Anion Insertion Engineering of Photonic Microstructure Enabling Ultrasensitive Glucose Visual Sensing

Abstract The dynamic volumetric modulation of polymer gels driven by borate‐diol interactions constitutes a well‐established and robust strategy for glucose detection and drug delivery systems. However, relying solely on a single molecular recognition element restricts the volumetric deformation of the polymer gel, resulting in insufficient swelling and consequently diminished sensitivity in glucose detection. Herein, a novel and scalable molecule insertion strategy is proposed to strengthen volumetric responsiveness via amplifying intermolecular electrostatic repulsion. By covalently integrating synergistic molecules bearing both diol and anionic functionalities into phenylboronic acid‐based copolymers, the glucose‐induced swelling of nanogels is enhanced by 2.88‐fold (0.025 m m 6,7‐dihydroxynaphthalene‐2‐sulfonate sodium). Meanwhile, the nanogel‐assembled 1D photonic crystal (1D PC) exhibits a 2.47‐fold increase in glucose responsiveness, the volumetric changes translate into vivid structural color shifts and enable intuitive visual glucose detection, achieving a high sensitivity of 15.4 nm mmol −1 L −1 and a rapid response rate of 1.55 nm s −1 . The interactions and deformation enhancement mechanism of nanogels are verified through theoretical calculations and in situ dynamic analysis at the molecular level. This molecular engineering approach offers a generalizable strategy for strengthening nanogel performance and photonic material responsiveness, advancing next‐generation colorimetric diagnostics and biomedical intelligence.