A Label-Free Nanogold DNAzyme-Cleaved Surface-Enhanced Resonance Raman Scattering Method for Trace UO_2~(2+) Using Rhodamine 6G as Probe

摘要

In pH5.5 2-(N-morpholino)-ethanosulfonic acid buffer solution containing 0.25 M NaCl at 80 ℃, 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 UO_2~(2+) 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 ΔI_(1360) was linear to UO_2~(2+) concentration in the range of 5-125 nmol/L, with a detection limit of 1.6 nmol/L. Using a 0.5-μmol/L Hg~(2+) as enhancer, a 2.5-100-nmol/L UO_2~(2+) can be determined.