Department of Analytical Chemistry; Reference Materials , Bundesanstalt für Materialforschung und -prüfung (BAM) , Richard-Willstätter-Straße 11 , 12489 Berlin , Germany.
Department of Chemistry , Humboldt-Universität zu Berlin , Brook-Taylor-Straße 2 , 12489 Berlin , Germany.
ACS Appl Mater Interfaces. 2019 Jan 9;11(1):1321-1334. doi: 10.1021/acsami.8b10306. Epub 2018 Dec 27.
Commercial bead-based assays are commonly built upon polystyrene particles. The polymeric carrier can be encoded with organic dyes and has ideal material properties for cytometric applications such as low density and high refractive index. However, functional groups are conventionally integrated during polymerization and subsequent modification is limited to the reactivity of those groups. Additionally, polystyrene as the core material leads to many hydrophobic areas still being present on the beads' surfaces even after functionalization, rendering the particles prone to nonspecific adsorption during an application. The latter calls for several washing steps and the use of additives in (bio)analytical assays. In this contribution, we show how these limitations can be overcome by using monodisperse polystyrene (PS) core/silica (SiO) shell particles (SiO@PS). Two different hydrophobic BODIPY (boron-dipyrromethene) dyes were encapsulated inside a poly(vinylpyrrolidone) (PVP) -stabilized polystyrene core in different concentrations to create 5-plex arrays in two separate detection channels of a cytometer. A subsequent modification of the silica shell with an equimolar APTES/PEGS (aminopropyltriethoxysilane/polyethylene glycol silane) blend added multifunctional properties to the hybrid core/shell microparticles in a single step: APTES provides amino groups for the attachment of a caffeine derivative (as a hapten) to create antigen-coupled microspheres; the PEG moiety effectively suppresses nonspecific binding of antibodies, endowing the surface with antifouling properties. The particles were applied in a competitive fluorescence immunoassay in suspension, and a highly selective wash-free assay for the detection of caffeine in beverages was developed as a proof of concept.
商用的基于珠子的检测通常是基于聚苯乙烯珠子。聚合物载体可以用有机染料进行编码，并且具有理想的材料特性，适用于细胞计量学应用，如低密度和高折射率。然而，功能基团通常是在聚合过程中整合的，并且随后的修饰仅限于这些基团的反应性。此外，尽管进行了功能化，但作为核心材料的聚苯乙烯仍然会在珠子表面上留下许多疏水区，导致在应用过程中颗粒容易发生非特异性吸附。这种情况需要进行多次洗涤步骤，并在（生物）分析检测中使用添加剂。在本研究中，我们展示了如何通过使用单分散聚苯乙烯（PS）核/二氧化硅（SiO）壳颗粒（SiO@PS）来克服这些限制。两种不同的疏水性 BODIPY（硼二吡咯甲烷）染料被包裹在聚（乙烯基吡咯烷酮）（PVP）稳定的聚苯乙烯核中，浓度不同，在细胞仪的两个独立检测通道中创建了 5 重阵列。随后，用等摩尔的 APTES/PEGS（氨丙基三乙氧基硅烷/聚乙二醇硅烷）混合物修饰二氧化硅壳，在单个步骤中为混合核/壳微球添加了多功能特性：APTES 提供了用于连接咖啡因衍生物（作为半抗原）的氨基，以创建抗原偶联的微球；PEG 部分有效地抑制了抗体的非特异性结合，赋予了表面抗污染的特性。这些颗粒被应用于悬浮液中的竞争性荧光免疫测定中，并开发了一种高选择性的免洗测定方法，用于检测饮料中的咖啡因，作为概念验证。
