Guo-Xi Liang

Fabrication of near-infrared-emitting CdSeTe/ZnS core/shell quantum dots and their electrogenerated chemiluminescence

New water-soluble CdSeTe/ZnS core-shell quantum dots with excellent near-infrared emission were synthesized via an aqueous solution method; they showed strong electrogenerated chemiluminescence and favorable biocompatibility.

Ultrasensitive Cu2+ sensing by near-infrared-emitting CdSeTe alloyed quantum dots.

The near-infrared (NIR)-emitting CdSeTe alloyed quantum dots (AQdots) that capped with L-cysteine were applied for ultrasensitive Cu(2+) sensing. The sensing approach was based on the fluorescence of the AQdots selectively quenched in the presence of Cu(2+). Experimental results showed a low interference response towards other metal ions. The possible quenching mechanism was discussed on the basis of the binding between L-cysteine and the metal ions. In addition, biomolecules have low effect on the fluorescence due to the minimized interferences in NIR region. The response of the NIR optical sensor was linearly proportional to the concentration of Cu(2+) ranging from 2 x 10(-8) to 2 x 10(-6) mol L(-1). Furthermore, it has been successfully applied to the detection of Cu(2+) in vegetable samples.

Preparation and bioapplication of high-quality, water-soluble, biocompatible, and near-infrared-emitting CdSeTe alloyed quantum dots

A facile method is developed for the preparation of high-quality, water-soluble, and near-infrared (NIR)-emitting CdSeTe alloyed quantum dots (AQdots) with L-cysteine as the capping agent. By changing the size and the composition of AQdots the photoluminescent quantum yield (QY) can reach as high as 53% and the emission color can be tuned between visible and NIR regions (580-814 nm). Furthermore, the prepared NIR-emitting AQdots have been successfully applied for HL-60 cell imaging and glucose and cholesterol assay, which demonstrates the great potential of the AQdots for biological applications.

Near infrared sensing based on fluorescence resonance energy transfer between Mn:CdTe quantum dots and Au nanorods.

A novel sensing system based on the near infrared (NIR) fluorescence resonance energy transfer (FRET) between Mn:CdTe quantum dots (Qdots) and Au nanorods (AuNRs) was established for the detection of human IgG. The NIR-emitting Qdots linked with goat anti-human IgG (Mn:CdTe-Ab1) and AuNRs linked with rabbit anti-human IgG (AuNRs-Ab2) acted as fluorescence donors and acceptors, respectively. FRET occurred by human IgG with the specific antigen-antibody interaction. And human IgG was detected based on the modulation in FRET efficiency. The calibration graph was linear over the range of 0.05-2.5 microM of human IgG under optimal conditions. The proposed sensing system can decrease the interference of biomolecules in NIR region and increase FRET efficiency in optimizing the spectral overlap of AuNRs with Mn:CdTe Qdots. This method has great potential for multiplex assay with different donor-acceptor pairs.

Colorimetric and Fluorescent Probe for Hypochlorite with High Selectivity

Rhodamine B thiohydrazide (RBS) was firstly employed as turn-on fluorescent probe for hypochlorite in aqueous solution and living cells. It exhibits a stable response to hypochlorite from 1.0×10-6 to 1.0×10-5 M with a detection limit of 3.3×10-7 M. The response of this probe to hypochlorite is fast and highly selective compared with other reactive oxygen species (such as .OH, 1O2, H2O2) and other common anions (such as X-, ClO2-, ClO4-, NO3-, NO2-, OH-, Ac-, CO32-, SO42-).

3.08 – Preparation and Analytical Applications of Quantum Dots

This chapter presents a general description of the preparation of quantum dots and their analytical application with optical and electrochemical assays, including fluorescence, reversible optics, electrochemiluminescence (ECL), cyclic voltammetry (CV), differential pulse voltammetry (DPV), and square wave voltammetry (SWV). It contains four main sections with the preparation of QDs, the fluorescent application, the ECL application, and the electrochemical application in inorganic substance analysis, organics analysis, immunoassay, and aptasensor.

Fabrication of the CdSeTe alloyed and CdSeTe/ZnS core-shell quantum dots

The near-infrared (NIR)-emitting quantum dots (Qdots) have great potential for the use in biological imaging and diagnostic applications. In our work, a facile method was developed for the preparation of high quality, water-soluble, and NIR-emitting CdSeTe alloyed Qdots (A-Qdots) with L-cysteine (L-cys) as capping agent. By changing the size and the composition of the A-Qdots, the photoluminescent quantum yields (QYs) can reach as high as 53% and the emission color can be tuned between visible and NIR regions. Based on the fluorescence of the A-Qdots selectively quenched in the presence of Cu2+, the NIR-emitting CdSeTe A-Qdots were applied in ultrasensitive Cu2+ sensing. Furthermore, the prepared CdSeTe A-Qdots have been successfully applied for cell imaging, glucose and cholesterol assay, which demonstrates the great potential of the Qdots for biological applications. In order to improve the biocompatibility of the CdSeTe A-Qdots, new water-soluble CdSeTe/ZnS core-shell Qdots (CS-Qdots) with excellent NIR emission were synthesized in aqueous solution. The prepared CS-Qdots not only possessed high QYs but also exhibited excellent photobstability and favorable biocompatibility. Moreover, the CS-Qdots showed high electrogenerated chemiluminescence (ECL) signal. These characteristics showed their potential applications in cell imaging and biosensing with high sensitivity.

Electrochemical Study on the Effect of Xanthine on Electrodeposition of Nanostructured Pt Thin Films and Pt(IV)-Xanthine Interaction

Nanostructured Pt thin films were electrodeposited in the presence of varying amounts of xanhtine. The electrodeposited Pt films exhibit different catalytic efficiency for methanol electro-oxidation. The anodic current of methanol decreases linearly with the increase of xanthine during the electrodeposition. The effect of xanthine on the catalytic efficiency of Pt films was studied by cyclic votlammetry (CV) and differential pulse voltammetry (DPV). The results of CV and DPV reveal the formation of a 2:1 complex between Pt(IV) and xanthine. The conditional stability constant of the complexes was determined to be 3.8×106.