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Studies on the significance of the metal centre on the activity of metal complexes have been less reported. Herein, we reported the synthesis and structural characterisation of copper and zinc complexes containing a Schiff-base type ligand, N,N′-bis(salicylidene)-9-(3,4-diaminophenyl)acridine (H2daasal). Single crystal X-diffraction analysis revealed that the structure of [Zn(daasal)] was monoclinic (space group P121/n1, unit cell parameters a = 10.6126(3) A, b = 30.5317(10) A, c = 11.0273(3) A, α = 90°, β = 111.0380(10) A, γ = 90°, V = 3334.90(17) A3, and Z = 4) with a dihedral angle of 74° across the salophen and acridine moieties. Electron spin resonance (ESR) spectroscopy studies suggested that [Zn(daasal)] was diamagnetic and [Cu(daasal)] was paramagnetic. ESR spectral analysis revealed that the monomeric form of [Cu(daasal)] was either square planar or square pyramidal. Detailed spectroscopic analysis and viscosity studies indicate that [Cu(daasal)] binds efficiently to CT DNA (∼9 times) than [Zn(daasal)], with a slight preference for the acridine unit rather than the salen moiety. Molecular docking studies suggest that [Cu(daasal)] efficiently intercalates into DNA with higher free energy values than the [Zn(daasal)] complex. Photocleavage studies reveal that [Cu(daasal)] cleaves plasmid pBR322 DNA effectively in the presence of a reducing agent. The mechanistic studies suggest that superoxide anion radicals (O2−˙) are formed as an intermediate and proceed to produce hydroxyl radicals (OH˙) to induce DNA photocleavage. In summary, we demonstrated that changing the metal centre in an effective ligand may offer an attractive method to produce efficient DNA intercalators.

Nitrated fatty acids (NO2 -FAs) act as anti-inflammatory signal mediators, albeit the molecular mechanisms behind NO2 -FAs' influence on diverse metabolic and signaling pathways in inflamed tissues are essentially elusive. Here, we combine fluorescence measurements with surface-specific sum frequency generation vibrational spectroscopy and coarse-grained computer simulations to demonstrate that NO2 -FAs alter lipid organization by accumulation at the membrane-water interface. As the function of membrane proteins strongly depends on both, protein structure as well as membrane properties, we consecutively follow the structural dynamics of an integral membrane protein in presence of NO2 -FAs. Based on our results, we suggest a molecular mechanism of the NO2 -FA in vivo activity: Driven by the NO2 -FA-induced lipid layer reorganization, the structure and function of membrane-associated (signaling) proteins is indirectly affected.

Herein, we present a simple and green method for the synthesis of gold nanoparticles (AuNPs) using the phytoproteins of spinach leaves. Under ambient sunlight irradiation, the isolated phytoprotein complex from spinach leaves reduces the gold chloride aqueous solution and stabilizes the formed AuNPs. As prepared nanoparticles were characterized by UV-visible spectroscopy, Fourier transform infra-red (FTIR) spectroscopy, zeta potential, transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDS). The surface plasmon resonance (SPR) maximum for AuNPs was observed at 520 nm. The zeta potential value estimated for the AuNPs is -27.0 mV, indicating that the NPs are well separated. Transmission electron micrographs revealed that the particles are spherical in nature with the size range from 10 to 15 nm. AuNPs act as a catalyst in the degradation of an azo dye, methyl orange in an aqueous environment. The reduction rate was determined to be pseudo-first order. Electrocatalytic efficiency of the synthesized AuNPs via this green approach was studied by chronoamperometry using ascorbic acid and hydrogen peroxide as a model compound for oxidation and reduction, respectively. Electrocatalytic studies indicate that the gold nanoparticles can be used to detect ascorbic acid and hydrogen peroxide in micromolar concentrations with response time less than 3s.

An easily accessible chemo-probe based on physical mixture of 2,4-dimethylpyrrole and 4-nitrobenzaldehyde has been developed. Based on NMR spectroscopic analysis, catalyst free formation of dipyrromethane was observed in the physical mixture of chemo-probe. The probe is utilized in effective colorimetric sensing of copper(II) ions present in environmental solutions by instantaneous appearance of red colour, even in the co-existence of various metal ions. The lowest detection limit of 2.51 μM for this chemo-probe towards copper(II) sensing is significantly lower than the WHO prescribed level (

With a vision of finding greener materials to synthesize nanoparticles, we report the production and isolation of levan, a polysaccharide with repeating units of fructose, from Acetobacter xylinum NCIM2526. The isolated levan were characterized using potassium ferricyanide reducing power assay, Fourier transform infra-red (FTIR) spectroscopy and (1)H nuclear magnetic resonance spectroscopy ((1)H NMR). To exploit levan in nanotechnology, we present a simple and greener method to synthesize silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) using biopolymer, levan as both reducing and stabilizing agents. The morphology and stability of the AgNPs and AuNPs were examined by transmission electron microscopy (TEM) and UV-vis absorption (UV-vis) spectroscopy. The possible capping mechanism of the nanoparticles was postulated using FTIR studies. As synthesized biogenic nanoparticles showed excellent catalytic activity as evidenced from sodium borohydride mediated reduction of 4-nitro phenol and methylene blue.

A facile method was reported for preparing silver nanoparticles (AgNPs) based on naturally occurring N -acylethanolamine (NAE) as a capping agent and sodium borohydride as a reducing agent. NAEs have been found in the infracted areas of canine myocardium and ischemic brain tissues. AgNPs prepared by N -steroylethanolamine (NSEA) are very stable and can be reliably and reproducibly synthesized. These particles have a capability to selective colorimetric sensing of the potentially hazardous Hg 2+ ion in water at micromolar concentration. The proposed method was successfully employed for the determination of Hg 2+ ion in blood plasma and also in various water bodies, such as tap water, pond water and sewage water. Further, degradation of hazardous organic pollutant, methylene blue dye, was explored using NSEA–AgNPs as catalyst. Besides selective sensing of Hg 2+ and degrading hazardous dye, NSEA–AgNPs also shows excellent catalytic activity in the reduction of nitro aromatics. In addition, NSEA–AgNPs shows bactericidal effect in Gram-positive and Gram negative test bacteria, for which the values of minimum inhibitory concentration were determined and reported. In summary, the NSEA–AgNPs reported in this work was a promising candidate for versatile application, such as a sensor, antimicrobial and catalyst.

Owing to the benign nature, plant extracts mediated green synthesis of metal nanoparticles (NPs) is rapidly expanding. In this study, we demonstrated the successful green synthesis of silver nanoparticles (AgNPs) by utilizing natural sunlight and redox protein complex composed of ferredoxin–NADP+ reductase (FNR) and ferredoxin (FD). The capping and stabilization of the AgNPs by the redox protein was confirmed by Fourier transform infrared spectroscopy. Light and redox protein is the prerequisite factor for the formation of AgNPs. The obtained result shows that the photo generated free radicals by the redox protein is responsible for the reduction of Ag+ to Ag0. Transmission electron microscopy revealed the formation of spherical AgNPs with size ranging from 10 to 15 nm. As-prepared AgNPs exhibit excellent catalytic activity toward the degradation of hazardous organic dyes, such as methylene blue, methyl orange and methyl red. These bio-inspired AgNPs is highly sensitive and selective in sensing hazardous mercury ions in the water at micromolar concentration. In addition, FNR/FD extract stabilized AgNPs showed good antimicrobial activity against gram positive and gram negative bacteria.