Chiral nanostructures represent one of the fastest growing fields of nanoscience and technology with broad impact from biology to information technologies. What drives the rapid development of this field are the uniquely high values of chiral anisotropy are attributed to resonances of incident electromagnetic radiation with plasmonic and excitonic states typical for metals and semiconductors as well as resonant states. Furthermore, engineering of sophisticated nanoscale chiroplasmonic constracts can encompass now multiple chiral geometries and sophisticated shapes.<br/><br/>In this study we address the problem of accurate localization of plasmonic nanoparticles (NPs) in biological media. The intra- and extracellular positioning of NPs and their constructs can dramatically alter their curative/diagnostic abilities and medical outcomes. However, the low signal-to-noise ratio of spectroscopic identifiers of their transmembrane transport denies their intracellular vs. extracellular localization even for cell cultures. Here we show that the chiroptical activity of DNA-bridged NP dimers allows one to pinpoint particle locations with respect to the cell interior. Circular dichroism peaks in the visible range change from negative to positive during transmembrane transport. The chirality reversal is associated with a spontaneous twisting motion around the DNA bridge caused by the large change in electrostatic repulsion between NPs when placed in cytosol. This finding opens the door for real-time observation of transmembrane transport of plasmonic nanodrugs, quantitative assessment of nanoscale interactions, and biomedical applications of chiral nanostructures, for instance in the photodynamic cancer therapy.

Chiroplasmonic nanoassemblies: Intracelular localization of nanoparticle dimers by chirality reversal

2019 Spring National Meeting

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