We have performed highly sensitive surface plasmon resonance (SPR) detection by colocalizing the evanescent near-fields and target molecular distribution. The colocalization is based on oblique metal evaporation to form nanogaps of a size under 100 nm without using electron-beam lithography. The concept was demonstrated by detecting siloxane-based biotin/streptavidin interactions. 50-nm nanogaps produced the largest amplification of optical signatures and two orders of magnitude enhancement of sensitivity over conventional thin film-based measurements. The enhancement is associated with efficient overlap of localized near-fields and target. Colocalized detection scheme is expected to provide clues to molecular sensitivity for SPR biosensing.
Bibliographical noteFunding Information:
This work was supported by the National Research Foundation (NRF) grants funded by the Korean Government (2009-0070732, 2010-0007993, 2011-0017500, and 2011-0029409).
All Science Journal Classification (ASJC) codes
- Physics and Astronomy (miscellaneous)