The dynamic concentration range is one of the major limitations of single-molecule fluorescence techniques. Here, we show how bottom-up nano-antennas enhance the fluorescence intensity in a reduced hot-spot, ready for biological applications. We use self-assembled DNA origami structures as a breadboard where gold nanoparticle dimers are positioned with nanometer precision. A maximum of almost 100fold intensity enhancement is obtained using 100 nm gold nanoparticles within a gap of 23 nm between the particles. The results obtained are in good agreement with numerical simulations. Due to the intensity enhancement introduced by the nano-antenna, we are able to perform single molecule measurements at concentrations as high as 500 nM which represents an increment of 2 orders of magnitude compared to conventional measurements. The combination of metallic nanoparticles with DNA origami structures with docking points for biological assays paves the way for the development of bottom-up inexpensive enhancement chambers for single molecule measurements at high concentrations where processes like DNA sequencing occur.

Date Published: 22 February 2013
PDF: 8 pages
Proc. SPIE 8595, Colloidal Nanocrystals for Biomedical Applications VIII, 859509 (22 February 2013); doi: 10.1117/12.2003565

Published in SPIE Proceedings Vol. 8595:
Colloidal Nanocrystals for Biomedical Applications VIII
Wolfgang J. Parak; Marek Osinski; Kenji Yamamoto, Editor(s)