Strongly coupled plasmonic metal nanoparticles with reversible pH-responsiveness and highly reproducible SERS in solution
Zichao Wei, Audrey Vandergriff, Chung‐Hao Liu, Maham Liaqat, Mu‐Ping Nieh, Lei Yu, Jie He
Abstract
-fold as compared to the response for discrete NPs at pH 12. Similarly, positively charged PAH-grafted AuNPs showed an opposite response to pH. We demonstrated that enhanced SERS with thiol-containing and charged molecular probes was indeed from the pH-driven solubility change of polymer ligands. Our method is different from the conventional SERS sensors in the solid state. With pH-responsive polymer-grafted NPs, SERS can be performed in solution with high reproducibility and sensitivity but without the need for sample pre-concentration. These findings could pave the way for innovative designs of polymer ligands for metal NPs where polymer ligands do not compromise interparticle plasmon coupling.