Complex Coacervate Core Micelles with Spectroscopic Labels for Diffusometric Probing of Biopolymer Networks

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• 作者：Nadia Bourouina ; Daan W. de Kort ; Freek J. M. Hoeben ; Henk M. Janssen ; Henk Van As ; Johannes Hohlbein ; John P. M. van Duynhoven ; J. Mieke Kleijn
• 刊名：Langmuir
• 出版年：2015
• 出版时间：November 24, 2015
• 年：2015
• 卷：31
• 期：46
• 页码：12635-12643
• 全文大小：550K
• ISSN：1520-5827

文摘

We present the design, preparation, and characterization of two types of complex coacervate core micelles (C3Ms) with cross-linked cores and spectroscopic labels and demonstrate their use as diffusional probes to investigate the microstructure of percolating biopolymer networks. The first type consists of poly(allylamine hydrochloride) (PAH) and poly(ethylene oxide)鈥損oly(methacrylic acid) (PEO-b-PMAA), labeled with ATTO 488 fluorescent dyes. We show that the size of these probes can be tuned by choosing the length of the PEO鈥揚MAA chains. ATTO 488-labeled PEO₁₁₃鈥揚MAA₁₅ micelles are very bright with 18 dye molecules incorporated into their cores. The second type is a ¹⁹F-labeled micelle, for which we used PAH and a ¹⁹F-labeled diblock copolymer tailor-made from poly(ethylene oxide)鈥損oly(acrylic acid) (mPEO₇₉-b-PAA₁₄). These micelles contain approximately 4 wt % of ¹⁹F and can be detected by ¹⁹F NMR. The ¹⁹F labels are placed at the end of a small spacer to allow for the necessary rotational mobility. We used these ATTO- and ¹⁹F-labeled micelles to probe the microstructures of a transient gel (xanthan gum) and a cross-linked, heterogeneous gel (魏-carrageenan). For the transient gel, sensitive optical diffusometry methods, including fluorescence correlation spectroscopy, fluorescence recovery after photobleaching, and super-resolution single nanoparticle tracking, allowed us to measure the diffusion coefficient in networks with increasing density. From these measurements, we determined the diameters of the constituent xanthan fibers. In the heterogeneous 魏-carrageenan gels, bimodal nanoparticle diffusion was observed, which is a signpost of microstructural heterogeneity of the network.