Bright G-Quadruplex Nanostructures Functionalized with Porphyrin Lanterns

Pathak, P.; Yao, W.; Hook, K. D.; Vik, R.; Winnerdy, F. R.; Brown, J. Q.; Gibb, B. C.; Pursell, Z. F.; Phan, A. T.; Jayawickramarajah, J. Bright G-Quadruplex Nanostructures Functionalized with Porphyrin Lanterns. Journal of the American Chemical Society 2019, 141, 12582-12591.

Abstract

The intricate arrangement of numerous and closely placed chromophores on nanoscale scaffolds can lead to key photonic applications ranging from optical waveguides and antennas to signal-enhanced fluorescent sensors. In this regard, the self-assembly of dye-appended DNA sequences into programmed photonic architectures is promising. However, the dense packing of dyes can result in not only compromised DNA assembly (leading to ill-defined structures and precipitates) but also to essentially nonfluorescent systems (due to π–π aggregation). Here, we introduce a two-step “tether and mask” strategy wherein large porphyrin dyes are first attached to short G-quadruplex-forming sequences and then reacted with per-O-methylated β-cyclodextrin (PMβCD) caps, to form supramolecular synthons featuring the porphyrin fluor fixed into a masked porphyrin lantern (PL) state, due to intramolecular host–guest interactions in water. The PL–DNA sequences can then be self-assembled into cyclic architectures or unprecedented G-wires tethered with hundreds of porphyrin dyes. Importantly, despite the closely arrayed PL units (∼2 nm), the dyes behave as bright chromophores (up to 180-fold brighter than the analogues lacking the PMβCD masks). Since other self-assembling scaffolds, dyes, and host molecules can be used in this modular approach, this work lays out a general strategy for the bottom-up aqueous self-assembly of bright nanomaterials containing densely packed dyes.

Last updated on 07/03/2024