Synthesis and Characterization of Silver and Gold Nanoparticles Using Aqueous Extract of Seaweed, Turbinaria conoides,

Silver and gold nanoparticles were synthesized using an aqueous extract of the seaweed Turbinaria conoides and their antibiofilm activity against marine biofilm forming bacteria is reported here. The UV-Vis spectra showed the characteristics SPR absorption band for Ag NPs at 421 and for Au NPs at 538 nm. Further, the synthesized nanoparticles were characterized using FT-IR, XRD, FESEM, EDX, and HRTEM analysis. Spherical and triangular nanostructures of the Ag and Au nanoparticles were observed between the size ranges of 2–17 nm and 2–19 nm, respectively. The synthesized Ag NPs are efficient in controlling the bacterial biofilm formation; however, Au NPs did not show any remarkable antibiofilm activity. The maximum zone of inhibition was recorded against E. coli (17.6±0.42 mm), followed by Salmonella sp., S. liquefaciens, and A. hydrophila. The macrotube dilution method inferred the MIC (20–40 µL mL−1) and MBC (40–60 µL mL−1) of Ag NPs. The CLSM images clearly showed the weak adherence and disintegrating biofilm formation of marine biofilm bacterial strains treated with Ag NPs. The Artemia cytotoxicity assay recorded the LC50 value of 88.914±5.04 µL mL−1. Thus the present study proved the efficiency of Ag NPs as a potent antimicrofouling agent and became the future perspective for the possible usage in the biofouling related issues in the aquaculture installations and other marine systems

Biofabrication and characterization of silver nanoparticles using aqueous extract of seaweed Enteromorpha compressa and its biomedical properties

Green synthesis of nanoparticles using seaweeds are fascinating high research attention nowadays and also gaining center of attention in biomedical applications. In this work, we have synthesized biocompatible and functionalized silver nanoparticles using an aqueous extract of seaweed Enteromorpha compressa as a reducing as well as stabilizing agent and their efficient antimicrobial and anticancer activity are reported here. The UV–vis spectra of AgNPs showed the characteristics SPR absorption band at 421 nm. The chemical interaction and crystalline nature of the AgNPs were evaluated by FT-IR and XRD studies. The XRD result of AgNPs shows typical Ag reflection peaks at 38.1°, 44.2°, 64.4° and 77.1° corresponding to (111), (200), (220) and (311) Bragg’s planes. The surface morphology and composition of the samples were observed by HRTEM, EDS and SAED pattern analyses. Spherical shaped Ag nano structures were observed in the size ranges between 4 and 24 nm with clear lattice fringes in the HRTEM image. This report reveals that seaweed mediated synthesis of AgNPs and sustained delivery of Ag ions to the bacterial and fungal surface have been reducing their growth rate which was evaluated by well diffusion assay. The synthesized AgNPs showed favorable cytotoxicity against Ehlrich Ascites Carcinoma (EAC) cells with IC50 value was recorded at 95.35 μg mL−1. This study showed cost effective silver nanoparticles synthesis with excellent biocompatibility and thus could potentially be utilized in biomedical and pharmaceutical applications

Pt Nanoparticles Supported on Mesoporous CeO₂ Nanostructures Obtained through Green Approach for Efficient Catalytic Performance toward Ethanol Electro-oxidation

In this report, an easy and green approach to the synthesis of mesoporous cerium oxide (CeO₂) nanostructures and followed by supporting platinum nanoparticles (NPs) on CeO₂ nanostructures (Pt/CeO₂) and their application as versatile electrocatalysts for ethanol electrooxidation has been established. The synthesis of mesoporous Pt/CeO₂ nanostructures involves two steps. First, mesoporous CeO₂ nanostructures were synthesized via macroalgae polymer mediated approach and followed by supporting of PtNPs of ca. 5–10 nm over the mesoporous CeO₂ nanostructures using seed-mediated chemical reduction process. The structural and spectroscopic characterization techniques such as transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman, X-ray photoelectron spectroscopy (XPS), and small-angle X-ray scattering (SAXS) studies confirm the strong coupling between PtNPs and the mesoporous CeO₂ support resulting in the generation of more oxygen vacancies, which can facilitate the enhanced charge transport at their functional interface. Significantly, the synthesized mesoporous Pt/CeO₂ nanostructures were found to show enhanced electrocatalytic activity for ethanol electrooxidation reaction. The enhanced performance is attributed to the synergistic effect of both mesoporous structure and the formation of more oxygen vacancies in the resultant Pt/CeO₂ nanostructures. Our facile and eco-friendly approach to the synthesis of mesoporous CeO₂ nanostructures that supports PtNPs with an excellent catalytic activity is validated as a promising strategy for potential applications in fuel cells