Abstract
Fabrication of flower-like nanostructures are gaining attention because of their high surface/volume ratio and extensive adsorption capacity. In the present investigation, flower-shaped, autofluorescent silver-silica (Ag-SiO2) hybrid nanoparticles have been fabricated exploiting diatoms as a source of nanosilica. Two different species of Gedaniella including G. flavovirens and G. mutabilis showed their efficacy in synthesizing fluorescent Ag-SiO2 nanoflowers (NFs) and nanospheres (NSs) against 9 mM silver nitrate solution, respectively. The biogenic nanoconjugate (Ag-SiO2) was characterized by Uv-vis spectroscopy, energy dispersive X-ray spectroscopy (EDS), scanning (SEM) and transmission (TEM) electron microscopy. Production of Ag-SiO2 hybrid nanoparticle was confirmed by observing both Ag and Si signals from a single nanoparticle in an EDS study. The broad and single absorption band at ~420 nm in Uv-vis spectroscopy confirmed proper miscibility and production of hybrid nanoparticles. The Ag-SiO2 nanohybrids revealed autofluorescent property under the blue light region (excitation ~450–490 nm). SEM images of particles synthesized by G. flavovirens revealed the production of microscopic flower shaped Ag-SiO2 particles with several layers of petals. A TEM study confirmed that the synthesized Ag-SiO2 NFs are variable in size with 100–500 nm in diameter. Decolorization of methylene blue after exposure to Ag-SiO2 particles confirmed catalytic activity of synthesized nanostructures. This eco-friendly method provides a new dimension in nanobiotechnology for biogenesis of such hierarchical nanostructure in a cost-effective way.
Highlights
Silver nanoparticles (AgNPs) are well known for their extensive antimicrobial activity [1] and applicability in different physical fields as catalysts [2], biosensors [3], conductive adhesives [4], in water treatment [5], ink-jet printing [6], protein sensing [7] and solar cell optimization [8], etc
Associated Morphological Changes in Ag+ Exposed Gedaniella The morphological changes in G. flavovirens and G. mutabilis due to Ag+ stress was preliminarily confirmed by observing color change in biomass
It was observed that AgSiO2 nanohybrid production against AgNO3 solution is possible by using G. flavovirens and G. mutabilis as reducing agents
Summary
Silver nanoparticles (AgNPs) are well known for their extensive antimicrobial activity [1] and applicability in different physical fields as catalysts [2], biosensors [3], conductive adhesives [4], in water treatment [5], ink-jet printing [6], protein sensing [7] and solar cell optimization [8], etc. The Ag particles are less stable and tend to aggregate To conquer this problem, AgNPs are needed to combine with some other nanoparticles. Ag-decorated silica nanoparticles have been synthesized by some chemical methods such as the wet-impregnation method [10] and metal-assisted chemical etching [11], which involves harmful chemicals like cetyltrimethylammonium bromide (CTAB) and hydrofluoric acid (HF). None of these techniques are environmentally friendly due to the involvement of hazardous chemicals. Only a single report regarding the synthesis of hybrid Ag-SiO2 nanodendrites by Halamphora subturgida is available [17]
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