Kadarkaraithangam Jeyasubramanian

Selective toxicity of ZnO nanoparticles toward Gram-positive bacteria and cancer cells by apoptosis through lipid peroxidation

UNLABELLED Nanoparticles are increasingly recognized for their utility in biological applications including nanomedicine. The present study investigated the toxicity of zinc oxide (ZnO) nanoparticles toward prokaryotic and eukaryotic cells. Cytotoxicity of ZnO to mammalian cells was studied using human myeloblastic leukemia cells (HL60) and normal peripheral blood mononuclear cells (PBMCs). Antibacterial activity of ZnO was also tested against the Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa, as well as the Gram-positive bacterium Staphylococcus aureus, and the effect was more pronounced with the Gram-positive than the Gram-negative bacteria. ZnO nanoparticles exhibited a preferential ability to kill cancerous HL60 cells as compared with normal PBMCs. The nanoparticles enhanced ultrasound-induced lipid peroxidation in the liposomal membrane. The work suggested two mechanisms underlying the toxicity of ZnO: (i) involvement of the generation of reactive oxygen species (ROS) and (ii) induction of apoptosis. The work also revealed potential utility of ZnO nanoparticles in the treatment of cancer, for their selective toxicity to cancer cells. FROM THE CLINICAL EDITOR The toxicity of zinc oxide to bacteria was related to the generation of reactive oxygen species and to the induction of apoptosis. Interestingly, these effects were differentially greater in human myeloblastic leukemia cells (HL60) than normal peripheral blood mononuclear cells.

Synthesis, spectral, redox and antimicrobial activities of Schiff base complexes derived from 1-phenyl-2,3-dimethyl-4-aminopyrazol-5-one and acetoacetanilide

Novel terdentate neutral complexes of CuII, NiII, CoII, MnII, ZnII, CdII, HgII, VOII, ZrOII and UO2II have been prepared using a Schiff base derived from 1-phenyl-2,3-dimethyl-4-aminopyrazol-5-one (4-aminoantipyrine) and acetoacetanilide. The structural features of the chelates have been confirmed by microanalytical data, i.r., u.v.–vis., 1H-n.m.r., e.s.r. and mass spectral techniques. Electronic absorption and i.r. spectra of the complexes indicate an octahedral geometry around the central metal ion, except for the VOII and ZrOII complexes which show square pyramidal geometry. The monomeric and neutral nature of the complexes are confirmed from their magnetic susceptibility and low conductance values. The cyclic voltammogram of the copper complex in MeCN at 300 K shows a quasi-reversible peak for the couple CuII/CuIII at Epc = 0.47 and Epa = 0.61 V versus Ag/AgCl and two irreversible peaks for CuII → CuI and CuI → Cu0 reduction at Epc = −0.63 and − 0.89 V respectively. The e.s.r. spectra of copper and vanadyl complexes in DMSO solution at 300 K and 77 K were recorded and their salient features are reported. The molecular orbital coefficients (α2, β2) were calculated for complexes. The antimicrobial activity of the ligand and its complexes have been extensively studied on microorganisms such as Staphylococcus aureus, Klebsiela pneumoniae, Bacillus subtillis, Escherichia coli, Citrobacter ferundii and Salmonella typhi. Most of the complexes have higher activities than that of the free ligand.

Redox and antimicrobial studies of transition metal(II) tetradentate Schiff base complexes

Neutral tetradentate chelate complexes of CuII, NiII, CoII, MnII, ZnII and VOII have been prepared in EtOH using Schiff bases derived from acetoacetanilido-4-aminoantipyrine and 2-aminophenol/2-aminothiophenol. Microanalytical data, magnetic susceptibility, i.r., u.v.–vis., 1H-n.m.r. and e.s.r. spectral techniques were used to confirm the structures of the chelates. Electronic absorption and i.r. spectra of the complexes suggest a square-planar geometry around the central metal ion, except for VOII and MnII complexes which have square-pyramidal and octahedral geometry respectively. The cyclic voltammetric data for the CuII complexes in MeCN show two waves for copper(II) → copper(III) and copper(II) → copper(I) couples, whereas the VOII complexes in MeCN show two waves for vanadium(IV) → vanadium(V) and vanadium(IV) → vanadium(III) couples. The e.s.r. spectra of the CuII, VOII and MnII complexes were recorded in DMSO solution and their salient features reported. The in vitro antimicrobial activity of the investigated compounds was tested against the microorganisms such as Salmonella typhi, Staphylococcus aureus, Klebsiella pneumoniae, Bacillus subtilis, Shigella flexneri, Pseudomonas aeruginosa, Aspergillus niger and Rhizoctonia bataicola. Most of the metal chelates have higher antimicrobial activity than the free ligands.

SYNTHESIS, SPECTROSCOPIC CHARACTERIZATION, REDOX, AND BIOLOGICAL SCREENING STUDIES OF SOME SCHIFF BASE TRANSITION METAL(II) COMPLEXES DERIVED FROM SALICYLIDENE-4-AMINOANTIPYRINE AND 2-AMINOPHENOL/ 2-AMINOTHIOPHENOL

Neutral complexes of Cu(II), Ni(II), Co(II), Mn(II), VO(IV) and Zn(II) have been synthesised from the Schiff bases derived from salicylidene-4-aminoantipyrine and 2-aminophenol/2-aminothiophenol. The structural features have been arrived at from their microanalytical, IR, UV-Vis., 1H NMR and ESR spectral data. All of the complexes exhibit square-planar geometry except the Mn(II) and VO(IV) complexes. The Mn(II) chelates show an octahedral environment and the VO(IV) chelates exist in a square-pyramidal geometry. The non-electrolytic and monomeric nature of the complexes are evidenced by their magnetic susceptibility and low conductance data. The electrochemical behaviour of the Cu(II), Mn(II) and VO(IV) complexes in DMSO at 300 °K were studied. [CuL1] complex shows an irreversible peak for the copper(II)/copper(I) couple at Epc1 = 0.16 V and Epa = 0.53V referenced to Ag/AgCl. The cyclic voltammogram of the [CuL2] complex in MeCN at 300°K shows a quasi-reversible peak for the couples copper(II)/copper(III) at Epc = 0.47 V and Epa = 0.61 V versus Ag/AgCl and two irreversible peaks for the copper(II) → copper(I) and copper(I) → copper(0) reduction at Epc = -0.63 V and -0.89 V, respectively. The [ MnL1] complex shows two irreversible couples, manganese(II)/manganese(I) and manganese(I)/manganese(0) at Epc = -0.10 V and -0.84 V with the direct oxidation at Epa = -0.70 V and -0.04 V, respectively. X-band ESR spectra of the Cu(II) and VO(IV) complexes in DMSO at 300 and 77°K were recorded and their salient features are reported. The biological activities of the metal chelates against the bacteria Staphylococcus aureus, Bacillus subtilis, Klebsiella pneumoniae, Salmonella typhi, Pseudomonas aeruginosa and Shigella flexneri and the fungi Aspergillus nigerand Rhizoctonia bataicolaare also reported. Most of the complexes have higher activities than those of the free Schiff bases and the control.

SYNTHESIS, SPECTRAL, REDOX, AND ANTIMICROBIAL ACTIVITY OF SCHIFF BASE TRANSITION METAL(II) COMPLEXES DERIVED FROM 4-AMINOANTIPYRINE AND BENZIL

ABSTRACT A novel quadridentate, N2O2-type Schiff base, synthesised from 1-phenyl-2,3-dimethyl-4-aminopyrazol-5-one (4-aminoantipyrine) and benzil, forms stable complexes with transition metal ions such as Cu(II), Ni(II), Co(II), Mn(II), Zn(II) and VO(IV) in ethanol. Microanalytical data, magnetic susceptibility, IR, UV-Vis., 1H NMR, ESR and mass spectral techniques were used to confirm the structures. Electronic absorption and IR spectra of the complexes suggest an octahedral geometry around the central metal ion, except for the VO(IV)complex which has a square pyramidal geometry. The non-electrolytic behaviour of the chelates was assessed from the low conductance data, except for the vanadyl complex and the dipyridinyl adducts of the copper complexes which show a higher conductance, supporting an electrolytic nature of these complexes. The monomeric nature of the chelates was confirmed by their magnetic susceptibility values. Cyclic voltammograms of the [CuLCl2] and [CuL(OAc)2] complexes in DMSO solution at 300 K show a quasi-reversible peak for the Cu(II)/Cu(I) couple at Epa=−0.02 V and 0.54 V and Epc=−0.28 V and 0.23 V, respectively. The peak potentials were found to be solvent-dependent. The cyclic voltammogram of the[VOL]SO4 complex in MeCN shows a quasi-reversible peak for the VO(IV)/VO(V) couple and another peak characteristic for the VO(IV)/VO(III) couple. The X-band ESR spectra of copper, manganese and vanadyl complexes in DMSO solution were recorded and their M.O. coefficients were also calculated. The in vitro antimicrobial activity of the investigated compounds and uncomplexed metal salts were tested against bacteria such as Staphylococcus aureus, Bacillus subtilis, Klebsiella pneumoniae, Salmonella typhi, Pseudomonous aeruginosa, Shigella flexneri and fungi such as Aspergillus niger and Rhizoctonia bataicola. Most of the metal chelates show higher antimicrobial activity for the above microorganisms than the free ligand and lower activity than the uncomplexed metal salts.

Synthesis, Structural Characterization, Redox, and Antibacterial Studies of 12‐Membered Tetraaza Macrocyclic Cu(II), Ni(II), Co(II), Zn(II), and VO(IV) Complexes Derived from 1,2‐(Diimino‐4′‐antipyrinyl)‐1,2‐diphenylethane and o‐Phenylenediamine

Abstract A tetraaza macrocyclic Schiff base (L), synthesized from 1,2‐(diimino‐4′‐antipyrinyl)‐1,2‐diphenylethane and o‐phenylenediamine, acts as a tetradentate ligand and forms solid cationic complexes with Cu(II), Ni(II), Co(II) and VO(IV) salts in ethanol. All the synthesized compounds were characterized by microanalytical data, magnetic susceptibility measurements, IR, UV‐Vis., 1H NMR, 13C NMR, ESR and mass spectral techniques. The IR and UV‐Vis. spectral data and magnetic susceptibilities of the complexes suggest that the [CuL]Cl2, [NiL]Cl2, [CoL]Cl2 and [ZnL]Cl2 complexes exhibit square‐planar geometry whereas the [CuL(Y)2]Cl2 complexes show octahedral geometry, where Y = pyridine (py), imidazole (im) or triphenylphosphine (PPh3). The [VOL]SO4 complex has a square‐pyramidal geometry. The electrolytic behaviour of the chelates was assessed from their molar conductance data. The monomeric nature of the chelates was confirmed from their magnetic susceptibility values. Cyclic voltammogram of the [CuL]Cl2 complex in MeCN reveals that the unusual oxidation states such as Cu(III), Cu(I) and Cu(0) are stabilized by the ligand systems. The [CuL(py)2]Cl2 and [CuL(im)2]Cl2 complexes strongly enhance the copper(0) → copper(II) oxidation while the [CuL(PPh3)2]Cl2 complex completely suppresses the Cu(II)/Cu(III) couple and copper(0) → copper(II) oxidation. The cyclic voltammogram of the Ni(II), Co(II) and VO(IV) complexes were also recorded in MeCN solution and their salient features are reported. The ESR spectra of the copper and vanadyl complexes in DMSO solution at 300 and 77 K were recorded and their M.O. coefficients were calculated. The investigated compounds and uncomplexed metal salts were tested against bacteria like Staphylococcus aureus, Bacillus subtilis, Klebsiella pneumoniae, Salmonella typhi, Pseudomonas aeruginosa and Shigella flexneri. The metal salts have higher activity than the free ligand and the metal chelates.

Enhancement in growth rate and productivity of spinach grown in hydroponics with iron oxide nanoparticles

Plants play a vital role in the energy and environmental ecosystem by providing food and oxygen for living organisms. Due to the increasing use of nanoparticles in the recent decade, the study on the effect of nanoparticles in environmental sectors (especially in agriculture) has become highly essential. In this study, we demonstrated the uptake of iron oxide (Fe2O3) nanoparticles by spinach via hydroponics and examined its effects on the growth rate and productivity of the spinach plant. The experimental studies such as plant growth (stem and root length) and biomass analysis revealed a dose and time dependent increase due to the uptake of Fe2O3. The vibrating sample magnetometer analysis revealed the increase in saturation magnetization of spinach plants as result of Fe uptake. Further, ICP analysis demonstrated an increase in iron content in spinach plants in a dose dependent manner. A mechanism for the uptake of Fe2O3 nanoparticles has been discussed with the help of FT-IR spectroscopy. The experimental studies might provide new insights into the application of Fe2O3 nanoparticles in the agriculture sector.

Novel and simple approach using synthesized nickel nanoparticles to control blood-sucking parasites.

The present study was on assessment of the anti-parasitic activities of nickel nanoparticles (Ni NPs) against the larvae of cattle ticks Rhipicephalus (Boophilus) microplus and Hyalomma anatolicum (a.) anatolicum (Acari: Ixodidae), fourth instar larvae of Anopheles subpictus, Culex quinquefasciatus and Culex gelidus (Diptera: Culicidae). The metallic Ni NPs were synthesized by polyol process from Ni-hydrazine as precursor and Tween 80 as both the medium and the stabilizing reagent. The synthesized Ni NPs were characterized by Fourier transform infrared (FTIR) spectroscopy analysis which indicated the presence of Ni NPs. Synthesized Ni NPs showed the X-ray diffraction (XRD) peaks at 42.76°, 53.40°, and 76.44°, identified as 111, 220, and 200 reflections, respectively. Scanning electron microscopy (SEM) analysis of the synthesized Ni NPs clearly showed that the Ni NPs were spherical in shape with an average size of 150 nm. The Ni NPs showed maximum activity against the larvae of R. (B.) microplus, H. a. anatolicum, A. subpictus, C. quinquefasciatus and C. gelidus with LC(50) values of 10.17, 10.81, 4.93, 5.56 and 4.94 mg/L; r(2) values of 0.990, 0.993, 0.992, 0.950 and 0.988 and the efficacy of Ni-hydrazine complexes showed the LC(50) values of 20.35, 22.72, 8.29, 9.69 and 7.83 mg/L; r(2) values of 0.988, 0.986, 0.989, 0.944 and 0.978, respectively. The findings revealed that synthesized Ni NPs possess excellent larvicidal parasitic activity. To the best of our knowledge, this is the first report on larvicidal activity of blood feeding parasites using synthesized Ni NPs.

Enhanced photodynamic efficacy and efficient delivery of Rose Bengal using nanostructured poly(amidoamine) dendrimers: potential application in photodynamic therapy of cancer

Photodynamic therapy (PDT) is a promising treatment methodology whereby diseased cells and tissues are destroyed by reactive oxygen species (ROS) by using a combination of light and photosensitizers (PS). The medical application of Rose Bengal (RB), photosensitizer with very good ROS generation capability, is limited due to its intrinsic toxicity and insufficient lipophilicity. In this report, we evaluate the potential of polyamidoamine (PAMAM) dendrimers in delivering RB and its phototoxic efficiency towards a model cancer cell line. The spherical, nanoscaled dendrimers could efficiently encapsulate RB and showed characteristic spectral responses. The controlled release property of dendrimer–RB formulation was clearly evident from the in vitro drug release study. ROS generation was confirmed in dendrimer–RB system upon white light illumination. Photosensitization of Dalton’s Lymphoma Ascite (DLA) cells incubated with dendrimer–RB formulation caused remarkable photocytotoxicity. Importantly, the use of dendrimer-based delivery system reduced the dark toxicity of RB.

Evaluating the effect of SiC content on iron-based nanocomposite

Iron has wide application in manufacturing industries and the objective of this study is to investigate the effect of silicon carbide (SiC) particles on iron-based nanocomposites. SiC is effectively reinforced into iron matrix by mechanical alloying process using high-energy ball mill. The Fe–SiC nanocomposites with various compositions of SiC viz., 15%, 20% and 25% are characterised using X-ray diffraction and atomic force microscopy. The nanocomposite powders are compacted and sintered into pellets. Their elastic properties, hardness and Poissons ratio are determined using the pulse echo technique. Moreover, the densities of the pellets are measured using Archimedes’ principle by the water immersion method.