Eco-Friendly Ferrimagnetic-Humic Acid Nanocomposites as Superior Magnetic Adsorbents.

Recyclable, cheap, eco-friendly, and efficient adsorbent materials are very important for the removal of pollution. In this work, we report the design and implementation of ferrimagnetic-humic acid nanocomposites as superior magnetic adsorbent for heavy metals. Ferrimagnetic and ferrimagnetic-humic acid nanocomposite particles with different morphologies were prepared using the coprecipitation method and hydrothermal synthesis method, respectively. The results show that the morphology of the nanoparticles prepared by the coprecipitation method is more uniform and the size is smaller than that by the hydrothermal synthesis method. Adsorption experiments show that the ferrimagnetic-humic acid nanoparticles prepared by the coprecipitation method has high sorption capacity for cadmium, and the maximum adsorption capacity is about 763 µg/g. At the same time, magnetic technology can be used to realize the recycling of ferrimagnetic-humic acid adsorbents.

Enhanced photoresponse of a MoS2 monolayer using an AAO template.

Monolayer two-dimensional transition metal dichalcogenides (TMDs) with direct band gaps, such as MoS2, have received great attention from researchers due to their peculiar band structure and physical properties. However, their extremely small thickness (0.65 nm for MoS2) results in a critically low light absorption efficiency, thus limiting their optoelectronic applications. To achieve the enhancement of the light-matter interaction in MoS2, a resonant Al/AAO (anodic alumina oxide template)/MoS2 trilayer nanocavity structure was designed and implemented in the present study. In such a system, the appropriate change in pore size and pore depth of the AAO template via control of the growth conditions allows one to adjust the thickness and refractive index of the dielectric layer (AAO). This nanocavity structure provides a possible way to regulate the light-matter interaction of MoS2 film.

Blue-emitting glutathione-capped copper nanoclusters as fluorescent probes for the highly specific biosensing of furazolidone.

Herein, a facile, straightforward and green method was developed to prepare copper nanoclusters by using glutathione (GSH) as the protecting agent and ascorbic acid as the reducing agent. The glutathione-templated copper nanoclusters (GSH-Cu NCs) were characterized through fluorescence spectroscopy, UV-vis absorption spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and fluorescence lifetime analysis. The as-synthesized Cu NCs showed blue fluorescence with a peak centered at 426 nm. The Cu NCs had excellent water solubility, stability and dispersibility. Based on the inner filter effect and static quenching mechanism, Cu NCs were employed to detect furazolidone in bovine serum samples. Under optimal detection conditions, a good linear relationship was observed between F0/F and the furazolidone concentration from 0.05 to 60 µM. The detection limit (LOD) was 0.012 µM. Furthermore, the fluorescence probe was successfully used in the quantification of furazolidone in bovine serum samples. In addition, this analytical method provides a rapid, easy and ultrasensitive fluorescence platform for the detection of furazolidone.

A sensitive OFF-ON-OFF fluorescent probe for the cascade sensing of Al3+ and F- ions in aqueous media and living cells.

A simple Schiff-base ligand 2-hydroxy-1-naphthaldehyde semicarbazone (HNS) was synthesized and characterized. Based on the combined effect of inhibition of CH[double bond, length as m-dash]N isomerization and chelation-enhanced fluorescence (CHEF), HNS functions as a fluorescence "turn on" sensor for Al3+ in buffered aqueous media. Based on the strong affinity of Al3+ to F- ions, the in situ generated Al3+-HNS complex can also be utilized as an effective chemosensor for F- sensing by metal displacement approach, ensuing quenching of fluorescence by the reversible return of HNS from Al3+-HNS complex. Thus a method using a single probe for the detection of both Al3+ and F- ions is developed. The system exhibits high selectivity and sensitivity for Al3+ and F- ions and the detection limits were found to be as low as 6.75 × 10-8 M and 7.89 × 10-7 M, respectively. Furthermore, the practical applicability of this probe has been examined in living cells.

Correction: A sensitive OFF-ON-OFF fluorescent probe for the cascade sensing of Al3+ and F- ions in aqueous media and living cells.

[This corrects the article DOI: 10.1039/D0RA02848G.].

Morphology and magnetic properties of Fe3O 4 nanodot arrays using template-assisted epitaxial growth.

Arrays of epitaxial Fe3O4 nanodots were prepared using laser molecular beam epitaxy (LMBE), with the aid of ultrathin porous anodized aluminum templates. An Fe3O4 film was also prepared using LMBE. Atomic force microscopy and scanning electron microscopy images showed that the Fe3O4 nanodots existed over large areas of well-ordered hexagonal arrays with dot diameters (D) of 40, 70, and 140 nm; height of approximately 20 nm; and inter-dot distances (D int) of 67, 110, and 160 nm. The calculated nanodot density was as high as 0.18 Tb in.(-2) when D = 40 nm. X-ray diffraction patterns indicated that the as-grown Fe3O4 nanodots and the film had good textures of (004) orientation. Both the film and the nanodot arrays exhibited magnetic anisotropy; the anisotropy of the nanoarray weakened with decreasing dot size. The Verwey transition temperature of the film and nanodot arrays with D ≥ 70 nm was observed at around 120 K, similar to that of the Fe3O4 bulk; however, no clear transition was observed from the small nanodot array with D = 40 nm. Results showed that magnetic properties could be tailored through the morphology of nanodots. Therefore, Fe3O4 nanodot arrays may be applied in high-density magnetic storage and spintronic devices.