Visual β‐Sheet‐to‐β‐Turn Transition in Luminescent Polymeric Vesicles for Color‐Reporting Drug Delivery

Abstract

Abstract The secondary structures of polymers significantly influence their properties; however, understanding and modulating polymer conformations remain substantial challenges. Particularly, the β‐turn conformation, which is prevalent in proteins, has not been reported in synthetic polymers due to its unclear formation mechanism and extremely poor stability. Additionally, there is a lack of visualization techniques to track conformational and functional transitions in polymers. Here, we designed and synthesized a novel tetraphenylethylene (TPE)‐decorated poly(L‐cysteine) derivative. Utilizing thioether oxidation as the driving force and strong aromatic‐aromatic interactions between TPE molecules as stabilizing mechanism, we reported for the first time a conformational transition from β‐sheet to β‐turn in polymers. This transition not only significantly enhances fluorescence intensity but also induces chirality and circularly polarized light (CPL) of TPE, providing a new dual‐modal approach to real‐time monitoring of conformational changes of polymer chains. Furthermore, the conformational transition can trigger specific drug release, with the release process visualized and quantitatively analyzed through fluorescent colors. Such conformation‐mediated structural and functional transformations hold significant potential for specific drug delivery and theragnosis of diseases such as cancer.