Dipartimento di Chimica "Giacomo Ciamician", Università di Bologna, Via Francesco Selmi, 2, 40126, Bologna, Italy.
Sci Rep. 2018 Nov 20;8(1):17095. doi: 10.1038/s41598-018-35257-y.
Understanding polarity gradients inside nanomaterials is essential to capture their potential as nanoreactors, catalysts or in drug delivery applications. We propose here a method to obtain detailed, quantitative information on heterogeneous polarity in multicompartment nanostructures. The method is based on a 2-steps procedure, (i) deconvolution of complex emission spectra of two solvatochromic probes followed by (ii) spectrally resolved analysis of FRET between the same solvatochromic dyes. While the first step yields a list of polarities probed in the nanomaterial suspension, the second step correlates the polarities in space. Colocalization of polarities falling within few nanometer radius is obtained via FRET, a process called here nanopolarity mapping. Here, Prodan and Nile Red are tested to map the polarity of a water-dispersable, multicompartment nanostructure, named PluS nanoparticle (NPs). PluS NPs are uniform core-shell nanoparticles with silica cores (diameter ~10 nm) and Pluronic F127 shell (thickness ~7 nm). The probes report on a wide range of nanopolarities among which the dyes efficiently exchange energy via FRET, demonstrating the coexistence of a rich variety of environments within nanometer distance. Their use as a FRET couple highlights the proximity of strongly hydrophobic sites and hydrated layers, and quantitatively accounts for the emission component related to external water, which remains unaffected by FRET processes. This method is general and applicable to map nanopolarity in a large variety of nanomaterials.
了解纳米材料内部的极性梯度对于挖掘其作为纳米反应器、催化剂或药物输送应用的潜力至关重要。我们在这里提出了一种方法，可以获得关于多隔室纳米结构中不均匀极性的详细、定量信息。该方法基于两步程序：（i）对两种溶致变色探针的复杂发射光谱进行解卷积，然后（ii）对相同溶致变色染料之间的 FRET 进行光谱分辨分析。虽然第一步提供了纳米材料悬浮液中探测到的一系列极性，但第二步则将极性在空间上关联起来。通过被称为纳米极性映射的 FRET 过程，可以获得在几纳米半径内的极性的共定位。这里，使用 Prodan 和 Nile Red 来绘制一种名为 PluS 纳米粒子（NPs）的水可分散多隔室纳米结构的极性。PluS NPs 是均匀的核壳纳米粒子，具有二氧化硅核（直径约 10nm）和 Pluronic F127 壳（厚度约 7nm）。探针报告了广泛的纳米极性范围，其中染料通过 FRET 有效地进行能量交换，证明了在纳米距离内存在多种环境的共存。它们作为 FRET 对的使用突出了强疏水区和水合层的接近性，并定量说明了与外部水相关的发射成分，该成分不受 FRET 过程的影响。该方法是通用的，适用于绘制各种纳米材料中的纳米极性。
