T. V. M. Sreekanth

Occurrence, physiological responses and toxicity of nickel in plants

The focus of the review is on the specific aspects of nickel’s effects on growth, morphology, photosynthesis, mineral nutrition and enzyme activity of plants. The mobility of nickel in the environment and the consequent contamination in soil and water is of great concern. Also, the detrimental effects of excessive nickel on plant growth have been well known for many years. Toxic effects of nickel on plants include alterations in the germination process as well as in the growth of roots, stems and leaves. Total dry matter production and yield was significantly affected by nickel and also causes deleterious effects on plant physiological processes, such as photosynthesis, water relations and mineral nutrition. Nickel strongly influences metabolic reactions in plants and has the ability to generate reactive oxygen species which may cause oxidative stress. More recent evidence indicates that nickel is required in small amounts for normal plant growth and development. Hence, with the increasing level of nickel pollution in the environment, it is essential to understand the functional roles and toxic effects of nickel in plants.

Dioscorea batatas Rhizome-Assisted Rapid Biogenic Synthesis of Silver and Gold Nanoparticles

Development of biologically inspired experimental process for the synthesis of nanoparticles is an important branch of nanotechnology. Here the authors have synthesized silver and gold nanoparticles (AgNPs and AuNPs) by using rhizome extract of Dioscorea batatas at 50°C (AuNps), AgNPs was carried out at 80°C as well as room temperature (25°C). The reductions of Ag and Au ions were observed by the color changes from colorless to brownish yellow, and dark yellow and dark red wine, respectively. The reaction was followed with the help of UV-visible spectrometer. The synthesized nanoparticles were characterized using Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscope analysis. The authors did not find, formation of gold nanoparticles at room temperature. Furthermore, this green biogenic approach is rapid and simple alternative to chemical synthesis methods.

Biogenic Synthesis of Gold Nanoparticles (Quasi-Spherical, Triangle, and Hexagonal) Using Lonicera Japonica Flower Extract and Its Antimicrobial Activity

The development of an eco-friendly and reliable process for the synthesis of metallic nanoparticles is an important step in the field of the nanotechnology. In the present study, gold nanoparticles (AuNPs) have been synthesized by bio-reduction of chloroauric acid using Lonicera japonica flower extract. AuNPs were characterized using UV-Visible absorption spectroscopy, FTIR, SEM, EDX, TEM, SAED, and XRD. The antimicrobial activity of these AuNPs was evaluated using Gram-positive (S. aureus and B. subtilis), Gram-negative (E. coli), and Fungi C. albicans and S. cerevisiae. The results showed that the combination of ampicillin with AuNPs results in better antimicrobial effects.

AgNPs: Green Synthesis, Characterization, Antimicrobial, and Cytotoxicity Studies of Methanol and Aqueous Extracts of Pseudocydonia sinensis (Chinese Quince) Fruit

Silver nanoparticles (AgNPs) are among the emerging nanoproducts that have gained increasing interest in the field of nanomedicine due to their unique properties and obvious therapeutic potential in treating a variety of diseases. The authors used a methanol and aqueous fruit extracts of Pseudocydonia sinensis to synthesize AgNPS. To their knowledge, this is the first report where Pseudocydonia sinensis fruit was found to be a suitable plant source for the green synthesis of AgNPs. The AgNPs were characterized by UV-visible spectroscopy, transmission electron microscopy, energy dispersive X-ray analysis, X-ray diffraction, and Fourier transform infrared spectroscopy. Green synthesized Meoh-AgNPs and aqueous-AgNPs were found toxic against S. aureus (KCTC 1916), B. substilis (lab culture), E. coli (KCTC 2441), C. albicans (lab culture), and S. cerevicae (KCCM 1020). MTT assay showed (B16/F10 melanoma cancer cell line) minimum cell inhibition (1.01%) was observed at 0.12mM and maximum cell inhibition (81.85%) at 1mM. Meoh-AgNPs appeared to be more active than aqueous-AgNPs. Furthermore, this green synthesis is a rapid and simple alternative to chemical synthesis.

Hansen Solubility Parameters in the Analysis of Solvent–Solvent Interactions by Inverse Gas Chromatography

The Flory–Huggins interaction parameters, for a solute with pure nonvolatile solvents and with binary mixtures of nonvolatile solvents were evaluated using Inverse Gas Chromatography (IGC) data at 403.15 K. The five solvents used have similar structure and nearly the same molar volume and their mixtures form regular solutions. The values were used to evaluate the Hansen solubility parameters (HSP) for the pure solvents and mixed solvent systems. The HSP are plotted as a function of composition of the polar solvent. The dispersion component, , and the polar component, , exhibited negative deviation whereas the hydrogen bonding component, , showed positive deviation in the four mixtures. However, the total solubility parameter was found to be almost linear with composition in the four binary systems. Further the total solubility parameter, , was used to calculate the molar excess heat of vaporization for the solvents (C78 + POH, C78 + PCN, C78 + TTF, and C78 + TMO) that was found to be negative for C78 (19,24-dioctadecyldotetracontane) + POH(18,23-dioctadecylhentetracontan-1-ol) and C78 + PCN(1-cyano-18,23-dioctadecylhentetracontane) systems and positive for C78 + TTF [19,24-bis(18,18,18-trifluorooctadecyl)-1,1,1,42,42,42-hexafluorodotetracontane), and C78 + TMO(17,22-bis-(16-methoxyhexadecyl)-1,38-dimethoxyoctatriacontane] and the other systems.

Surface Analysis of Poly (Ethylene Glycol) Methyl Ether by Inverse Gas Chromatography

The surface characterization of poly (ethylene glycol) methyl ether (PEGME) was carried out using inverse gas chromatography (IGC) in the temperature range 393.15 to 443.15 K. The thermodynamic parameters, the dispersive component of the surface energy, , and the acid-base character of the surface of the PEGME were estimated using the retention time of different nonpolar and polar probes at infinite dilution. The specific free energy of adsorption, ΔG a , the specific enthalpy of adsorption, ΔH a , and the specific entropy of adsorption, ΔS a , of polar probes on polymer were determined. The values of ΔH a were correlated with both the donor and the modified acceptor numbers of the probes to quantify the acidic Ka and the basic Kb parameters of the PEGME surface. The values obtained for the Ka and Kb parameters indicate that the PEGME surface has basic character.