Plasmonic Biosensors with Biocompatible Nanosilver

Noble metal nanoparticles and their unique plasmonic properties allow them to be used as agents for novel in-vivo bio-applications, such as targeted drug delivery and cancer cell therapy [1]. Nanosilver is the optimum such material because of its lowest losses of the plasmonic properties in the visible spectrum. The toxic nanosilver surface [2], however, can destroy the surrounding healthy tissue and thus, challenges its safe employment [3]. Therefore, “curing” nanosilver’s toxicity would open up its use for such innovative biological applications. Here, nanosilver particles are hermetically coated with a thin SiO₂ layer using a scalable aerosol method [4]. Uncoated or partially coated nanosilver exhibits substantial toxicity against E. coli bacteria, while encapsulating it prevents this. The performance of these ready-to-use, biocompatible nanosilver particles as biosensors is demonstrated by measuring the adsorption of bovine serum albumin (BSA) in a model sensing experiment. The silica coating prevents nanosilver agglomeration and thus, apart from the limited toxicity, enhances the biosensitivity.

[1] Sotiriou, G. A., Hirt, A. M., Lozach, P. Y., Teleki, A., Krumeich, F. & Pratsinis, S. E. Hybrid, Silica-Coated, Janus-like Plasmonic-Magnetic Nanoparticles. Chem. Mater. 23, 1985-1992 (2011).

[2] Sotiriou, G. A. & Pratsinis, S. E. Antibacterial activity of nanosilver ions and particles. Environ. Sci. Technol. 44, 5649-5654 (2010).

[3] Sotiriou, G. A., Sannomiya, T., Teleki, A., Krumeich, F., Vörös, J. & Pratsinis, S. E. Non-Toxic Dry-Coated Nanosilver for Plasmonic Biosensors. Adv. Funct. Mater. 20, 4250-4257 (2010).