Portable, quantitative, and sequential monitoring of copper ions and pyrophosphate based on a DNAzyme-Fe3O4 nanosystem and glucometer readout

In this report, portable, quantitative, and sequential monitoring of copper ions and pyrophosphate (PPi) with a single sensor based on a DNAzyme-Fe₃O₄ system and glucometer readout was performed. Initially, streptavidin was functionalized on the surface of magnetic Fe₃O₄ spheres through glutaraldehyde. Then, an invertase-modified DNA Cu substrate was connected to the magnetic Fe₃O₄ spheres by a specific reaction between streptavidin and biotin. The sensing system was formed by a hybridization reaction between the Cu substrate and Cu enzyme. In the presence of Cu²⁺, Cu²⁺ will recognize the Cu DNA substrate and form an “off-on” signal switch, thereby resulting in the separation of invertase from the Fe₃O₄ nanospheres. PPi recognizes Cu²⁺ to form a Cu²⁺-PPi complex, resulting in an “on-off” signal switch. Under optimized conditions, linear detection ranges for Cu²⁺ and PPi of 0.01–5 and 0.5–10 μM, and detection limits for Cu²⁺ and PPi of 10 nM and 500 nM, respectively, were obtained. Good selectivity was achieved for the analysis of Cu²⁺ and PPi. Satisfactory results were achieved for this biosensor during the determination of Cu²⁺ in real tap samples and PPi in human urine samples. This verified that the sensor is portable and low cost, and can be applied to the sequential monitoring of multiple analytes with a single point-of-care biosensor.

An easily fabricated palladium nanocatalyst on magnetic biochar for Suzuki–Miyaura and aryl halide cyanation reactions

A sustainable biochar material for the synthesis of a novel heterogeneous catalyst for organic reactions is reported.

Photocatalytic degradation of model pharmaceutical pollutant by novel magnetic TiO2@ZnFe2O4/Pd nanocomposite with enhanced photocatalytic activity and stability under solar light irradiation

In the last decades, the use of magnetic nanocomposites as a catalyst was considered for removal of organic pollutants due to its easy separation. Therefore, initially, TiO₂@ZnFe₂O₄/Pd nanocomposite was prepared and then used in the photodegradation of diclofenac under direct solar irradiation in the batch and continuous systems. The structure, morphology and other specifications of produced nanocatalyst were determined via XRD, VSM, FESEM/EDX, FTIR, GTA, UV-Vis, Zeta potential, XPS and ICP-OES. The effective factors on diclofenac removal via nanophotocatalyst viz. pH, catalyst concentration, initial concentration of diclofenac, and flow rate and column length on diclofenac photodegradation were studied. Based on the results, the optimal rate for pH, catalyst concentration, and initial concentration of diclofenac was 4, 0.03 g/l and 10 mg/l respectively. Pd-coated TiO₂@ZnFe₂O₄ magnetic photocatalyst had higher photocatalytic activity in diclofenac photodegradation in relation to ZnFe₂O₄ and TiO₂@ZnFe₂O₄ under solar light irradiation. The findings showed that after five recycles, the photocatalytic efficiency did not show much reduction i.e. the removal efficiency from 86.1% in the first cycle reduced only to 71.38% in the last cycle. Likewise, in this study, with flow rate reduction and column length increase diclofenac degradation rate increased.

Templated synthesis of nickel nanoparticles embedded in a carbon layer within silica capsules

The encapsulation of small non-noble metal nanoparticles (NPs) within an inorganic layer has received considerable attention owing to their enhanced stability and high catalytic activity. Using a combination of emulsion-free polymerization, inner RF-Ni2+ and outer SiO2 coating, and subsequent carbonization treatment, herein, we have fabricated worm-like structured Ni-based composites in which a high density of nickel NPs are embedded in a carbon layer and also entrapped by SiO2 nanocages. We find that the carbonization temperature plays a vital role in adjusting the size of the Ni NPs. A detailed examination of the encapsulated nickel particles synthesized at 700 °C exhibited the best performance on the catalysis of the reduction of 4-NPs. Moreover, owing to the good alloying ability of the Ni NPs with noble metal NPs, the Ni-Pd alloy NPs are also entrapped in the SiO2 nanocages, which exhibit better performance on the catalysis than the Ni-based composites. The encapsulation of Ni-Pd alloys within SiO2 nanocages also improves stability against agglomeration and metal separation during catalytic operation.

g-C3N4/γ-Fe2O3/TiO2/Pd: a new magnetically separable photocatalyst for visible-light-driven fluoride-free Hiyama and Suzuki–Miyaura cross-coupling reactions at room temperature

g-C₃N₄/γ-Fe₂O₃/TiO₂/Pd is developed as a new magnetically separable photocatalyst for efficient fluoride-free Hiyama and Suzuki–Miyaura cross-coupling reactions at room temperature under visible light irradiation.