Extracellular biosynthesis of silver nanoparticles using the fungus Aspergillus fumigatus

Bhainsa, Kuber C.; D’Souza, S.F.

doi:10.1016/j.colsurfb.2005.11.026

Cited by 985 publications

(398 citation statements)

References 10 publications

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“…All particles used in this study where characterised for size/distribution using two methods; Dynamic Light Scattering (DLS) and Scanning Electron Microscopy (SEM). In addition particle purity and coatings (where applicable) were confirmed using UV-Visible absorption spectroscopy [5], X-ray diffraction spectroscopy (XRD) [4], and atomic absorption spectroscopy (AAS) [13]. Colloidal stability was assessed using zeta potential analysis [27].…”

Section: Nanoparticle Characterisationmentioning

confidence: 99%

Antimicrobial properties of nano-silver: A cautionary approach to ionic interference

Sheehy¹,

Casey²,

Murphy³

et al. 2015

Journal of Colloid and Interface Science

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a b s t r a c tHypothesis: Metallic nanoparticles such as nano-silver have found many applications as alternative antimicrobials in recent years. However methods for determining their proposed antimicrobial activity have received little attention to date. The disk diffusion assay is commonly used as a demonstration of antimicrobial properties and is a regular feature in synthetic nanoparticle papers. The aim of this study was to assess its effectiveness in demonstrating the ''nanoparticle specific'' antimicrobial properties in the absence of ionic contributions from unreacted reducing agents and or impurities. Experiments: The disk diffusion assay was carried out on a range of silver nanoparticles, both in-house synthesised and commercially available, using Escherichia coli ATCC 25922 as a model organism. Results: Capped and purified nanoparticles show no antimicrobial activity despite claims to the contrary for this assay. Results will be discussed in terms of the need for researchers without a background in microbiology to understand the mechanism of antimicrobial action before choosing an assay. Also discussed is the importance understanding the physiochemical characteristics of when interpreting results. Finally the relevance of the results in terms establishing protocols for method development for 'nanoparticle specific' antimicrobial properties will also be considered.

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Section: Nanoparticle Characterisationmentioning

confidence: 99%

Antimicrobial properties of nano-silver: A cautionary approach to ionic interference

Sheehy¹,

Casey²,

Murphy³

et al. 2015

Journal of Colloid and Interface Science

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“…Filamentous fungi on the other hand are capable of synthesizing the silver nanoparticles extracellularly but the downstream processing and the biomass handling make them difficult [10][11][12].…”

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confidence: 99%

Extracellular synthesis of silver nanoparticles using dried leaves of pongamia pinnata (L) pierre

et al. 2010

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Extract of oven dried leaves of Pongamia pinnata (L) Pierre was used for the synthesis of silver nanoparticles. Stable and crystalline silver nanoparticles were formed by the treatment of aqueous solution of AgNO 3 (1mM) with dried leaf extract of Pongamia pinnata (L) Pierre. UV-visible spectroscopy studies were carried out to quantify the formation of silver nanoparticles. Transmission electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy were used to characterize the silver nanoparticles. TEM image divulges that silver nanoparticles are quite polydispersed, the size ranging from 20 nm to 50 nm with an average of 38 nm. Water soluble heterocyclic compounds such as flavones were mainly responsible for the reduction and stabilization of the nanoparticles. Silver nanoparticles were effective against Escherichia coli (ATCC 8739), Staphylococcus aureus (ATCC 6538p), Pseudomonas aeruginosa (ATCC 9027) and Klebsiella pneumoniae (clinical isolate). The move towards extracellular synthesis using dried biomass appears to be cost effective, eco-friendly to the conventional methods of nanoparticles synthesis.

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“…6 These AgNPs are usually localized extracellularly, 6 which would simplify the downstream processing. 7,8 Although the biosynthesis of AgNPs has been demonstrated with a variety of bacteria, fungi, and actinomycetes, 6 the mechanism of this process is yet to be elucidated, which will be helpful for the enhancement of AgNP synthesis 9 as well as our understanding of the biomineralization of silver and the formation of naturally occurring AgNPs. 10 Several studies suggested that nitrate reductase (NR) was involved in this bioreduction process.…”

Section: ■ Introductionmentioning

confidence: 99%

Superoxide-Mediated Extracellular Biosynthesis of Silver Nanoparticles by the Fungus Fusarium oxysporum

Yin

Xiao-ya

et al. 2016

Environ. Sci. Technol. Lett.

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The biosynthesis of silver nanoparticles (AgNPs) by microorganisms has become a hot topic in recent years, although its mechanism is still not well understood. Here we report the extracellular biosynthesis of AgNPs by the fungus Fusarium oxysporum through a superoxide-dependent mechanism. Reduction of Ag + to AgNPs in the extracellular region of F. oxysporum was verified by transmission electron microscopy, while the superoxide produced extracellularly by F. oxysporum was evidenced by chemiluminescence. We further demonstrated that the biosynthesis of AgNPs was inhibited by a superoxide scavenger or the inhibitor of NADH oxidases, and the addition of NADH significantly improved the formation of AgNPs. These results demonstrated that, for the first time, the fungus F. oxysporum can mediate the synthesis of AgNPs through the enzymatic generation of extracellular superoxide, which is helpful in understanding the biosynthesis of AgNPs and the biomineralization and transformation of silver and other metals or metalloids.

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Extracellular biosynthesis of silver nanoparticles using the fungus Aspergillus fumigatus

Cited by 985 publications

References 10 publications

Antimicrobial properties of nano-silver: A cautionary approach to ionic interference

Antimicrobial properties of nano-silver: A cautionary approach to ionic interference

Extracellular synthesis of silver nanoparticles using dried leaves of pongamia pinnata (L) pierre

Superoxide-Mediated Extracellular Biosynthesis of Silver Nanoparticles by the Fungus Fusarium oxysporum

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