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.

中文翻译：

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聚合物纳米粒子修饰的T细胞的基于荧光和无荧光标记的表征。

细胞是用于运输和递送纳米颗粒货物的有吸引力的载体。基于细胞的载体的使用允许人们增强对载药的聚合物和聚合物纳米颗粒的生物分布的控制。基于细胞的递送系统发展中的一个关键要素是纳米颗粒货物对基于细胞的载体的装载，这可以通过有效载荷的内在化或通过固定在细胞表面上来实现。通常使用基于荧光的技术（例如流式细胞术和共聚焦显微镜）来监测纳米颗粒对细胞的表面修饰或细胞对纳米颗粒的内在化。尽管这些技术被广泛使用，但是荧光标记的使用也带来一些风险并且具有一些缺点。荧光染料可能会漂白，浸出，纳米粒子或改变纳米粒子的理化特性以及它们与细胞的相互作用和被细胞摄取。使用poly（d，升乳酸），其装载有香豆素6，BODIPY503分之493，或DIO染料作为模型系统的纳米颗粒，本文表明，使用物理包埋的荧光标记可导致假阴性或错误的结果。已发现使用包含共价连接的荧光染料的纳米颗粒可提供一种可靠的方法来监测细胞表面的偶联反应并定量分析装饰有纳米颗粒的细胞。最后，表明光学衍射断层扫描是表征纳米粒子修饰细胞的一种有吸引力的替代技术，它消除了对荧光标记的需求。