In Situ Insights into the Nucleation and Growth Mechanisms of Gold Nanoparticles on Tobacco Mosaic Virus

Abstract

Biotemplated syntheses have emerged as an efficient strategy to control the assembly of metal nanoparticles (NPs) and generate promising plasmonic properties for sensing or biomedical applications. However, understanding the nucleation and growth mechanisms of metallic nanostructures on biotemplate is an essential prerequisite to developing well-controlled nanotechnologies. Here, we used liquid cell Transmission Electron Microscopy (TEM) to reveal how the formation kinetics of gold NPs affects their size and density on Tobacco Mosaic Virus (TMV). These in situ insights are used as a guideline to optimize bench-scale synthesis with the possibility to homogenize the coverage and tune the density of gold NPs on TMV. In line with in situ TEM observations, fluorescence spectroscopy confirms that the nucleation of NPs occurs on the virus capsid rather than in solution. The proximity of gold NPs on TMV allows shifting the plasmonic resonance of the assembly in the biological window.

Gold and Iron Oxide Nanoparticle Assemblies on Turnip Yellow Mosaic Virus for In-Solution Photothermal Experiments

“…XPS was performed on a KAlpha+ system (Thermo Fisher Scientific, East-Grinstead, UK) equipped with a micro-focused and monochromatic Al Kα X-ray source (1486.6 eV, 12 kV) with an X-ray spot size of 400 μm. TEM was carried out after depositing drops of the nano-biohybrid’s aqueous solutions onto carbon-coated copper grids using a JEM 2100F plus microscope (JEOL, Tokyo, Japan), operating at 200 kV [ 43 ]. ζ potential and hydrodynamic diameter measurements were performed on a Malvern Nano Zetasizer setup (Malvern Panalytical, Worcestershine, UK), operating with a laser of 633 nm, on colloidal dispersions of the nano-biohybrids in distilled water.…”

Getting Hold of the Tobamovirus Particle – Why and How? Purification Routes over Time and a New Customizable Approach

“…Many of these profit from a considerable surface enhancement and good steric accessibility of the nanorods equipped, e.g., with coatings of conductive or catalytically active metals, semi-conductors or alloys [18,22,[155][156][157], chromophores [158], polymers [159], and even fullerenes [160] or metal-organic frameworks [161]. The resulting ʹsmart materialsʹ and virus-assisted devices have been prepared for applications in fundamental research [162], energy storage and conversion [163,164], data memory [165], environmental remediation [166], as antireflective coatings [167], ferrofluids with increased magnetoviscosity [66], fibres for metal nanoparticle production, and many more [168, and above-listed exemplary review articles, [169][170][171].…”

“…The huge number of rapidly developing tobamovirus applications led us to assume that only a few particle purification protocols have become standard during recent years, due to their ease, efficiency, speed, low requirements for instrumentation, or simply their good description in widely recognized studies. However, this guess has only partially been confirmed by a small set of ʹtest drillingsʹ in technology-oriented publications from distinct areas of research and different countries: Virion precipitation from pre-cleared plant homogenates, often by way of PEG, in combination with differential and, in part of the studies, density gradient or cushion centrifugation, seems most frequently employed all over the world [134,138,162,164,172,177,[189][190][191][192][193][194][195]. Nevertheless, a considerable variety of deviating conditions in the serial processing steps is found for one and the same tobamovirus species, and even within single research groups, different protocols are applied.…”

Getting Hold of the Tobamovirus Particle—Why and How? Purification Routes over Time and a New Customizable Approach

“…Many of these profited from considerable surface enhancement and good steric accessibility of the nanorods equipped, e.g., with coatings of conductive or catalytically active metals, semi-conductors or alloys [ 18 , 22 , 159 , 160 , 161 ], chromophores [ 162 ], polymers [ 163 ], and even fullerenes [ 164 ] or metal-organic frameworks [ 165 ]. The resulting ‘smart materials’ and virus-assisted devices have been prepared for applications in fundamental research [ 166 ], energy storage and conversion [ 167 , 168 ], data memory [ 169 ], environmental remediation [ 170 ], as antireflective coatings [ 171 ], ferrofluids with increased magnetoviscosity [ 67 ], fibers for metal nanoparticle production, and many more, as given in exemplary review articles [ 172 , 173 , 174 , 175 ].…”

“…The huge number of rapidly developing tobamovirus applications led us to assume that only a few particle purification protocols have become standard during recent years, due to their ease, efficiency, speed, low requirements for instrumentation, or simply their good description in widely recognized studies. However, this guess has been confirmed only partially by a small set of ‘test drillings’ in technology-oriented publications from distinct areas of research and different countries: Virion precipitation from pre-cleared plant homogenates, often by way of PEG ( Section 2.3 ), in combination with differential and, in some studies, density gradient or cushion centrifugation ( Section 2.4 ), seems most frequently employed all over the world [ 138 , 142 , 166 , 168 , 176 , 180 , 191 , 192 , 193 , 194 , 195 , 196 , 197 ]. Nevertheless, a considerable variety of conditions applied in the serial processing steps are often found even for a single tobamovirus species, and different protocols are applied by individual research groups.…”