Yilin Wang

Label-free turn-on fluorescent detection of melamine based on the anti-quenching ability of Hg2+ to gold nanoclusters

In this work, we proposed a facile, environmentally friendly and cost-effective assay for melamine with BSA-stabilized gold nanoclusters (AuNCs) as a fluorescence reader. Melamine, which has a multi-nitrogen heterocyclic ring, is prone to coordinate with Hg(2+). This property causes the anti-quenching ability of Hg(2+) to AuNCs through decreasing the metallophilic interaction between Hg(2+) and Au(+). By this method, detection limit down to 0.15 µM is obtained, which is approximately 130 times lower than that of the US food and Drug Administration estimated melamine safety limit of 20 µM. Furthermore, several real samples spiked with melamine, including raw milk and milk powder, are analyzed using the sensing system with excellent recoveries. This gold-nanocluster-based fluorescent method could find applications in highly sensitive detection of melamine in real samples.

Carbon dots based fluorescent sensor for sensitive determination of hydroquinone

In this paper, a novel biosensor based on Carbon dots (C-dots) for sensitive detection of hydroquinone (H2Q) is reported. It is interesting to find that the fluorescence of the C-dots could be quenched by H2Q directly. The possible quenching mechanism is proposed, which shows that the quenching effect may be caused by the electron transfer from C-dots to oxidized H2Q-quinone. Based on the above principle, a novel C-dots based fluorescent probe has been successfully applied to detect H2Q. Under the optimal condition, detection limit down to 0.1 μM is obtained, which is far below U.S. Environmental Protection Agency estimated wastewater discharge limit of 0.5 mg/L. Moreover, the proposed method shows high selectivity for H2Q over a number of potential interfering species. Finally, several water samples spiked with H2Q are analyzed utilizing the sensing method with satisfactory recovery. The proposed method is simple with high sensitivity and excellent selectivity, which provides a new approach for the detection of various analytes that can be transformed into quinone.

Facile fabrication of CuO nanowire modified Cu electrode for non-enzymatic glucose detection with enhanced sensitivity

In this paper the fabrication of CuO nanowires (CuO NWs) by a facile two-step method is reported. Cu(OH)2 nanowires (Cu(OH)2 NWs) on a copper surface were prepared at room temperature by a simple solution-based procedure, and subsequent calcinations of Cu(OH)2 NWs led to the formation of CuO NWs. The morphologies and structures of Cu(OH)2 NWs and CuO NWs were characterized by scanning electron microscopy and X-ray diffraction. Electrochemical measurements showed that the CuO NWs modified Cu electrode exhibited good electrocatalytic behavior for the detection of glucose with a wide linear range from 2 μM to 3.56 mM (R2 = 0.9984), a low detection limit down to 0.05 μM, and a high sensitivity of 1886.3 μA mM−1 cm−2. The sensor also displayed a high selectivity, an acceptable reproducibility, an excellent long-term stability and good repeatability. Moreover, the as-prepared sensor has great potential in practical applications.

Highly sensitive and rapid visual detection of ricin using unmodified gold nanoparticle probes

Herein, a sensitive and selective colorimetric biosensor for the detection of ricin was demonstrated with a 40-mer ricin-binding aptamer (RBA) as recognition element and unmodified gold nanoparticles (AuNPs) as probe. The sensitivity of the assay was greatly improved after optimizing several key parameters such as the amount of aptamer adsorbed on AuNPs, the concentration of NaCl, and the reaction time after adding NaCl. The linear range for the current analytical system was from 0.31 nM to 11.55 nM. The corresponding limit of detection (LOD) was 0.31 nM. Some different proteins such as thrombin (Th), horseradish peroxidase (HRP), lysozyme (Lys), glucose oxidase (GOx), and bovine albumin (BSA) showed no or just a little interference in the determination of ricin. This colorimetric aptasensor is superior to the other conventional methods owing to its simplicity, low cost, high sensitivity and detection with the naked eye, which can be used in real samples.

CuO nanothorn arrays on three-dimensional copper foam as an ultra-highly sensitive and efficient nonenzymatic glucose sensor

A CuO nanothorns/Cu foam (NTs-CuO/Cu foam) was synthesized using a low-cost and facile method. The morphology and composition of the NTs-CuO/Cu foam were characterized using SEM, TEM and XRD. Copper foam as the current collector played a key role in the formation of the NTs-CuO/Cu foam. The CuO nanothorns were freely grown on copper foam, and can make contact with the underneath conductive copper foam directly. The NTs-CuO/Cu foam was used as an electrocatalyst for the detection of glucose in an electrochemical sensor. The CuO nanothorns/Cu foam electrode shows an extremely high sensitivity of 5.9843 mA mM−1 cm−2 and a low detection limit of 0.275 μM based on a signal to noise ratio of 3. Due to its excellently high sensitivity, stability and anti-interference ability, the NTs-CuO/Cu foam will be a promising material for constructing practical non-enzymatic glucose sensors.

Fabrication of cuprous sulfide nanorods supported on copper foam for nonenzymatic amperometric determination of glucose and hydrogen peroxide

Cu2S nanorods supported on three-dimensional copper foam (Cu2S NRs@Cu foam) are in situ prepared by a low-cost and facile method. The structural and morphological characterization of the Cu2S NRs@Cu foam is executed using scanning electron microscopy, transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The high conductivity of copper foam as a current collector can facilitate charge and mass transfer, and the copper foam with an open framework provides large amounts of anchoring sites for the deposition of Cu2S NWs during the synthesis of the Cu2S NRs@Cu foam. Consequently, the Cu2S NRs@Cu foam works as an electrocatalyst for the detection of glucose and H2O2. Electrochemical measurements of the biosensor show an extremely high sensitivity of 11.7508 mA mM−1 cm−2 and a low detection limit of 0.07 μM for the electrocatalytic oxidation of glucose. The nonenzymatic sensor also exhibits a good response toward hydrogen peroxide with a high sensitivity of 1.686 mA mM−1 cm−2. The detection limit is calculated to be 0.2 μM. This method provides an efficient and promising strategy for the construction of practical non-enzymatic glucose and hydrogen peroxide sensors.