Matrix-Engineered Self-Assembly of Fluorophores Based on Acidic Annealing for Robust Cellular Imaging

A key limitation of fluorescein derivatives is acid-induced aggregation, resulting in an inactivation. However, the aggregates obtained after acid annealing showed a 50-fold enhancement of fluorescence compared with the original powder. Herein, we incorporated a polymer or surfactant matrix into the acidic annealing procedure, and the self-assembling properties of fluorescein derivatives in the presence of the matrix are exploited to alter the molecular structure, thereby modifying the optical properties and ultimately producing fluorescent materials with enhanced brightness. Varying the type and concentration of dyes and matrices as well as the assembly time can modulate the geometry of the particles. These biocompatible particles exhibit efficient cellular uptake and superior imaging capabilities, positioning them as potent carriers for traceability. The stability of the assembly against light exposure and high temperatures demonstrates its practical application capabilities. By synergizing host-guest recognition with supramolecular engineering, this work not only redefines acid adaptation mechanisms but also establishes a universal design strategy for multifunctional supramolecular architecture, which expands applications in complex biological systems and opens new pathways for engineering advanced superstructures.