Nano-visualization of Hydrogel Dynamics via Surface Plasmon-Enhanced Aggregation-Induced Emission

Abstract

Understanding conformational transitions in hydrogels is essential for deciphering their stimulus-responsive behavior, yet real-time, label-free monitoring at the nanoscale has remained a fundamental barrier. Here, we introduce surface plasmon coupling aggregation-induced emission (SPCAIE) as a new observational paradigm that enables in situ visualization of hydrogel dynamics with sub-nanometer axial displacement sensitivity. Our approach establishes a synergistic, label-free feedback loop between molecular conformation and optical output by merging the interfacial sensitivity of plasmonics with the microenvironmental responsiveness of non-covalently embedded AIE luminogens. This new transduction mechanism directly converts intrinsic nanoscale motions into quantifiable, amplified optical signals, overcoming the limitations of conventional invasive or ensemble-averaging techniques. The SPCAIE framework not only reveals previously inaccessible stimulus-induced rearrangements in hydrated environments, but also establishes a generalizable principle for probing soft matter interfaces. Our work provides a transformative conceptual and methodological platform for analyzing the dynamics of hydrated soft materials, with broad applicability to diverse stimulus-responsive polymer systems, opening new pathways in soft matter research and advanced material design.