Preparation of mesopourous Fe3O4 nanoparticle with template reagent: Tannic acid and the catalytic performance

Tannic acid-mediated synthesis of flower-like mesoporous MnO2 nanostructures as T1-T2 dual-modal MRI contrast agents and dual-enzyme mimetic agents

This study introduces a simple method for preparing a new generation of MnO2 nanomaterials (MNMs) using tannic acid as a template. Two shapes of MnO2 NMs, flower-like M1-MnO2 and near-spherical M2-MnO2, were prepared and compared as dual-active nanozymes and contrast agents in magnetic resonance imaging (MRI). Various parameters, including the crystallinity, morphology, magnetic saturation (Ms), surface functionality, surface area, and porosity of the MNMs were investigated. Flower-like M1-MnO2 NMs were biocompatible and exhibited pH-sensitive oxidase and peroxidase mimetic activity, more potent than near-spherical M2-MnO2. Furthermore, the signal intensity and r1 relaxivity strongly depended on the crystallinity, morphology, pore size, and specific surface area of the synthesized MNMs. Our findings suggest that flower-like M1-MnO2 NM with acceptable dual-enzyme mimetic (oxidase-like and peroxidase-like) and T1 MRI contrast activities could be employed as a promising theranostic system for future purposes.

Preparation of tannic acid and L-cysteine functionalized magnetic composites for synergistic enrichment of N-glycopeptides followed by mass spectrometric analysis

Glycoprotein is involved in a variety of biological activities and has been linked to a number of diseases. Glycopeptide enrichment prior to mass spectrometry (MS) detection is crucial to reduce interference, improve detection efficiency, and analyze proteomics deeply and comprehensively. Here, we prepared a novel magnetic hydrophilic material combining tannic acid (TA) and L-cysteine (L-Cys) through a simple and fast procedure. Owing to the synergistic hydrophilic interaction of TA and L-Cys, the obtained adsorbent material shows excellent enrichment performance toward N-glycopeptides with low detection limit, high selectivity, and good reusability. Besides, the material can also be utilized for the enrichment of N-glycopeptides in human serum and saliva, which shows its application prospect in complex biological samples.

An environmentally benign synthesis of Fe3O4 nanoparticles to Fe3O4 nanoclusters: Rapid separation and removal of Hg(II) from an aqueous medium

In the field of nanotechnology, nanoadsorbents have emerged as a powerful tool for the purification of contaminated aqueous environments. Among the variety of nanoadsorbents developed so far, magnetite (Fe₃O₄) nanoparticles have drawn particular interest because of their quick separation, low cost, flexibility, reproducibility, and environmentally benign nature. Herein, we describe a new strategy for the synthesis of Fe₃O₄ nanoclusters, which is based on the use of naturally available edible mushrooms (Pleurotus eryngii) and environmentally benign propylene glycol as a solvent medium. By tuning the temperature, we successfully convert Fe₃O₄ nanoparticles into Fe₃O₄ nanoclusters via hydrothermal treatment, as evidenced by transmission electron microscopy. The Fe₃O₄ nanoclusters are functionalized with an organic molecule linker (dihydrolipoic acid, DHLA) to remove hazardous Hg(II) ions selectively. Batch adsorption experiments demonstrate that Hg(II) ions are strongly adsorbed on the material surface, and X-ray photoelectron and Fourier transform infrared spectroscopy techniques reveal the Hg(II) removal mechanism. The DHLA@Fe₃O₄ nanoclusters show a high removal efficiency of 99.2 % with a maximum Hg(II) removal capacity of 140.84 mg g^-1. A kinetic study shows that the adsorption equilibrium is rapidly reached within 60 min and follows a pseudo second-order kinetic model. The adsorption and separation system can be readily recycled using an external magnet when the separation occurs within 10 s. We have studied the effect of various factors on the adsorption process, including pH, concentration, dosage, and temperature. The newly synthesized superparamagnetic DHLA@Fe₃O₄ nanoclusters open a new path for further development of the medical, catalysis, and environmental fields.