School of Pharmacy, University of Otago, Dunedin 9016, New Zealand.
Department of Chemistry & Nano-science Center, University of Copenhagen, DK-2100 Copenhagen, Denmark.
ACS Appl Bio Mater. 2021 Apr 19;4(4):3155-3165. doi: 10.1021/acsabm.0c01563. Epub 2021 Mar 25.
Cell-penetrating peptides (CPPs) are known to interact with cell membranes and by doing so enhance cellular interaction and subsequent cellular internalization of nanoparticles. Yet, the early events of membrane interactions are still not elucidated, which is the aim of the present work. Surface conjugation of polymeric nanoparticles with cationic CPPs of different architecture (short, long linear, and branched) influences the surface properties, especially the charge of the nanoparticles, and therefore provides the possibility of increased electrostatic interactions between nanoparticles with the cell membrane. In this study, the physicochemical properties of CPP-tagged poly(lactic--glycolic acid) (PLGA) nanoparticles were characterized, and nanoparticle-cell interactions were investigated in HeLa cells. With the commonly applied methods of flow cytometry as well as confocal laser scanning microscopy, low and similar levels of nanoparticle association were detected for the PLGA and CPP-tagged PLGA nanoparticles with the cell membrane. However, single particle tracking of CPP-tagged PLGA nanoparticles allowed direct observation of the interactions of individual nanoparticles with cells and consequently elucidated the impact that the CPP architecture on the nanoparticle surface can have. Interestingly, the results revealed that nanoparticles with the branched CPP architecture on the surface displayed decreased diffusion modes likely due to increased interactions with the cell membrane when compared to the other nanoparticles investigated. It is anticipated that single particle approaches like the one used here can be widely employed to reveal currently unresolved characteristics of nanoparticle-cell interaction and aid in the design of improved surface-modified nanoparticles for efficient delivery of therapeutics.
细胞穿透肽（CPPs）已知与细胞膜相互作用，从而增强纳米颗粒与细胞的相互作用和随后的细胞内化。然而，细胞膜相互作用的早期事件仍未阐明，这是本工作的目的。具有不同结构（短、长线性和支化）的阳离子 CPP 对聚合物纳米颗粒进行表面缀合，会影响表面性质，特别是纳米颗粒的电荷，从而提供了增加纳米颗粒与细胞膜之间静电相互作用的可能性。在这项研究中，表征了 CPP 标记的聚（乳酸-乙醇酸）（PLGA）纳米颗粒的物理化学性质，并在 HeLa 细胞中研究了纳米颗粒-细胞相互作用。通常应用流式细胞术和共聚焦激光扫描显微镜的方法，检测到 PLGA 和 CPP 标记的 PLGA 纳米颗粒与细胞膜的低水平和相似水平的纳米颗粒缔合。然而，CPP 标记的 PLGA 纳米颗粒的单颗粒跟踪允许直接观察单个纳米颗粒与细胞的相互作用，从而阐明了 CPP 结构对纳米颗粒表面的影响。有趣的是，结果表明，与其他研究的纳米颗粒相比，表面具有支化 CPP 结构的纳米颗粒显示出扩散模式减少，这可能是由于与细胞膜的相互作用增加所致。预计像这里使用的这种单颗粒方法可以广泛用于揭示纳米颗粒-细胞相互作用目前尚未解决的特征，并有助于设计改进的表面修饰纳米颗粒，以实现治疗药物的有效传递。
