Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Facultad de Ciencias Exactas, Universidad Nacional de La Plata - CONICET Sucursal 4, Casilla de Correo 16, 1900 La Plata, Argentina.
Nanoscale. 2017 Jun 29;9(25):8647-8656. doi: 10.1039/c7nr01787a.
Coating strategies of inorganic nanoparticles (NPs) can provide properties unavailable to the NP core alone, such as targeting, specific sensing, and increased biocompatibility. Non-covalent amphiphilic NP capping polymers function via hydrophobic interactions with surface ligands and are extensively used to transfer NPs to aqueous media. For applications of coated NPs as actuators (sensors, markers, or for drug delivery) in a complex environment, such as biological systems, it is important to achieve a deep understanding of the factors affecting coating stability and behavior. We have designed a system that tests the coating stability of amphiphilic polymers through a simple fluorescent readout using either polarity sensing ESIPT (excited state intramolecular proton transfer) dyes or NP FRET (Förster resonance energy transfer). The stability of the coating was determined in response to changes in polarity, pH and ionic strength in the medium. Using the ESIPT system we observed linear changes in signal up to ∼20-25% v/v of co-solvent addition, constituting a break point. Based on such data, we propose a model for coating instability and the important adjustable parameters, such as the electrical charge distribution. FRET data provided confirmatory evidence for the model. The ESIPT dyes and FRET based methods represent new, simple tools for testing NP coating stability in complex environments.
无机纳米粒子（NPs）的涂层策略可以提供 NP 核心本身所不具备的特性，例如靶向性、特定感应和提高的生物相容性。非共价两亲性 NP 封端聚合物通过与表面配体的疏水相互作用发挥作用，并广泛用于将 NPs 转移到水介质中。对于涂覆 NPs 在复杂环境（如生物系统）中作为执行器（传感器、标记物或药物输送）的应用，了解影响涂层稳定性和行为的因素非常重要。我们设计了一种系统，该系统使用极性感应 ESIPT（激发态分子内质子转移）染料或 NP FRET（Förster 共振能量转移）通过简单的荧光读出测试两亲聚合物的涂层稳定性。通过在介质中改变极性、pH 值和离子强度来确定涂层的稳定性。使用 ESIPT 系统，我们观察到信号线性变化，直到添加共溶剂的体积比达到约 20-25%，构成一个转折点。基于这些数据，我们提出了涂层不稳定性的模型以及重要的可调参数，例如电荷分布。FRET 数据提供了对模型的确认证据。ESIPT 染料和基于 FRET 的方法代表了在复杂环境中测试 NP 涂层稳定性的新的、简单工具。
