Non-Toxic Dry-Coated Nanosilver for Plasmonic Biosensors

Authors

  • Georgios A. Sotiriou,

    1. Particle Technology Laboratory, Institute of Process Engineering, Department of Mechanical and Process Engineering, Sonneggstrasse 3, ETH Zurich, 8092 Zurich (Switzerland)
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  • Takumi Sannomiya,

    1. Laboratory of Biosensors and Bioelectronics, Department of Information Technology and Electrical Engineering, Materials Research Center, ETH Zurich, CH-8092 Zürich (Switzerland)
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  • Alexandra Teleki,

    1. Particle Technology Laboratory, Institute of Process Engineering, Department of Mechanical and Process Engineering, Sonneggstrasse 3, ETH Zurich, 8092 Zurich (Switzerland)
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  • Frank Krumeich,

    1. Particle Technology Laboratory, Institute of Process Engineering, Department of Mechanical and Process Engineering, Sonneggstrasse 3, ETH Zurich, 8092 Zurich (Switzerland)
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  • Janos Vörös,

    1. Laboratory of Biosensors and Bioelectronics, Department of Information Technology and Electrical Engineering, Materials Research Center, ETH Zurich, CH-8092 Zürich (Switzerland)
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  • Sotiris E. Pratsinis

    Corresponding author
    1. Particle Technology Laboratory, Institute of Process Engineering, Department of Mechanical and Process Engineering, Sonneggstrasse 3, ETH Zurich, 8092 Zurich (Switzerland)
    • Particle Technology Laboratory, Institute of Process Engineering, Department of Mechanical and Process Engineering, Sonneggstrasse 3, ETH Zurich, 8092 Zurich (Switzerland).
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Abstract

The plasmonic properties of noble metals facilitate their use for in vivo bio-applications such as targeted drug delivery and cancer cell therapy. Nanosilver is best suited for such applications as it has the lowest plasmonic losses among all such materials in the UV-visible spectrum. Its toxicity, however, can destroy surrounding healthy tissues and thus, hinders its safe use. Here, that toxicity against a model biological system (Escherichia coli) is “cured” or blocked by coating nanosilver hermetically with a about 2 nm thin SiO2 layer in one-step by a scalable flame aerosol method followed by swirl injection of a silica precursor vapor (hexamethyldisiloxane) without reducing the plasmonic performance of the enclosed or encapsulated silver nanoparticles (20–40 nm in diameter as determined by X-ray diffraction and microscopy). This creates the opportunity to safely use powerful nanosilver for intracellular bio-applications. The label-free biosensing and surface bio-functionalization of these ready-to-use, non-toxic (benign) Ag nanoparticles is presented by measuring the adsorption of bovine serum albumin (BSA) in a model sensing experiment. Furthermore, the silica coating around nanosilver prevents its agglomeration or flocculation (as determined by thermal annealing, optical absorption spectroscopy and microscopy) and thus, enhances its biosensitivity, including bioimaging as determined by dark field illumination.

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