Kaliaperumal Selvaraj

Biogenic synthesis of silver nanoparticles using Nicotiana tobaccum leaf extract and study of their antibacterial effect

A green synthesis of silver nanoparticle was carried out using tobacco leaf extract. Synthesized nanoparticles were characterized using UV-Vis absorption spectroscopy, TEM, EDAX, FT-IR and photoluminescence study, respectively. UV-Vis absorption spectroscopy of prepared silver colloidal solution showed absorption maxima at 418 nm. Excitation maximum and emission maximum obtained from photoluminescence study were found at 414 and 576 nm, respectively. TEM analysis showed average particle size of 8 nm, while SAED pattern confirmed the crystalline nature of synthesized nanoparticles. FT-IR analysis indicated the involvement of carboxyl (-C= O), hydroxyl (-OH) and amine (NH) functional groups of tobacco leaf extract in preparation of silver nanoparticles. EDAX analysis showed proportion of silver (54.55%) among other elements in nanoparticle. Pseudomonas aeruginosa and Escherichia coli DH5� showed highest sensitivity towards silver nanoparticles.

Biosynthesis of Se nanoparticles and its effect on UV-induced DNA damage

This paper reports, an environmentally benign procedure of synthesis and characterizations of selenium nanoparticles and their protective effect against UV-induced DNA damage activities. An aqueous leaf extract of lemon plant was used as a precursor for synthesis of colloidal selenium nanoparticles. Resulting nanoparticles were characterized using UV-vis spectrophotometer, photoluminescence, TEM, EDAX, FT-IR and XRD, respectively. Selenium colloidal solution exhibited an absorption maximum at 395 nm and produced an emission maximum at 525 nm. Transmission electron microscopy followed by selected area electron diffraction pattern analysis indicated the formation of spherical, polydispersed, crystalline, selenium nanoparticles of diameter ranging from (∼60 to 80 nm). X-ray diffraction studies showed the formation of 111, 200 and 220 planes of face-centered cubic (fcc) selenium. EDAX analysis confirmed the presence of selenium in nanosphere. Fourier transformed infrared spectroscopic investigation reveled the involvement of carboxyl (−C=O), hydroxyl (−OH), amine (−NH) functional group of lemon plant extract in preparation of selenium nanoparticles. MTT assay as well single cell gel electrophoresis assay or comet assay revealed that synthesized selenium nanoparticles, caused less cell death of lymphocytes and prevented DNA damage, when cells were exposed to UVB. The fluorescent property of selenium nanoparticles can be used as diagnostic agent. Further, their anti DNA damaging property can be investigated as a chemotherapeutic agent in cancer therapy.

Defluoridation using biomimetically synthesized nano zirconium chitosan composite: Kinetic and equilibrium studies

The present study reports a novel approach for synthesis of Zr nanoparticles using aqueous extract of Aloe vera. Resulting nanoparticles were embedded into chitosan biopolymer and termed as CNZr composite. The composite was subjected to detailed adsorption studies for removal of fluoride from aqueous solution. The synthesized Zr nanoparticles showed UV-vis absorption peak at 420nm. TEM result showed the formation of polydispersed, nanoparticles ranging from 18nm to 42nm. SAED and XRD analysis suggested an fcc (face centered cubic) Zr crystallites. EDAX analysis suggested that Zr was an integral component of synthesized nanoparticles. FT-IR study indicated that functional group like NH, CO, CN and CC were involved in particle formation. The adsorption of fluoride on to CNZr composite worked well at pH 7.0, where ∼99% of fluoride was found to be adsorbed on adsorbent. Langmuir isotherm model best fitted the equilibrium data since it presented higher R(2) value than Freundlich model. In comparison to pseudo-first order kinetic model, the pseudo-second order model could explain adsorption kinetic behavior of F(-) onto CNZr composite satisfactorily with a good correlation coefficient. The present study revealed that CNZr composite may work as an effective tool for removal of fluoride from contaminated water.

Efficient sorption and photocatalytic degradation of malachite green dye onto NiS nanoparticles prepared using novel green approach

The extract of the Asparagus racemosus leaf tissue works as a stabilizing and capping agent and assists the formation of stable colloidal nanoparticles. Nanoparticles were characterized using UV-vis spectrophotometer, photoluminescence, TEM, EDAX and XRD, respectively. Transmission electron microscopy followed by selected area electron diffraction pattern analysis indicated the formation of near spherical, polydispersed, crystalline NiS of diameter ranging from 4-27 nm. X-ray diffraction studies showed the formation of 110, 101, 300, 021, 220, 221, 131, 410, 401, 321, 330 and 021 planes of hexagonal NiS. EDAX analysis confirmed the presence of Ni and S in nanosphere. The maximum sorption capacity (qm) of NiS nanoparticles for MG dye was found to be 64.85 mg/g. Decolorization as well as disintegration of malachite green under white light illumination was confirmed by LC-MS studies. Results of the present study suggest that nanosized NiS can play an instrumental role in photocatalytic degradation of malachite green dye present in water bodies.

Disintegrable NIR Light Triggered Gold Nanorods Supported Liposomal Nanohybrids for Cancer Theranostics

In this work, facile synthesis and application of targeted, dual therapeutic gold nanorods-liposome (GNR-Lipos) nanohybrid for imaging guided photothermal therapy and chemotherapy is investigated. The dual therapeutic GNR-Lipos nanohybrid consists of GNR supported, and doxorubicin (DOX) loaded liposome. GNRs not only serve as a photothermal agent and increase the drug release in intracellular environment of cancer cells, but also provide mechanical strength to liposomes by being decorated both inside and outside of bilayer surfaces. The designed nanohybrid shows a remarkable response for synergistic chemophotothermal therapy compared to only chemotherapy or photothermal therapy. The NIR response, efficient uptake by the cells, disintegration of GNR-Lipos nanohybrid, and synergistic therapeutic effect of photothermal and chemotherapy over breast cancer cells MDA-MB-231 are studied for the better development of a biocompatible nanomaterial based multifunctional cancer theranostic agent.

A DFT based assay for tailor-made terpyridine ligand–metal complexation properties

Electron-rich terpyridine ligand and its metal complexes have a potential to grow as responsive surfaces by adapting their physicochemical properties as a function of environment. The responsiveness is brought about by judicious molecular level designing that is currently hindered due to lack of information and control on terpyridine (TPy)–metal (M) interactions at single molecule level. So far there is no organised understanding on the binding of different metals with TPy ligand and ways to modulate it. Being a large conjugated system, TPy has a large scope to be functionalised with electron exchanging groups to alter its electronic structure and consequently its binding with metal atoms. In first report of such a kind, using density functional theory (DFT), we demonstrate that convenient modulation of TPy-M binding is possible through functionalisation of TPy for , Ru, Fe, Mo and Au. Electron donating groups viz., CH, OCH, CH, NH and electron withdrawing groups viz., CF, COOH, CN and NO are considered for functionalisation of TPy ligand. Significantly, the present work focuses on the functionalisation at 4 and 4 positions of TPy molecule. The role of such a functionalisation in influencing the ligands structure–property correlation is missing in the literature to the best of our knowledge. The present investigation quantifies that by pertinent functionalisation of TPy, TPy-M binding energies can be modified up to 60 kcal/mol. Our results reveal that functionalisation leads to a considerable charge redistribution within the TPy-M complex with carbon atoms in pyridine rings functioning as major electron sink/source with a corresponding red/blue shift of stretching frequency. This modifies the red-ox, optical and other chemical properties of TPy-M complexes. In brief, the present report illustrates a way to design ligands such as TPy for diverse applications through tailor-made functionalisation using electronic structure methodology.

A redox-mediated 3D graphene based nanoscoop design for ultracapacitor applications

Contemporary energy storage devices significantly rely on the rational design of micro and nano-structural features of electrode materials for efficient ion transport. A judicious concept of utilizing the extended charge mobility on the third dimension along with an active redox couple to significantly maximize the capacitance has been demonstrated via (a) the fabrication of a 3D network from 2D graphene and (b) the introduction of an active redox species. Compared with traditional graphene systems, an unprecedented 8-fold gain of capacitance that was sustained with minimal loss even beyond 5000 cycles is achieved and is reported for the first time. This was due to the complementary advantage of both the electric double layer capacitance of the 3D graphene electrode and the redox-mediated pseudocapacitance of K3Fe(CN)6 in alkaline electrolytes. Colloidal polystyrene spheres with a tunable size range were used as sacrificial templates for generating the 3D network. This design outperforms others, is an excellent candidate as an ultracapacitor and is envisaged to lead to new opportunities in several electrochemical applications.