Illuminating Biomimetic\nNanochannels: Unveiling Macroscopic\nAnticounterfeiting and Photoswitchable Ion Conductivity via Polymer\nTailoring

Artificial photomodulated channels represent a significant\nadvancement\ntoward practical photogated systems because of their remote noncontact\nstimulation. Ion transport behaviors in artificial photomodulated\nchannels, however, still require further investigation, especially\nin multiple nanochannels that closely resemble biological structures.\nHerein, we present the design and development of photoswitchable ion\nnanochannels inspired by natural channelrhodopsins (ChRs), utilizing\nphotoresponsive polymers grafted anodic aluminum oxide (AAO) membranes.\nOur approach integrates spiropyran (SP) as photoresponsive molecules\ninto nanochannels through surface-initiated atom transfer radical\npolymerization (SI-ATRP), creating a responsive system that modulates\nionic conductivity and hydrophilicity in response to light stimuli.\nA key design feature is the reversible ring-opening photoisomerization\nof spiropyran groups under UV irradiation. This transformation, observable\nat the molecular level and macroscopically, allows the surface inside\nthe nanochannels to switch between hydrophobic and hydrophilic states,\nthus efficiently modulating ion transport via changing water wetting\nbehaviors. The patternable and erasable polySP-grafted AAO, based\non a controllable and reversible photochromic effect, also shows potential\napplications in anticounterfeiting. This study pioneers achieving\nmacroscopic anticounterfeiting and photoinduced photoswitching through\nreversible surface chemistry and expands the application of polymer-grafted\nstructures in multiple nanochannels.