Nanolayered manganese-calcium oxide as an efficient and environmentally friendly catalyst for alcohol oxidation

Dual enzymes-mimic activity of nanolayered manganese-calcium oxide for fluorometric determination of metformin

There are different analytical methods available for the determination of metformin, as an oral hypoglycemic and antidiabetic drug, in biological samples. However, most of these methods suffer from some drawbacks, including high-priced materials and equipment, damaging chemical reagents, time-consuming nature, and tedious operation procedures. So, in this work a new, sensitive and simple method was reported for the detection of metformine. In this regard, nanolayered manganese-calcium oxide (NL-MnCaO₂) were synthesized and characterized using scanning electron microscopy (SEM), fourier transform infrared (FTIR) spectroscopy, and X-ray powder diffraction (XRD) techniques. Also, we studied the enzyme-like activity of synthesized particles and reported a bifunctional nanozyme, which performs the dual roles for peroxidase and catalase-mimicking. The results demonstrated the hindering effect of metformin on the peroxidase-mimic activity of NL-MnCaO₂ and this effect was increased by raising metformin concentration. So, a sensitive fluorometric detection system was designed for the analytical assay of metformin, based on the terephthalic acid (TA)-H₂O₂ reaction with NL-MnCaO₂. An acceptable linearity was observed between the metformin concentration and fluorescence quenching of the system in the range of 0.07-0.77 mM. Limit of detection (LOD) and limit of quantification (LOQ) were 0.17 μM and 0.96 μM, respectively. The proposed system was applied for the estimation of metformin concentration in serum samples by recoveries of 86.68-106%. So, the proposed fluorometric method provides some main advantages such as wide linear range, low detection limit, rapid detections, high sensitivity, and good practicability for the determination of metformin in biological samples.

An ultrasensitive label-free colorimetric biosensor for the detection of glucose based on glucose oxidase-like activity of nanolayered manganese-calcium oxide

During the last years, enzyme-based biosensors have gained much more attention among the researchers and have had great success in the determination of different biological macromolecules. Nanomaterials with intrinsic enzyme-mimic activity are widely used in biomedicine as artificial enzymes. Here, we report glucose oxidase-mimic activity of nanolayered manganese-calcium (Mn-Ca) oxide nanoparticles (NL-MnCaO₂). In this work, NL-MnCaO₂nanoparticles were synthesized and characterized using different techniques including transmission electron microscopy (TEM), scanning electron microscopy (SEM), fourier-transform infrared spectroscopy (FTIR) and powder X-ray diffraction (XRD). Also, the ability of these compounds for the glucose and hydrogen peroxide (H₂O₂) determination was investigated. A non-enzymatic strategy for the colorimetric detection of glucose and H₂O₂ was reported which can be utilized not only for the rapid detection and analysis of glucose by the naked eye but also the quantitative assay of glucose by spectrophotometry. The in situ generated H₂O₂ and gluconic acid (GA) from the oxidation of glucose through the glucose oxidase-mimicking activity of NL-MnCaO₂ was detected using a colorimetric method. Also, the results confirmed the application of these compounds for the detection of glucose in human serum samples with a detection limit (LOD) of 6.12 × 10^-6 M. The results showed that NL-MnCaO₂ can be used as an alternative for the natural enzymes and act as a simple, sensitive and enzyme-free biosensor for the detection of glucose in real samples. The proposed strategy shows some advantages including sensitivity, short detection time and low detection limit.

Selective oxidation of n-buthanol to butyraldehyde over MnCo2O4 spinel oxides

Partial oxidation of n-butanol to butyraldehyde, propionaldehyde and acetaldehyde over MnCo₂O₄ spinel oxides has been investigated.

Efficient aerobic oxidation of alcohols catalyzed by NiGa hydrotalcites in the absence of any additives

The surface Brønsted OH basic site on NiGa hydrotalcites was suggested to be the key active site for the oxidation.

Nano-sized Mn oxides as true catalysts for alcohol oxidation by a mononuclear manganese(ii) complex

We propose that nano-sized Mn oxides are true catalysts for the oxidation of some alcohols to aldehydes in the presence of a mononuclear manganese(ii) complex, and Oxone as an oxidant.