A Label-Free Nanogold DNAzyme-Cleaved Surface-Enhanced Resonance Raman Scattering Method for Trace UO22+ Using Rhodamine 6G as Probe

In pH5.5 2-(N-morpholino)-ethanosulfonic acid buffer solution containing 0.25 M NaCl at 80 degrees C, the single-stranded substrate DNA hybridizes with the enzyme DNA to form double-stranded DNA (dsDNA). The substrate chain of dsDNA could be cracked catalytically by UO22+ to produce a short single-stranded DNA (ssDNA) that adsorbed on the nanogold (NG) surface to form a stable nanogold-ssDNA conjugate and then further combine with rhodamine 6G (RhG) to form a NG-ssDNA-RhG conjugate that can be monitored by the surface-enhanced resonance Raman scattering (SERRS) spectral technique at 1,360 cm(-1). Under the selected conditions, the increased SERRS intensity Delta I-1360 was linear to UO22+ concentration in the range of 5-125 nmol/L, with a detection limit of 1.6 nmol/L. Using a 0.5-mu mol/L Hg2+ as enhancer, a 2.5-100-nmol/L UO22+ can be determined.