Sensoring Strategies Using Quantum Dots: A Critical View

Direct Detection of Potential Pyrethroids in Yangtze River via an Imprinted Multilayer Phosphorescence Probe

A novel tailored multilayer probe for monitoring potential pyrethroids in the Yangtze River was proposed. The room-temperature phosphorescence method was applied to realize a detection strategy that is superior to the fluorescence method. Efficient Mn-doped ZnS quantum dots with uniform size of 4.6 nm were firstly coated with a mesoporous silica to obtain a suitable intermediate transition layer, then an imprinted layer containing bifenthrin specific recognition sites was anchored. Characterizations verified the multilayer structure convincingly and the detection process relied on the electron transfer-induced fluorescence quenching mechanism. Optional detection time and standard detection curve were obtained within a concentration range from 5.0 to 50 μmol L^-1. The stability was verified to be good after 12 replicates. Feasibility of the probe was proved by monitoring water samples from the Zhenjiang reach of the Yangtze River. The probe offers promise for direct bifenthrin detection in unknown environmental water with an accurate and stable phosphorescence analysis strategy.

Analysis of penicillamine using Cu-modified graphene quantum dots synthesized from uric acid as single precursor

A simple methodology was developed to quantify penicillamine (PA) in pharmaceutical samples, using the selective interaction of the drug with Cu-modified graphene quantum dots (Cu-GQDs). The proposed strategy combines the advantages of carbon dots (over other nanoparticles) with the high affinity of PA for the proposed Cu-GQDs, resulting in a significant and selective quenching effect. Under the optimum conditions for the interaction, a linear response (in the 0.10–7.50 µmol/L PA concentration range) was observed. The highly fluorescent GQDs used were synthesized using uric acid as single precursor and then characterized by high resolution transmission electron microscopy, Raman spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, fluorescence, and absorption spectroscopy. The proposed methodology could also be extended to other compounds, further expanding the applicability of GQDs.

Dual-emission ratiometric fluorescence detection of aspirin in human saliva: onsite naked-eye detection and high stability

A highly stable ratiometric fluorescence probe based on dual-emission QDs was designed for the visual detection of aspirin in human saliva.

Cerium(III) Ion Sensing Based on Graphene Quantum Dots Fluorescent Turn-Off

In this work, graphene quantum dots (GQDs) was synthesized through hydrothermal method and used as a photoluminescent bulk nano-chemosensor for detection of Ce³⁺ ion in the aqueous solution. The synthesized GQD was characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), UV-Visible absorption and fluorescence emission spectroscopy. The sheet diameters of the synthesized GQDs were mainly distributed in the range of 15-20 nm. The interactions of GQDs with common cations and lanthanide ions were studied by fluorescence spectroscopy. Among the tested cations, Ce³⁺ ions was able to quench the fluorescence emission intensity of the GQD selectively. This quenching can be attributed to a redox mechanism between Ce³⁺ ion on the GQDs surface.

Photoelectrochemical glucose biosensor based on a dehydrogenase enzyme and NAD+/NADH redox couple using a quantum dot modified pencil graphite electrode

A simple, disposable and economical modified electrode was prepared by electrodeposition of hybrid quantum dots onto a pencil graphite electrode surface and immobilization of glucose dehydrogenase onto the quantum dot modified electrode.