Institut des Matériaux and Institut des Sciences et Ingénierie Chimiques, Laboratoire des Polymères, École Polytechnique Fédérale de Lausanne (EPFL), Bâtiment MXD, Station 12, CH-1015 Lausanne, Switzerland.
Institute of Microengineering, Optics Laboratory, École Polytechnique Fédérale de Lausanne (EPFL), Bâtiment BM, Station 17, CH-1015 Lausanne, Switzerland.
Biomacromolecules. 2021 Jan 11;22(1):190-200. doi: 10.1021/acs.biomac.0c00969. Epub 2020 Sep 15.
Cells are attractive carriers for the transport and delivery of nanoparticulate cargo. The use of cell-based carriers allows one to enhance control over the biodistribution of drug-loaded polymers and polymer nanoparticles. One key element in the development of cell-based delivery systems is the loading of the cell-based carrier with the nanoparticle cargo, which can be achieved either by internalization of the payload or by immobilization on the cell surface. The surface modification of cells with nanoparticles or the internalization of nanoparticles by cells is usually monitored with fluorescence-based techniques, such as flow cytometry and confocal microscopy. In spite of the widespread use of these techniques, the use of fluorescent labels also poses some risks and has several drawbacks. Fluorescent dyes may bleach, or leach from, the nanoparticles or alter the physicochemical properties of nanoparticles and their interactions with and uptake by cells. Using poly(d,l-lactic acid) nanoparticles that are loaded with Coumarin 6, BODIPY 493/503, or DiO dyes as a model system, this paper demonstrates that the use of physically entrapped fluorescent labels can lead to false negative or erroneous results. The use of nanoparticles that contain covalently tethered fluorescent dyes instead was found to provide a robust approach to monitor cell surface conjugation reactions and to quantitatively analyze nanoparticle-decorated cells. Finally, it is shown that optical diffraction tomography is an attractive, alternative technique for the characterization of nanoparticle-decorated cells, which obviates the need for fluorescent labels.
细胞是纳米颗粒载体运输和递送的理想载体。使用基于细胞的载体可以增强对载药聚合物和聚合物纳米颗粒的生物分布的控制。基于细胞的递药系统的发展的一个关键因素是将纳米颗粒有效负载到基于细胞的载体上，这可以通过内吞作用或通过固定在细胞表面来实现。用纳米颗粒对细胞进行表面修饰或用细胞内化纳米颗粒通常可以通过基于荧光的技术（如流式细胞术和共聚焦显微镜）进行监测。尽管这些技术得到了广泛的应用，但荧光标记的使用也存在一些风险和缺点。荧光染料可能会从纳米颗粒中漂白或浸出，或者改变纳米颗粒的物理化学性质及其与细胞的相互作用和摄取。本文使用负载有香豆素 6、BODIPY 493/503 或 DiO 染料的聚（DL-乳酸）纳米颗粒作为模型系统，证明了使用物理包埋的荧光标记可能导致假阴性或错误的结果。相反，使用共价键合荧光染料的纳米颗粒被发现是一种可靠的方法，可以监测细胞表面缀合反应，并对经纳米颗粒修饰的细胞进行定量分析。最后，表明光学衍射层析成像（optical diffraction tomography）是一种有吸引力的替代技术，可用于表征经纳米颗粒修饰的细胞，从而避免了对荧光标记的需求。
