Aggregation-induced emission (AIE)-active gold nanoclusters stabilized by cationic cellulose through ligand rigidification

Gold nanoclusters (Au NCs) are attractive luminescent materials because of their discrete electronic states and strong quantum confinement effects. However, their fluorescence efficiency is often limited in aqueous environments due to thermal deactivation. In this study, we enhanced the aggregation-induced emission (AIE) of Au NCs by implementing a multiligand strategy involving 6-aza-2-thiothymine (ATT) and L -arginine (Arg), followed by electrostatic complexation with cationic polymers, specifically cationic cellulose (C-Polymer). The Arg ligands restrict the intramolecular motion of surface-bound ATT, thereby reducing non-radiative decay. The addition of the C-Polymer further stabilized the ligand shell through electrostatic binding and conformational rigidification, leading to a fluorescence quantum yield increase from 0.31 to 0.71 and a lifetime extension from 20.7 ns to 24.4 ns. Comparative studies with polyethyleneimine (PEI) demonstrated the superior performance of cationic cellulose due to its permanent charge and structural rigidity. These findings offer a promising strategy for engineering ligand–polymer hybrid nanoclusters with enhanced emission properties and potential applications in fluorescence sensing, bioimaging, and optoelectronics. • The gold nanoclusters were stabilized using a dual-ligand system consisting of ATT and L -arginine. • Cationic cellulose induces conformational rigidification of surface ligands via electrostatic complexation. • The aggregation-induced emission (AIE) was significantly enhanced by polymer complexation. • The fluorescence quantum yield increased from 0.31 to 0.71, with a prolonged lifetime. • Cationic cellulose outperformed polyethyleneimine in enhancing emissions.