Functionalized gold nanoparticles as nanosensor for sensitive and selective detection of silver ions and silver nanoparticles by surface-enhanced Raman scatteringElectronic supplementary information (ESI) available: Experimental procedures and additional figures. See DOI: 10.1039/c2an35670h

We have developed a surface-enhanced Raman scattering (SERS) nanosensor firstly for Ag ions and Ag nanoparticles detection based on 2-mercaptoisonicotinic acid (2MNA)-functionalized Au nanoparticles. Ag + can coordinate with 2MNA resutling in a variation of its SERS spectrum, which is used as a criterion to determine Ag + in a solution. This sensor exhibits a detection limit no more than 25 nM and has a high selectivity against other metal ions. More importantly, it can be directly applied in real sample detection. Ag + and Ag nanoparticles in solution can be determined using our presented nanosensor according to the changes of SERS signals.