Alexis Debut

Experimental and theoretical study of linewidth narrowing in Brillouin fiber ring lasers

In Brillouin fiber lasers, the phase fluctuations of the pump laser are transferred to the emitted Stokes field after being strongly reduced. The result is a linewidth narrowing that we study both experimentally and theoretically. We derive simple expressions to connect the linewidths of the waves interacting in the fiber, and we show that the magnitude of the narrowing effect depends only on the acoustic damping rate and the cavity loss rate. We successfully compare these theoretical predictions with experimental results obtained by recording the response of a Brillouin fiber ring laser to frequency modulation of the pump field.

Sonochemical Synthesis of Silver Nanoparticles Using Starch: A Comparison

A novel approach was applied to synthesize silver nanoparticles using starch under sonication. Colloidal silver nanoparticles solution exhibited an increase of absorption from 420 to 440 nm with increase starch quantity. Transmission electron microscopy followed by selected area electron diffraction pattern analysis indicated the formation of spherical, polydispersed, amorphous, silver nanoparticles of diameter ranging from 23 to 97 nm with mean particle size of 45.6 nm. Selected area electron diffraction (SAED) confirmed partial crystalline and amorphous nature of silver nanoparticles. Silver nanoparticles synthesized in this manner can be used for synthesis of 2-aryl substituted benzimidazoles which have numerous biomedical applications. The optimized reaction conditions include 10 ml of 1 mM AgNO3, 25 mg starch, 11 pH range, and sonication for 20 min at room temperature.

Green synthesis of silver nanoparticles using Andean blackberry fruit extract

Green synthesis of nanoparticles using various plant materials opens a new scope for the phytochemist and discourages the use of toxic chemicals. In this article, we report an eco-friendly and low-cost method for the synthesis of silver nanoparticles (AgNPs) using Andean blackberry fruit extracts as both a reducing and capping agent. The green synthesized AgNPs were characterized by various analytical instruments like UV–visible, transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The formation of AgNPs was analyzed by UV–vis spectroscopy at λmax = 435 nm. TEM analysis of AgNPs showed the formation of a crystalline, spherical shape and 12–50 nm size, whereas XRD peaks at 38.04°, 44.06°, 64.34° and 77.17° confirmed the crystalline nature of AgNPs. FTIR analysis was done to identify the functional groups responsible for the synthesis of the AgNPs. Furthermore, it was found that the AgNPs showed good antioxidant efficacy (>78%, 0.1 mM) against 1,1-diphenyl-2-picrylhydrazyl. The process of synthesis is environmentally compatible and the synthesized AgNPs could be a promising candidate for many biomedical applications.

Green Approach for Fabrication and Applications of Zinc Oxide Nanoparticles

Zinc oxide nanoparticles (ZnO-NPs) are known to be one of the multifunctional inorganic compounds which are widely used in everyday applications. This study aims to fabricate ZnO-NPs using grapefruit (Citrus paradisi) peel extract with particle size ranging from 12 to 72 nm. Structural, morphological, and optical properties of the synthesized nanoparticles have been characterized by using UV-Vis spectrophotometer, TEM, DLS, and FTIR analysis. They show the significant photocatalytic degradation efficiency (>56%, 10 mg/L, 6 h) against methylene blue and antioxidant efficacy (≥80% for 1.2 mM) against 1,1-diphenyl-2-picrylhydrazyl. From the results obtained it is suggested that green ZnO-NPs could be used effectively in environmental safety applications and also can address future medical concerns.

Lantana camara berry for the synthesis of silver nanoparticles

ABSTRACT Objective To synthesize the silver nanoparticles (AgNPs) by reduction of silver ions into nano silver, using ripened berry extract of Lantana camara and evaluate its antioxidant activity against 1, 1-diphenyl-2- picrylhydrazyl. Methods The prepared AgNPs were characterized by visual, UV-visible spectrophotometer, dynamic light scattering and transmission electron microscopy with selected area electron diffraction. Results Transmission electron microscopy and dynamic light scattering analysis confirmed the AgNPs are spherical and 75.2 nm average sized. Selected area electron diffraction analysis supports that the obtained nanoparticles were in crystalline form. In addition, the antioxidant efficacy of prepared AgNPs was found to be higher than berry extract against 1, 1-diphenyl-2- picrylhydrazyl. Conclusions From the results obtained it is suggested that surface modified AgNPs at lower concentration, showed higher antioxidant activity than berry extract against 1, 1-diphenyl-2- picrylhydrazyl and could be used effectively in future ethno pharmacological concerns.

Extracellular green synthesis of silver nanoparticles using Amazonian fruit Araza (Eugenia stipitata McVaugh)

Abstract An eco-friendly method for the extracellular synthesis of silver nanoparticles (AgNPs) using aqueous Araza fruit extract and their antioxidant activity was investigated. It was observed that UV–Vis absorption peak is dependent on various parameters such as pH, temperature, and change of time. The initial appearance of the yellow color with intense surface plasmon bands at 430–450 nm, then transmission electron microscopy, scanning electron microscopy and X-ray diffraction analysis revealed the formation of 15–45 nm sized, spherical and crystalline AgNPs. Fourier transform infrared spectroscopy depicted that malic acid, citric acid, and carotenoids of Araza fruit involved in the synthesis of AgNPs. In addition, the surface modified AgNPs (77.42%, 1 mL) showed nearly double antioxidant efficiency than Araza fruit extract (35.30%, 1 mL) against 1, 1-diphenyl-2-picrylhydrazyl. The present study highlights the possibility of using the Araza fruit to synthesize AgNPs, which could be used effectively in the present and future antioxidant agent.

Ionic Liquid Based Silica Tuned Silver Nanoparticles: Novel Approach for Fabrication

A novel synthetic method for the fabrication of silver nanoparticles has been developed in the presence silica functionalized ionic liquids. The synthesized AgNPs are with particle size ranging from 25 to 50 nm and further characterized by UV-vis spectroscopy, dynamic light scattering, transmission electron microscopy, and Fourier transform infrared spectroscopy. Selected area electron diffraction confirmed the formation of metallic Ag. The method provides several advantages such as green solvent, shorter reaction time and could be used effectively in future engineering or medical concerns.

One pot synthesis and characterization of gold nanocatalyst using Sacha inchi (Plukenetia volubilis) oil: Green approach.

In this report, a simple and cost-effective methodology has been developed to obtain gold nanoparticles (AuNPs) using Sacha inchi (Plukenetia volubilis) oil in the presence of sunlight. The spectroscopic and morphological properties of AuNPs were characterized by using UV-vis spectroscopy, transmission electron microscopy (TEM), particle size analyzer, and X-ray diffraction (XRD). UV-vis and TEM reveal that the nanostructure of the gold particles has surfaced plasmon resonance at 515-520nm and is almost spherical in shape with an average size of 5-15nm. XRD studies confirmed the face cubic center (fcc) unit cell structure of AuNPs. The as-synthesized AuNPs showed remarkable photocatalytic decomposition of the methylene blue (>75%) without using any reducing agent and weak antioxidant activity (21-16%) against 1,1-diphenyl-2-picrylhydrazyl at the different sunlight exposure times. The experimental approach is promising and suggested that the sunlight is a good source of energy for enhancement of AuNP synthesis via Sacha inchi oil and its photocatalytic activity.

Peptides conjugated to silver nanoparticles in biomedicine – a “value-added” phenomenon

Nanotechnology is gaining impetus in the present century and particularly the use of nanoparticles (NPs), whose properties are significantly different from the larger matter. These have found wider and potential applications in the fields of medicine, energy, cosmetics, environment and biomedicine. Among the NPs, silver nanoparticles (AgNPs) are of particular interest for scientists and technologists due to their unique physico-chemical and biological properties. Besides, AgNPs by themselves also possess broad-spectrum microbial activity, which has further expanded their application in both academia and industries. On the other hand, research and drug discovery in the field of peptides is surging. Chemistry and biology of peptides have seen a renaissance in this century as many of the peptide-based therapeutics have entered the market and many more are in the different phases of clinical trials. To fuel this, peptides have also found numerous applications in nanotechnology. Taking advantage of these two scenarios, namely, AgNPs and peptides, conjugation of these entities have emerged as a powerful technique and have opened the doors for a new revolution. Keeping this motivation in mind, we here present a mini-review on the combined concept of AgNPs and peptides.

Reliable Tools for Quantifying the Morphogical Properties at the Nanoscale

We have developed a fast, reliable and robust code to analyze size distributions and morphological properties of nanostructures. A segmentation algorithm, based on watershed transformation, has been implemented and tested. We have used consistent definitions to quantify the sphericity, roundness and roughness, which critically modify the physicochemical properties at the nanoscale. Finally, our approach has been applied to some example systems. We demonstrate that our code can be applied to guide the synthesis of nanoparticles, to distinguish dead from living bacteria and also to predict the reactivity of nanoparticles used for environmental remediation.