Strategic Engineering of Sub-5 nm Dyes@CDs Nanoassemblies Platform for Super Resolution Imaging

The design and construction of fluorescence probes with small size, high quantum yield, photostability, and solubility in an aqueous solution to achieve biomarker have become a focus of interest in super-resolution bioimaging application. Herein, four kinds of GFP-like supramolecular nanoassemblies (SNAs) are constructed in a very facile manner by the host-guest interaction between isopercolic acid derivatives (IADs) and cyclodextrin (CD). H-1 NMR, Fourier transform infrared spectroscopy (FT-IR) and single crystal structure well prove the formation of SNAs. Moreover, compared to the initial state, the fluorescence quantum yield of the SNAs is dramatically improved through suppressing nonradiative relaxation pathways and shielding quenchers. The bimolecular exciton-exciton annihilation (bmEA) process under the high pumping fluence has been suppressed effectively. Both the improved gain and the reduced loss facilitate the buildup of stimulated emission and enable the high stimulated emission efficiency of these SNAs. Sub-5 nm IADs@beta-CDs-mediated STED imaging exhibits excellent stimulated emission depletion (STED) performance: high photostability, low saturation intensity (approximate to 0.50 MW cm(-2)), and high resolution (30 nm) under PSTED-775 nm of 109 MW cm(-2). This supramolecular strategy avoids the tedious molecular synthesis process and paves a new pathway for insights into building up novel high-performance STED probes.

Automated summary

This study demonstrates the construction of supramolecular nanoassemblies (SNAs) through host-guest interactions between isopercolic acid derivatives (IADs) and cyclodextrin (CD), resulting in improved fluorescence quantum yield and suppression of nonradiative relaxation pathways. The SNAs showed high stimulated emission efficiency and excellent STED imaging performance, paving a new pathway for the development of novel high-performance STED probes.