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Schematic illustration of the application of the novel material WP5–GDY/GCE for the electrochemical sensing of methylamphetamine (MA).

Detection technology for the determination of drugs, such as ketamine (KT), in sewage is of great significance in drug inspection and criminal investigation. Herein, we propose the utilization of ketamine magnetic molecularly imprinted polymers (Fe

To develop a convenient method for sensitive and selective determination of Ce3+ in aqueous phase with complicated matrices, a carbon paste electrode (CPE) modified with ion imprinted polymers (IIPs) were fabricated. The polymers were prepared by precipitation polymerization using Ce3+ as template, allyl phenoxyacetate (APA) as monomer, ethylene glycol dimethacrylate (EGDMA) as crosslinker and azobisisobutyronitrile (AIBN) as initiator under the molar ratio of Ce3+, APA and EGDMA as 1:4:40, respectively. Ce3+ was detected directly by differential pulse adsorptive stripping voltammetry (DPASV) and its oxidation peak appears at about 0.93 V. All parameters affecting the sensor's response are optimized and a calibration curve is plotted at a linear range of 1.0 × 10−6–1.0 × 10−5 mol/L and 1.0 × 10−5–2.0 × 10−4 mol/L with the detection limit of 1.5 × 10−7 mol/L. All other rare earth ions have no interference with the determination of Ce3+ even at a concentration 500 times higher than that of Ce3+. This sensor was successfully applied to determination of Ce3+ in two catalyst sample solutions with RSD≤3.3% (n = 5) and recoveries in the range of 99.2%–106.5% at our optimal conditions.

To solve the problem that the ion-imprinted membrane modified on glassy carbon electrode (GCE) usually easily falls off, a screen printed electrode (SPE) which has a relative rough surface than GCE, was selected as the base electrode for preparation of an ion-imprinted sensor for determination of Eu(III). The sensor was obtained by modifying SPE successively with carboxylic multiwalled carbon nanotubes (MWCNs-COOH) as signal amplifying element and Eu(III) ion-imprinted membrane (Eu(III)-IIM) as specific recognition material. To avoid damaging SPE by thermal initiation, the Eu(III)-IIM was prepared via radical photopolymerization at 380 nm using azobisisobutyronitrile (AIBN) as initiator. Differential pulse adsorptive stripping voltammetry (DPASV) was used for determination of Eu3+ by the obtained sensor. After the detection condition was optimized in detail, the sensor showed a linear response to Eu3+ in the concentration range of 1.0 × 10−7–1.0 × 10−3 mol L−1 with the detection limit of 4.0 × 10−8 mol L−1. The obtained sensor possesses of good regeneration, stability and practicability, it can maintain more than 95% of its original response after used more than 30 times or stored in the water for two months. The satisfactory results with the relative standard deviation (RSD) of less than 3.5% (n = 5) were obtained for the determination of europium in water samples by the novel sensor.

As a result of the increasing applications in different fields, europium has become a threat to the environment and human health. Thus, it is necessary to develop a simple and rapid method for determination of europium in trace level. In this paper, a sensor for determination of Eu3+ was established by modifying a screen printed electrode (SPE) successively with poly catechol as signal amplifying element and Eu(III) ion-imprinted membrane fabricated by sol-gel method as the recognition material. After the factors influenced the sensitivity of the sensor for Eu3+ was optimized in detail, Eu3+ can be determined by differential pulse adsorptive stripping voltammetry (DPASV) in the concentration range of 3.0 × 10−7–1.0 × 10−3 mol L−1 with the detection limit of 1.0 × 10−7 mol L−1. The fabricated sensor owns outstanding selectivity, perfect stability and good regeneration. 50-fold excess concentration of rare earth ions such as Ce3+, Tb3+, Ho3+, Dy3+, Er3+, Gd3+, Pr3+, Nd3+, Yb3+ and 100-fold excess concentration of other metal ions such as Fe3+, Ni3+, Cu2+, Zn2+ and Co2+ have no influence on the determination of 1.0 × 10−5 mol L−1 Eu3+. The obtained sensor, which can maintain >90% of its original response after used >60 times or stored in the water for 2 months, has been satisfactorily used to detect Eu3+ in water samples with the relative standard deviation (RSD) of

In this study, a molecularly imprinted electrochemical sensor based on graphene/Au nanoparticles (G@AuNPs) compound materials and molecularly imprinted membrane (MIM) modified glassy carbon electrodes (GCEs) was developed for the sensitive detection of colchicine in pharmaceuticals and serum (MIM/G@AuNPs/GCE). The film was formed by the in situ polymerization of colchicine-imprinted membranes on the G@AuNPs-modified GCE using methacrylic acid as the functional monomer. The specific surface area, catalytic performance, and electrical conductivity of the electrode increased on account of the formation of G@AuNPs compound materials, thereby improving the sensitivity of the sensor. The MIM as a preconcentrator exhibited chemical selectivity. Under optimal conditions, the MIM/G@AuNPs/GCE sensor exhibited high selectivity and high anti-interference ability. Moreover, good linearity was obtained in the range of 1.2 × 10−8 to 1.2 × 10−6 mol L−1 and 1.2 × 10−6 to 1.0 × 10−4 mol L−1 of colchicine with a detection limit of 4.8 × 10−9 mol L−1. The sensor was successfully applied for the direct determination of colchicine in colchicine tablets and human serum samples, with a relative standard deviation of less than 3.1% (n = 5) and recoveries ranging from 97.5% to 110.0%.

For the aim to detect Ce(III) in food with selectivity, sensitivity and speediness, a electrochemical sensor (Ce(III)-IIM/PC/GCE) was constructed by electropolymerization of a poly-catechol (PC) film on glassy carbon electrode (GCE) followed by modifying a Ce(III) ion-imprinted membrane (IIM) formed with electropolymerization using o-phenylenediamine as monomer. After that, a differential pulse adsorptive stripping voltammetry (DPASV) was developed for determination of Ce(III) by the obtained sensor. Under the optimal conditions, the sensor possesses good reproducibility and storage stability. Furthermore, it can be used directly for determination of Ce(III) in the concentration range of 3.0 × 10− 12–1.0 × 10− 4 mol L− 1 with the limit of detection of 1.0 × 10− 12 mol L− 1. Since over 50-fold excess concentration of Fe3 +, Cu2 + and Ni2 + will produce some interferences in the direct determination of Ce(III), an extraction method was adopted when it be used in food. After extraction of the samples with 1-phenyl-3-methyl-4-benzoyl-5-benzopyrazolone (PMBP), Ce(III) can be determined by Ce(III)-IIM/PC/GCE in the presence of > 500-fold excess concentration of Fe3 +, Cu2 + and Ni2 + with the limit of detection of 4.7 × 10− 9 mol L− 1. The sensor was successfully applied to determine cerium in food after extracted by PMBP with a relative standard deviation (RSD) of

In this work, Fe3O4@ZIF-8 core-shell magnetic composite was synthesized by a solvothermal method and used to remove Pb2+ and Cu2+ from wastewater. Various characterization techniques (SEM, TEM, XRD, BET, VSM, and TGA) indicated that the Fe3O4@ZIF-8 microspheres were stable and had a high specific surface area (724.7 m2/g). The factors that affected the performance of Fe3O4@ZIF-8 during the removal of Pb2+ and Cu2+ from wastewater are discussed, including the adsorbent amount, pH, temperature, contact time, concentration, ionic strength, and coexisting ions. Moreover, the adsorption processes were well described by the Langmuir model, and the uptake capacities of Fe3O4@ZIF-8 were calculated to be 719.42 mg/g for Pb2+ and 301.33 mg/g for Cu2+. In addition, Fe3O4@ZIF-8 also had fast adsorption kinetics for the uptake of Pb2+ and Cu2+ from wastewater, and it only took 20 min and 60 min to reach adsorption equilibrium, respectively. More importantly, the material could be reused at least four times. The mechanism study showed that ion-exchange and coordination reactions were the main Pb2+ and Cu2+ removal mechanisms of Fe3O4@ZIF-8. Thus, the synthesized Fe3O4@ZIF-8 composite is a promising candidate material for removing Pb2+ and Cu2+ from wastewater.

In this study, a magnetic electrochemical sensor, Fe3O4@PDA-DMSA, was triumphantly fabricated by covalently modifying dimercaptosuccinic acid (DMSA) around magnetic polydopamine (Fe3O4@PDA). PDA with many functional groups can act as the starting points for covalent modification with desired molecules, and DMSA containing abundant sulfhydryl and carboxyl groups can be used as an excellent candidate. This magnetic nanocomposite synergistically exhibits several functions (especially high magnetic susceptibility), which can own unique advantages in electrochemical sensing applications. It was employed to enrich target analytes to design a novel electrochemical sensor for reliably monitoring of Pb(II) and Cu(II) in environmental samples, resulting from the specific chelation mechanisms between metal ions and functional groups. X-ray photoelectron spectral data demonstrate the main chelation mechanisms of this process. The synergistic effect among Fe3O4, PDA, and DMSA enhances the electrochemical sensitivity and accelerates the electron transfer. Under optimized conditions, the linear responses to Pb(II) and Cu(II) within the concentration range of 0.5–50 μg L−1 was obtained with the detection limits of 0.1 and 0.2 μg L−1, respectively. The little to no interference generated from common coexisting anions/cations allows the designed sensor to operate in diverse environmental conditions for practical applications. Such method of covalent modification can be used for designing sensitive electrochemical sensors for monitoring heavy metal ions.

In this work, an amperometric sensor was developed for the selective recognition and sensitive determination of palladium in complex matrices using a glassy carbon electrode (GCE) modified with a novel ion-imprinted membrane (IIM) and graphene. Graphene enhanced the sensor's electron transfer and sensitivity. The electrode surface was first directly modified with graphene through the electrodeposition of graphene oxide. An ion-imprinted polymer membrane was subsequently synthesized on this modified surface via in situ polymerization in acetonitrile using allylurea (NAU) as a functional monomer, ethylene glycol dimethacrylate (EGDMA) as cross-linking agent, and azobisisobutyronitrile as an initiator at a molar ratio of template (PdCl2) to NAU to EGDMA of 1:4:40. Amperometric i-t curves were measured for the determination of palladium. The designed modified electrode was shown a linear response to Pd(II) ions in the range of 2.0 × 10− 8–2.0 × 10− 4 mol L− 1 of Pd(II) ion with a detection limit of 6.4 × 10− 9 mol L− 1. Metal ions present at concentrations 15 times higher than that of Pd(II) did not interfere with the determination of Pd(II). The sensor was successfully applied to determine palladium in catalyst and plant samples with a relative standard deviation (RSD) of less than 3.3% (n = 5) and recoveries in the range of 99.2–106.5%.

In this study, Fe3O4@PDA@MnO2 core-shell magnetic nanocomposites were synthesized for the first time, and used to enrich target analyte to construct an electrochemical sensor for sensitive detection of trace Pb(II) in the environmental samples. A dense polydopamine (PDA) coating was firstly formed on the surface of Fe3O4 to ensure high stability because the developed method is employed under strongly acidic conditions. Then a high adsorption capacity MnO2 shell can be simply introduced to the surface of the PDA as a result of the redox activity between PDA and KMnO4. Differential pulse voltammetry (DPV) was applied for determining target metal ions. Chemical and electrochemical factors, including quantity of Fe3O4@PDA@MnO2 nanocomposites, preconcentration solutions pH, preconcentration time and supporting electrolytes, were optimized. Under excellent conditions, the designed sensor demonstrated a linear response to Pb(II) within the range of 0.1–150 μg L−1 and with a detection limit of 0.03 μg L−1. The proposed methodology exhibited excellent performance in selectivity, sensitivity and long-term stability, and was also successfully applied to determine Pb(II) in the real water samples. This study suggested that Fe3O4@PDA@MnO2 nanocomposites are a better alternative to Pb(II) analysis resulting from its low cost, low toxicity, strong adsorption, and good reproducibility.

A novel method for determination of inorganic arsenic in natural water, based on nano ferric hydroxides (FeOOH) preconcentration and electrochemistry detection has been developed. As the nano α-FeOOH could successfully act as the adsorbent and electrode matrix modifier, the method presents great potential in practical routine analysis of inorganic arsenic. With optimization of the experimental conditions, nano α-FeOOH modified carbon paste electrode (α-FeOOH@CPE) was obtained by mixing 0.03 g of nano α-FeOOH and 0.02 g graphite powder in n-eicosane as an adhesive and then embedding them in a Teflon tube. Cyclic voltammetry, chronoamperometry and high resolution transmission electron microscopy were used to check and confirm the presence of nano α-FeOOH on the carbon paste electrodes. According to the results, α-FeOOH@CPE showed a considerably higher response to As(III) in comparison with the bare CPE, indicating the α-FeOOH has well selective enrichment for As(III). The developed modified electrode showed a linear range of 1.0 × 10-8 ~ 2.0 × 10-5 mol·L-1 and detection limit of 5.0 nmol·L-1 (S/N = 3). The newly prepared carbon paste electrode was successfully applied for As(III) determination in Yangzonghai Lake water with RSD of less than 3.6 % (n = 3) and recovery in the range of 100.7 ~ 115.0 %. DOI: http://dx.doi.org/10.5755/j01.ms.24.4.18499

A rhodium (III) ion carbon paste electrode (CPE) based on an ion imprinted polymer (IIP) as a new modifying agent has been prepared and studied. Rh(III) ion imprinted polymer was synthesized by copolymerization of acrylamide-Rh(III) complex and ethylene glycol dimethacrylate according to the precipitation polymerization. Acrylamide acted as both functional monomer and complexing agent to create selective coordination sites in a cross-linked polymer. The ion imprinted carbon paste electrode (IIP-CPE) was prepared by mixing rhodium IIP-nanoparticles and graphite powder in n-eicosane as an adhesive and then embedding them in a Teflon tube. Amperometric i-t curve method was applied as the determination technique. Several parameters, including the functional monomer, molar ratio of template, monomer and cross-linking agent, the amounts of IIP, the applied potential, the buffer solution and pH have been studied. According to the results, IIP-CPE showed a considerably higher response in comparison with the electrode embedded with non-imprinted polymer (NIP), indicating the formation of suitable recognition sites in the IIP structure during the polymerization stage. The introduced electrode showed a linear range of 1.00×10-8~3.0×10-5 mol·L-1 and detection limit of 6.0 nmol L-1 (S/N = 3). The IIP-CPE was successfully applied for the trace rhodium determination in catalyst and plant samples with RSD of less than 3.3% (n = 5) and recoveries in the range of 95.5~102.5%.

An electrochemical sensor for podophyllotoxin (PPT) based on the molecular imprinting polymer (MIP) membranes was constructed. The sensor was prepared by electropolymerizing o-phenylenediamine (o-PD) on a glassy carbon electrode (GCE) in the presence of PPT as template, and then removing the template by immersing the modified GCE in ethanol. Experimental parameters such as the types of monomer, scan cycles, concentration of o-PD and extraction condition were optimized. Under optimal conditions, the sensor exhibits a good selectivity and high sensitivity. A good linearity was obtained in the range of 4 x 10-8 mol · L(-1) to 3.2 x 10(-5) mol · L(-1) with an estimated detection limit of 4.8 x 10(-9) mol · L(-1). The sensor was applied to the determination of PPT in podophyllum hexandrum and human serum samples with satisfactory results.

To develop a rapid and simple method for sensitive determination of artemisinin (ART) in complicated matrices, a novel electrochemical sensor was constructed by in-situ polymerization of ART-imprinted membranes (ART-MIMs) on the surface of graphene (G) modified glassy carbon electrode (GCE) using acrylamide (AM) as functional monomer, ethylene glycol dimethacrylate (EGDMA) as cross-linking agent after the experimental parameters for the preparation of ART-MIMs such as functional monomer, molar ratio of template, monomer and cross-linking agent together with extraction condition were optimized. Under the optimal conditions, the sensor named as ART-MIM/G/GCE exhibited a good selectivity, high sensitivity and considerably better resistance against some analogs of artemisinin such as dihydroartemisinin (DHA), artemether (ARM) and artesunate (ARTS). The calibration graph for the determination of artemisinin by the sensor was linear in the range of 1.0 × 10(-8)mol L(-1) to 4.0 × 10(-5)mol L(-1) with the detection limit of 2.0 × 10(-9)mol L(-1). Meanwhile, this sensor possessed of good regeneration, stability and practicability. It could retain more than 94% of its original response after used at least 80 times or stored in water at room temperature for 60 days. The obtained sensor was successfully applied to determine the contents of artemisinin in the extract of Artemisia annua L. with the relative standard deviation (RSD) of less than 3.5% (n=5).

The aim of this study is to investigate the dose distribution in the process of X-ray imaging at Shanghai Synchrotron Radiation Facility. We used the Monte Carlo software EGSnrc based on the statistics of the beamline BL13W to simulate the actual irradiation environment and calculate the dose distribution. Three different sizes of sources and two different tomographic models were created to predict the dose distribution at different regions of interest (ROI) with different fields of view (FOV). The simulation results showed that the dose in ROI is higher. The dose accumulated in the ROI with smaller FOV was more concentrated and relatively smaller compared with the larger FOV. This calculated dose distribution provides guidance for in-vivo animal experiments and other applications such as microbeam therapy.

To develop a convenient method for sensitive and selective determination of platinum in complicated matrices, an ion-imprinted electrode was studied by in situ polymerization of Pt(IV) ion-imprinted membranes (Pt(IV)-IIMs) on the surface of a glassy carbon electrode (GCE). After the experimental parameters for the preparation of Pt(IV)-IIMs such as functional monomer, molar ratio of template, monomer and cross-linking agent together with extraction condition were optimized, an electrode with good regeneration, high stability and specific recognition to Pt(IV) was obtained by modifying GCE with Pt(IV)-IIMs prepared in acetonitrile using allylurea (NAU) as functional monomer, ethylene glycol dimethacrylate (EGDMA) as cross-linking agent, azobisisobutyronitrile (AIBN) as initiator under the molar ratio of template (H2PtCl6), NAU and EGDMA as 1 : 4 : 40. The resulting electrode named as Pt(IV)-IIMs/GCE exhibits high response sensitivity to Pt(IV) in phosphate buffer (pH 5.29). The calibration graph for the determination of Pt(IV) by Pt(IV)-IIMs/GCE is linear in the range of 2.0 × 10−8 ∼ 2.5 × 10−4 mol L−1 with a detection limit of 4.0 × 10−9 mol L−1. No metal ions tested at a concentration 25 times higher than that of Pt(IV) interfered in the determination. The electrode was successfully applied to determine platinum in catalyst and plant samples with a relative standard deviation (RSD) of less than 3.0% (n = 5) and recoveries in the range of 97.8–103.6%.

A Novel Carbon Paste Electrode Based on Ion-Imprinted Polymer for Determination of Iridium To develop a convenient method for sensitive and selective determination of iridium in complicated matrices, a carbon paste electrode based on iridium ion imprinted polymer (IIP) was fabricated. Iridium ion selective cavities were created in the 2-(allylthiol) nicotinic acid based cross-linked polymer. In order to fabricate the sensor, carbon particles and polymer powder were mixed with melted n-eicosane. An explicit difference in the response was observed between the electrodes modified with ion imprinted polymer (IIP) and non imprinted polymer (NIP), indicating proper performance of the recognition sites of the IIP. Various factors, known to affect the response behavior of selective electrode, were investigated and optimized. The resulting sensor named as Ir(III) ion imprinted polymer carbon paste electrode (Ir(III)-IIP/CPE) exhibits high response sensitivity to Ir(III) in acetate buffer (pH 3.6). The calibration graph is linear in the range of 2.85×10-8∼2.31×10-5 mol L-1 with the detection limit of 7.84×10-9 mol L-1(S/N). The electrode showed high selectivity for iridium in the presence of common potential interferers was found to show satisfactory results, it was successfully applied to the determination of iridium in real samples.

Grating-based phase-contrast is a hot topic in recent years owing to its excellent imaging contrast capability on soft tissues. Although it is compatible with conventional X-ray tubes and applicable in many fields, long scanning time, and high radiation dose obstruct its wider use in clinical and medical fields, especially for computed tomography applications. In this study, we solve this challenge by reducing the projection views and compensating the loss of reconstruction quality through dual-dictionary learning algorithm. The algorithm is implemented in two steps. First, estimated high-quality absorption images are obtained from the first dual-quality dictionary learning, which uses the correspondence between high-quality images and low-quality ones reconstructed from highly under-sampled data. Then, the second absorption-phase dual-modality dictionary learning is adopted to yield both estimated phase and absorption images, resulting in complementary information for both modality images. Afterwards the absorption and phase images are gradually improved in iterative reconstructions. By using SSIM RMSE measurements and visual assessment for enlarged regions of interest, our proposed method can improve the resolution of these two modality images and recover smaller structures, as compared to conventional methods.

A novel strategy for the preparation of amperometric immunosensor for rapid determination of α-1-fetoprotein (AFP) in human serum has been developed. TiO 2 nanoparticles (NPs) were prepared by solvothermal reaction using TiCl 4 as raw materials and the mixture of ionic liquids and doubly distilled water as solvent. α-1-fetoprotein antibody (AFP Ab) was mixed with TiO 2 NPs/chitsotan (CHIT) solution and immobilized onto the surface of a glassy carbon electrode. AFP (Ab) functionalized Au NPs were used as catalytic labels for the amperometric detection of AFP by means of the electrocatalyzed reduction of Au NPs to H 2 O 2 . The electrochemical behavior of the immunosensor was studied. Other experimental conditions such as pH, immunoreactions temperature and time were also studied. The prepared immunosensor offers an excellent amperometric response for AFP ranging from 1.0 to 160.0 ng/mL with a detection limit of 0.1 ng/mL. The result shows that the immunosensor displays rapid response, high sensitivity, good reproducibility and favorable stability.

Gold nanoelectrode ensembles were produced by electrodeposition using multiwalled carbon nanotubes (MWNTs) as template. A new third generation amperometric biosensor for hydrogen peroxide was developed based on adsorption of horseradish peroxidase (HRP) at the glassy carbon (GC) electrode modified with Au nanoelectrode ensembles/multiwalled carbon nanotubes/chitosan film. The resulting HRP biosensor offered an excellent detection for hydrogen peroxide at −0.11 V with a linear response range of 2.08 × 10−7 to 7.6 × 10−3 M with a correlation coefficient of 0.998, and response time

Polypyrrole (PPy) nanotubes have been synthesized by chemical oxidative polymerization of pyrrole within the pores of polycarbonate membrane using the technology of diffusion of solutes. The nanotubes array prepared by the proposed method can be considered as nanoelectrode ensembles (NEEs). An amperometric uric acid sensor based on PPy NEEs has been developed and used for determination of uric acid in human serum samples. The electrode can direct response to uric acid at potential of 0.60V vs. SCE with wide linear range of 1.52×10

A solvothermal method has been used to synthesize anatase-type TiO2 nanoparticles (NPs) using ionic liquid (1-ethyl-3-methylimidazolium-ethyl sulfate) as cosolvent and modifier. Palladium nanoparticles were electrodeposited on the glassy carbon (GC) electrode modified with synthesized TiO2 nanoparticles/chitosan film in the presence of glycin. The resulting amperometric sensor was used for direct determination of uric acid in human serum samples. Ionic liquid, TiO2, and Pd nanoparticles were characterized by infrared spectra (IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). This sensor offered an excellent detection for uric acid at 0.60 V in a linear response range of 4.42 × 10−5 to 7.98 × 10–3 M with a correlation coefficient of 0.997. The sensor displays rapid response, expanded linear response range, excellent repeatability, and excellent stability.

Gold nanowires were produced by electrodeposition in polycarbonate membrane, with an average diameter of 200 nm and a height of about 2 μm. The nanowire array prepared by the proposed method can be considered as nanoelectrode ensembles (NEEs). An amperometric pesticides sensor based on gold NEEs has been developed and used for determination of phoxim and dimethoate in vegetable samples. The electrochemical performance of the gold NEEs has also been studied by the amperometric method. The electrode provided a linear response over a concentration range of 5.9 × 10−5 to 1.2 × 10−2 M for phoxim with a detection limit of 4.8 × 10−6 M and 6.3 × 10−5 to 1.1 × 10−2 M for dimethoate. This sensor displayed high sensitivity and selectivity, long-term stability and wide linear range. In addition, the ellipsis of enzyme and the reactivation of enzyme make the operation simple. This sensor has been used to determine pesticides in a real vegetable sample.

In this work, we designed a new fluorescent oligonucleotides-stabilized silver nanoclusters (DNA/AgNCs) probe for sensitive detection of mercury and copper ions. This probe contains two tailored DNA sequence. One is a signal probe contains a cytosine-rich sequence template for AgNCs synthesis and link sequence at both ends. The other is a guanine-rich sequence for signal enhancement and link sequence complementary to the link sequence of the signal probe. After hybridization, the fluorescence of hybridized double-strand DNA/AgNCs is 200-fold enhanced based on the fluorescence enhancement effect of DNA/AgNCs in proximity of guanine-rich DNA sequence. The double-strand DNA/AgNCs probe is brighter and stable than that of single-strand DNA/AgNCs, and more importantly, can be used as novel fluorescent probes for detecting mercury and copper ions. Mercury and copper ions in the range of 6.0–160.0 and 6–240 nM, can be linearly detected with the detection limits of 2.1 and 3.4 nM, respectively. Our results indicated that the analytical parameters of the method for mercury and copper ions detection are much better than which using a single-strand DNA/AgNCs.