Plasmonic Ag Nanostructures as Sensors, Microreactors and Security Labels

In this seminar, I will discuss three aspects of our work on using metallic Ag nanostructures for sensing, catalysis, anti-counterfeiting applications. In the first part, we demonstrate the fabrication of a plasmonic “liquid marble” as a substrate-less analytical platform which, when coupled with ultrasensitive SERS, enables simultaneous multiplex quantification and the identification of ultratrace analytes across separate phases. Our plasmonic liquid marble is suitable for the quantitative examination of ultratrace analytes, with detection limits as low as 0.3 fmol. We also extend plasmonic liquid marble as reaction rate-controllable catalytic miniature reactors. The catalytic liquid marble is capable of catalyzing methylene blue reduction efficiency close to 100% and excellent reusability over 5 catalytic cycles. The use of catalytic liquid marbles is highly attractive alternative miniature reactors, suitable for support-free heterogeneous catalysis of small volume reactions.

In the last section, we introduce the concept of plasmonic security labels using Ag nanowire structures. By tuning their polarization dependent surface-enhanced Raman spectroscopy (SERS) imaging, we are able to selectively read-out the encoded SERS information. Our plasmonic security labels exhibit very narrow spectral fingerprint vibration, which is more specific than broad-band systems, which are ideal candidates as an advanced security solution.