Biosynthesis of gold nanoparticles by the extreme bacterium <em>Deinococcus radiodurans</em> and an evaluation of their antibacterial properties

Biosynthesis of Au, Ag and Au&ndash;Ag bimetallic nanoparticles using protein extracts of <em>Deinococcus radiodurans</em> and evaluation of their cytotoxicity

“…The absorption spectra of the suspensions exhibited a characteristic absorption peak at 545 nm ( Figure 1B), owing to the surface plasmon resonance (SPR) of AuNPs. 31 As for the formation of the Drp-AgNPs from the reaction of Ag(I) and protein extracts, a stable brown color together with the significant characteristic SPR absorption at 414 nm was observed within ~24 h ( Figure 1C and D). The controls (metal ion solution or protein extracts alone) had neither corresponding color changes nor characteristic absorptions, indicating that the protein extracts were involved in the formations of NPs.…”

“…[27][28][29] Recently, the synthesis of AgNPs and AuNPs via the cultures of D. radiodurans with silver and gold ions was investigated. 30,31 Moreover, surface layer protein lattices of D. radiodurans exhibited a biotemplating effect on the preformed AuNPs, into ordered arrays. 32 The intracellular proteins containing metal capturing and reducing groups might provide a reducing microenvironment for the formation of metal NPs.…”

“…32 The intracellular proteins containing metal capturing and reducing groups might provide a reducing microenvironment for the formation of metal NPs. In the previous work, 31 we proposed the involvement of proteins in the biosynthesis of AuNPs by the cultures of D. radiodurans incubated with HAuCl 4 solution. To date, the biosynthetic mechanism and evaluation of cytotoxicity of Au, Ag or Au-Ag bimetallic NPs synthesized using protein extracts of D. radiodurans remains unexplored.…”

“…31,33 The particle size of NPs was measured using ImageJ software (National Institutes of Health, Bethesda, MD, USA). The energy-dispersive X-ray spectroscopy (EDS) was recorded by focusing the electron beam onto a region of the sample surface to perform elemental analysis of the test samples in an area scan mode.…”

“…An electric field of 150 mV was applied to monitor the electrophoretic velocity of the particles. 31 Three independent samples were run at the same time, and the representative data were presented.…”