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

Abstract 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). 1 H 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@β‐CDs‐mediated STED imaging exhibits excellent stimulated emission depletion (STED) performance: high photostability, low saturation intensity ( ≈ 0.50 MW cm −2 ), and high resolution (30 nm) under P STED‐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.