AVS 53rd International Symposium
    Biomaterial Interfaces Tuesday Sessions
       Session BI2-TuM

Paper BI2-TuM12
Label-Free Biosensing in Array Format Utilizing Surface-Adsorbed Core-Shell Nanoparticle Layers

Tuesday, November 14, 2006, 11:40 am, Room 2014

Session: Biodiagnostic Innovation
Presenter: R. Dahint, University of Heidelberg, Germany
Authors: R. Dahint, University of Heidelberg, Germany
E. Trileva, University of Heidelberg, Germany
H. Acunman, University of Heidelberg, Germany
U. Konrad, University of Heidelberg, Germany
M. Zimmer, University of Heidelberg, Germany
V. Stadler, German Cancer Research Center, Germany
M. Himmelhaus, University of Heidelberg, Germany
Correspondent: Click to Email
A novel method for spatially resolved, label-free biosensing based on core-shell nanoparticle films is presented. For the preparation of the layers, polystyrene particles of 350 nm in diameter are self-assembled on a gold-coated substrate to form a random-close-packed monolayer. Afterwards, the nanoparticle layer is covered with a metal film by first depositing gold colloid of 2-3 nm in size, followed by an electroless plating step. The resulting surface shows a pronounced optical extinction upon reflection of white light with the extinction maximum located in the NIR region of the electromagnetic spectrum. When organic molecules bind to the surface, the peak position of this maximum shows a pronounced red-shift. In case of octadecanethiol adsorption, a peak shift of 55 nm on average has been observed, which is about five times that of established label-free sensing methods based on propagating and localized surface plasmons. By immobilizing a pattern of different peptides on the nanoparticle layers and reacting the surface with specific antibodies it has been demonstrated that biospecific interactions can be label-free detected in array formats with high sensitivity. For the suppression of non-specific adsorption, which may lead to false results in the identification of binding events, the peptides have been embedded into an inert matrix material based on poly(ethylene glycol). In the future we intend to immobilize high-density peptide libraries onto the nanoparticle layers by combinatorial synthesis to facilitate in situ, parallel, time-resolved, and label-free screening of biospecific binding processes.