Sensitive and selective localized surface plasmon resonance light-scattering sensor for Ag+ with unmodified gold nanoparticles.

A novel localized surface plasmon resonance (LSPR) light-scattering sensor for Ag(+) was developed with unmodified gold nanoparticles (AuNPs), based upon the specific recognition property of Ag(+) with a cytosine-cytosine mismatched base pair. The addition of Ag(+) induced the oligonucleotide 5'-TAC ATA CAT ACT ATC TAT CTA-3' to be desorbed from the surface of the AuNPs, resulting in the aggregation of AuNPs, accompanied by a dramatic enhancement of the LSPR light-scattering intensity. The enhancement of LSPR light-scattering intensity was proportional to the concentration of Ag(+) in the range of 0.13-1.12 μM, with a limit of detection of 62.0 nM. The results were also proved by a colorimetric method. Furthermore, this method can provide satisfactory results for the determination of Ag(+) in water samples and industrial products.