Nano-decolorization of methylene blue by Phyllanthus reticulatus iron nanoparticles: an eco-friendly synthesis and its antimicrobial, phytotoxicity study.

The present study was investigated to synthesis the iron nanoparticles (FeNPs) using the leaf extract of Phyllanthus reticulatus. The phytosynthesized FeNPs exhibited UV-visible absorption peaks at 229 nm and its crystalline nature was confirmed through XRD. FT-IR analysis revealed the presence of various functional groups which are responsible for the bioreduction of FeNPs. The SEM results showed that FeNPs were aggregated, irregular sphere shaped with rough surfaces and EDX spectrum recorded densely occupied iron nanoparticles region. The particle size range of the synthesized iron nanoparticles was 185.6 nm. The FeNPs showed potential methylene blue decolourisation activity which was visually observed by gradual colour change in the dye solution from deep blue to colorless. The control exhibited no change in coloration during exposure to sunlight and the iron nanoparticles completely disintegrated the methylene blue within 10 s in 10 mg/L methylene blue (98%), whereas the color change was decreased when the concentration of the dye increased. In addition, the phyto-synthesized FeNPs exhibited extensive antibacterial and antifungal activity against the selected pathogens. Phytotoxicity assay confirms the potential of biosynthesized iron nanoparticles as a fertilizer for the growth of green gram seeds. Thus the present study leads to development of cost-effective green synthesis, reduction of toxic chemicals and its extensive applications in the biological sciences.

Microwave-assisted green synthesis of fluorescent carbon quantum dots from Mexican Mint extract for Fe3+ detection and bio-imaging applications.

Biomass-derived carbon quantum dots have drawn special interest owing to their admirable photostability, biocompatibility, fluorescence, high solubility, sensitivity and environmentally friendly properties. In the present work, the Carbon Quantum Dots (CQDs) was synthesized from the Plectranthus amboinicus (Mexican Mint) leaves via the microwave-assisted reflux method. The strong absorption peaks observed from UV-vis spectra at 291 and 330 nm corresponds to the π-π* and n-π* transitions, respectively, reveal the formation of CQDs. The synthesized CQDs showed bright blue fluorescence under UV irradiation with a fluorescence quantum yield of 17% and a maximum emission of 436 nm in the blue region at an excitation wavelength of 340 nm. The HRTEM analysis elucidates that the synthesized CQDs were crystalline and spherical in shape with a particle size of 2.43 ± 0.02 nm. The FT-IR spectroscopy confirms the presence of the different functional groups such as -OH, -CH, CO and C-O. The chemical composition of CQD was revealed through XPS analysis. The synthesized CQDs were used as a fluorescent probe to detect different metal ions, where high selectivity was obtained for Fe3+ ions through quenching phenomenon. The emission intensity of CQD showed a good linear relationship with R2 = 0.9111 with the concentration of Fe3+ ions in the range of 0-15 µM. The fluorescence emission of CQD was turned OFF upon the binding of Fe3+ ions and turned - ON with the addition of ascorbic acid. With this fluorescent turn ON-OFF behaviour of CQD, the NOT and IMPLICATION logic gates were constructed and studied for different input conditions. The biocompatibility of CQD was tested via MTT assay using MCF7 breast cancer cell line, which revealed that CQD synthesized from the Mexican Mint leaves possess less cytotoxicity. Further, the prepared CQD was applied effectively as fluorescent probes in a cell imaging application.

Green biomimetic silver nanoparticles utilizing the red algae Amphiroa rigida and its potent antibacterial, cytotoxicity and larvicidal efficiency.

The present investigation reports a simple, rapid, inexpensive, and eco-friendly approach for synthesizing Amphiroa rigida-mediated silver nanoparticles (AR-AgNPs) for the first time. The biomimetic synthesized AR-AgNPs were characterized by both spectral and microscopic analysis. The UV-visible spectrum showed the surface plasmon peak at 420 nm, which indicated the formation of AR-AgNPs. X-ray diffraction characterization of AR-AgNPs showed a face-centered cubic crystal (25 nm) and the transmission electron microscope micrograph showed spherical shape. The functional group of polysaccharide that plays a major role as a stabilizing and reducing agent is confirmed by Fourier-transform infrared spectroscopy. The biomimetic synthesized AR-AgNPs showed antibacterial activity against Staphylococcus aureus (21 ± 0.2 mm) and Pseudomonas aeruginosa (15 ± 0.2 mm). Further, the cytotoxic effects of AR-AgNPs against MCF-7 human breast cancer cells were observed through acridine orange-ethidium bromide and Hoechst staining. Besides, AR-AgNPs are found to be inhibit the growth of 3rd and 4th instar larvae of Aedes aegypti in a dose-dependent manner.

Sunroot mediated synthesis and characterization of silver nanoparticles and evaluation of its antibacterial and rat splenocyte cytotoxic effects.

A rapid, green phytosynthesis of silver nanoparticles (AgNPs) using the aqueous extract of Helianthus tuberosus (sunroot tuber) was reported in this study. The morphology of the AgNPs was determined by transmission electron microscopy (TEM). Scanning electron microscopy-energy-dispersive spectroscopy (SEM-EDS) and X-ray powder diffraction (XRD) analysis confirmed the presence of AgNPs. Fourier transform infrared spectroscopy (FTIR) analysis revealed that biomolecules in the tuber extract were involved in the reduction and capping of AgNPs. The energy-dispersive spectroscopy (EDS) analysis of the AgNPs, using an energy range of 2-4 keV, confirmed the presence of elemental silver without any contamination. Further, the synthesized AgNPs were evaluated against phytopathogens such as Ralstonia solanacearum and Xanthomonas axonopodis. The AgNPs (1-4 mM) extensively reduced the growth rate of the phytopathogens. In addition, the cytotoxic effect of the synthesized AgNPs was analyzed using rat splenocytes. The cell viability was decreased according to the increasing concentration of AgNPs and 67% of cell death was observed at 100 µg/mL.

A comparative study on bioactive constituents between wild and in vitro propagated Centella asiatica.

Centella asiatica (Umbelliferae) has been used for centuries in Indian ayurvedic medicine for the treatment of a wide number of health disorders. The aim of this study was to estimate and compare the concentration of bioactive compounds between wild and in vitro propagated C. asiatica plants. A marked decrease in the total phenolic compounds, flavonoids, and ascorbic acid was observed between in vitro propagated and wild type plants collected from wet land habitat. The radical scavenging activity of the wild type plant extracts also varied with the habitats. This study clearly indicates that environmental factors play a crucial role in the plant metabolic activity and medicinal activity.

Acorus calamus rhizome extract mediated biosynthesis of silver nanoparticles and their bactericidal activity against human pathogens.

Silver nanoparticle (AgNP) synthesis and characterization is an area of vast interest due to their broader application in the fields of science and technology and medicine. Plants are an attractive source for AgNP synthesis because of its ability to produce a wide range of secondary metabolites with strong reducing potentials. Thus, the present study describes the synthesis of AgNPs using aqueous rhizome extract of Acorus calamus (sweet flag). The AgNP formation was evaluated at different temperatures, incubation time and concentrations of AgNO3 using Response surface methodology based Box-Behnken design (BBD). The synthesized AgNPs were characterized by UV-Visible spectroscopy, Fourier transform infra-red spectroscopy (FTIR), X-ray diffraction (XRD), and Scanning electron microscopy-energy-dispersive spectroscopy (SEM-EDS). The surface plasmon resonance found at 420 nm confirmed the formation of AgNPs. SEM images reveal that the particles are spherical in nature. The EDS analysis of the AgNPs, using an energy range of 2-4 keV, confirmed the presence of elemental silver without any contamination. The antibacterial activity of synthesized AgNPs was evaluated against the clinical isolates Staphylococcus aureus and Escherichia coli and it was found that bacterial growth was significantly inhibited in a dose dependent manner. The results suggest that the AgNPs from rhizome extract could be used as a potential antibacterial agent for commercial application.

Biosynthesis and characterization of silver nanoparticles using panchakavya, an Indian traditional farming formulating agent.

Synthesis of silver nanoparticles (AgNPs) with biological properties is of vast significance in the development of scientifically valuable products. In the present study, we describe simple, unprecedented, nontoxic, eco-friendly, green synthesis of AgNPs using an Indian traditional farming formulating agent, panchakavya. Silver nitrate (1 mM) solution was mixed with panchakavya filtrate for the synthesis of AgNPs. The nanometallic dispersion was characterized by surface plasmon absorbance measuring 430 nm. Transmission electron microscopy showed the morphology and size of the AgNPs. Scanning electron microscopy-energy-dispersive spectroscopy and X-ray diffraction analysis confirmed the presence of AgNPs. Fourier transform infrared spectroscopy analysis revealed that proteins in the panchakavya were involved in the reduction and capping of AgNPs. In addition, we studied the antibacterial activity of synthesized AgNPs. The synthesized AgNPs (1-4 mM) extensively reduced the growth rate of antibiotic resistant bacteria such as Aeromonas sp., Acinetobacter sp., and Citrobacter sp., according to the increasing concentration of AgNPs.