Photoinduced Silver Nanoparticles/Nanorings on Plasmid DNA Scaffolds

Abstract

Biological scaffolds are being actively explored for the synthesis of nanomaterials with novel structures and unexpected properties. Toroidal plasmid DNA separated from the Bacillus host is applied as a sacrificial mold for the synthesis of silver nanoparticles and nanorings. The photoirradiation method is applied to reduce Ag(I) on the plasmid. The nanoparticles are obtained by varying the concentration of the Ag(I) ion solution and the exposure time of the plasmid-Ag(I) complex under UV light at 254 nm and room temperature. It is found that the plasmid serves not only as a template but also as a reductant to drive the silver nucleation and deposition. The resulting nanoparticles have a face-centered cubic (fcc) crystal structure and 20-30 nm average diameter. The detailed mechanism is discussed, and other metals or alloys could also be synthesized with this method.

Engineering nanoparticle synthesis using microbial factories

“… Milestones in nanoparticle research (above) [9–19] compared with that of genetic engineering (below) [20–26]…”

“… Different modes of nanoparticle biosynthesis by microorganisms a CdS quantum dots produced in genetically engineered E. coli [29] b Gold nanoparticles produced on the membrane if Synechocystis sp. PCC 6803 [30] c Silver nanoparticles produced by P. aeruginosa SM1 [31] d Silver nanoparticles on plasmid scaffolds [19] e Magnetite nanoparticles produced in Rhodospirillum rubrum [32]. Parts of the figure are reproduced with permission…”

Nanoparticle biosynthesis using unicellular and subcellular supports

“…11 In that study, plasmids with circular DNA composed of 3980 nucleotides were isolated from the Bacillus host. The plasmids were allowed to form stable complexes with Ag ions through electrostatic attraction.…”

“…For example, the reduction process that forms gold nanoparticles in the biosystems receives electrons from proteins 8,14,15 or NADPH coupled with glutathione. 17,18 The Ag nanoparticle preparations were observed in biosynthesis via electron donation from the enzyme-mediated reducing process, 9 plasmid scaffolded and reduced process, 11 and cytochrome-supporting reduction. 12 The Cu and FeMn nanoparticle synthesis processes used proteins and reducing-enzyme-mediated reducing processes, respectively.…”

An aerosol-based soft lithography to fabricate nanoscale silver dots and rings for spectroscopic applications

“…However, increasing the purity of the metal layer through additional wet chemical steps and subsequent environmental impacts still need to be resolved for generalization. 14,15 In the present work, we show for the first time the possibility to synthesize silver (Ag) grains organized in nanoscale dots and rings using a technique based on aerosol lithography with Pd nanoparticles and the subsequent ELD of Ag. Unlike conventional lithographic methods that rely on many preliminary steps, 16 the present method enables fabrication of nanoscale dots and rings without much use of toxic agents and temporary layers/templates.…”