Plasmonic stability of nanostructures plays a pivotal role in reproducible and robust surface enhanced Raman scattering (SERS) signals. Traditionally, surface modification is utilized to promote nanoparticle stability; however, SERS activity is often reduced by these chemistries because of the well-known distance dependence of the SERS effect. Herein, we evaluate how silica membranes promote the plasmonic stability of gold coated silver (Ag@Au) nanoparticles for the simultaneous detection of uranyl in solution as a function of pH, ionic strength, and temperature. Gold functionalization by 3-mercaptopropionate (MPA) promotes coordination and serves as a spectroscopic indicator of uranyl down to sub-nM concentrations. These studies reveal that uranyl detection is independent of pH as long as the protonation state of MPA and solubility of uranyl remain constant. This leads to a robust sensing window from pH 3 to 7, ionic strengths up to 150 mM, and temperatures up to 37 °C (for 10+ hours). As a result, microporous silica membranes promote robust SERS measurements for the important and possible biological, chemical, and radiological toxin, uranyl.

Exploiting microporous silica membranes for plasmonics and SERS

ACS Spring Meeting 2021

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