Innovative Platform for Transmission Localized Surface Plasmon Transducers and Its Application in Detecting Heavy Metal Pd(II)

Transmission localized surface plasmon resonance (T-LSPR) transducers based on the characteristic surface plasmon absorption band of Au island films have become increasingly attractive. The first and main bottleneck hampering the development of T-LSPR sensors is instability, manifested as change in the surface plasmon absorbance band following immersion in organic solvents and aqueous solutions. In this paper, we innovate the platform for T-LSPR transducer by using remarkably stable and highly adhesive Au/Al2O3 nanocomposite film. Isolated Au nanoparticles embedded in dielectric matrix Al2O3 were prepared by a simple one-step radio frequency magnetron cosputtering technique. The obtained nanocomposite film is exceedingly stable during immersion in solvents, drying, and binding of different molecules; it successfully passes the adhesive tape test and sonication treatment. The superior stability and adhesion, obtained without the use of any intermediate adhesion layer or protective overlayer, is attributed to (1) the Au nanoparticles embedment and Al2O3 rim formation during the sputtering process and (2) the resistance of element Al in matrix to the nucleophilic attack by the solvent molecules. Given this success, we believe that tire Au/Al2O3 nanocomposite film holds promise as an innovative sensing platform in T-LSPR detection technology, as demonstrated here for the Pd(II) sensing process with excellent sensitivity and low detection limit.