Competing host-guest interactions to explore the alkyl anion transport in photo-responsive, space-confined hydrogels

<h2>Summary</h2> Photo-responsive hydrogel systems have attracted significant attention for their controllability, intelligent responsiveness, and reversibility. This study delves into the effect of tunable space-confined networks on anion transport in photo-responsive hydrogels. Employing azobenzene (Azo) and <i>β</i>-cyclodextrin (<i>β</i>-CD), the hydrogel was loaded into anodic aluminum oxide (AAO) to form the AAO-hydrogel membrane. Sodium dodecyl sulfonate (SDS) is chosen to investigate mass transmembrane transport. In low-degree space-confined aluminum oxide-hydrogel membrane (LSAHM), a looser structure was formed due to the breakup of the connection between Azo and <i>β</i>-CD with ultraviolet (UV)-light irradiation. With visible-light (vis-light) irradiation, the SDS is replaced with <i>trans</i>-Azo due to the more stable <i>trans</i>-Azo@<i>β</i>-CD complex, resulting in narrow channels. For high-degree space-confined AHM (HSAHM), the interaction between SDS and <i>β</i>-CD could be omitted due to space confinement. Also, controllable SDS-assisted cationic peptide transport is achieved with HSAHM. This work provides a comprehensive analysis of hydrogel structure variations, offering nuanced approaches to hydrogel design.