Copper(II) complexes as catalyst for the aerobic oxidation of o-phenylenediamine to 2,3-diaminophenazine

Screening of oxidative behavior in catalytic amyloid assemblies

Once considered a thermodynamic minimum of the protein fold or as simply by-products of a misfolding process, amyloids are increasingly showing remarkable potential for promoting enzyme-like catalysis. Recent studies have demonstrated a diverse range of catalytic behaviors that amyloids can promote way beyond the hydrolytic behaviors originally reported. We and others have demonstrated the strong propensity of catalytic amyloids to facilitate redox reactions both in the presence and in the absence of metal cofactors. Here, we present a detailed protocol for measuring the oxidative ability of supramolecular peptide assemblies.

Recent Advancements in Metal and Non-Metal Mixed-Doped Carbon Quantum Dots: Synthesis and Emerging Potential Applications

In nanotechnology, the synthesis of carbon quantum dots (CQDs) by mixed doping with metals and non-metals has emerged as an appealing path of investigation. This review offers comprehensive insights into the synthesis, properties, and emerging applications of mixed-doped CQDs, underlining their potential for revolutionary advancements in chemical sensing, biosensing, bioimaging, and, thereby, contributing to advancements in diagnostics, therapeutics, and the under standing of complex biological processes. This synergistic combination enhances their sensitivity and selectivity towards specific chemical analytes. The resulting CQDs exhibit remarkable fluorescence properties that can be involved in precise chemical sensing applications. These metal-modified CQDs show their ability in the selective and sensitive detection from Hg to Fe and Mn ions. By influencing their exceptional fluorescence properties, they enable precise detection and monitoring of biomolecules, such as uric acid, cholesterol, and many antibiotics. Moreover, when it comes to bioimaging, these doped CQDs show unique behavior towards detecting cell lines. Their ability to emit light across a wide spectrum enables high-resolution imaging with minimal background noise. We uncover their potential in visualizing different cancer cell lines, offering valuable insights into cancer research and diagnostics. In conclusion, the synthesis of mixed-doped CQDs opens the way for revolutionary advancements in chemical sensing, biosensing, and bioimaging. As we investigate deeper into this field, we unlock new possibilities for diagnostics, therapeutics, and understanding complex biological processes.

A Ni(II) coordination polymer with dual electrochemical functions: synthesis, crystal structure, hydrogen evolution reaction and l-ascorbic acid sensing

A two-dimensional Ni(II) coordination polymer (NiCP) of the formula {[NiL(terephthalate)(H2O)2]·2H2O} n (L = bis(1-(pyridin-4-ylmethyl)-benzimidazol-2-ylmethyl)ether), has been obtained from a solvothermal reaction, and characterized by single-crystal X-ray diffraction, elemental analysis, and IR and UV/Vis spectra. The coordinated terephthalate anions and the L ligands connect the Ni(II) ions in two directions, resulting in the construction of a corrugated layered structure. The electrochemical properties of a NiCP-CPE composite electrode supported by this coordination polymer were studied. For the electrocatalytic hydrogen evolution reaction, the required overpotential of this electrode (NiCP-CPE) is −521 mV when the current density reaches 10 mA cm−2. Compared with the solid carbon paste electrode (sCPE, −976 mV), the smaller overpotential proves effective electrocatalysis of the coordination polymer of the hydrogen evolution reaction. The doped electrode also exhibits high-efficiency in the electrochemical sensing of l-ascorbic acid in water, showing a detection limit of 0.28 μM in a linear range of 0.4–4000 μM.

Observation of intermediates by online mass spectrometry to demonstrate the multiple mechanisms of dye-sensitized photocatalysis

Online mass spectrometry was applied to reveal multiple mechanisms of visible-light irradiated dye-sensitized photocatalysis for o-phenylenediamine oxidation. The reactants, products and short-lived intermediates were recorded and dynamically tracked. Dimer and unexpected trimer intermediates were observed to deduce the stepwise aerobic photooxidation mechanism with multiple routes, which was supported by theoretical calculations.

Self-Assembling Catalytic Peptide Nanomaterials Capable of Highly Efficient Peroxidase Activity

The self-assembly of short peptides gives rise to versatile nanomaterials capable of promoting efficient catalysis. We have shown that short, seven-residue peptides bind hemin to produce functional catalytic materials which display highly efficient peroxidation activity, reaching a catalytic efficiency of 3×105  m-1  s-1 . Self-assembly is essential for catalysis as non-assembling controls show no activity. We have also observed peroxidase activity even in the absence of hemin, suggesting the potential to alter redox properties of substrates upon association with the assemblies. These results demonstrate the practical utility of self-assembled peptides in various catalytic applications and further support the evolutionary link between amyloids and modern-day enzymes.

o-Phenylenediamine as a reaction-based probe for the fluorescent detection of Ce(IV) ions

o-Phenylenediamine as a new fluorescent probe is designed for detecting Ce(IV) ions. The mechanism of detection relies on the oxidative activity of Ce(IV) ions, which can promote the oxidative cyclization of o-Phenylenediamine leading to the formation of fluorescent 2,3-diaminophenazine and giving a more than 150-fold fluorescence enhancement. Furthermore, the o-Phenylenediamine fluorescent probe was effectively used for the detection of Ce(IV) ions in river water, tap water, rainwater, and lateritic soil from Ganzhou.

A smartphone-based double-channel fluorescence setup for immunoassay of a carcinoembryonic antigen using CuS nanoparticles for signal amplification

Sensitive detection of cancer biomarkers is valuable for clinical diagnosis and treatment assessment of cancers.