Photoreduced Ag/sodium alginate supramolecular hydrogel as a sensitive SERS membrane substrate for rapid detection of uranyl ions.

Background: In the fields of environmental monitoring and nuclear emergency, in order to obtain the relevant information of uranyl-induced environmental pollution and nuclear accident, it is necessary to establish a rapid quantitative analytical technique for uranyl ions. As a new promising technique, surface-enhanced Raman scattering (SERS) is hopeful to achieve this goal. However, uranyl ions are easily desorbed from SERS substrates under acidic conditions, and the structures of SERS substrates will be destroyed in the strong acidic aqueous solutions.

Highly sensitive and selective determination of uranyl ions based on Ag/AgO-COF composite SERS substrate.

Uranium is an essential nuclear material in civilian and military areas; however, its extensive application raises concerns about the potential safety issues in the fields of environmental protection and nuclear industry. In this study, we developed an Ag/AgO-COF (covalent-organic framework) composite SERS substrate to detect uranyl ions (UO) in environmental aqueous solutions. Herein, the strong SERS effect of uranyl adsorbed in Ag/AgO composite and the high adsorption efficiency of COF TpPa-1 were combined to realize the trace detection of uranyl ions.

Highly Sensitive Adsorption and Detection of Iodide in Aqueous Solution by a Post-Synthesized Zirconium-Organic Framework.

Effective methods of detection and removal of iodide ions (I) from radioactive wastewater are urgently needed and developing them remains a great challenge. In this work, an Ag decorated stable nano-MOF UiO-66-(COOH) was developed for the I to simultaneously capture and sense in aqueous solution. Due to the uncoordinated carboxylate groups on the UiO-66-(COOH) framework, Ag was successfully incorporated into the MOF and enhanced the intrinsic fluorescence of MOF.

DNAzyme recognition triggered cascade signal amplification for rapid and highly sensitive visual detection of uranyl ions.

This work presents a rapid and highly sensitive colorimetric assay using bifunctional DNA probe decorated agarose microbeads (MBs) coupled with a cascade signal amplification system, including rolling circle amplification (RCA) and the hemin/G-quadruplex-catalyzed colorimetric reaction, for visualized detection of uranyl ions. The DNA probe integrates the UO-specific DNAzyme/substrate as the target recognition unit and a DNA primer as the signal conversion unit. The presence of uranyl ions induces the efficient cleavage of the DNA substrates with the catalysis of DNAzyme.

Plasmon catalytic PATP coupling reaction on Ag-NPs/graphite studied electrochemical surface-enhanced Raman spectroscopy.

The p-aminothiophenol (PATP) coupling reaction on plasmon substrates such as Ag and Au nanoparticles has received extensive attention since the catalytic effect of the surface plasmon was found. Currently, in situ kinetic studies of this reaction are rare, especially those focusing on the specific role of the hot electron-hole carriers. Here, in situ electrochemical surface-enhanced Raman spectroscopy (SERS) is developed to study the plasmon catalytic reaction of PATP in a controlled aqueous environment involving the factors of O2, electron and hole carriers, and solution pH.

In Situ Surface-Enhanced Raman Spectroscopy Detection of Uranyl Ions with Silver Nanorod-Decorated Tape.

Surface-enhanced Raman spectroscopy (SERS) has been utilized for rapid analysis of uranyl ions (UO ) on account of its fast response and high sensitivity. However, the difficulty of fabricating a suitable SERS substrate for in situ analysis of uranyl ions severely restricts its practical application. Hence, we proposed flexible and adhesive SERS tape decorated with silver nanorod (AgNR) arrays for in situ detection of UO .

Flexible and adhesive tape decorated with silver nanorods for in-situ analysis of pesticides residues and colorants.

A flexible adhesive tape decorated with SERS-active silver nanorods (AgNRs) in the form of an array nanostructure is described. The tape was constructed by transferring the AgNRs nanostructures from silicon to the transparent tape by a "paste & peel off" procedure. The transparent, sticky, and flexible properties of commercial tapes allow almost any SERS-inactive irregular surface to be detected in-situ by pasting the SERS tape onto the position to be analyzed.

The contribution of photoinduced charge-transfer enhancement to the SERS of uranyl(VI) in a uranyl-AgO complex.

Charge-transfer (CT) is an important enhancement mechanism in the field of surface-enhanced Raman scattering (SERS) that typically increases the Raman intensity of molecules by as much as 10-100 times. Herein, a low-cost AgO aggregates substrate was prepared via a facile chemical precipitation method, and the calculated CT-based enhancement factor of the uranyl ions adsorbed on it reached as high as 10, a metal-comparable value. The efficient photoinduced CT process from the valence band of AgO to the LUMO of uranyl ions under appropriate excitation sources resulted in the repulsion of the axial oxygen atoms of the OUO bond, which enhanced its polarizability, creating a more intense Raman mode.

Rapid and sensitive detection of uranyl ion with citrate-stabilized silver nanoparticles by the surface-enhanced Raman scattering technique.

Uranium contamination poses a huge threat to human health due to its widespread use in the nuclear industry and weapons. We proposed a simple and convenient wet-state SERS method for uranyl detection based on the citrate-stabilized silver nanoparticles. The effect of citrate on the detection performance was also discussed.

Surface-Enhanced Raman Scattering Detection of Pesticide Residues Using Transparent Adhesive Tapes and Coated Silver Nanorods.

The efficient extraction of analytes from complex and severe environments is significant for promoting the surface-enhanced Raman scattering (SERS) technique to actual applications. In this paper, a proof-of-concept strategy is proposed for the rapid detection of pesticide residues by utilizing the flexible, transparent, and adhesive properties of commercial tapes and SERS performance of AlO-coated silver nanorod (AgNR@AlO) arrays. The function of tapes is to rapidly transfer the analytes from the actual surface to the SERS substrate.

Simultaneous fluorescent detection of multiple metal ions based on the DNAzymes and graphene oxide.

A novel fluorescent detection strategy for simultaneous detection of Cu, Pb and Mg based on DNAzyme branched junction structure with three kinds of DNAzymes and graphene oxide (GO) was presented. Three fluorophores labeled DNA sequences consisted with enzyme-strand (E-DNA) and substrate strand (S-DNA) were annealed to form DNAzyme branched junction structure. In the presence of target metal ion, the DNAzyme was activated to cleave the fluorophore labeled S-DNA.

Self-assembly of silver nanoparticles as high active surface-enhanced Raman scattering substrate for rapid and trace analysis of uranyl(VI) ions.

A facile surface-enhanced Raman scattering (SERS) substrate based on the self-assembly of silver nanoparticles on the modified silicon wafer was obtained, and for the first time, an advanced SERS analysis method basing on this as-prepared substrate was established for high sensitive and rapid detection of uranyl ions. Due to the weakened bond strength of OUO resulting from two kinds of adsorption of uranyl species ("strong" and "weak" adsorption) on the substrate, the ν symmetric stretch vibration frequency of OUO shifted from 871cm (normal Raman) to 720cm and 826cm (SERS) along with significant Raman enhancement. Effects of the hydrolysis of uranyl ions on SERS were also investigated, and the SERS band at ~826cm was first used to approximately define the constitution of uranyl species at trace quantity level.

[Design and Fabrication of Silver Nanoparticles/Graphen Complex Substrate and Its Application for Detecting Uranium (Ⅵ)].

Uranium is one of the important nuclear materials to nuclear industry. Because of the direct disposal of spent fuel, there is still a huge possibility that uranium migrates into the groundwater, causing water contamination. It is of great importance to understand the concentration and their species distribution in aqueous solutions.

Enzyme-free and label-free ultra-sensitive colorimetric detection of Pb(2+) using molecular beacon and DNAzyme based amplification strategy.

An enzyme-free and label-free colorimetric Pb(2+) sensor based on DNAzyme and molecular beacon (MB) has been developed and demonstrated by recycle using enzyme strand for signal amplification. The substrate strand DNA (S-DNA) of DNAzyme could be converted into MB structure with base pairs of stem part at the both ends. The MB could hybridize with enzyme strand DNA (E-DNA) to form DNAzyme, and be activated and cleaved in the presence of Pb(2+).

Ultrasensitive visual detection of DNA with tunable dynamic range by using unmodified gold nanoparticles and target catalyzed hairpin assembly amplification.

A simple and novel strategy for enzyme-free ultrasensitive DNA detection platform has been present here based on gold nanoparticles (AuNPs) colorimetry and target catalyzed hairpin assembly amplification. Three hairpin auxiliary probes (H1, H2, and H3) are designed with signal-stranded DNA (ssDNA) sticky ends which could effectively stabilize AuNPs against salt-induced aggregation. However, a cascade of assembly steps with H1, H2, and H3 are activated in the presence of the target DNA, followed by a disassembly step in which H3 displaces the target DNA from the complex, freeing the target DNA to catalyze the self-assembly of additional branched junctions.