Rapid fabrication of nanoporous iron by atmospheric plasma for efficient wastewater treatment.

Nanoporous (NP) iron with large surface area is highly desired for wastewater degradation catalysis. However, it remains a challenge for the fabrication of NP-Fe because the conventional aqueous dealloying or liquid metal dealloying are not applicable. Herein, a novel and universal plasma-assisted electro-dealloying technique was utilized to fabricate NP-Fe. The NP-Fe demonstrates evenly distributed pore structure. The pore density can be tuned by the variation of the ratio of Fe and Zn in the precursor, and the average pore size can be tuned by the processing time. Owing to its large specific surface area, the NP-Fe shows excellent wastewater degradation performance, which is 26 times better than that of commercial zero-valent iron catalysts. This study provides a useful approach to fabricate NP active metals with enhanced catalytic performance.

Nanoporous iron oxide nanoparticle: hydrothermal fabrication, human serum albumin interaction and potential antibacterial effects.

Nanoporous iron oxide (Fe3O4) nanoparticles (NIONPs) have been widely used as promising agents in biomedical applications. Herein, the NIONPs were synthesized by one-step hydrothermal method and well-characterized by FESEM and TEM investigations. Afterwards, their interaction with human serum albumin (HSA) was studied using a wide range of biophysical approaches, including intrinsic and extrinsic fluorescence, far and near UV-CD, and UV-Vis spectroscopic methods as well as molecular docking investigation. Furthermore, the antibacterial effect of NIONPs was examined on the standard strains of the following pathogenic bacteria, Staphylococcus aureus (ATCC 25923), Klebsiella penumoniae (ATCC 33883), Enterococcus faecalis (ATCC 29212) and Pseudomonas aeruginosa (ATCC 27853). The results showed the feasible fabrication of spherical-shaped NIONPs with an average diameter of around 100 nm. Intrinsic fluorescence spectroscopy data depicted that NIONPs formed a complex with HSA by a KSV value of 0.092 (µg/ml)-1. Extrinsic fluorescence, near UV-CD and UV-vis spectroscopic methods revealed that NIONPs induced some changes on the quaternary structure of HSA, whereas Tm measurement and far UV-CD spectroscopy showed some slight changes on the secondary structure of HSA even in the presence of high concentration of NIONPs. Molecular docking study disclosed that Fe3O4 nanoclusters with varying morphologies and dimensions could interact with different residues on the surface of HSA molecules. In addition, antibacterial assays exhibited a significant inhibition on both Gram-positive and Gram-negative pathogenic bacteria. In conclusion, these NPs can be used as promising antibacterial agents.Communicated by Ramaswamy H. Sarma.

Gold-loaded nanoporous ferric oxide nanocubes for electrocatalytic detection of microRNA at attomolar level.

A crucial issue in microRNA (miRNA) detection is the lack of sensitive method capable of detecting the low levels of miRNA in RNA samples. Herein, we present a sensitive and specific method for the electrocatalytic detection of miR-107 using gold-loaded nanoporous superparamagnetic iron oxide nanocubes (Au-NPFe2O3NC). The target miRNA was directly adsorbed onto the gold surfaces of Au-NPFe2O3NC via gold-RNA affinity interaction. The electrocatalytic activity of Au-NPFe2O3NC was then used for the reduction of ruthenium hexaammine(III) chloride (RuHex, [Ru(NH3)6]3+) bound with target miRNA. The catalytic signal was further amplified by using the ferri/ferrocyanide [Fe(CN)6]3-/4- system. These multiple signal enhancement steps enable our assay to achieve the detection limit of 100aM which is several orders of magnitudes better than most of the conventional miRNA sensors. The method was also successfully applied to detect miR-107 from cancer cell lines and a panel of tissue samples derived from patients with oesophageal squamous cell carcinoma with excellent reproducibility (% RSD = < 5%, for n = 3) and high specificity. The analytical accuracy of the method was validated with a standard RT-qPCR method. We believe that our method has the high translational potential for screening miRNAs in clinical samples.

Role of CuO in improving NH3 and SO2 capture on nanoporous Fe2O3 sorbents.

In this work, mixed Fe/Cu oxides as sorbents for SO2 and NH3 removal were investigated. Nanoporous iron oxide mixed with 10, 20 and 30 at.% CuO were prepared by thermal decomposition of the corresponding oxalates at 250 °C for 5 h in air. The mixed Fe/Cu oxalates were obtained from the co-precipitation of iron/copper sulfate and ammonium oxalate during ultrasonication. The physical properties of the oxalate precursors and the resulting mixed Fe/Cu oxides were characterized with SEM, TGA-DSC, FTIR, powder XRD and Mössbauer spectroscopy. The porosity was studied by N2 adsorption-desorption isotherms and small angle X-ray scattering. Evenly dispersed CuO hindered the crystallization of Fe2O3, which significantly increased the specific BET surface area from 211 m2/g for Fe2O3 to 354 m2/g for Fe0.8Cu0.2Ox. As a result, SO2 and NH3 adsorption on Fe0.8Cu0.2Ox were enhanced by about 70% compared to Fe2O3. Compared to Fe2O3-impregnated activated carbons, nanoporous Fe0.8Cu0.2Ox could capture five times more SO2 per unit weight, which will be attractive for applications in respirators with lower weight and smaller size.