Cyclodextrin-modified core-shell particle synthesis and photonic crystal film formation for redox-mediated surface...

In recent years, extensive efforts have been made to develop and utilize smart optical materials. Carbohydrate-based materials are abundant, readily accessible, and essential for advancing sustainable science and ecological cycles. Carbohydrates containing α-glycosidic linkages are naturally generated, and cyclodextrin represents a typical oligosaccharide with such a structure. The ring-shaped architecture of cyclodextrin has been widely studied because, unlike conventional chemical bonds, it enables host-guest interactions based on noncovalent binding. Incorporating cyclodextrin into nanosized, highly uniform core-shell particles could enable the production of photonic crystal films. A synthesis route for the preparation of β-cyclodextrin-modified core-shell particles with host functionality has been reported and characterized at the molecular and material levels. The molecular structures and particle-based optical film formation were validated by spectroscopic and microscopic analysis. The resulting photonic crystal films displayed vivid structural colors. Their capture property was demonstrated by a decrease in the electrochemical redox signal arising from host-guest interactions with ferrocene, while maintaining structural coloration after capture. These findings highlight the potential of the developed system for applications involving selective particle-surface interactions that can be triggered by an electrochemical response. This method will pave the way to new capturing and separation strategies and optical anti-counterfeiting technologies.