Deciphering the targets of axonal projections plays a pivotal role in interpreting neuronal function and pathology. Neuronal tracers are indispensable tools for uncovering the functions and interactions between different subregions of the brain. However, the selection of commercially available neuronal tracers is limited, currently comprising small molecule dyes, viruses, and a handful of synthetic nanoparticles. Here, we describe a series of polymer-based nanoparticles capable of retrograde transport along neurons in vivo in mice. These polymeric nanoparticle neuronal tracers (NNTs) are prepared with a palette of fluorescent labels. The morphologies, charges, and optical properties of NNTs are characterized by analytical methods including fluorescence microscopy, electron microscopy, and dynamic light scattering. Cytotoxicity and cellular uptake were investigated to analyze cellular interactions in vitro. Regardless of the type of fluorophore used in labeling, each tracer was of similar morphology, size, and charge and was competent for retrograde transport in vivo. The platform provides a convenient, scalable synthetic approach for nonviral tracers labeled with a range of fluorophores for in vivo neuronal projection mapping.

中文翻译：

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多色聚合物纳米粒子神经元示踪剂

破译轴突投射的目标在解释神经元功能和病理学中起着关键作用。神经元示踪剂是揭示大脑不同子区域之间的功能和相互作用的必不可少的工具。但是，市售神经元示踪剂的选择是有限的，目前包括小分子染料，病毒和少数合成纳米颗粒。在这里，我们描述了一系列能够在体内沿神经元逆行转运的基于聚合物的纳米颗粒在小鼠中。这些聚合纳米粒子神经元示踪剂（NNT）是用荧光标记调色板制备的。NNT的形态，电荷和光学性质通过包括荧光显微镜，电子显微镜和动态光散射在内的分析方法来表征。细胞毒性和细胞摄取进行了研究，以分析细胞相互作用的体外。不管用于标记的荧光团类型如何，每个示踪剂的形态，大小和电荷均相似，并且能够在体内逆行转运。该平台为非病毒示踪剂提供了方便，可扩展的合成方法，该示踪剂标记了一系列荧光团，用于体内神经元投射作图。