Regiospecific Plasmonic Assemblies for in Situ Raman Spectroscopy in Live Cells

Abstract

Multiple properties of plasmonic assemblies are determined by their geometrical organization. While high degree of complexity was achieved for plasmonic superstructures based on nanoparticles (NPs) little is known about the stable and structurally reproducible plasmonic assemblies made up from geometrically diverse plasmonic building blocks. Among other possibilities they open the door for the preparation of regiospecific isomers of nanoscale assemblies significant both from fundamental point of view and optical applications. Here we present a synthetic method for complex assemblies from NPs and nanorods (NRs) based on selective modification of NRs with DNA oligomers. Three types of assemblies denoted as End, Side, and Satellite isomers which display distinct elements of regiospecificity, were prepared with the yield exceeding 85%. Multiple experimental methods independently verify various structural features, uniformity, and stability of the prepared assemblies. The presence of interparticle gaps with finely controlled geometrical parameters and inherently small size comparable with those of cellular organelles fomented their study as intracellular probes. Against initial expectations SERS intensity for End, Side, and Satellite isomers was found to be dependent primarily on the number of the NPs in the superstructures rationalized with the help of electrical field simulations. Incubation of the label-free NP-NR assemblies with HeLa cells indicated sufficient field enhancement to detect structural lipids of mitochondria and potentially small metabolites. This provided the first proof-of-concept data for the possibility of real-time probing of local organelle environment in live cells. Further studies should include structural optimization of the assemblies for multitarget monitoring of metabolic activity and further increase in complexity for applications in transformative optics.

Tailoring the interplay between electromagnetic fields and nanomaterials toward applications in life sciences: a review

“…This is actually a fascinating property of plasmonics using EM-active NPs, with many applications besides SERS sensing. 228 Controlled assemblies of plasmonic NPs have been reported to improve SERS sensitivity, whether it is formed by few NPs 234 or by two-dimensional self-assemblies in large supports. 235 Last, photothermal biosensing is briefly introduced.…”

Exocytosis of peptide functionalized gold nanoparticles in endothelial cells

“…Following these aims, several research groups have successfully investigated various aspects of interactions between functional nanoparticulate systems and cells. [6][7][8][9][10][11][12][13][14] For example, Brust and co-workers shed light on the intracellular fate of spherical gold nanoparticles coated with cell penetrating peptides and suggested ways of pre-programming nanoparticle migration within the cytoplasm. 15,16 Alternatively Mirkin and colleagues performed a systematic study on the internalization rate of DNA modified gold nanoparticles and suggested new directions for targeted gene therapy.…”

Scanning angle Raman spectroscopy: Investigation of Raman scatter enhancement techniques for chemical analysis

“…543 The regiospecific nanostructures display a new level of control over the placement of nanoparticles, which can lead to structures with optimal SERS enhancements. Specific assemblies (i.e., nanorod surrounded by nanospheres)…”