Hydrothermal and sonochemical synthesis of a nano-sized nickel(II) Schiff base complex as a precursor for nano-sized nickel(II) oxide; spectroscopic, catalytic and antibacterial properties

Fabrication of silicon-based nickel nanoflower-encapsulated gelatin microspheres as an active antimicrobial carrier

Local antibiotic application might mitigate the burgeoning problem of rapid emergence of antibiotic resistance in pathogenic microbes. To accomplish this, delivery systems must be engineered. Hydrogels have a wide range of physicochemical properties and can mimic the extracellular matrix, rendering them promising materials for local antibacterial agent application. Here, we synthesized antibacterial silicon (Si)-based nickel (Ni) nanoflowers (Si@Ni) and encapsulated them in gelatin methacryloyl (GelMA) using microfluidic and photo-crosslink technology, constructing uniform micro-sized hydrogel spheres (Si@Ni-GelMA). Si@Ni and Si@Ni-GelMA were characterized using X-ray diffraction, transmission electron microscopy, and scanning electron microscopy. Injectable Si@Ni-GelMA exhibited excellent antibacterial activities owing to the antibiotic effect of Ni against Pseudomonas aeruginosa, Klebsiella pneumoniae, and methicillin-resistant Staphylococcus aureus, while showing negligible cytotoxicity. Therefore, the Si@Ni-GelMA system can be used as drug carriers owing to their injectability, visible light-mediated crosslinking, degradation, biosafety, and superior antibacterial properties.

Synthesis of Cu(OH)2 nanowires modified by Fe3O4@SiO2 nanocomposite via green and innovative method with antibacterial activity and investigation of magnetic behaviours

In this study, green synthesis of modified Cu(OH)₂ nanowires by Fe₃O₄@SiO₂ core-shell nanospheres was easily performed via chemical reduction. In other words, the direct coating of Cu(OH)₂ on Fe₃O₄@SiO₂ was successfully realized without the extra complicated procedures. Various concentrations of synthesized nanocomposites were tested on pathogenic and nosocomial bacteria. In this study, the structural information and characterization of Fe₃O₄@SiO₂/Cu(OH)₂ nanowires (FSCNWs) were obtained using FE-SEM, FT-IR, EDX and X-ray diffraction. This nanocomposite can effectively kill important infectious bacteria, including Staphylococcus aureus, Escherichia coli, Staphylococcus saprophyticus, Pseudomonas aeruginosa and Klebsiella pneumoniae. Studies have shown that FSCNW nanocomposites affect common antibiotic-resistant bacteria. This result confirms the function of FSCNW as an effective, beneficial and environmentally friendly antibacterial agent that can used in a wide range of applications in medicine. FSCNWs can be separated conveniently from bacteria-containing solutions using a magnet. Compared with nanocomposites based on other metals such as silver and gold, the use of FSCNWs in water treatment has been recommended because of the precursor of copper for its low price and less toxicity. In addition to its special properties such as mild reaction conditions, green synthesis methods, admissible magnetic properties, easy separation, high antibacterial activity and beneficial efficiency.

Injectable hyaluronic acid hydrogel encapsulated with Si-based NiO nanoflower by visible light cross-linking: Its antibacterial applications

Bacterial infections have become a severe threat to human health and antibiotics have been developed to treat them. However, extensive use of antibiotics has led to multidrug-resistant bacteria and reduction of their therapeutic effects. An efficient solution may be localized application of antibiotics using a drug delivery system. For clinical application, they need to be biodegradable and should offer a prolonged antibacterial effect. In this study, a new injectable and visible-light-crosslinked hyaluronic acid (HA) hydrogel loaded with silicon (Si)-based nickel oxide (NiO) nanoflowers (Si@NiO) as an antibacterial scaffold was developed. Si@NiO nanoflowers were synthesized using chemical bath deposition before encapsulating them in the HA hydrogel under a mild visible-light-crosslinking conditions to generate a Si@NiO-hydrogel. Si@NiO synthesis was confirmed using scanning electron microscopy, transmission electron microscopy, and powder X-ray diffraction. As-prepared Si@NiO-hydrogel exhibited enhanced mechanical properties compared to a control bare hydrogel sample. Moreover, Si@NiO-hydrogel exhibits excellent antibacterial properties against three bacterial strains (P. aeruginosa, K. pneumoniae, and methicillin-resistant Staphylococcus aureus (>99.9% bactericidal rate)) and negligible cytotoxicity toward mouse embryonic fibroblasts. Therefore, Si@NiO-hydrogel has the potential for use in tissue engineering and biomedical applications owing to its injectability, visible-light crosslink ability, degradability, biosafety, and superior antibacterial property.

Biocompatible Core–Shell-Structured Si-Based NiO Nanoflowers and Their Anticancer Activity

Compared to most of nano-sized particles, core–shell-structured nanoflowers have received great attention as bioactive materials because of their high surface area with the flower-like structures. In this study, core–shell-structured Si-based NiO nanoflowers, Si@NiO, were prepared by a modified chemical bath deposition method followed by thermal reduction. The crystal morphology and basic structure of the composites were characterized by powder X-ray diffraction (PXRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), specific surface area (BET) and porosity analysis (BJT), and inductively coupled plasma optical emission spectrometry (ICP-OES). The electrochemical properties of the Si@NiO nanoflowers were examined through the redox reaction of ascorbic acid with the metal ions present on the surface of the core–shell nanoflowers. This reaction favored the formation of reactive oxygen species. The Si@NiO nanoflowers showed excellent anticancer activity and low cytotoxicity toward the human breast cancer cell line (MCF-7) and mouse embryonic fibroblasts (MEFs), respectively, demonstrating that the anticancer activities of the Si@NiO nanoflowers were primarily derived from the oxidative capacity of the metal ions on the surface, rather than from the released metal ions. Thus, this proves that Si-based NiO nanoflowers can act as a promising candidate for therapeutic applications.

New Antimicrobial Strategies Based on Metal Complexes

Traditional organic antimicrobials mainly act on specific biochemical processes such as replication, transcription and translation. However, the emergence and wide spread of microbial resistance is a growing threat for human beings. Therefore, it is highly necessary to design strategies for the development of new drugs in order to target multiple cellular processes that should improve their efficiency against several microorganisms, including bacteria, viruses or fungi. The present review is focused on recent advances and findings of new antimicrobial strategies based on metal complexes. Recent studies indicate that some metal ions cause different types of damages to microbial cells as a result of membrane degradation, protein dysfunction and oxidative stress. These unique modes of action, combined with the wide range of three-dimensional geometries that metal complexes can adopt, make them suitable for the development of new antimicrobial drugs.

Synthesis of nickel nanoparticles by a green and convenient method as a magnetic mirror with antibacterial activities

In this work, a simple protocol was described for the synthesis of nickel magnetic mirror nanoparticles (NMMNPs) including antibacterial activities. The identification of NMNPs was carried out by field-emission scanning electron microscopy (FESEM) images, energy-dispersive X-ray (EDX) analysis, X-ray diffraction (XRD) pattern, transmission electron microscopy (TEM) images and vibrating sample magnetometer (VSM) curve. The antibacterial activities are investigated against S. aureus and E. coli as the Gram-positive and Gram-negative bacteria, respectively. The UV-Vis absorption was also studied in the present of NMMNPs at different time intervals that disclosed decreasing of the bacterial concentration. More than 80% of the bacteria were disappeared after treating in the presence of NMMNPs for 18 h. The Ni-NPs revealed an excellent mirror attribute with a well-controlled transmission (7%). A better light-reflectivity over conventional glass or a mercury mirror proved their utility for domestic uses in comparison with conventional mirrors as rather toxic materials like mercury. Owing to its magnetic properties, this kind of mirror can be easily made onto glass by using an external magnet. An ordered crystalline structure, admissible magnetic properties, substantial antibacterial activities, tunable mirror properties, mild reaction conditions, and overall, the facile synthesis are the specific features of the present protocol for the possible uses of NMMNPs in diverse applications.

Metal complexes driven from Schiff bases and semicarbazones for biomedical and allied applications: a review

Schiff bases are versatile organic compounds which are widely used and synthesized by condensation reaction of different amino compound with aldehydes or ketones known as imine. Schiff base ligands are considered as privileged ligands as they are simply synthesized by condensation. They show broad range of application in medicine, pharmacy, coordination chemistry, biological activities, industries, food packages, dyes, and polymer and also used as an O2 detector. Semicarbazone is an imine derivative which is derived from condensation of semicarbazide and suitable aldehyde and ketone. Imine ligand-containing transition metal complexes such as copper, zinc, and cadmium have shown to be excellent precursors for synthesis of metal or metal chalcogenide nanoparticles. In recent years, the researchers have attracted enormous attention toward Schiff bases, semicarbazones, thiosemicarbazones, and their metal complexes owing to numerous applications in pharmacology such as antiviral, antifungal, antimicrobial, antimalarial, antituberculosis, anticancer, anti-HIV, catalytic application in oxidation of organic compounds, and nanotechnology. In this review, we summarize the synthesis, structural, biological, and catalytic application of Schiff bases as well as their metal complexes.

Fluorescent organotin compounds as dyes in silk fibroin (Bombyx mori): ultrasound-assisted synthesis, chemo-optical characterization, cytotoxicity, and confocal fluorescence microscopy

The fluorescent silk fibroin (FSF) is useful in a number of biomedical applications.

Synthesis of spherical Fe3O4 nanoparticles from the thermal decomposition of iron (III) nano-structure complex: DFT studies and evaluation of the biological activity

A novel Fe(III) Schiff base complex of the [FeL₂(NO₃)₂]NO₃ type where L = 2-((pyridin-4-yl)methyleneamino)-3-aminomaleonitrile was synthesized using the reflux and sonochemical methods and their antibacterial and antifungal activity were evaluated. The nanoparticles of iron oxide (Fe₂O₃) were obtained from the iron nano-structure complex as a precursor after calcination at 600 ˚C for 3 h. All the synthesized compounds were characterized by various spectroscopic techniques. The results of SEM showed that the morphology of iron nano-structure complex was rod-like while the morphology of the Fe₂O₃ nano powder was spherical. The results of the biological studies indicated that the iron nano-structure complex showed a stronger antibacterial and antifungal efficiency than its bulk complex. Finally, the empirical geometrical parameters of complexes revealed a good agreement with calculated ones at DFT-B3LYP level.

Synthesis and characterization of [Cu(salen)]2 coordination nano-assembly by a green and simple method

Hierarchical structured microplates consisting of nanoparticles were grown based on a self-assembly approach via a hydrothermal synthesis route without using any additive. Experimental parameters, such as reaction temperature, time and solvent play crucial roles in determining the morphology of final product. The nanoscale shape and macroscopically assembled architecture of [Cu(salen)]2 {salen = N,N′-bis(salicylidene)1,2-ethyelenediimine} crystals were totally controlled by preparation conditions for crystal growth. The synthesized [Cu(salen)]2 hierarchical architectures were characterized with UV-Vis, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermogravimetric (TGA) analyses. The thickness of the fabricated plates changes from 25 nm to 3.5 μm. The as-prepared nanoplates are actually composed of nanoparticles with diameters under 100 nm. Furthermore, the formation mechanism of the microplates decorated with nanorods has also been discussed, based on the influence of the kinetics of nucleation and crystal growth.

Cobalt(ii/iii), nickel(ii) and copper(ii) coordination clusters employing a monoanionic Schiff base ligand: synthetic, topological and computational mechanistic aspects

Nine coordination clusters (M = Co^II/III, Ni^II, Cu^II) using a monoanionic Schiff base ligand were synthesized and characterized. A series of transformations occur in the ligand in certain compounds.

Green synthesis of nanorod Ni(salen) coordination complexes using a simple hydrothermal method

New one-dimensional nanomaterials, nanorods of a Ni(salen) coordination compound, were synthesized by a hydrothermal route in green solvent without any surfactant.

Synthesis of wide band gap nanocrystalline NiO powder via a sonochemical method

A sonochemistry-based synthesis method was used to produce nanocrystalline nickel oxide powder with ≈ 20 nm average crystallite diameter from Ni(OH)(2) precursor. Ultrasound waves were applied to the primary solution to intensify the Ni(OH)(2) precipitation. Dried precipitates were calcined at 320°C to form nanocrystalline NiO particles. The morphology of the produced powder was characterized by transmission electron microscopy. Using sonochemical waves resulted in lowering of the size of the nickel oxide crystallites. FT-IR spectroscopy and X-ray diffraction revealed high purity well-crystallized structure of the synthesized powder. Photoluminescence spectroscopy confirmed production of a wide band-gap structure.