Showing papers by "Ruma Pal published in 2016"

Cyanobacteria assisted biosynthesis of silver nanoparticles—a potential antileukemic agent

Abstract: Recently, silver nanoparticles (SNPs) have received much attention in nanooncology due to their unique therapeutic properties. The aim of this study was to determine the anticancer activity of biosynthesized SNPs against blood cancer along with their antibacterial property. Here, the cyanobacterial strain, Lyngbya majuscula, was used as successful bio-reagent for SNP production. The healthy growing trichomes were exposed to 9 mM silver nitrate solution in the dark for nanosilver production. The synthesized particles were tested for their nanostructure using UV–vis spectroscopy (absorption maxima at 415 nm) and other methods. Presence of elemental silver and the crystallographic nature of the particles were confirmed by EDAX analysis and XRD, respectively. The surface topography, size, and shape of SNPs were determined by AFM and TEM studies. Smooth-surfaced spherical shaped particles with an ∼20–50-nm size range were produced. The average hydrodynamic diameter and zeta potential value of the produced SNPs were 149 nm and −35.2 mV, respectively, indicating high stability of the particles. The fully characterized SNPs were then tested for their effectiveness as antibacterial agents against the Gram-negative bacterium Pseudomonas aeruginosa. The antiproliferative activity of SNP was also screened against three leukemic cell lines (K562, MOLT-3, and REH) through MTT assay. The SNP synthesized by L. majuscula showed dose- and time-dependent anticancer activity in REH cells. DAPI staining clearly revealed the fragmentation of nuclei of cancer cells due to SNP treatment. Data taken together showed that biosynthesis of SNP aided by L. majuscula enhanced the antiproliferative activity of leukemic cells as well as the antibacterial activity against P. aeruginosa.

Efficacy of EDTA and Phosphorous on Biomass Yield and Total Lipid Accumulation in Two Green Microalgae with Special Emphasis on Neutral Lipid Detection by Flow Cytometry

Abstract: Chlorella ellipsoidea and Chlorococcum infusionum , promising microalgae for biodiesel feedstock production, were treated with ethylenediaminetetraacetate (EDTA) and phosphorous to induce stress which was then followed by flow cytometry to study the enhanced intracellular neutral lipid content. Treatment resulted in up to a threefold increase in total lipid content of Chlorella (41.8±1.9% at 16 days of incubation period) and more than twofold increases in Chlorococcum (31.3±1.0%at 18 days of incubation period) under phosphorous starvation in the culture. It was observed that maximum biomass yields in Chlorella and Chlorococcum were 1.56±0.06 and 2.17±0.12 g/L at 1.5 g/L of phosphorous after 20 and 18 days of incubation periods, respectively. The qualitative analyses of neutral lipid bodies under stress conditions were performed by confocal microscopy and revealed bright golden-yellow lipid droplets in stress exposed cells. Significant increase of monounsaturated fatty acids under the nutrient limited conditions was suitable to produce biodiesel. The maximum biomass (g/L) and lipid content (% dry cell weight) at different stresses showed significant results ( Ρ < 0.05) by single-factor Analysis of Variance (ANOVA) followed by Duncan's Multiple Range Test (DMRT).

Gold (III) bioreduction by cyanobacteria with special reference to in vitro biosafety assay of gold nanoparticles

Abstract: Bioreduction of Au3+ to Au0 and subsequent synthesis of gold nanoparticles using three cyanobacterial strains Leptolyngbya tenuis, Coleofasciculus chthonoplastes, and Nostoc ellipsosporum was investigated. The optimized condition for maximum gold nanoparticle synthesis was determined as 20 mg cyanobacterial biomass per 100 mL of 15 mg L−1 Au3+ solution as inoculum size at pH 5. At the onset of nanoparticle synthesis (up to 3 h) increased activity of catalase, ascorbate peroxidase, super oxide dismutase, and malondialdehyde content along with rapid loss of pigments and protein content (1–72 h) indicated gold toxicity at cellular level. Associated changes in thallus morphology were also significant. Nostoc biomass produced spherical- to irregular-shaped nanoparticles with diverse sizes and small number of nanorods. On the other hand, Coleofasciculus showed nanoparticle synthesis at extracellular medium which was either absent in Nostoc or very low in Leptolyngbya. Biosafety analysis by MTT assay using peripheral blood mononuclear cells (PBMC), two cancer cell lines viz. T cell acute (T-ALL) and human acute lymphoblastic leukemia (MOLT-4) and antibacterial effect against Pseudomonas aeruginosa and Staphylococcus aureus showed no toxic effect of synthesized gold nanoparticles.

Cyanobacteria mediated green synthesis of gold-silver nanoalloy

Abstract: Green synthesis is a significant process for non-toxic metal nanoparticle production employing plant materials. In the present investigation we reported an environmentally friendly method for gold-silver nano-alloy biosynthesis using a cyanobacterial strain, Lyngbya majuscula as bio-reagent. On exposure of Lyngbya thallus to equimolar solution of gold and silver (1 mM, pH 4) for 72 hrs and subsequent pink coloration of the experimental biomass indicated the nanoparticle synthesis. Extracted nanoparticles showed a distinct single plasmon band at 481 nm and further EDX analysis confirmed the presence of both the metals Au and Ag in nano-alloy form. It was also observed from TEM study that all the synthesized particles were spherical in nature with a size range of ~5-25 nm. The SEM pictures of the metal treated biomass confirmed the intra and extracellular nano-alloy formation. The XRD analysis of particle loaded biomass revealed that the 2θ values appeared at 38.2°, 44.5°, 64.8°and 77.8° that were indexed at (111), (200), (220) and (311) lattice planes. Presence of different functional groups viz. N-H, C=C, C–O, C=O on the surface of nanoparticles were recorded by FTIR. Overall, this technique requires low energy and less manufacturing cost for metal alloy biosynthesis.

Diatom-based biosynthesis of gold-silica nanocomposite and their DNA binding affinity

Abstract: We report an eco-friendly method for biosynthesis of gold-silica (Au-SiO2) nanocomposite using a diatom, Amphora copulata, as reducing agent. The live cells of Amphora covered by siliceous frustules reacted with hydrogen tetra-auro chlorate (HAuCl4), and Au-SiO2 particles were synthesized after 72 h of reaction. Energy-dispersive X-ray (EDAX) analysis confirmed the presence of Au and SiO2 nanoparticles in a composite form, and their characterization was done by UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), and scanning (SEM) and transmission (TEM) electron microscopy. The SEM study revealed that composite particles were deposited on the siliceous frustules of live cells, whereas in dead diatom cells, the surface remained unchanged. The TEM analysis confirmed the synthesis of triangular-, spherical-, and hexagonal-shaped Au-SiO2 particles with 5 to 45-nm size range. Biogenic Au-SiO2 nanoparticles were tested for DNA binding affinity by agarose gel electrophoresis and TEM study after 30 min of interaction with isolated DNA from the green alga, Pithophora. The synthesized nanoparticles were found to bind with DNA molecules without any surface modification. The TEM images of Au-SiO2 particles, taken after interaction with DNA, showed the arrangement of particles in specific manner which formed a “Y”-shaped, chain-like, and coiling structure, indicating that the diatom-based bio-synthesized Au-SiO2 particles were very efficient in binding with DNA which could be applied in the bio-medical field directly.

Biogenic synthesis of gold nanoparticle using fractioned cellular components from eukaryotic algae and cyanobacteria

Abstract: Summary In the present investigation fractioned cellular components like intact pigment bearing thylakoids/chloroplasts, carotenoids, protein, polysaccharides were extracted from the cyanobacterium Anabaena sphaerica and green alga Chlorococcum infusionum. Each of these extracts was used separately in search for efficient reducing agents during gold nanoparticle (GNP) production in pro- and eukaryotic algal cell systems. The whole biomass and extracted compounds or cellular structures were exposed in 25 mg L−1 aqueous hydrogen tetrachloroaurate solutions separately at room temperature. Isolated viable chloroplasts from C. infusionum and thylakoids from A. sphaerica were found to be able to reduce gold ions. The protein extracts of both strains were also able to synthesize GNP at 4°C. Extracted polysaccharides of the two strains responded differently. Polysaccharides from A. sphaerica showed positive response in GNP synthesis, whereas no change was observed for C. infusionum. The carotenoids extracts from both strains acted like an efficient reducing agent. Initially the reducing efficiency of these extracted components was confirmed by the appearance of purple color in biomass or in experimental media. The GNPs, synthesized within the biomass were extracted by sonication with sodium citrate. The UV–vis spectroscopy of extracted purple colored suspensions and media showed the absorption bands at approximately 530–540 nm indicating a strong positive signal of GNP synthesis. Transmission electro n microscopy determined the size and shapes of the particles. The X-ray diffraction study of the synthesized GNP revealed that the 2θ values appeared at 38.2°, 44.5°, 64.8° and 77.8°. Amongst all, isolated thylakoids and chloroplast showed only spherical GNP production with variable size range at pH 4. Monodisperse GNPs were also synthesized by isolated thylakoids and chloroplast at pH 9. A detailed morphological change of gold treated biomass was revealed employing scanning electron microscopy. The fluorescent property of gold loaded cells was studied by fluorescence microscopy.

An integrated salinity-driven workflow for rapid lipid enhancement in green microalgae for biodiesel application

Abstract: A laboratory based integrated approach was undertaken for improvement of lipid accumulation in green microalgae under sodium chloride (NaCl) stress. The maximum biomass yields (1.22 ± 0.04 g L−1 in Chlorella and 1.31 ± 0.04 g L−1 in Chlorococcum) were obtained in the media with initial NaCl concentrations at 2 g L−1 (for Chlorella) and 0.05 g L−1 (for Chlorococcum) after 14 days of culture. Interestingly, maximum lipid accumulation obtained was 45.8 ± 0.4% w/v for Chlorella (on day eight) and 36.33 ± 0.56% w/v for Chlorococcum (on day ten) at an exposure of 5 g L−1 and 1.5 g L−1 NaCl concentrations, respectively. Fatty acid profiles of methyl esters for neutral and polar lipid fractions showed the presence of myristic (C14:0), palmitic (C16:0), palmitoleic (C16:1), oleic (C18:1) and linoleic (C18:2) acids as major fatty acids. Fluorescence intensities (% positive Nile red stained cells) of neutral and polar lipid fractions were also higher in NaCl stress conditions. A significant correlation between polar lipid and neutral lipid was found in both Chlorella (r2 = 0.979) and Chlorococcum (r2 = 0.972). Flow cytometric study demonstrated a positive fluorescence signal for neutral and polar lipid bodies related to Nile red fluorescence. Associated biochemical changes, like those in total chlorophyll, carotenoid, carbohydrate and protein contents, were determined under variable NaCl concentrations. The elemental compositions (CHNS) and CO2 fixation rate were assessed using high lipid yielding cells under optimum NaCl concentrations. Biodiesel fuel properties were obtained from high lipid yielding cells of the test microalgae and compared with Indian and international diesel standards. Finally large-scale cultivation of Chlorella ellipsoidea was performed in a hybrid photobioreactor (800 L capacity) and the highest biomass and lipid content obtained was 1.66 ± 0.09 g L−1 (at 8 days) and 54.73 ± 1.78% w/v (at 10 days) at 5 g L−1 NaCl respectively. This optimized NaCl concentration makes it an economical substitute for biodiesel production on a large scale.

New and rare records of filamentous green algae from Indian Sundarbans Biosphere Reserve

Abstract: A total 36 taxa of filamentous green algae including chlorophytes and charophytes were recorded from different habitats of Indian Sundarbans, of which 31 taxa were newly reported from this World famous biosphere reserve. During regular exploration for 3 years, 7 species of Spirogyra, 5 species of each Cladophora and Oedogonium, 3 species of Microspora, 2 species of each Chaetomorpha, Rhizoclonium, Ulothrix, Zygnema and Enteromorpha and single species of each from Ulva, Pithophora, Geminella, Temnogyra, Chara and Nitella were recorded in fresh water to brackish water habitats of Indian Sundarbans. Two species of Rhizoclonium viz. R. hookeri and R. fontanum were found as epiphytic mat on mangrove tree trunk of Avicennia alba and Bruguiera gymnorrhiza. New and rare species were described compared to early records based on morphotaxonomy. Documentation of Camera Lucida drawing, light and scanning electron micrographs have also included in the present investigation.