TY - JOUR A1 - Sarma, Dominik A1 - Carl, Peter A1 - Climent Terol, Estela A1 - Schneider, Rudolf A1 - Rurack, Knut T1 - Multifunctional polystyrene core/silica shell microparticles with antifouling properties for bead-based multiplexed and quantitative analysis JF - ACS Applied Materials and Interfaces N2 - 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 (SiO2) shell particles (SiO2@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. KW - Core−shell particles KW - Bead-based assay KW - Multiplex KW - Antifouling surface KW - Mixed surface PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-472931 UR - https://pubs.acs.org/doi/10.1021/acsami.8b10306 DO - https://doi.org/10.1021/acsami.8b10306 SN - 1944-8244 VL - 11 IS - 1 SP - 1321 EP - 1334 PB - American Chemical Society CY - Online Library AN - OPUS4-47293 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Climent Terol, Estela A1 - Wan, Wei A1 - Weller, Michael G. A1 - Rurack, Knut T1 - Novel specific bio-gated hybrid materials and their integration into versatile platforms for advanced sensing applications N2 - Methods for the rapid and sensitive detection of target analytes are gaining importance in medical diagnostics and environmental monitoring, in the security, occupational health and safety as well as food sectors. Among all of the methods employed for rapid tests, lateral flow assays (LFAs) are the most commonly used, and hundreds of test kits based on this technique are available on the market. A major drawback is that most of these capture agents either indicate the analyte only indirectly, and in most cases a second binding agent able to bind directly or indirectly to the analytes is necessary (e.g., a secondary labeled antibody). Furthermore, in certain cases in which the (ultra)trace detection of an analyte is required, the traditional approach of a certain number of probe molecules being conjugated to a particular support is not sufficient. Therefore, novel concepts implementing steps of effective signal amplification are urgently required. Keeping in mind these limitations, we thought that the sensitivity of these systems should be improvable through employment of gated reporter molecule-releasing hybrid nanoparticle materials on novel lateral flow devices. On one hand, the gated sensor material can produce a massive signal amplification, by releasing many reporter molecules only after chemical recognition of a few analyte molecules has taken place in an independent and separate step at the pore openings. On the other hand, the employment of tailored capture materials for the selective interaction with the released reporter molecules in a second arbitrary zone on the strip allows to concentrate or focus the latter for more efficient detection or to create selective multi-spot detection zones, which renders the simultaneous detection of several reporter molecules at the same time in multiplexed detection of various analytes possible. For that purpose, we have prepared several stimuli-responsive materials for small-molecule sensing based on specific interactions between biomolecules such as antibodies with the corresponding analytes for the detection of certain explosives. In order to prepare these bio-capped materials, we have selected silica mesoporous nanoparticles (MSNs) as inorganic support due to their unique properties such as defined void structure, high inner surface area and flexible functionalization chemistry. These MSNs are loaded with a brightly fluorescent indicator dye, and the external surface is subsequently functionalized with suitable molecules able to interact with antibodies, efficiently inhibiting dye release. The opening protocol and delivery of the entrapped dye is reminiscent of a displacement reaction involving the presence of the target analyte, producing a displacement of the biomolecule and allowing the detection of the target analyte. The presentation discusses general aspects of system design as well as analytical performance and highlights the integration into a lateral-flow assay, showing as an example the determination of the explosives TATP, TNT and PETN with fluorescence readout, in single-substance and multiplexing modes. T2 - EBS 2019 CY - Florence, Italy DA - 18.02.2019 KW - Bio-gated hybrid materials KW - Signal amplification KW - Explosives determination KW - Fluorescence KW - Rapid test KW - Dip-stick assay PY - 2019 AN - OPUS4-47920 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -