Guiqing Wen

Resonance Scattering Spectral Detection of Trace Hg2+ Using Aptamer-Modified Nanogold as Probe and Nanocatalyst

Single-strand DNA (ssDNA) was used to modify 10 nm nanogold to obtain an aptamer-modified nanogold resonance scattering (RS) probe (AussDNA) for detection of Hg(2+). In the presence of NaCl, Hg(2+) interacts with AussDNA to form very stable double-strand T-Hg(2+)-T mismatches and release nanogold particles that aggregate to large nanogold clusters causing the RS intensity at 540 nm to be enhanced linearly. On those grounds, 1.3-1667 nM Hg(2+) can be detected rapidly by the aptamer-modified nanogold RS assay, with a detection limit of 0.7 nM Hg(2+). If the large nanogold clusters were removed by membrane filtration, the excess AussDNA in the filtrate solution exhibits a catalytic effect on the new Cu(2)O particle reaction between NH(2)OH and Cu(2+)-EDTA complex at 60 degrees C. The excess AussDNA decreased with the addition of Hg(2+), which led the Cu(2)O particle RS intensity at 602 nm to decrease. The decreased RS intensity (DeltaI(602nm)) had a linear response to Hg(2+) concentration in the range of 0.1-400 nM, with a detection limit of 0.03 nM Hg(2+). This aptamer-modified nanogold catalytic RS method was applied for the detection of Hg(2+) in water samples, with sensitivity, selectivity, and simplicity.

A highly selective nanogold-aptamer catalytic resonance scattering spectral assay for trace Hg2+ using HAuCl4-ascorbic acid as indicator reaction

Single strand DNA (ssDNA) was used to modify nanogold to obtain a nanogold-aptamer resonance scattering (RS) probe (NGssDNA) for Hg(2+), based on the formation of stable thymine-Hg(2+)-thymine (T-Hg(2+)-T) mismatches and aggregation of the released nanogold particles. After removing the aggregated particles by filtrate membrane, the excess NGssDNA in the filtration solution exhibit catalytic effect on the gold particle reaction between HAuCl(4) and ascorbic acid (AA) that appear as RS peak at 596nm. When Hg(2+) concentration increased, the RS intensity at 596nm decreased. The decreased intensity is linear to Hg(2+) concentration in the range of 0.00008-0.888ng/mL Hg(2+), with detection limit of 0.000034ng/mL. The nanogold-aptamer catalytic RS assay was applied to determination of Hg(2+) in water with satisfactory results.

Functional Nucleic Acid Nanoparticle-Based Resonance Scattering Spectral Probe

Highly sensitive and selective resonance Rayleigh scattering (RRS) and surface enhanced resonance Raman scattering (SERRS) spectral detection technique are developed by combining the functional nucleic acid including aptamer and DNAzyme, and nanoparticle such as gold/silver (NG/NS) aggregation and catalysis reaction. The recent progress of resonance scattering spectral technologies including RRS and SERRS are reviewed in this paper.

Catalysis of aptamer-modified AuPd nanoalloy probe and its application to resonance scattering detection of trace UO22+

AuPd nanoalloy and nanopalladium with a diameter of 5 nm were prepared, using sodium citrate as the stabilizing agent and NaBH(4) as the reductant. The nanocatalyst containing palladium on the surface exhibited a strong catalytic effect on the slow NiP particle reaction between NiCl(2) and NaH(2)PO(2), and the NiP particle system showed a resonance scattering (RS) peak at 508 nm. The RS results showed that the Pd atom on AuPd nanoalloy surface is the catalytic center. Combining the aptamer cracking reaction of double-stranded DNA (dsDNA)-UO(2)(2+), AuPd nanoalloy aggregation, and AuPd nanoalloy catalysis, both AuPd nanoalloy RS probe and AuPd nanoalloy catalytic RS assays were developed for the determination of 40-250 pmol L(-1) UO(2)(2+) and 5.0-50 pmol L(-1) UO(2)(2+), respectively.

A novel nanocatalytic SERS detection of trace human chorionic gonadotropin using labeled-free Vitoria blue 4R as molecular probe

In pH 7.4 Na2HPO4-NaH2PO4 buffer solution containing the peptide probes for human chorionic gonadotropin (hCG), silver nanoparticles (AgNPs) were aggregated to big AgNPs clusters that exhibited very weak catalytic effect on the gold nanoparticle reaction of H2O2-HAuCl4. When hCG was present in the peptide probe solution, the AgNPs did not aggregate and it had strong catalytic effect on the gold nanoparticle reaction with a strong resonance Rayleigh scattering (RRS) peak at 370nm and a strong surface enhanced Raman scattering (SERS) peak at 1615cm(-1) in the presence of molecular probe of Victoria blue 4R (VB4R). With the increase of the hCG concentration, the catalysis enhanced due to the nanocatalyst of AgNPs increasing, and the RRS intensity increased at 370nm. The increased RRS intensity was linear to the hCG concentration in 0.05-10ng/mL, with a linear regression equation of ΔI370nm=409.8C +294. And the SERS intensity at 1615cm(-1) increased linearly with the hCG concentration in the range of 0.05-20ng/mL, with a linear regression equation of ΔI1615cm-1=142C+134. Based on this, two new methods of nanocatalytic SERS and RRS were proposed for the determination of trace hCG.

A new resonance Rayleigh scattering method for the determination of trace O3 in air using rhodamine 6G as probe

O3 reacted with the H3BO3-KI solution to produce I3−, and it reacted with rhodamine 6G to form associated particles that exhibited a resonance Rayleigh scattering peak at 418 nm. Based on this, a 0.25–25 μM O3 can be determined, with a detection limit of 0.07 μM.

Highly sensitive and selective determination of fluorine ion by graphene oxide/nanogold resonance Rayleigh scattering-energy transfer analytical platform

In pH 4.0 acetate buffer solution, fluorine ions react with fluorine reagent (FR) and La(III) to generate blue ternary complex that exhibited strong absorption at about 370 nm. Upon addition of graphene oxide/nanogold (GO/NG) as resonance Rayleigh scattering (RRS) spectral probe with strong RRS peak at 370 nm, the color changed to gray, and the RRS intensity decreased with the increase of fluorine ion concentration due to the RRS energy transfer (RRSET) from GO/NG to the complex. Under the selected condition, the decreased RRS peak ΔI370 nm was linear to fluorine ion concentration in the range of 6.0 × 10(-8)-1.3 × 10(-5)mol/L, with a detection limit of 3.0 × 10(-8)mol/L F(-). This RRSET method was applied to the analysis of fluorine in toothpaste and water samples, with satisfactory results.

Selective determination of trace boron based on resonance Rayleigh scattering energy transfer from nanogold aggregate to complex of boric acid–azomethine-H

The nanogold particles were aggregated to stable nanogold aggregates as nanoprobes that exhibited a resonance Rayleigh scattering (RRS) peak at 400 nm in the pH 5.6 NH4Ac–HAc buffer solutions and in the presence of azomethine-H (AMH). Upon addition of boric acid, it reacts with AMH to form AMH–boric acid (AMH–B) complexes. When the complexes (as receptors) are close to the nanogold aggregates (as donors), the RRS-energy transfer (ET) takes place, which results in the RRS signal quenching at 400 nm. The quenching intensity responds linearly with the concentration of boron over 5–500 ng mL−1 B.

A new resonance Rayleigh scattering method for trace Pb, coupling the hydride generation reaction with nanogold formation

Pb2+ was oxidized to Pb4+ and was reduced to PbH4 gas by NaBH4, and the gas was reacted with Au3+ to form nanogold that exhibited a resonance Rayleigh scattering effect at 286 nm. Based on this, 0.2 × 10−6–33.6 × 10−6 mol L−1 Pb can be detected, with a detection limit of 7.0 × 10−8 mol L−1.

A highly sensitive and selective resonance Rayleigh scattering method for bisphenol A detection based on the aptamer–nanogold catalysis of the HAuCl4–vitamin C particle reaction

Based on the catalytic effect of the bisphenol A aptamer-modified gold nanoparticle (Apt–GN) on the HAuCl4-vitamin C (VC) particle reaction and its resonance Rayleigh scattering effect at 370 nm, 3.33–333.3 ng mL−1 bisphenol A was detected, with a detection limit of 0.083 ng mL−1.