A series of N-substituted tetrabromphthalimide derivatives was synthesized by condensation reaction using tetrabromophthalic anhydride with 3,5-diamino-1,2,4-triazole/ 2,6-diaminopyridine/ 2,6-diamino-4-hydroxy pyrimidine/ o-tolidine. All the synthesized phthalimide derivatives were characterized by elemental analysis, infrared, and NMR spectroscopy. In vitro antibacterial evaluation was carried out for the synthesized compounds. Results revealed that compound 1 showed potential activity against Escherichia coli (100 μg/mL) and Streptococcus mutans (150 μg/mL). On the basis of antibacterial activity, compound 1 was selected for DNA binding interaction, though DNA target most of the antibacterial drugs. The DNA binding modes of the compound 1 with Ct-DNA (calf thymus) were studied by absorption measurements, hydrodynamic measurements and cyclic voltammetry methods. Molecular docking also confirms that compound 1 recognizes both the strands of the DNA dodecamer d(CGCGAATTC GCG) 2 within minor groove and showing the best binding capability with the duplex. Compound 1 also showed better antioxidant activity by 2,2-diphenyl-1-picryl-hydrazyl (DPPH) free radical and hydrogen peroxide.

The work reported in this paper describes the preparation, morphology, stability and sensitivity of Ag-nanoparticles towards sunlight using Allium sativum, garlic extract for the first time. The synthesized silver particles show an intense surface plasmon resonance band in the visible region at 410 nm. The position of the wavelength maxima, blue and red shift, strongly depends on the sunlight and pH. TEM analysis revealed the presence of spherical, different size (from 5.0 to 30 nm) and garlic constituents bio-conjugated, stabilized and/or layered silver nanoparticles. The concentrations of garlic extract, cetyltrimethylammonium bromide, Ag(+) ions and reaction time play vital roles for nucleus formation and the growth processes. Sulfur-containing biomolecules of extract, especially cysteine, are responsible for the reduction of Ag(+) ions into metallic Ag(0). The agglomeration number of the silver nanoparticles (N Ag) and the average number of free electrons per particle (n fe) are calculated and discussed.

Herein, we investigated new phthalimide-based Schiff base molecules as promising DNA-binding and free radical scavenging agents. Physicochemical properties of these molecules were demonstrated on the basis of elemental analysis, ultraviolet-visible (UV-Vis), infra-red (IR), H and C nuclear magnetic resonance (NMR) spectroscopy. All spectral data are agreed well with the proposed Schiff base framework. The DNA-binding potential of synthesized compounds were investigated by means of UV-visible, fluorescence, iodide quenching, circular dichroism, viscosity and thermal denaturation studies. The intrinsic binding constants (K ) were calculated from absorption studies were found to be 1.1 × 10 and 1.0 × 10 M for compounds 2a and 2b suggesting that compound 2a binding abilities with DNA were stronger than the compound 2b. Our studies showed that the presented compounds interact with DNA through groove binding. Molecular docking studies were carried out to predict the binding between Ct-DNA and test compounds. Interestingly, in silico predictions were corroborated with in vitro DNA-binding conclusions. Furthermore, the title compounds displayed remarkable antioxidant activity compared with reference standard.

Escherichia coli is a harmful Gram-negative bacterium commonly found in the gut of warm-blooded organisms and affects millions of people annually worldwide. In this study, we have synthesized a ZnO–CuO nanocomposite (NC) by a co-precipitation method and characterized the as-synthesized NC using FTIR spectroscopy, XRD, Raman spectroscopy, and FESEM techniques. To fabricate the immunosensor, the ZnO–CuO NC composite was screen-printed on gold-plated electrodes followed by physisorption of the anti-LPS E. coli antibody. The biosensor was optimized for higher specificity and sensitivity. The immunosensor exhibited a high sensitivity (11.04 μA CFU mL–1) with a low detection limit of 2 CFU mL–1 with a redox couple. The improved performance of the immunosensor is attributed to the synergistic effect of the NC and the antilipopolysaccharide antibody against E. coli. The selectivity studies were also carried out with Staphylococcus aureus to assess the specificity of the immunosensor. Testing in milk samples was done by spiking the milk samples with different concentrations of E. coli to check the potential of this immunosensor. We further checked the affinity between ZnO–CuO NC with E. coli LPS and the anti-LPS antibody using molecular docking studies. Atomic charge computation and interaction analyses were performed to support our hypothesis. Our results discern that there is a strong correlation between molecular docking studies and electrochemical characterization. The interaction analysis further displays the strong affinity between the antibody–LPS complex when immobilized with a nanoparticle composite (ZnO–CuO).

No abstract