Spectrophotometric and fluorometric detection of DNA/BSA interaction, antimicrobial, anticancer, antioxidant and catalytic activities of biologically active methoxy substituted pyrimidine-ligand capped copper nanoparticles.

New Schiff base ligand (DPMN) was synthesized from the condensation of 2-hydroxy-5-nitrobenzaldehyde and 2-amino-4,6-dimethoxypyrimidine which was confirmed by spectroscopic and analytical methods. Solid air stable copper nanoparticles (DPMN-CuNPs) were synthesized from its copper chloride salt and it is stabilized by the prepared Schiff base ligand by phase transfer assisted synthesis which is a modified Brust-Schiffrin technique. The formation of ligand stabilized copper nanoparticles was confirmed by UV-Visible and FT-IR spectroscopic techniques. The size, surface morphology and quality of DPMN-CuNPs were analyzed by SEM and TEM techniques. Antioxidant activities of DPMN and DPMN-CuNPs with DPPH, SOD, peroxide and nitrous oxide were analyzed by electronic absorption spectroscopy. DNA interaction between DPMN and DPMN-CuNPs with CT-DNA was carried out using electronic absorption, fluorescence, viscometric measurements and cyclic voltammetric techniques. Interaction between BSA and the synthesized compounds analyzed by electronic absorption spectroscopy, Antimicrobial studies confirmed that the synthesized DPMN-CuNPs possess significant biological activities than DPMN. Anticancer results suggest that prepared DPMN-CuNPs have significant anticancer activity against different cancer cell lines and least toxic effect against the normal (NHDF) cell line. Other than the positive response in biological evaluation, our DPMN-CuNPs possess good catalytic activity in methyl orange reduction, methylene blue degradation and nitro phenol reduction.

Strong and nonspecific synergistic antibacterial/antibiofilm impact of nano-silver biosynthesized and decorated with active ingredients of Oscimum basilicum L.

In this study, Ocimum basilicum (a proven broad spectrum medicinal plant for broad-spectrum pharmacological activities) leaf extract was used as conjugates for the fabrication of silver nanoparticles (AgNP). Color change of the reaction mixture and UV-Visible spectrophotometry indicated the fabrication of silver nanoparticles, further X-ray diffraction (XRD) crystallography, scanning electron microscopy (SEM), transmission electron microscopic images (TEM), and Selected area electron diffraction (SAED) confirms the purity, monodispersity, and morphology including size (22.4 nm) and conjugated functional group of Ocimum basilicum. The conjugation of functional OH, N-O, and C=O groups was confirmed by Fourier-transform infrared spectroscopy (FT-IR). The engineered AgNP have shown significantly efficient antibacterial and antibiofilm activities (92.7% biofilm inhibition) on diverse clinical strains and thus showed its potential for use in clinical applications.

Environmentally Benign Carbon Nanodots Prepared from Lemon for the Sensitive and Selective Fluorescence Detection of Fe(III) and Tannic Acid.

Photoluminescent carbon nanodots (CNDs) were prepared using a biocarbon source of lemon extract. The obtained CNDs are of spherical shape and are enriched with the carboxylic acid fucntionalities. CNDs exhibited a fluorescence emission at 445 nm and unveiled blue luminescence in ultraviolet excitation. The influences of pH and ionic strength toward the stability of CNDs were investigated in detail and the obtained stability authenticates their applicability in different environmental conditions. The competitive binding of Fe3+ with CNDs quenches the fluorescence behavior of CNDs and was further quenched with the selective complex formation of Fe3+ with tannic acid (TA). The interference experiments specified that CNDs-Fe3+ assembly selectively detected TA and the co-existing molecules have not influenced the quenching effect of TA with CNDs-Fe3+. The analytical reliability of constructed sensor was validated from the recovery obtained in the range of 91.66-107.02% in real samples. Thus the low cost and environmentally benign CNDs prepared from natural biomass provide new avenues in the fluorescence detection of biologically significant metal ions and biomolecules, facilitating their competency in on-site applications of real environmental samples.

A Schiff's base receptor for red fluorescence live cell imaging of Zn2+ ions in zebrafish embryos and naked eye detection of Ni2+ ions for bio-analytical applications.

An interesting dual chemoreceptor (QAMP) was synthesized to quantify the presence of two environmentally as well as biologically important Zn2+/Ni2+ ions in a highly selective manner using different analytical techniques. The fluorescence profile was enhanced to 663 nm (red region) due to the formation of its 1 : 1 complex with Zn2+ at room temperature even in the presence of other interfering ions such as Cd2+ and Hg2+. Moreover, it exhibits excellent chromo-isomerism with Ni2+ ions. Meanwhile, this assay could be successfully oriented with molecular logic functions of AND, OR, NOR and NOT logic gates. The obtained large Stokes shift (∼274 nm) value and red emission promoted this receptor as a potential tool for biological studies (e.g. live cell imaging in cancer cell line and zebrafish models).

Mixed ligand copper(II) complexes of phenanthroline/bipyridyl and curcumin diketimines as DNA intercalators and their electrochemical behavior under Nafion and clay modified electrodes.

The mode of binding of copper(II) mixed ligand complexes of phen/bpy and Knoevenagel condensate of curcumin (4-salicylidene-1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione) and 4-X-anilines with herring sperm DNA has been investigated using spectral and electrochemical techniques in Tris-HCl buffer pH 7.1. On titration with DNA, usual hypochromism and unusual (large) red shift (30-35 nm) for some of these complexes were observed in their absorption spectra of intense intraligand (IL) pi-pi* transition around 420 nm. Variations in the absorbance due to their interaction with DNA on time scale were also investigated, under fixed concentrations of complex and DNA. On interaction with DNA, the quasi-reversible CuII/I redox couple slightly improves its reversibility with considerable decrease in current intensity. The intercalation of these copper complexes into the DNA base pairs was also investigated by gel retardation assay method. All the experimental results indicate that the phen mixed copper(II) complexes intercalate more effectively into the DNA base pairs than their bpy counterparts. Significant differences in the redox behavior of these copper(II) complexes under electrochemically modified GC electrodes with Nafion and K10 Montmorillonite clay have also been investigated and discussed.

Spectral and redox studies on mixed ligand complexes of cobalt(III) phenanthroline/bipyridyl and benzoylhydrazones, their DNA binding and antimicrobial activity.

Cobalt(III) complexes of the type [Co(N-N)2L](ClO4)2.H2O [where L=anionic form of para-substituted benzaldehyde-benzoylhydrazone (BHBX-); X=H, Me, OMe, OH, Cl or NO2; N-N=2,2'-bipyridine (bpy) or 1,10-phenanthroline (phen)] have been synthesized and characterized through UV-Vis, IR, NMR and electrochemical studies. The IR spectral frequencies support the mode of coordination of BHBX to the metal through the imino nitrogen and enolic oxygen atoms. The electronic absorption spectra exhibit metal to ligand charge transfer (MLCT) transition around 450 nm together with intraligand (IL) bands that are comparable to that of [Co(phen/bpy)3]3+. In acetonitrile solution these complexes show two well defined redox couples corresponding to Co(III/II) and Co(II/I) processes. Binding of these complexes with herring sperm DNA have been investigated by spectroscopic and voltammetric methods. The lower binding constant values of these complexes with respect to the [Co(phen/bpy)3]3+ are ascribed to the polar interaction of the substituted benzoylhydrazone moiety with the sugar-phosphate backbone of the DNA. The UV spectrum shows reasonable hypochromism with slight (2-4 nm) red shift, while the cyclic voltammogram shows decrease in current intensity along with a very small shift in the formal potential of the Co(III/II) redox couple. These experimental results indicate that phen mixed ligand complexes bind to DNA through an intercalative mode more effectively than their bpy counterparts. These complexes are also found to have good antimicrobial activity.