A novel reusable glutathione-modified magnetic fluorescent nanosensor for highly sensitive determination and removal of Cu2+

Magnetic Fluorescent Quantum Dots Nanocomposites in Food Contaminants Analysis: Current Challenges and Opportunities

The presence of food contaminants can cause foodborne illnesses, posing a severe threat to human health. Therefore, a rapid, sensitive, and convenient method for monitoring food contaminants is eagerly needed. The complex matrix interferences of food samples and poor performance of existing sensing probes bring significant challenges to improving detection performances. Nanocomposites with multifunctional features provide a solution to these problems. The combination of the superior characteristics of magnetic nanoparticles (MNPs) and quantum dots (QDs) to fabricate magnetic fluorescent quantum dots (MNPs@QDs) nanocomposites are regarded as an ideal multifunctional probe for food contaminants analysis. The high-efficiency pretreatment and rapid fluorescence detection are concurrently integrated into one sensing platform using MNPs@QDs nanocomposites. In this review, the contemporary synthetic strategies to fabricate MNPs@QDs, including hetero-crystalline growth, template embedding, layer-by-layer assembly, microemulsion technique, and one-pot method, are described in detail, and their advantages and limitations are discussed. The recent advances of MNPs@QDs nanocomposites in detecting metal ions, foodborne pathogens, toxins, pesticides, antibiotics, and illegal additives are comprehensively introduced from the perspectives of modes and detection performances. The review ends with current challenges and opportunities in practical applications and prospects in food contaminants analysis, aiming to promote the enthusiasm for multifunctional sensing platform research.

Ligand-Capped CdTe Quantum Dots as a Fluorescent Nanosensor for Detection of Copper Ions in Environmental Water Sample

In this work, as a novel fluorescent nano-sensor, a ligand-capped CdTe QDs (CdTe-L QDs) was designed for the detection and quantification of Cu²⁺ ions in environmental water samples. The synthesized QDs were characterized by transmission electron microscopy (TEM), thermo-gravimetric (TG) analysis, Fourier transform infrared (FTIR), UV-Vis spectrophotometry and fluorescence spectroscopy. Optical properties of the produced nanosensor were monitored by UV-Vis and fluorescence spectrophotometry. It was observed that fluorescence intensity of the produced nano-sensor selectively quenched by adding Cu²⁺ ions in comparison to other metal ions tested. Using CdTe-L QDs, a rapid and facile analytical method was developed to determine Cu²⁺ ions in the concentration range of 5.16 ± 0.07 × 10^- 8 mol L^- 1-1.50 ± 0.03 × 10^- 5 mol L^- 1 with a detection limit of 1.55 ± 0.05 × 10^- 8 mol L^- 1. The nanosensor was successfully applied for the determination of Cu²⁺ ions in various water samples, and the results were compared with the standard method. Graphical Abstract.

Preparation of novel magnetic and fluorescent CS–Fe3O4@CdSeS nanoparticles for simultaneous removal and optical determination of trace copper ions

Simultaneous removal and detection of copper ions by CS–Fe₃O₄@CdSeS is achieved with high saturation adsorption capacity and high sensitivity.