SERS-active carboxymethyl cellulose-based gold nanoparticles: high-stability in hypersaline solution and selective response in the Hofmeister series

Abstract

Gold nanoparticles (AuNP) were directly synthesized with sodium carboxymethyl cellulose (CMC) by a simple one-pot procedure, exhibiting surprising protection against salt-induced aggregation. The AuNP@CMC nanoparticles are reactive towards thiol ligands such as 4-mercaptopyridine (4MPy) and 2,4,6-trimercapto-1,3,5-triazine (TMT) indicating a labile character for the CMC coating. Aggregation can be promoted by those ligands combined with salt induced effects along the Hofmeister series, allowing one to explore the local enhanced electric fields (hot spots) as surface enhanced Raman (SERS) sensors. Such behavior is selective for several salts within the Hofmeister series, exposing the role of the ligand exchange dynamics in the system.