A novel strategy of nanosized herbal Plectranthus amboinicus, Phyllanthus niruri and Euphorbia hirta treated TiO2 nanoparticles for antibacterial and anticancer activities.

Titanium dioxide nanoparticles exhibit good anticancer and antibacterial activities. They are known to be environmentally friendly, stable, less toxic, and have excellent biocompatibility nature. Due to these properties, they are well suited for biological applications particularly in biomedical applications such as drug delivery and cancer therapy. In this research article, three medicinal herbs namely, Plectranthus amboinicus (Karpooravalli), Phyllanthus niruri (Keezhanelli), and Euphorbia hirta (Amman Pacharisi), were used to modify the surface of the TiO2 nanoparticles. The synthesized nanoparticles were subjected to various characterization techniques. The samples are then subjected to MTT assay to determine cell viability. KB oral cancer cells are used for the determination of the anticancer nature of the pure and bio modified nanoparticles. It is observed that Plectranthus amboinicus-Phyllanthus niruri modified TiO2 nanoparticles exhibit excellent anticancer activities among other bio modified and pure samples. The samples are then examined for antibacterial activities against three Gram-negative bacterial strains namely, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and two Gram-positive bacterial strains namely, Staphylococcus aureus and Streptococcus mutans, respectively. Among the modified and pure samples, Plectranthus amboinicus showed good antibacterial activity against Gram-positive and Gram-negative bacteria. In the Flow cytometry analysis, the generation of p53 protein expression from Plectranthus amboinicus-Phyllanthus niruri modified TiO2 nano herbal particles shows the anti-cancerous nature of the sample. Then to determine the toxic nature of the Plectranthus amboinicus-Phyllanthus niruri modified TiO2 nano herbal particles against normal cells, the NPs were subjected to MTT assay against normal L929 cells, and it was found to be safer and less toxic towards the normal cells.

Interface driven energy-filtering and phonon scattering of polyaniline incorporated ultrathin layered molybdenum disulphide nanosheets for promising thermoelectric performance.

The hybrid of organic conducting polymers and inorganic materials with ultralow thermal conductivity, which is a promising strategy for the realization of polymer based effective thermoelectric (TE) applications. In this work, ultrathin layered molybdenum disulphide (MoS2) nanosheets/PANI nanocomposites are prepared by hydrothermal route. The effect of varying PANI wt% in the nanocomposites and its interface effect on thermoelectric properties are well investigated. The successful incorporation of PANI between the MoS2 layers confirmed by high resolution transmission electron microscope (HRTEM). The significantly enhanced potential difference of MoS2/ PANI nanocomposites with increasing PANI content is well clarified by the increased Seebeck value. The variable range hopping property is identified and conductivity is raised up highly due to insertion of PANI in layered van der Waal's gap of MoS2. The effective interface facilitates charge for fast transport. The reduced thermal conductivity is observed of about 0.248 W*m-1*K-1 for 2.5 wt% addition of PANI. The key factor is that the stability of the sample is improved for MoS2/ PANI nanocomposites than pristine MoS2. Our work paved a new approach to improve TE performance by preparing TE MoS2 material through simple chemical route.

Bio-modified TiO2 nanoparticles with Withania somnifera, Eclipta prostrata and Glycyrrhiza glabra for anticancer and antibacterial applications.

Titanium dioxide nanoparticles exhibit good anticancer and antibacterial activities. They are known to be environmentally friendly and stable, less toxic and excellent biocompatibility nature. In this paper we report the biological properties of pure TiO2 nanoparticles modified with Withania somnifera (Ashwagandha), Eclipta prostrata (Karisalankanni) and Glycyrrhiza glabra (Athimathuram) for biological applications. X-ray diffraction results revealed the anatase nature of the samples. From the TEM analyses, it is observed that there is an increase in the particle size of the bio modified samples. UV results show the red shift for the bio modified samples when compared with the pure samples. The samples are then subjected to MTT assay to determine the cell viability. KB oral cancer cells are used for the determination of anticancer nature of the pure and bio modified nanoparticles. It is observed that Withania somnifera - Eclipta prostrate modified TiO2 nanoparticles exhibit excellent anticancer activities among other bio modified and pure samples. The samples are then examined for their antibacterial activities against three Gram-negative bacterial strains namely, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and two Gram-positive bacterial strains namely, Staphylococcus aureus and Streptococcus mutans. Among the modified and pure samples, Withania somnifera - Eclipta prostrata showed good antibacterial nature against Gram-positive and Gram-negative bacteria.

Ultrathin layered MoS2 nanosheets with rich active sites for enhanced visible light photocatalytic activity.

Edge-rich active sites of ultrathin layered molybdenum disulphide (MoS2) nanosheets were synthesized by a hydrothermal method. The effect of pH on the formation of MoS2 nanosheets and their photocatalytic response have been investigated. Structural and elemental analysis confirm the presence of S-Mo-S in the composition. Morphological analysis confirms the presence of ultrathin layered nanosheets with a sheet thickness of 10-28 nm at pH 1. The interplanar spacing of MoS2 layers is in good agreement with the X-ray diffraction and high-resolution transmission electron microscopy results. A comparative study of the photocatalytic performance for the degradation of methylene blue (MB) and rhodamine B (RhB) by ultrathin layered MoS2 under visible light irradiation was performed. The photocatalytic activity of the edge-rich ultrathin layered nanosheets showed a fast response time of 36 min with the degradation rate of 95.3% of MB and 41.1% of RhB. The photocatalytic degradation of MB was superior to that of RhB because of the excellent adsorption of MB than that of RhB. Photogenerated superoxide radicals were the key active species for the decomposition of organic compounds present in water, as evidenced by scavenger studies.

Ruthenium based metallopolymer grafted reduced graphene oxide as a new hybrid solar light harvester in polymer solar cells.

A new class of pyridyl benzimdazole based Ru complex decorated polyaniline assembly (PANI-Ru) was covalently grafted onto reduced graphene oxide sheets (rGO) via covalent functionalization approach. The covalent attachment of PANI-Ru with rGO was confirmed from XPS analysis and Raman spectroscopy. The chemical bonding between PANI-Ru and rGO induced the electron transfer from Ru complex to rGO via backbone of the conjugated PANI chain. The resultant hybrid metallopolymer assembly was successfully demonstrated as an electron donor in bulk heterojunction polymer solar cells (PSCs). A PSC device fabricated with rGO/PANI-Ru showed an utmost ~6 fold and 2 fold enhancement in open circuit potential (Voc) and short circuit current density (Jsc) with respect to the standard device made with PANI-Ru (i.e., without rGO) under the illumination of AM 1.5 G. The excellent electronic properties of rGO significantly improved the electron injection from PANI-Ru to PCBM and in turn the overall performance of the PSC device was enhanced. The ultrafast excited state charge separation and electron transfer role of rGO sheet in hybrid metallopolymer was confirmed from ultrafast spectroscopy measurements. This covalent modification of rGO with metallopolymer assembly may open a new strategy for the development of new hybrid nanomaterials for light harvesting applications.

Controlled synthesis of organic ligand passivated ZnO nanostructures and their photocatalytic activity under visible light irradiation.

Zinc oxide (ZnO) nanostructures were synthesized and their photocatalytic activity was evaluated using methylene blue (MB) as a model pollutant. Ethylenediamine (EDA) was used as a passivating agent to control the morphology and size of the ZnO nanostructures. In the absence of EDA, agglomerated ZnO nanoparticles were obtained. The addition of EDA at varying concentrations considerably influenced the morphological size. The as-prepared samples were extensively characterized using various techniques. The morphology- and size-dependent photocatalytic degradation of MB was studied under visible light irradiation. The maximum degradation efficiency was observed for ZnO nanoflakes; the MB-related absorbance peak completely disappeared after 15 min of irradiation. Furthermore, the effect of various photocatalytic reaction parameters, such as pH (3-12) of the solution, the concentration of the dye (5, 10, 15, and 20 ppm), and the dosage of the photocatalyst (25, 50, 75, and 100 mg L(-1)), on the photodegradation of MB was investigated to determine the maximum degradation efficiency. The optimum values of solution pH, dye concentration, and photocatalyst dosage were 11, 10 ppm, and 75 mg L(-1), respectively.

Effect of organic-ligands on the toxicity profiles of CdS nanoparticles and functional properties.

CdS nanoparticles are one among the most promising agents for fluorescent imaging. Hence, it is essential to develop new strategies to overcome the cytotoxicity of these nanoparticles. Surface modification is one of the simplest and effective techniques. This paper assesses the effect of surface modification on toxicity of the CdS nanoparticles. Unmodified CdS and surface-modified CdS nanoparticles were synthesized in an aqueous medium using a wet chemical route at room temperature. The surface modification of the CdS nanoparticles with polyvinylpyrrolidone (PVP) and cysteine was confirmed using infrared absorption studies. The diameters of unmodified CdS, PVP-modified CdS, and cysteine-modified CdS nanoparticles were determined using HRTEM. They exhibited luminescence in the range from 500 to 800 nm. The cytotoxic effects of these CdS nanoparticles were investigated in cultures of Vero cells. The results indicated that Vero cell viability was higher for the surface-modified CdS nanoparticles than for the unmodified CdS nanoparticles. The reduction in the toxicity was related to the nature of the capping agents used for the surface modification, and the particle size.

Amino acid-mediated synthesis of zinc oxide nanostructures and evaluation of their facet-dependent antimicrobial activity.

ZnO nanostructures (ZnO-NSs) of different morphologies are synthesized with the amino acids L-alanine, L-threonine, and L-glutamine as capping agents. X-ray diffraction (XRD) shows the formation of a crystalline wurtzite phase of ZnO-NSs. The surface modification of ZnO-NSs due to the capping agents is confirmed using Fourier transform infrared (FTIR) spectroscopy. Photoluminescence spectroscopy reveals that the concentration of surface defects correlates positively with the number of polar facets in ZnO-NSs. The antimicrobial activity of the ZnO-NSs has been tested against Escherichia coli and the common pathogens Staphylococcus aureus, Klebsiella pneumoniae, and Bacillus subtilis. Culture-based methods in rich medium show up to 90% growth inhibition, depending on the ZnO-NSs. Flow cytometry analyses indicate that the reactive oxygen species (ROS) generated by ZnO-NSs contribute mostly to the antibacterial activity. Control experiments in minimal medium show that amino acids and other reducing agents in Luria-Bertani (LB) medium quench ROS, thereby decreasing the antimicrobial activity of the ZnO-NSs.

Uniaxial growth of <100> zinc (tris) thiourea sulphate (ZTS) single crystal by Sankaranarayanan-Ramasamy (SR) method and its characterizations.

<100> directed single crystals of zinc (tris) thiourea sulphate, a semi-organic compound, have been grown at an average growth rate of 2mm per day by Sankaranarayanan-Ramasamy (SR) method. Transparent ZTS crystal of size 70mm length and 15mm diameter was grown. The growth conditions have been optimized. Chemical etching, Vickers microhardness, UV-Vis NIR, dielectric constant and dielectric loss analysis were made on conventional and SR method grown ZTS crystals. Thermo gravimetric and differential thermal analysis was carried out to determine the thermal properties of the grown crystal. The NLO efficiency of the crystal has been confirmed using the Kurtz powder technique. The comparative study indicates that the crystal quality of unidirectional grown ZTS crystal is better compared to conventional slow evaporation method grown crystal.

Growth and characterization of novel organic optical crystal: Anilinium D-tartrate (ADT).

A novel organic nonlinear optical (NLO) crystal of anilinium d-tartrate (abbreviated as ADT) has been grown by the solution growth (slow evaporation) method at room temperature. Transparent crystals of dimensions 4mm×2mm×1mm were obtained. The grown single crystal was subjected to different characterization analyses in order to find out its suitability for device fabrication. Single crystal X-ray diffraction analysis reveals that ADT crystallizes in triclinic system with non-centrosymmetric space group P1. FTIR spectrum was recorded to explore information of the functional groups. The placement of protons and carbon was determined using (1)H NMR and (13)C NMR spectral analyses. The SHG output of ADT was recorded by Kurtz-Perry powder technique. The range of optical absorption was ascertained by recording UV-vis spectrum. The PL spectrum of ADT shows green emission. The dielectric behavior of ADT was investigated at 30°C, 70°C and 105°C are reported. Thermal properties were investigated by thermo gravimetric, differential thermal and differential scanning calorimetric analyses.

Synthesis and characterization of a new organic nonlinear optical crystal: L-phenylalaninium maleate.

l-Phenylalaninium maleate (abbreviated as LPM) chemical formula C(9)H(12)NO(2)(+).C(4)H(3)O(4)(-), a new organic nonlinear optical crystal was grown by slow evaporation technique. Transparent needle shaped crystal of dimensions 7mmx1mmx0.5mm was obtained. Single crystals of LPM have been subjected to X-ray diffraction analysis to estimate the lattice parameters and the space group. The powder X-ray diffractogram of the crystal has been recorded and the reflections from various planes are identified. The XRD studies confirm the crystalline nature. The qualitative analysis on the crystal has been carried out using Fourier transform infrared (FTIR) and Fourier transform Raman (FTRaman) spectral measurements. The presence of hydrogen and carbon in the grown crystal was confirmed by using proton and carbon nuclear magnetic resonance (NMR) spectral analyses. Optical behaviour of the crystal was investigated using UV-vis spectroscopy. The thermal stability of the crystal was analysed with the aid of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The nonlinear optical (NLO) property of the crystal was tested by Nd:YAG laser source.