We report the surface functionalization of anionic layer by layer nanoparticles (LbL NPs) with cationic tumor-penetrating peptides (TPPs) via electrostatic adsorption while retaining particle stability and charge characteristics. This strategy eliminates the need for structural modifications of the peptide and enables facile functionalization of surface chemistries difficult to modify or inaccessible via covalent conjugation strategies. We show that both carboxylated and sulfated LbL NPs are able to accommodate linear and cyclic TPPs and used fluorescence-based detection assays to quantify peptide loading per NP. We also demonstrate that TPP activity is retained upon adsorption, implying sufficient numbers of peptides take on the appropriate surface orientation, enabling efficient uptake of functionalized NPs in vitro, as characterized via flow cytometry and deconvolution microscopy. Overall, we believe that this strategy will serve as a broadly applicable approach to impart electrostatically assembled NPs with bioactive peptide motifs.

中文翻译：

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带有功能肽基序的纳米粒子表面的静电共轭。

我们报告通过静电吸附，同时保留粒子稳定性和电荷特征的层与阳离子肿瘤穿透肽（TPPs）的纳米颗粒（LbL NPs）阴离子层的表面功能化。该策略消除了对肽的结构修饰的需要，并且使得难以通过共价缀合策略修饰或难以获得的表面化学的功能化。我们表明，羧化和硫酸化的LbL NP都能够适应线性和环状TPP，并使用基于荧光的检测方法来量化每个NP的肽负载量。我们还证明了TPP的活性在吸附后得以保留，这意味着足够数量的肽具有适当的表面取向，从而能够在体外有效吸收官能化的NP，通过流式细胞术和反卷积显微镜表征。总体而言，我们认为该策略将作为一种广泛适用的方法，以赋予静电组装的具有生物活性肽基序的NP。