Bioinspired optical antennas: gold plant viruses

Abstract

The ability to capture the chemical signatures of biomolecules (i.e., electron-transfer dynamics) in living cells will provide an entirely new perspective on biology and medicine. This can be accomplished using nanoscale optical antennas that can collect, resonate and focus light from outside the cell and emit molecular spectra. Here, we describe biologically inspired nanoscale optical antennas that utilize the unique topologies of plant viruses (and thus, are called gold plant viruses) for molecular fingerprint detection. Our electromagnetic calculations for these gold viruses indicate that capsid morphologies permit high amplification of optical scattering energy compared to a smooth nanosphere. From experimental measurements of various gold viruses based on four different plant viruses, we observe highly enhanced optical cross-sections and the modulation of the resonance wavelength depending on the viral morphology. Additionally, in label-free molecular imaging, we successfully obtain higher sensitivity (by a factor of up to 10 6 ) than can be achieved using similar-sized nanospheres. By virtue of the inherent functionalities of capsids and the plasmonic characteristics of the gold layer, a gold virus-based antenna will enable cellular targeting, imaging and drug delivery. Keywords: molecular sensor; nanophotonics; optical antenna; optical spectroscopy; plant virus; plasmonics; plasmonic resonant energy transfer (PRET); surface enhanced Raman scattering (SERS) INTRODUCTIONIn current nanotechnology, the development of nanoscale optical antennas that are capable of receiving and transmitting light in unique light-electron interactions called 'surface plasmons' 1 is of considerable interest because of the potential applications of such antennas in molecular detection, 2-4 multiple harmonic generation, 5,6 plasmonic photovoltaics, 7 optoelectronics, 8 negative-index materials 9 and more. In particular, the use of an optical antenna as a molecular sensor permits the dynamic detection of chemical signatures in a non-invasive and label-free manner. Moreover, the detection sensitivity can reach the single-molecule level. 3,10 These powerful characteristics distinguish the optical antenna as a potential method for unraveling the inherent complexity of biological systems (i.e., cells), which is a difficult task using current techniques.To be suitable for use as a biomolecular sensor in cellular systems, an optical antenna should not interfere with cellular components and should be efficiently accessible (or mobile) to subcellular regions. These characteristics can be achieved by exploiting the nanoscale size and chemical stability of non-fixed, biochemical-moiety-containing nanoparticles. In this context, gold nanospheres have been successfully demonstrated to be capable of actively targeting subcellular regions and carrying imaging agents and drugs. 11,12 However, the smooth surfaces of chemically synthesized gold nanoparticles do not impart these nanoparticles with ideal functionality for molecular fingerprint detect...

Advances in optoplasmonic sensors – combining optical nano/microcavities and photonic crystals with plasmonic nanostructures and nanoparticles

“…Symmetric nanoscale surface features which create plasmonic hot spots also exist, in terms of structural appearance, in protein capsids of natural nanoparticles such as viruses. In a reproduction of virus shapes, plasmonic nanoparticles were obtained with a 10 6 higher sensitivity as compared to spheres with tuneable hot spots and, for the future, their biological counterparts for sensing molecules intracellularly ( Figure 2H) [29].…”

Dispersed gold nanoparticles potentially ruin gold barley yellow dwarf virus and eliminate virus infectivity hazards

“…1c). In our study, we interfered the bio Nanoparticles (virus) with metal Nanoparticles (Au) in the plant system to find out ability to capture the chemical electron transfer dynamics of the two molecules, which could provide an entirely new perspective on biology (Hong et al 2015). We selected the most severe BYDV-PAV isolates having spherical morphological capsid that permit high amplification of optical scattering energy in the presence of AuNPs for nano application.…”

“…We propose that the unique and detailed structures of viral capsids can be used as strong plasmonic templates by conjugating novel metals onto their surfaces. The plasmonic metal layer formed in this manner will function as an optical antenna to amplify and convert incident light into confined nanoscale volumes (Hong et al 2015). Gold viruses can utilize the molecular sensing capability of optical antennas and the biochemical properties of viral capsids (Wu et al a AuNPs have two different peaks appearing in the zeta sizer chart at a range of (1-100) dispersed by their sizes 3.151 and 31.67 nm with different intensities: 75.3% for the former and 24.7% for the latter, b Zeta potential distribution has three hetero different peaks in one limited range from -100 to 0 with negative charge -(10.8, 31.0 and 54.0) mV, respectively; c Ultraviolet absorption spectrum of 27.30 g leaves from the infected cultivar with ratio A260/ A280 is 0.62 mg/ml virus yield 2010).…”

“…In many conditions, capsids are produced in huge amounts either by the infection of plants or by the subunit(s) expression of a variety of heterologous systems, given their relative simplicity, stability and ease of production (Lomonossoff and Evans 2011). Thus, the advantage of the morphological characteristics of plant viruses can be taken by integrating AuNPs as a novel metal onto the external surfaces of their capsids for highly sensitive and selective molecular spectroscopic detection such as localized electronic absorption and vibration spectroscopy (Hong et al 2015). Variable performance of gold capsids was individually visible in four different types of damage or ruined VLPs: (1) puffed particle, (2) deteriorated particle and decorated with AuNPs, (3) ruined particle, and (4) vanished particles (Fig.…”

“…Moreover, using asymmetric gold coupling leaves parts of the native capsid uncovered that can interact with host cells and biochemically alter functions. Such gold virus nanoparticles can metaphorically work as 'nanosatellites' exploring 'cellular galaxies' (Hong et al 2015). Therefore, biological structures and biomolecules are promising tools for bionanotechnological applications.…”