Jingting Hu

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.

Facile synthesis of Prussian blue @ gold nanocomposite for nonenzymatic detection of hydrogen peroxide

A sensitive hydrogen peroxide (H2O2) sensor was fabricated based on a Prussian blue @ gold nanocomposite (PB@Au). Au nanoparticles (Au NPs) were first electrodeposited on a glassy carbon electrode (GCE) to increase the conductivity and to catalyze the chemical deposition of PB. Electrochemical measurements showed that the PB@Au modified electrode exhibited good electrocatalytic behavior for the detection of H2O2 with a wide linear range from 2 μM to 8.56 mM (R2 = 0.9980), a low detection limit down to 0.1 μM (S/N = 3), and a high sensitivity of 39.72 μA mM−1. The sensor also displayed a good anti-interference ability, an acceptable reproducibility, an excellent long-term stability and good repeatability. The desirable recoveries achieved in disinfected fetal bovine serum verified that the developed sensor could have a potential use in the detection of H2O2 in real samples. Moreover, the operating simplicity and low expense of the fabrication made the as-prepared electrode attractive.

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.

Effect of glycerine addition on the synthesis of boron carbide from condensed boric acid–polyvinyl alcohol precursor

Boron carbide (B4C) powder was synthesized by heating a gel precursor with pyrolysis and carbothermal processes. The gel precursor was prepared by the condensation reaction of boric acid (H3BO3) and polyvinyl alcohol (PVA) at a weight ratio of 1/2 with the addition of various amounts of glycerine. The effects of glycerine addition on the synthesis of B4C powder were studied. It was observed that glycerine could promote the condensation reaction and resulted in a pyrolyzed precursor with a much finer distribution of B2O3 in the carbon matrix. This led to a significant reduction of residual free carbon in the B4C powder. Moreover, the morphology of the B4C powder was also found to be closely related to the glycerine addition.