Kasi Gopinath | Bharathiar University, Coimbatore, Tamilnadu, INDIA (original) (raw)

Papers by Kasi Gopinath

Journal of Nanostructure in Chemistry, 2014

This work reports an ecofriendly approach for the synthesis of Ruthenium nanoparticles (Ru NPs) u... more This work reports an ecofriendly approach for the synthesis of Ruthenium nanoparticles (Ru NPs) using aqueous leaf extract of Gloriosa superba. G. superba contains cholidonic, superbine, colchicine, gloriosol, phytosterils and stigmasterin, which are found to be responsible for the bio-reduction of Ru NPs. The synthesized Ru NPs were characterized using UV-Vis spectroscopy, Fluorescence spectra, FTIR, XRD, SEM and EDX analyses. UV-Vis spectra of the aqueous medium containing Ru NPs showed a gradual decrease of the absorbance peak observed at 494 nm. Fluorescence spectra of Ru NPs emission (k em) exhibited at 464 nm are attributed to the Ru=N p bonds transition. The biomolecules responsible for the reduction of Ru NPs were analyzed by FTIR. XRD results confirmed the presence of Ru NPs with hexagonal crystal structure. The calculated crystallite sizes using Scherrer formula are in the range from 25 to 90 nm. Scanning electron microscopy ascertained spherical nature of the Ru NPs. The EDX analysis showed the complete elemental composition of the synthesized Ru NPs. The synthesized Ru NPs exhibited good antibacterial performance against gram-positive and gram-negative bacterial strains, which was studied using standard disc diffusion method. The synthesis of Ru NPs by this method is rapid, facile and can be used for various applications.

Journal of Cluster Science, 2017

The green fabrication of metal nanoparticles using botanical extracts is gaining increasing resea... more The green fabrication of metal nanoparticles using botanical extracts is gaining increasing research attention in nanotechnology, since it does not require high energy inputs or the production of highly toxic chemical byproducts. Here, silver (Ag), gold (Au) and their bimetallic (Ag/Au) nanoparticles (NPs) were green synthesized using the Gloriosa superba aqueous leaf extract. Metal NPs were studied by spectroscopic (UVevisible spectroscopy, fluorescence spectroscopy, FT-IR spectroscopy, XRD and EDX) and microscopic (AFM and TEM) analysis. AFM and TEM showed that Ag and Au NPs had triangular and spherical morphologies, with an average size of 20 nm. Bimetallic Ag/Au NPs showed spherical shapes with an average size of 10 nm. Ag and Ag/Au bimetallic NPs showed high antibacterial and antibiofilm activities towards Gram-positive and Gram-negative bacteria. Overall, the proposed synthesis route of Ag, Au and Ag/Au bimetallic NPs can be exploited by the pharmaceutical industry to develop drugs effective in the fight against microbic infections.

The aim of the present study was to synthesize CeO 2 nanoparticles using plant pathogenic fungus ... more The aim of the present study was to synthesize CeO 2 nanoparticles using plant pathogenic fungus F. solani and also to study the antibacterial activity as well as the influence on the inhibition of biofilm formation against the biomedically important bacterial 10 strains namely Staphylococcus aureus, Psedomonas aeriginosa, Escherichia coli and Klebsiella pneumoniae. Thermogravimetric/Differential thermal analysis (TG/DTA) suggested the crystallization temperature of as-synthesized CeO 2 nanopowder at 400 o C. Powder X-ray diffraction analysis and Raman spectroscopy substantiated the presence of CeO 2 nanoparticles with cubic fluorite structure. The contribution of functional groups corresponding to F. solani fungal supernatant for the synthesis of CeO 2 nanoparticles was studied by Fourier transform infrared (FTIR) spectroscopy. Room temperature photoluminescence spectrum of 15 calcined CeO 2 nanopowder was recorded. Field emission scanning electron microscopy (FESEM) equipped with energy dispersive X-ray spectroscopy (EDAX) ascertained the formation of homogeneously distributed spherical shaped CeO 2 nanoparticles. Furthermore, Transmission electron microscopy (TEM) demonstrated the spherical morphology of the CeO 2 nanoparticles having the size ranging from 20 to 30 nm and also selected area electron diffraction (SAED) pattern revealed the polycrystalline nature of CeO 2 nanoparticles, which is consistent with the XRD results. The presence of surface oxidation states Ce (3d) and O (1s) of CeO 2 nanoparticles was 20 confirmed by X-ray Phoelectron Spectroscopy (XPS) analysis. Antibacterial activity of CeO 2 nanoparticles was evaluated by disc diffusion method and it showed highest activity against P. aeruginosa as well as K. pneumoniae. In addition, the inhibition on biofilm formation by CeO 2 nanoparticles has also been examined by confocal laser scanning microscopy (CLSM). Furthermore, the electrochemical property of biosynthesized CeO 2 nanoparticles was studied by cyclic voltammetry technique. 25

Sucrose is a major commodity in worldwide. In half a century the progress towards the understandi... more Sucrose is a major commodity in worldwide. In half a century the progress towards the understanding of the chemistry, structure, physical and functional properties of the sucrose molecule have been rapid. It was crystallized from the hot methanol extract of the rhizome powder
of Gloriosa superba by using slow evaporation method at room temperature. The synthesized sucrose crystal lattice parameters were characterized by single crystal X-ray diffraction analysis. The presences of organic functional groups in the grown crystal were identified by FT-IR and Micro Raman analyses. The optical parameter of the grown single crystal was analyzed by UV-visible spectroscopy and maximum absorption was occurred at 253 nm. In addition, HOMO, LUMO, Molecular Electrostatic Potential (MESP), non-linear optical and several thermodynamic properties
were analyzed by the DFT calculations. The thermal degradation of the sucrose crystal was tested by Thermo Gravimetric/Differential Thermal Analysis (TG/DTA).

Cerium oxide nanoparticles (CeO2 NPs) were synthesized using Aspergillus niger culture filtrate. ... more Cerium oxide nanoparticles (CeO2 NPs) were
synthesized using Aspergillus niger culture filtrate. The
mycosynthesized CeO2 NPs were characterized by UV–
Visible (UV–Vis), Fourier Transform Infrared (FT-IR),
X-ray diffraction (XRD), Micro Raman, Thermogravi-
metric/Differential Thermal Analysis (TG/DTA), Photo-
luminescence, and Transmission Electron Microscopy
(TEM) analyses. UV–Vis spectrum exhibited a corre-
sponding absorption peak for CeO2 NPs at 296 nm, and
the functional groups present in the fungal filtrate
responsible for the synthesis of NPs were analyzed by
FT-IR. The further characterization of the mycosynthe-
sized CeO2 NPs revealed particles of the cubic structure
and spherical shape, with the particle sizes ranging from
5 to 20 nm. The antibacterial activity of CeO2 NPs was
examined in respect of two Gram-positive (G?) bacteria
(Streptococcus pneumoniae, Bacillus subtilis) and two
Gram-negative (G-) bacteria (Proteus vulgaris, Escher-
ichia coli) by disk diffusion method. The test results for
CeO2 NPs at a concentration of 10 mg/mL showed
higher activities on the zone of inhibition of up to
10.67 ± 0.33 and 10.33 ± 0.33 mm against Streptococ-
cus pneumonia and Bacillus subtilis, respectively, The
CeO2 NPs caused 100 % mortality on first instar of
Aedes aegypti at 0.250 mg/L concentration after 24-h exposure. The mycosynthesis of CeO2 NPs is a simple,
cost-effective and eco-friendly approach and it will also
potentially helpful to control pathogenic bacteria and
dengue vector.

CeO2 nanoparticles (NPs) were green synthesized using Gloriosa superba L. leaf extract. The synth... more CeO2 nanoparticles (NPs) were green synthesized using Gloriosa superba L. leaf extract. The synthesized nanopar-
ticles retained the cubic structure, which was confirmed by X-ray diffraction studies. The oxidation states of the
elements (C (1s), O (1s) and Ce (3d)) were confirmed by XPS studies. TEM images showed that the NPs possessed
spherical shape and particle size of 5 nm. The Ce–O stretching bands were observed at 451 cm−1 and 457 cm−1
from the FT-IR and Raman spectra respectively. The band gap of the CeO2 NPs was estimated as 3.78 eV from the
UV–visible spectrum. From the photoluminescence measurements, the broad emission composed of eight dif-
ferent bands were found. The antibacterial studies performed against a set of bacterial strains showed that
Gram positive (G+) bacteria were relatively more susceptible to the NPs than Gram negative (G−) bacteria.
The toxicological behavior of CeO2 NPs was found due to the synthesized NPs with uneven ridges and oxygen
defects in CeO2 NPs.

A standard protocol for the mass propagation from root explants of Gloriosa superba L. was develo... more A standard protocol for the mass propagation from root explants of Gloriosa superba L. was developed. Murashige and Skoog (MS) basal medium have been supplemented with different concentration and combination of phytohormones viz. 2,4-Dichlorophenoxy acetic acid (2,4-D), Indole-3acetic acid (IAA), 6-Benzyl aminopurine (BAP), Gibberellic acid ( ), Indole-3-propionic acid (IPA), α-napthalene acetic acid (NAA) and Indole-GA 3 3-butyric acid (IBA). The maximum percentage of yellowish callus (94.40%) were obtained from the root explants on MS medium supplemented with concentration of (2.0 mg/L), (1.0 mg/L), (0.75 mg/L) for 2, 4-D, IAA and NAA, respectively. The development of roots from the callus were highly regenerated (93.80%) on MS medium with combination of (8.0 mg/L), IAA (4.0 mg/L) and BAP (2.0 mg/L). Rooted callus were transferred into GA 3 half strength of MS medium containing BAP (3.0 mg/L), IBA (1.0 mg/L) and IPA (0.75 mg/L) to produce dark greenish shoots (90.60%). The rooted shoots were transferred into small polythene bags which contain a sterilized cow dung powder, sand and red soil in the ratio of 1:2:3 and kept in a mist house. After acclimatization in the mist house, the regenerated plantlets were hardened in the greenhouse and transferred into soil, which showed 80% survival rate.

This study reveals the synthesis of spherical gold nanoparticles (Au NPs) using aqueous fruit ext... more This study reveals the synthesis of spherical gold nanoparticles (Au NPs) using aqueous fruit extract of Terminalia arjuna, which contains tannin, terpenoid, saponins, flavonoids, glycosides and polyphenolic compounds. The synthesized Au NPs were characterized by UV-visible spectroscopy (UV-vis), Fourier transform infrared (FTIR), X-ray diffraction (XRD), atomic force microscopy (AFM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), dynamic light scattering (DLS) and zeta potential (ZP) analyses. UV-visible spectra of the fruit extract containing Au NPs showed a surface plasmon resonance peak at 523 nm. FTIR analysis was performed to analyze the biomolecules responsible for the reduction of Au NPs. FTIR analysis clearly showed that Au NPs were capped with plant compounds. The EDX analysis was used to identify the elemental composition of the synthesized Au NPs. The high crystallinity of Au NPs with a face-centered cubic phase is evident to XRD patterns. AFM and TEM observations revealed that synthesized Au NPs were spherical shape with the range 20-50 nm. DLS measurement revealed that Au NPs were obtained in the average size of 25 nm and it is found to be stable at 21.9 mV through ZP analysis. The synthesized Au NPs were investigated for its antibacterial activity. By contrast, Au NPs did not show any antibacterial activity against Gram-positive and Gram-negative bacteria. The Au NPs were treated with two different concentrations (500 and Electronic supplementary material The online version of this article (

Green synthesis is one of the rapid, reliable, and best routes for the synthesis of silver nanopa... more Green synthesis is one of the rapid, reliable, and best routes for the synthesis of silver nanoparticles (Ag NPs). The current study revealed that the aqueous leaf extract of Pterocarpus santalinus, which contains steroids, saponins, tannins, phenols, triterpenoids, flavonoids, glycosides, and glycerides, is found to be responsible for bioreduction during the synthesis of spherical Ag nanoparticles. The formed Ag NPs were characterized by ultraviolet-visible (UV-vis), Fourier transform-infrared (FT-IR), X-ray diffraction (XRD), atomic force microscopy (AFM), energy-dispersive X-ray spectroscopy (EDX), and scanning electron microscopy (SEM) analysis. UV-vis spectra of the aqueous medium containing silver nanoparticles showed a surface plasmon resonance peak at 418 nm. FT-IR analysis was performed to analyze the biomolecules responsible for the reduction of Ag NPs. XRD results confirmed the presence of silver nanoparticles with face-centered cubic structure. The EDX analysis showed the completed inorganic composition of the synthesized Ag NPs. AFM analysis exemplified the results of particle sizes (41 nm). The calculated crystallite sizes are in the range of 20 to 50 nm, and the spherical nature of the Ag NPs was ascertained by SEM. The synthesized Ag NPs exhibited good antibacterial potential against gram-positive and gram-negative bacterial strains. The zone of inhibition effect of antibacterial activity depends upon the concentration of Ag NPs.

This work reports an ecofriendly approach for the synthesis of Ruthenium nanoparticles (Ru NPs) u... more This work reports an ecofriendly approach for the synthesis of Ruthenium nanoparticles (Ru NPs) using aqueous leaf extract of Gloriosa superba. G. superba contains cholidonic, superbine, colchicine, gloriosol, phytosterils and stigmasterin, which are found to be responsible for the bio-reduction of Ru NPs. The synthesized Ru NPs were characterized using UV-Vis spectroscopy, Fluorescence spectra, FTIR, XRD, SEM and EDX analyses. UV-Vis spectra of the aqueous medium containing Ru NPs showed a gradual decrease of the absorbance peak observed at 494 nm. Fluorescence spectra of Ru NPs emission (k em ) exhibited at 464 nm are attributed to the Ru=N p bonds transition. The biomolecules responsible for the reduction of Ru NPs were analyzed by FTIR. XRD results confirmed the presence of Ru NPs with hexagonal crystal structure. The calculated crystallite sizes using Scherrer formula are in the range from 25 to 90 nm. Scanning electron microscopy ascertained spherical nature of the Ru NPs. The EDX analysis showed the complete elemental composition of the synthesized Ru NPs. The synthesized Ru NPs exhibited good antibacterial performance against gram-positive and gram-negative bacterial strains, which was studied using standard disc diffusion method. The synthesis of Ru NPs by this method is rapid, facile and can be used for various applications.

This present work reports an ecofriendly approach for the synthesis of spherical gold nanoparticl... more This present work reports an ecofriendly approach for the synthesis of spherical gold nanoparticles (Au NPs) using aqueous leaf extract of Terminalia arjuna. T. arjuna contains arjunetin, leucoanthocyanidins and hydrolyzable tannins, which are found to be responsible for the bio-reduction of Au NPs. The formed Au NPs were characterized by UV-vis, FTIR, XRD, AFM and TEM analysis. UV-visible spectra of the aqueous medium containing gold nanoparticles showed a surface plasmon resonance peak at 530 nm. FT-IR analysis was performed to analyze the biomolecules responsible for the reduction of Au NPs. XRD results confirmed the presence of gold nanoparticles with face centered cubic structure. The calculated crystallite sizes are in the range of 20 to 50 nm and the spherical nature of the Au NPs was ascertained by transmission electron microscopy. The efficacy of the synthesized Au NPs was tested for the mitotic cell division and pollen germination. It is suggested that Au NPs induces the mitotic cell division and pollen germination. There was no cytotoxic effect of Allium cepa root tip cells and Gloriosa superba pollen grains.

An efficient protocol was developed for highly regenerative capacity from leaf explant of Withani... more An efficient protocol was developed for highly regenerative capacity from leaf explant of Withania somnifera (L.) Dunal -an endangered medicinal plant. Calli were regenerated from four different explants like leaves, cotyledons, hypocotyls and epicotyls. MS supplemented with different concentrations of 2,4-D, BAP and NAA were used. The calli (94.33 ± 1.20%) were obtained from the leaf explant in 2,4-D 3.0 mg/l. The highest number of multiple shoots (85.67 ± 0.88%) were obtained from the leaf callus at 4.0 mg/l BAP. Shootlets forming calli were transferred to the rooting medium containing 10.0 mg/l NAA to produce multiple roots (89.33 ± 0.88%). The regenerated rooted shootlets were transferred to small polythene bags, which contain a sterilized cow-dung, sand and red soil (1 : 2 : 3) and kept in a mist house. After acclimation in the mist house the regenerated plantlets were hardened in the greenhouse and transferred to soil, which showed 85% survival rate. This new protocol was standardized for easy mass propagation of W. somnifera using leaf explant.

The development of eco-friendly methods for the synthesis of nanomaterial shape and size is an im... more The development of eco-friendly methods for the synthesis of nanomaterial shape and size is an important area of research in the field of nanotechnology. The present investigation deals with the extracellular rapid biosynthesis of gold nanoparticles using Fusarium solani culture filtrate. The UV-vis spectra of the fungal culture filtrate medium containing gold ion showed peak at 527 nm corresponding to the plasmon absorbance of gold nanoparticles. FTIR spectra provide an evidence for the presence of heterocyclic compound in the culture filtrate, which increases the stability of the synthesized gold nanoparticles. The X-ray analysis respects the Bragg's law and confirmed the crystalline nature of the gold nanoparticles. AFM analysis showed the results of particle sizes (41 nm). Transmission electron microscopy (TEM) showed that the gold nanoparticles are spherical in shape with the size range from 20 to 50 nm. The use of F. solani will offer several advantages since it is considered as a non-human pathogenic organism. The fungus F. solani has a fast growth rate, rapid capacity of metallic ions reduction, NPs stabilization and facile and economical biomass handling. Extracellular biosynthesis of gold nanoparticles could be highly advantageous from the point of view of synthesis in large quantities, time consumption, eco-friendly, non-toxic and easy downstream processing.

Journal of Nanostructure in Chemistry, 2014

Journal of Cluster Science, 2017

This work reports an ecofriendly approach for the synthesis of Ruthenium nanoparticles (Ru NPs) u... more This work reports an ecofriendly approach for the synthesis of Ruthenium nanoparticles (Ru NPs) using aqueous leaf extract of Gloriosa superba. G. superba contains cholidonic, superbine, colchicine, gloriosol, phytosterils and stigmasterin, which are found to be responsible for the bio-reduction of Ru NPs. The synthesized Ru NPs were characterized using UV-Vis spectroscopy, Fluorescence spectra, FTIR, XRD, SEM and EDX analyses. UV-Vis spectra of the aqueous medium containing Ru NPs showed a gradual decrease of the absorbance peak observed at 494 nm. Fluorescence spectra of Ru NPs emission (k em ) exhibited at 464 nm are attributed to the Ru=N p bonds transition. The biomolecules responsible for the reduction of Ru NPs were analyzed by FTIR. XRD results confirmed the presence of Ru NPs with hexagonal crystal structure. The calculated crystallite sizes using Scherrer formula are in the range from 25 to 90 nm. Scanning electron microscopy ascertained spherical nature of the Ru NPs. The EDX analysis showed the complete elemental composition of the synthesized Ru NPs. The synthesized Ru NPs exhibited good antibacterial performance against gram-positive and gram-negative bacterial strains, which was studied using standard disc diffusion method. The synthesis of Ru NPs by this method is rapid, facile and can be used for various applications.