A Label-Free Deoxyribozymes Resonance Rayleigh Scattering Assay for Trace Lead(II) Based on Nanogold Catalysis of Chloroauric Acid-Vitamin C Particle Reaction

A novel and highly sensitive nanocatalytic surface plasmon resonance-scattering analytical platform for detection of trace Pb ions

Gold nanoparticles (AuNP) have catalysis on the reaction of HAuCl4-H2O2. The produced AuNP have strong resonance Rayleigh scattering (RRS) effect and surface-enhanced resonance Raman scattering (SERS) effect when Victoria blue B (VBB) and rhodamine S (RhS) were used as probes. The increased RRS/SERS intensity respond linearly with the concentration of gold nanoparticles (AuNPB) which synthesized by NaBH4 over 0.038-76 ng/mL, 19-285 ng/mL, 3.8-456 ng/mL respectively. Four kinds of tested nanoparticles have catalysis on the HAuCl4-H2O2 particles reaction. Thus, a novel nanocatalysis surface plasmon resonance-scattering (SPR-S) analytical platform was developed for AuNP. The DNAzyme strand hybridized with the substrate strand to form double-stranded DNA (dsDNA) which couldn't protect AuNPc to aggregate to AuNPc aggregations, having strong RRS effect. Upon addition of Pb(2+), dsDNA could be cracked by Pb(2+) to produce single-stranded DNA (ssDNA) that adsorbed on the AuNPc surface to form AuNPc-ssDNA conjugates. The conjugates have strong catalysis on HAuCl4-H2O2 reaction. With increased Pb(2+) concentration, the concentration of AuNPc-ssDNA increased and lead to the catalytic activity stronger. The increased RRS intensity responds linearly with Pb(2+) concentration over 16.7-666.7 nmol/L. The SERS intensity responded linearly with the concentration of Pb(2+) over 50-500 nmol/L.

Quantitative analysis of trace Pb(II) by a DNAzyme cracking-rhodamine 6G SERRS probe on Au(core)Ag(shell) nanosol substrate

In pH 7.2 Tris-HCl buffer solution containing 0.09 mol/L NaCl at 80°C, the single-stranded substrate DNA hybrids with the enzyme DNA to form double-stranded DNA (dsDNA). The substrate chain of dsDNA could be cracked catalytically by Pb(2+) to produce a short single-stranded DNA (ssDNA) that adsorbed on the Au(core)Ag(shell) nanoparticle (Au/AgNP) surface to form stable Au/AgNP-ssDNA conjugate to prevent aggregation by NaCl, and it combined with rhodamine 6G (RhG) to form RhG-Au/AgNP-ssDNA probe that exhibited a strong surface-enhanced resonance Raman scattering (SERRS) peak at 1510 cm(-1). With the increase of Pb(2+) concentration, the SERRS peak increased linearly due to the more RhG-Au/AgNP-ssDNA probe forming. Under the selected conditions, the increased SERRS intensity ΔI was linear to Pb(2+) concentration in the range of 5.0×10(-8)-7.0×10(-7) mol/L, with a detection limit of 7×10(-9) mol/L Pb(2+).

DNAzyme-functionalized gold nanoparticles for biosensing

Recent progress in using DNAzyme-functionalized gold nanoparticles (AuNPs) for biosensing is summarized in this chapter. A variety of methods, including those for attaching DNA on AuNPs, detecting metal ions and small molecules by DNAzyme-functionalized AuNPs, and intracellular applications of DNAzyme-functionalized AuNPs are discussed. DNAzyme-functionalized AuNPs will increasingly play more important roles in biosensing and many other multidisciplinary applications. This chapter covers the recent advancement in biosensing applications of DNAzyme-functionalized gold nanoparticles, including the detection of metal ions, small molecules, and intracellular imaging.