摘要
蛋白冠(protein corona)是纳米颗粒与血浆蛋白之间发生非特异性相互作用后在表面吸附的蛋白层。近年来研究表明,在纳米颗粒表面修饰特定血浆蛋白质构建蛋白冠具有延长纳米颗粒血液半衰期、促进纳米颗粒靶向递送等作用,引起载药系统研究的广泛关注。其中,以血液中含量最为丰富的蛋白质白蛋白构建白蛋白冠(albumin corona)研究最为广泛。基于此,本文系统性总结了构建白蛋白冠的方法及其在药物制剂研究中的应用,以期为药物制备过程中构建白蛋白冠提供参考。
蛋白冠(protein corona)是纳米颗粒与血浆蛋白之间发生非特异性相互作用后在表面吸附的蛋白层,于2007年首次被提出,用于描述生物环境中生物分子在纳米颗粒表面形成的涂
白蛋白是人血中含量最丰富的血浆蛋白,它是一种天然转运蛋白,具有循环半衰期长、肿瘤蓄积、肿瘤细胞靶向性、多配体结合位点、高生物相容性等特点。在纳米颗粒表面形成白蛋白冠能够充分发挥白蛋白在药物递送中的优势(见

图1 有无白蛋白冠的情况下纳米载体在体内的生物反应过程
A:各种血浆蛋白立即吸附在裸露的纳米载体上,导致快速清除;B:在纳米载体表面预形成白蛋白冠能抑制血浆蛋白的吸附,延长血液循环时间,促进肿瘤蓄积
载体表面形成白蛋白冠能够抑制调理素(如免疫球蛋白G和补体)的吸附,从而减少载体被血液中单核巨噬细胞系统摄取,减少调理作用,延长血液循环时间。本课题组的前期研究中设计了一种基于脂质的纳米混悬液,将其注射入体内后其表面形成蛋白冠,在体外将该纳米混悬液与血浆共孵育,通过透射电子显微镜观察到其表面形成蛋白冠。一方面防止药物的突然释放,另一方面延长了纳米粒的生物半衰
白蛋白依赖淋巴系统从细胞外间隙返回循环,使其很容易在淋巴引流不良的肿瘤部位聚积。此外,由于肿瘤生长迅速,新陈代谢活跃的肿瘤急需营养,肿瘤组织的白蛋白摄入量大大增加。因此,载体表面的白蛋白冠能促进载体的肿瘤蓄积,例如Zhang
白蛋白与细胞受体的相互作用使之主动靶向肿瘤细
血脑屏障在生理pH下带负电
白蛋白含有3个同源的螺旋结构域(Ⅰ~Ⅲ),每个螺旋结构域分为A和B亚域,具有多个药物结合位
药物制剂的生物相容性一直以来受到研究人员的广泛关注,具有良好生物相容性、低不良反应的药物制剂更具有临床转化前景。白蛋白是人体主要的循环蛋白之一,将载体包封在白蛋白中能降低毒性、提高生物相容
目前,药物载体构建白蛋白冠的方法主要包括两种(见

图2 药物载体设计中白蛋白冠的构建方法
A:载药纳米颗粒在体外与白蛋白孵育形成白蛋白冠;B:表面修饰白蛋白结合基团的载药纳米颗粒吸附血液白蛋白形成白蛋白冠
马来酰亚胺是一种含有双键的有机物,其双键能与巯基发生迈克尔加成反应形成硫醚
白蛋白结合域(albumin-binding domain,ABD)是一种由46个氨基酸组成的多肽,对白蛋白有很强的亲和力。基于此,Yousefpour
白蛋白结合肽(albumin-binding peptide,ABP)是由20个氨基酸组成的多肽,对不同物种的血浆白蛋白有很高的亲和力。基于此,Miyakawa
然而,ABD和ABP的种类繁多,在药物制剂研究过程中合理地选择相应的种类对于提高药物载体的递送效率十分关键,根据特定的制剂选择相应的ABD和ABP是有必要的。此外,ABD和ABP通常与重组产生的治疗性蛋白在基因上融合,因此在药物制剂研究过程中,两蛋白间的接头序列的选择十分重要,合理地选择蛋白间的接头序列有利于多肽的折叠及其稳定性。
伊文思蓝(evans blue,EB)能插入白蛋白的疏水区,并与之形成稳定复合
陈小元团队在基于EB的领域做出了实质性的贡献,例如,为解决合成纳米疫苗的安全和质量问题,该小组设计了分子纳米疫苗,可在体内自组装形成白蛋白与纳米疫苗的复合物,该疫苗被有效递送至淋巴结,不良反应小,具有极大临床转化的潜
聚多巴胺(polydopamine,PDA)能够在血清中募集完整白蛋白并促进纳米颗粒的跨内皮转运和细胞摄
分子印迹(molecularly imprinted polymers, MIP)的基本概念是在目标分子存在的情况下聚合功能性单体,并通过冻结聚合结构中的单体来制造目标分子(如白蛋白)的模板,除去白蛋白后,印记空腔在大小和形状上与白蛋白互补,从而特异性吸附白蛋白。例如,Takeuchi
纳米颗粒能通过疏水作用、静电作用等非特异性吸附血液中的蛋白质形成蛋白
目前研究人员对蛋白冠担忧的同时已经认识到其在药物递送中的机会,特别是基于具有良好调节作用的蛋白质构建蛋白冠。白蛋白凭借其循环半衰期长、肿瘤蓄积、肿瘤细胞靶向性、多配体结合位点、高生物相容性在蛋白冠的构建中受到广泛的研究。与此同时,在构建白蛋白冠的道路上仍存在很多困难与挑战,如马来酰亚胺相关的前药溶解度较差,载体表面形成的白蛋白容易被血浆蛋白置换,白蛋白冠的形成厚度难以得到控制等。针对以上困难,研究人员做出了巨大的努力,如合成聚乙二醇化的马来酰亚胺基序以提高其修饰载体的溶解度,利用化学方法将白蛋白与载体连接以减少其他血浆蛋白的置换等。尽管面临上述挑战,随着对白蛋白冠深入研究,药物递送领域将开辟出振奋人心的新途径。
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