The use of self-assembled nanoparticles for drug delivery has received significant attention in recent years. However, the dynamic nature of self-assembled polymeric systems means there is a need to develop greater understanding of the inherent stability of these systems. In particular, understanding if these materials remain as discrete nanoparticles, or if there is dynamic exchange of material between particles is critical. Herein, we labelled pH-responsive nanoparticles with fluorescent dyes and then investigated the change in fluorescence when the particles were mixed with unlabelled nanoparticles in order to investigate their potential for polymer rearrangement. Nanoparticles were formed by the nanoprecipitation of pH-responsive poly(ethylene glycol)-block-poly(2-(diethylamino)ethyl methacrylate) (PEG-b-PDEAEMA) as the shell and poly(2-(diethylamino)ethyl methacrylate)-random-poly(2-(diisopropylamino)ethyl methacrylate) (PDEAEMA-r-PDPAEMA) as the core. The core and shell were labelled by incorporating pentafluorophenyl methacrylate (PFPMA) in core or shell respectively and then coupling with either Sulfo-cyanine5 amine or Cyanine3 amine. Exchange of material between nanoparticles was probed by tracking changes in the self-quenching of fluorescently labelled polymers in the core of the nanoparticles. The fluorescence intensity of the labelled nanoparticles was stable when mixed with unlabelled nanoparticles at physiological pH (pH 7.4), suggesting there is limited migration of polymers between particles in this system. This study provides important insights into the use of non-crosslinked nanoparticles under biologically relevant conditions.

近年来，自组装的纳米颗粒用于药物递送的使用受到了广泛的关注。然而，自组装聚合物系统的动态性质意味着需要对这些系统的固有稳定性有更多的了解。特别是，了解这些材料是否保留为离散的纳米粒子，或者粒子之间是否存在动态交换至关重要。本文中，我们用荧光染料标记了pH响应纳米颗粒，然后研究了将颗粒与未标记的纳米颗粒混合时荧光的变化，以研究其聚合物重排的潜力。纳米颗粒通过pH响应聚（乙二醇）的纳米沉淀形成-嵌段-聚（2-（二乙氨基）乙基甲基丙烯酸酯）（PEG-b -PDEAEMA）作为外壳，而聚（2-（二乙基氨基）甲基丙烯酸乙酯）-无规- （2-（二异丙基氨基）甲基丙烯酸乙酯）（PDEAEMA- r-PDPAEMA）为核心。通过分别在核或壳中掺入甲基丙烯酸五氟苯酯（PFPMA），然后与磺化花青5胺或花青3胺偶联，对核和壳进行标记。通过追踪纳米颗粒核心中荧光标记聚合物的自猝灭变化来探测纳米颗粒之间的材料交换。当在生理pH（pH 7.4）下与未标记的纳米粒子混合时，标记的纳米粒子的荧光强度是稳定的，这表明该系统中粒子之间的聚合物迁移有限。这项研究为生物学相关条件下非交联纳米粒子的使用提供了重要的见识。