic acid groups, while at a low pH, the amides hydrolyze to regenerate the amine groups to carry cationic charges.