Synthesis and characterization of BiVO4 nanoparticles for environmental applications.

In the present study, a chemical precipitation method is adopted to synthesize bismuth vanadate nanoparticles. The calcination temperature dependent photocatalytic and antibacterial activities of BiVO4 nanoparticles are examined. The structural analysis evidences the monoclinic phase of BiVO4 nanoparticles, where the grain size increases with calcination temperature. Interestingly, BiVO4 nanoparticles calcined at 400 °C exhibit superior photocatalytic behaviour against methylene blue dye (K = 0.02169 min-1) under natural solar irradiation, which exhibits good stability for up to three cycles. The evolution of antibacterial activity studies using a well diffusion assay suggest that the BiVO4 nanoparticles calcined at 400 °C can act as an effective growth inhibitor of pathogenic Gram-negative (P. aeruginosa & A. baumannii) and Gram-positive bacteria (S. aureus).

An inhibitory action of chitosan nanoparticles against pathogenic bacteria and fungi and their potential applications as biocompatible antioxidants.

Chitosan is the second most abundant polymer obtained from the byproduct of seafood. Chitosan and its derivatives and chitosan loaded drugs are the recent area of interest against microbial pathogenesis. The cationic chitosan nanoparticles (ChNPs) interact with the anionic surfaces of the microbial cell membrane, which promotes antimicrobial activity. Although, ChNPs are potential against pathogenic microbes, selection of adaptable, suitable and cost effective synthesis method is much important. In the present study, ChNPs were synthesized adopting ionic gelation using sodium tripolyphosphate as a cross linking agent and characterized by FTIR, DLS, SEM and TEM analysis. ChNPs were investigated for antimicrobial activity against bacterial (Escherichia coli and Staphylococcus aureus) and fungal (Candida albicans) pathogens. ChNPs showed bactericidal activity at the lower minimum inhibitory concentration of about 40-80 µg mL-1. Interestingly, ChNPs exhibits biocompatible antioxidant property by inhibiting DPPH free radicals at 76% and also proven to be a potential candidate against the microbial pathogenesis with an inevitable applications in biomedicine.

Degradation of synthetic dye, Rhodamine B to environmentally non-toxic products using microalgae.

In the present study a potential freshwater microalgae Coelastrella sp. was selected for degradation of synthetic dye, Rhodamine B in batch culture system. Effect of several physico-chemical parameters that influence the decolorization followed by degradation ability was investigated (inoculum concentration, initial dye concentration, temperature and pH) and optimal experimental condition was ascertained. The optimum operating conditions were found to be [Dye]=100 mg l(-1); [temperature]=30°C; with 10% of inoculum at a pH of 8. Under these conditions, a maximum of 80% decolorization of the dye was achieved in 20 days. Peroxidase activity of the isolate was also determined and it was found to be 2.1 µmol min mg(-1) of protein. The actual break down of the dye was confirmed by using various analytical techniques such as GC-MS, TLC, FTIR and UV-vis spectral analysis. Small aliphatic chains, small chain alcohols and ketones were obtained after degradation of Rhodamine B. These are the evidences that showed that microalgae play a vital role on dye degradation to non-toxic products effectively.

Biogenic silver nanoparticles for cancer treatment: an experimental report.

A generation of nanoparticles research has discussed recently. It is mandatory to elaborate the applications of biogenic nanoparticles in general and anticancereous property in particular. The present study was aimed to investigate the in vitro cytotoxicity effect of biogenic silver nanoparticles (AgNPs) against human breast cancer (MCF-7) cells towards the development of anticancer agent. Biogenic AgNPs were achieved by employing Sesbania grandiflora leaf extract as a novel reducing agent. It was well characterized by FESEM, EDAX and spectral studies showed spherical shaped nanoparticles in the size of 22 nm in slightly agglomerated form. It was surprising that biogenic AgNPs showed cytotoxic effect against MCF-7 cell lines were confirmed by MTT, AO-EB, Hochest and COMET assays. There was an immediate induction of cellular damage in terms of loss of cell membrane integrity, oxidative stress and apoptosis were found in the cell which treated with AgNPs. This may be a first report on anti-MCF-7 property of biogenic AgNPs in the fourth generation of nanoparticles research. It is necessary to study the formulation and clinical trials to establish the nano drug to treat cancer cells.

Gold nanoparticles from pro and eukaryotic photosynthetic microorganisms--comparative studies on synthesis and its application on biolabelling.

Today, a material science focuses on the nanoparticles synthesis in general and synthesizing them by biological entity in particular for their marvel production and its remarkable property. In this present study, synthesis of gold nanoparticles using photosynthetic microorganisms such as Coelastrella sp. (eukaryotes) and Phormidium sp. (prokaryotes) were reacted with Chloroauric acid (HAuCl(4)) and bioaccumulation was assessed. Various techniques were adopted for characterization of nanoparticles and compared. It was found to be 25 nm sized nanotriangles and 30 nm sized spherical shaped nanoparticles were synthesized by prokaryotic and eukaryotic microorganisms respectively by TEM analysis. Biogenic gold nanoparticles have potent antioxidant property and the interaction of gold nanoparticles with DNA was evaluated that biogenic nanoparticles were actively bound to DNA in increased concentration. It was revealed that biogenic nanoparticles have wide range of applications depends on the biological entity used. Selection of suitable biological entity is very much important for the production of nanoparticles with desirable shapes and size for the biomedical applications.

Synthesis of anisotropic silver nanoparticles using novel strain, Bacillus flexus and its biomedical application.

Synthesis of metallic nanoparticles has attracted by bacterial based production and alternative to physical and chemical approaches. The present work was focused to nominate a bacterial strain for synthesis of potential silver nanoparticles. The target was achieved by screening of 127 isolates from silver mining wastes. A strain designated S-27 found to be a potential candidate for rapid synthesis of silver nanoparticles among tested microorganisms. It was subjected to molecular characterization by 16S rDNA sequence analysis. It was found that S-27 belonging to Bacillus flexus. Synthesis of silver nanoparticles was achieved by addition of culture supernatants with aqueous silver nitrate solution, immediately it turns to brown colour solution showed a peak at 420 nm corresponding to the plasmon absorbance of silver nanoparticles by UV-vis spectroscopy. Various instrumentation techniques, such as AFM, FESEM, XRD and FTIR, were adopted to characterize the synthesized nanoparticles. Anisotropic nanoparticles, such as spherical and triangular shaped nanoparticles, have been synthesized and sizes were found to be 12 and 65 nm, respectively. It was stable in aqueous solution in five months period of storage at room temperature in the dark. Synthesized nanoparticles showed efficacy on antibacterial property against clinically isolated multi-drug resistant (MDR) microorganisms. It is suggested that biogenic synthesis of nanoparticles have wide-application in medicine and physical chemistry and it can produce with eco-friendly, easy downstream processing and rapid scale-up processing.

Biosynthesis of silver nanoparticles from Tribulus terrestris and its antimicrobial activity: a novel biological approach.

In the recent decades, increased development of green synthesis of nanoparticles is inevitable because of its incredible applications in all fields of science. There were numerous work have been produced based on the plant and its extract mediated synthesis of nanoparticles, in this present study to explore that the novel approaches for the biosynthesis of silver nanoparticles using plant fruit bodies. The plant, Tribulus terrestris L. fruit bodies are used in this study, where the dried fruit body extract was mixed with silver nitrate in order to synthesis of silver nanoparticles. The active phytochemicals present in the plant were responsible for the quick reduction of silver ion (Ag(+)) to metallic silver nanoparticles (Ag(0)). The reduced silver nanoparticles were characterized by Transmission Electron Microscope (TEM), Atomic Force Microscope (AFM), XRD, FTIR, UV-vis spectroscopy. The spherical shaped silver nanoparticles were observed and it was found to be 16-28 nm range of sizes. The diffraction pattern also confirmed that the higher percentage of silver with fine particles size. The antibacterial property of synthesized nanoparticles was observed by Kirby-Bauer method with clinically isolated multi-drug resistant bacteria such as Streptococcus pyogens, Pseudomonas aeruginosa, Escherichia coli, Bacillus subtilis and Staphylococcus aureus. The plant materials mediated synthesis of silver nanoparticles have comparatively rapid and less expensive and wide application to antibacterial therapy in modern medicine.

Biodiversity and molecular evolution of microalgae on different epiphytes and substrates.

An exploration of the microalgal biodiversity from different epiphytes and substrates of pool water in temple at Tiruchirappalli District was studied. Totally ten epiphytic forms were selected for this investigation. In that, totally 44 species of 30 genera belonging to 3 families of the Chlorophyceae, Cyanophyceae (heterocystous and non-heterocystous) and Bacillariophyceae were identified and recorded. The dominant species in this environment were Cyanobacteria (Chroococcus sp. and Oscillatoria sp., Phormidium sp.), Green algae (Tetradron sp. and Scenedesmus sp.) and Diatom (Fragilaria sp. and Navicula sp.) were documented. The molecular taxonomy of cyanobacteria were also analyzed, in this regards, DNA was extracted; 16S rDNA gene was amplified and sequenced. The evolutionary relationship was found in the epiphytic microalgae by Neighbour-Joining method by construction of phylogenetic tree.

Evaluation of efficient extraction methods for recovery of photosynthetic pigments from microalgae.

Microalgal species are known to have pigments in their cellular constitute at the maximum and are valuable bioactive products. In the present study focused was on the evaluation of efficient extraction methods for photosynthetic pigments from microalgal species. They are, Chlorella sp., Acrochaete sp., Phormidium chlorinum, Jaaginema pseudogeminatum and Chroococcus sp. There are four different extraction methods were adopted for active recovery and are economically feasible such as direct extraction, mechanical grinding, heating and preheated solvent method. It was found that mechanical grinding method has extract two fold increased amount than the other methods. Additionally, this methods is inexpensive, less laborious and active extraction. It is suggested that this method could be used for the extraction of photosynthetic pigments from microalgae for pharmaceutical to biotechnological purpose.

Plant extract mediated synthesis of silver and gold nanoparticles and its antibacterial activity against clinically isolated pathogens.

Biosynthesis of nanoparticles is under exploration is due to wide biomedical applications and research interest in nanotechnology. Bioreduction of silver nitrate (AgNO(3)) and chloroauric acid (HAuCl(4)) for the synthesis of silver and gold nanoparticles respectively with the plant extract, Mentha piperita (Lamiaceae). The plant extract is mixed with AgNO(3) and HAuCl(2), incubated and studied synthesis of nanoparticles using UV-Vis spectroscopy. The nanoparticles were characterized by FTIR, SEM equipped with EDS. The silver nanoparticles synthesized were generally found to be spherical in shape with 90 nm, whereas the synthesized gold nanoparticles were found to be 150 nm. The results showed that the leaf extract of menthol is very good bioreductant for the synthesis of silver and gold nanoparticles and synthesized nanoparticles active against clinically isolated human pathogens, Staphylococcus aureus and Escherichia coli.