Continuous Detection of Pb(II) utilizing Chitosan-Graphene Oxide Surface Plasmon Resonance Sensors based on Ag/Au and Au/Ag/Au Nanolayers

This work demonstrates the effect of Ag/Au and Au/Ag/Au nanolayers on the performance of chitosan (CS)-graphene oxide (GO) surface plasmon resonance (SPR) sensors for Pb(II) ion detection. The CS-GO SPR sensors are  fabricated on a bi-metallic 40 nm Ag/10 nm Au and tri-metallic 10 nm Au/40 nm Ag/10 nm Au nanolayers. The  sensors are tested with Pb(II) ion solution of concentrations 0.1 to 5 ppm using SPR spectroscopy. The results show  that the CS-GO SPR sensor on the bimetallic Ag/Au gives a gradual shift in SPR angle from 0.1 to 1 ppm and slightly  linear from 3 to 5 ppm. Meanwhile, the CS-GO SPR sensor on the tri-metallic Au/Ag/Au nanolayers provides an  extended linearity range from 1 to 5 ppm with the highest shift in SPR angle of 1.8o. Additionally, the tri-metallic CS-GO SPR sensor also exhibits the greatest SNR of 0.25 as compared to 0.15 of the one on the bi-metallic nanolayers.  Thus, the studies prove that the tri-metallic Au/Ag/Au nanolayer is an effective and simple approach to improve the performance of a CS-GO SPR sensor for Pb(II) ion detection.