In situ green synthesis of Ag nanoparticles on herbal tea extract (Stachys lavandulifolia)-modified magnetic iron oxide nanoparticles as antibacterial agent and their 4-nitrophenol catalytic reduction activity

Ag Nanoparticles Stabilized on Cyclodextrin Polymer Decorated with Multi-Nitrogen Atom Containing Polymer: An Efficient Catalyst for the Synthesis of Xanthenes

In attempt to broaden the use of cyclodextrin polymer for catalytic purposes, a novel covalent hybrid system was prepared through growth of multi-nitrogen atom containing polymer (PMelamine) derived from reaction of ethylenediamine and 2,4,6-trichloro-1,3,5-triazine on the functionalized cyclodextrin polymer (CDNS). The resulting hybrid system was then utilized as a catalyst support for the immobilization of silver nanoparticles through using Cuscuta epithymum extract as a naturally-derived reducing agent. The catalytic activity of the catalyst, Ag@CDNS-N/PMelamine, for the synthesis of xanthenes through reaction of aldehydes and dimedone in aqueous media was examined. The results showed high catalytic activity and recyclability of the catalyst. It was believed that cyclodextrin in the backbone of the catalyst could act both as a capping agent for Ag nanoparticles and phase transfer agent to bring the hydrophobic substrates in the vicinity of the catalytic active sites and accelerate the reaction rate. Multi-nitrogen atoms on the polymer, on the other hand, could improve the Ag NPs anchoring and suppress their leaching.

Nanocarrier-mediated antioxidant delivery for liver diseases

Liver is the principal detoxifying organ and metabolizes various compounds that produce free radicals (FR) constantly. To maintain the oxidative/antioxidative balance in the liver, antioxidants would scavenge FR by preventing tissue damage through FR formation, scavenging, or by enhancing their decomposition. The disruption of this balance therefore leads to oxidative stress and in turn leads to the onset of various diseases. Supplying the liver with exogeneous antioxidants is an effective way to recreate the oxidative/antioxidative balance in the liver homeostasis. Nevertheless, due to the short half-life and instability of antioxidants in circulation, the methodology for delivering antioxidants to the liver needs to be improved. Nanocarrier mediated delivery of antioxidants proved to be an ingenious way to safely and efficiently deliver a high payload of antioxidants into the liver for circumventing liver diseases. The objective of this review is to provide an overview of the role of reactive oxygen species (oxidant) and ROS scavengers (antioxidant) in liver diseases. Subsequently, current nanocarrier mediated antioxidant delivery methods for liver diseases are discussed.

Green Silver Nanoparticles Confined in Monolithic Silica Disk-packed Spin Column for Human Serum Albumin Preconcentration

Background:

In recent times many new uses have been found for nanomaterials that have undergone homogenous immobilization within porous supports. For this paper, immobilization of SNPs on a thiol-functionalized silica monolith using a fast, easy, environmentally friendly and costeffective process was performed. This was achieved by modifying the surface of a silica-based monolith using thiol groups, and then we fabricated green SNPs in situ, reducing an inorganic precursor silver nitrate solution (AgNO3) by employing tangerine peel extract as a reducing reagent, with Ag-thiol bonds forming along the monument. Doing this allows monoliths to be prepared in such a way that, as TEM analysis demonstrated, SNPs are evenly distributed along the rod's length. Once the materials had been fabricated, they were employed as a sorbent by being placed in a centrifuge. The SNP-thiol functionalized silica monolith was then tested using a standard protein (HSA).

Methods:

The process involves creating monolithic materials by employing a two-part sol-gel technique before modifying the surface of the silica-based monolith using thiol groups for hosting purposes. Homogenous surface coverage was achieved through the use of a non-toxic "green" reducing reagent (tangerine peel extract) to reduce a silver nitrate solution in place to create SNPs joined to the pore surface of a thiol-functionalized silica monolith, employing bonds of Ag-thiol. Once these materials were synthesized, they were classified by utilizing a number of methods based on SEM coupled with EDAX, TEM, AFM and BET analysis. The silica-based monolith, embedded with constructed SNPs, was employed as a sorbent in the preconcentration of human serum albumin (HSA).

Results:

The performance of the fabricated materials was measured against a silica-based monolith with no SNPs. Also, a silica monolith with constructed SNPs embedded was employed to capture HSA within a sample of human urine mixed with a double detergent concentrate (SDS). Such a monolith containing functionalized SNPs can be a highly effective sorbent for preconcentration of proteins in complex samples.

Conclusion:

It was shown to have superior performance compared to a bare silica-based monolith. Additionally, it was shown that a monolithic column modified by SNPs could preconcentrate spiked HSA in urine samples.

Antibacterial, Antibiofilm, Antiquorum Sensing, Antimotility, and Antioxidant Activities of Green Fabricated Ag, Cu, TiO2, ZnO, and Fe3O4 NPs via Protoparmeliopsis muralis Lichen Aqueous Extract against Multi-Drug-Resistant Bacteria

Consideration of lichen organisms as the ecofriendly source of metal nanoparticles (MNPs) and metal oxide NPs (MONPs) synthesis is seldom. In this study, Ag and Cu MNPs as well as TiO₂, ZnO, and Fe₃O₄ MONPs were green synthesized by Protoparmeliopsis muralis lichen aqueous extract. First, physicochemical characterization by UV-vis spectroscopy, XRD, FT-IR, FESEM, and TEM techniques demonstrated the presence possibility of secondary metabolites around formed MNPs/MONPs with different diameters and shapes (spherical, triangular, polyhedral, and cubic). The antibacterial, antibiofilm, antiquorum sensing, and antioxidant abilities of these MNPs/MONPs against multi drug resistant (MDR) bacterium (Staphylococcus aureus ATCC 43300) and reference bacteria (Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853) were then evaluated by in vitro tests. Results of disc diffusion and MIC/MBC assays of Ag NPs as an effective antibacterial agent illustrated a higher sensitivity of the P. aeruginosa pathogen than E. coli and S. aureus. In next steps, a significant reduction was observed in the biofilm formation of each bacterium and pyocyanin synthesis by P. aeruginosa under Ag NPs. This investigation presents novel clean production of five MNPs/MONPs with prominent advantages of being ecofriendly and cost-effective and having antipathogen properties.

Synergistic effects of multi-active sites in silver modified Bi°-BiVO4 toward efficient reduction of aromatic nitrobenzene

In this work, we report on the preparation of silver nanoparticles modified bismuth/bismuth vanadate (Bi°-BiVO₄) catalyst with multi-active sites toward efficient reduction of aromatic nitrobenzene, aiming to tailor the synergistic effects of multi-active sites and specify the underlying catalytic mechanism. The as-prepared catalysts were characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray and X-ray photoelectron spectroscopy. It is observed that Ag nanoparticles with diameter of ˜30 nm were anchored evenly on the surface of rod-shaped BiVO₄, which offered multi-active sites to contact with the reactants effectively and transfer interfacial electron to 4-nitrophenol (4-NP) rapidly. The activity factor k of Ag/Bi°-BiVO₄ for 4-NP reduction is estimated to ˜3933.4 min^-1 g^-1, which is much higher than that obtained from pristine BiVO₄ catalyst, Bi° and noble metal Ag nanoparticles. According to the experimental results, the reaction mechanism and reaction path of 4-NP reduction for BiVO₄, Bi and Ag were studied through the density functional theory (DFT) theoretical calculation, which suggested that they exhibit synergistic catalytic effect in the reaction process. This work may provide a feasible foundation for the mechanism research of semiconductor reduction to 4-nitrophenol.

Facile and Robust Solvothermal Synthesis of Nanocrystalline CuInS₂ Thin Films

This work demonstrates that the solvothermal synthesis of nanocrystalline CuInS₂ thin films using the amino acid l-cysteine as sulfur source is facile and robust against variation of reaction time and temperature. Synthesis was carried out in a reaction time range of 3–48 h (at 150 °C) and a reaction temperature range of 100–190 °C (for 18 h). It was found that at least a time of 6 h and a temperature of 140 °C is needed to produce pure nanocrystalline CuInS₂ thin films as proven by X-ray and electron diffraction, high-resolution transmission electron microscopy, and energy-dispersive X-ray spectroscopy. Using UV-vis spectroscopy, a good absorption behavior as well as direct band gaps between 1.46 and 1.55 eV have been determined for all grown films. Only for a reaction time of 3 h and temperatures below 140 °C CuInS₂ is not formed. This is attributed to the formation of metal ion complexes with l-cysteine and the overall slow assembly of CuInS₂. This study reveals that the reaction parameters can be chosen relatively free; the reaction is completely nontoxic and precursors and solvents are rather cheap, which makes this synthesis route interesting for industrial up scaling.