Gold nanorod production by cyanobacteria—a green chemistry approach

Abstract

Intracellular bioconversion of auric ion (Au 3+ ) to gold nanorod (Au 0 ) by the cyanobacterium Nostoc ellipsosporum has been observed for the first time in laboratory condition. The nanorods were produced within the cell after exposing the healthy growing filaments to 15 mg L −1 gold (III) solution (pH 4.5) for 48 h at 20°C. The gold nanoparticles were extracted with sodium citrate solution and were subjected to UV-Visible spectroscopy. The characteristic surface-multiple plasmon bands at 560, 610, and 670 nm were observed. The nature and size of the particles were determined by transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray diffraction (XRD), and zeta potential studies. The nanorod size ranged from 137 to 209 nm in length and 33 to 69 nm in diameter. DLS study revealed the average hydrodynamic size as 435 nm and XRD study indicated the reduction of Au 3+ to Au 0 . Methods of extraction and preservation of gold nanorod particles have also been studied.

Screening of different algae for green synthesis of gold nanoparticles

“…The gold nanoparticle solutions extracted in the present study were purple, because of the excitation of surface plasmon vibrations in the gold nanoparticles (Mulvaney, 1996). After Au (III) exposure, the purple, ruby red or blue colorations of microorganisms are due to the reduction of Au (III) to Au (0) and subsequent formation of Au nanoparticles intra-and/or extracellularly (Druff et al, 1987;Chow & Zukoski, 1994;Lujan et al, 1994;Chakraborty et al, 2009;Parial et al, 2012). The present study shows that the three selected cyanobacteria, Phormidium valderianum, P. tenue and Microcoleus chthonoplastes, and the two chlorophycean algae Ulva intestinalis and Rhizoclonium fontinale, have potential as bionano-factories, and this is evident from the visual transformation of the algal thalli from green to deep purple.…”

“…25). demonstrated a green chemical approach for the controlled biosynthesis of gold nanorods by Nostoc ellipsosporum without any shape anisotropy (Parial et al, 2012).…”

“…Synthesis of nanogold has also been reported in algae, including Chlorella vulgaris (Ting et al, 1995), Sargassum wightii (Singaravelu et al, 2007) and Plectonema boryanum (Lengke et al, 2006a(Lengke et al, , 2006b). Gold nanoparticle synthesis by cyanobacteria (such as Lyngbya majuscula and Spirulina subsalsa), green algae (Rhizoclonium hieroglyphicum and R. riparium) and diatoms (Nitzschia obtusa and Navicula minima) has recently been reported by Chakraborty et al (2006Chakraborty et al ( , 2009 and Nayak et al (2006), and biosynthesis of gold nanorods by Nostoc ellipsosporum by Parial et al (2012).…”

Microalgae in Biotechnological Application: A Commercial Approach

“…In the same year, the present group reported cyanobacteria-and algae-based systemic process of gold and silver nanoparticle synthesis and published a series of papers on biosynthesis of gold nanoparticle by cyanobacteria (such as Lyngbya majuscula and Spirulina subsalsa ), green algae ( Rhizoclonium hieroglyphicum and R. riparium ), Spirogyra and diatoms ( Nitzschia obtusa and Navicula minima ) (Chakraborty et al 2006(Chakraborty et al , 2009Nayak et al 2006a ;Roychoudhury and Pal 2014 ). Screening for different algae as bioreagent of GNP production and biosynthesis of gold nanorods by Nostoc ellipsosporum was done by Parial et al ( 2012 ); Parial and Pal ( 2014 ) and of silver nanoparticles by Roychoudhury et al (2014) (Fig. 2.7 ).…”

Formation of Variously Shaped Gold Nanoparticles by Anabaena laxa

“…Spirulina platensis is the most frequently mentioned cyanobacterial species able to produce AuNPs [33,34] and thus can be regarded as a model microorganism in this group. Other species described in the literature include Nostoc ellipsosporum [35], Phormidium valderianum, Phormidium tenue [36], Anabaena flos-aquae [29] and Anabaena sp. [28].…”