Synthesis of 5-[(2-hydroxynaphthalen-1-yl)diazenyl]isophthalic acid and its application to electrocatalytic oxidation and determination of adrenaline, paracetamol, and tryptophan

Oatmeal-derived carbon loaded with Pt nanoparticles using a "two-fold benefit approach" for sensitive detection of the biomolecule adrenaline

In this study, we innovatively synthesized nitrogen-doped carbon microspheres (NCS) derived from oatmeal. By utilizing polyoxometalates (POM) as both reducing and linking agents, we achieved uniform loading of platinum nanoparticles (Pt NPs) onto the surface of the NCS. The composite nanoparticles constructed from Pt/polyoxometalate/nitrogen-doped carbon microspheres (Pt/POM/NCS) fully exploit the synergistic catalytic effect, demonstrating superior performance in adrenaline detection. The method has a linear range of 2.59 to 1109.59 μM, a detection limit as low as 0.25 μM (S/N = 3), and a sensitivity of 0.74 μA μM-1 cm-2. Additionally, it exhibits high stability and strong anti-interference ability. The recoveries in human serum were 98.51 % to 101.25 %.

Facile synthesis of Pt/polyoxometalate/hollow carbon sphere tri-component nanoparticles via a "double gain strategy" for high-performance electrochemical sensing of adrenaline

In this study, we designed and successfully synthesized the Pt/polyoxometalate/hollow carbon sphere (Pt/POM/HCS) tri-component nanoparticles (NPs) by a pollution-free, efficient, and convenient method. HCSs with outstanding chemical stability and conductivity are self-generated by acid etching and calcination of silica spheres synthesized by a hard template method. HCSs have a hollow internal structure that provides specific three-dimensional storage space, and can increase the surface area. The mesoporous system is beneficial to providing numerous mass transfer passageways and immobilizing NPs. In addition, we introduced a "double gain strategy", by taking advantage of POMs as reducing and bridging agents, to achieve the loading of ultrafine Pt NPs on the surface of HCSs. Pt NPs have excellent stability and unique electrocatalytic activity. As a result of the synergistic effect of HCSs and ultrafine Pt NPs, the electrochemical sensing of adrenaline exhibits high-performance catalytic activity, sensitivity, suitable linearity range (0.16 μM-1.195 mM), and low limit of detection (57.5 nM, S/N = 3), excellent stability, and reproducibility. The developed platform is a sensitive and effective adrenaline electrical sensing platform with broad practical application prospects.

Application of Nanotechnology in Analysis and Removal of Heavy Metals in Food and Water Resources

Toxic heavy metal contamination in food and water from environmental pollution is a significant public health issue. Heavy metals do not biodegrade easily yet can be enriched hundreds of times by biological magnification, where toxic substances move up the food chain and eventually enter the human body. Nanotechnology as an emerging field has provided significant improvement in heavy metal analysis and removal from complex matrices. Various techniques have been adapted based on nanomaterials for heavy metal analysis, such as electrochemical, colorimetric, fluorescent, and biosensing technology. Multiple categories of nanomaterials have been utilized for heavy metal removal, such as metal oxide nanoparticles, magnetic nanoparticles, graphene and derivatives, and carbon nanotubes. Nanotechnology-based heavy metal analysis and removal from food and water resources has the advantages of wide linear range, low detection and quantification limits, high sensitivity, and good selectivity. There is a need for easy and safe field application of nanomaterial-based approaches.

Carbon/FexOy magnetic composites obtained from PET and red mud residues: paracetamol and dye oxidation

Composite materials from PET and red mud (RM) wastes were used as catalysts for environmental application such as the wastewater treatment. The PET-RM catalysts were obtained by a mechanical mixture of the residues followed by thermal treatment under an N₂ atmosphere (300°C/1 h). An additional activation of the composites with CO₂ was investigated (at 800-900°C) to reduce the red mud basicity. The CO₂ activation affected the composites surface area and reduced their carbon content. XRD revealed that the haematite (α-Fe₂O₃) and maghemite/magnetite are the main iron oxides present in the composites. Mössbauer characterization indicated the formation of reduced iron species (Fe²⁺), highly reactive, after the composites heat treatment. The materials were very active catalysts for methylene blue (MB) and paracetamol (PRC) removal from aqueous solution. The catalytic activity revealed to be dependent on the surface area and mainly of the presence of reduced iron species in the catalysts. The MB removal reached 97% for both PET-RM 800/2 h and PET-RM 800/5 h, after 1 h of reaction. In the case of PRC, the highest removal was also obtained for PET-RM 800/2 h and PET-RM 800/5 h, of ≈25% and 40%, respectively. The contaminants removal mechanism likely occurred through combined adsorption and Fenton-like oxidation processes.