Fluorescent Probes Based on AIEgen‐Mediated Polyelectrolyte Assemblies for Manipulating Intramolecular Motion and Magnetic Relaxivity

Abstract

Uniting photothermal therapy (PTT) with magnetic resonance imaging (MRI) holds great potential in nanotheranostics. However, the extensively utilized hydrophobicity‐driven assembling strategy not only restricts the intramolecular motion‐induced PTT, but also blocks the interactions between MR agents and water. Herein, we report an aggregation‐induced emission luminogen (AIEgen)‐mediated polyelectrolyte nanoassemblies (APN) strategy, which bestows a unique “soft” inner microenvironment with good water permeability. Femtosecond transient spectra verify that APN well activates intramolecular motion from the twisted intramolecular charge transfer process. This de novo APN strategy uniting synergistically three factors (rotational motion, local motion, and hydration number) brings out high MR relaxivity. For the first time, APN strategy has successfully modulated both intramolecular motion and magnetic relaxivity, achieving fluorescence lifetime imaging of tumor spheroids and spatio‐temporal MRI‐guided high‐efficient PTT.

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“…The SMIs consisting of charged polymer backbones with mobile counter charges have been recently demonstrated as ionic semiconductors. SMIs have been used for various ionotronic devices due to their excellent thermal/air stability associated with the fixed charges on the polymers, including fluorescent probes, [56] water harvesting, [57] and solid tunable lenses. [58] A lamellar-forming poly(styrene-block-2vinyl pyridine) (PS-b-P2VP) film was prepared by spin-coating a 7 wt% BCP solution in propyl glycol monomethyl ether acetate on a Si substrate.…”