Antibiotic‐Loaded Polysaccharide Films With Persistent Room‐Temperature Phosphorescence for Antibacterial Anti‐Counterfeiting Applications

ABSTRACT Persistent room‐temperature phosphorescence (p‐RTP) materials hold great promise for high‐security anti‐counterfeiting and information encryption. However, integrating p‐RTP with efficient, light‐independent antibacterial activity remains a significant challenge. Herein, we systematically investigate the RTP properties of representative antibiotics and introduce a simple doping strategy to fabricate antibacterial p‐RTP materials by introducing antibiotics (quinolone and sulfonamide) into polysaccharides. These antibiotic‐loaded polysaccharide films with high flexibility and transparency exhibit bright afterglow with phosphorescence lifetimes up to 316.4 ms (a 739% enhancement over pristine antibiotic powders), enabled by hydrogen‐bonding networks and rigid confinement that suppress non‐radiative triplet decay. Triplet‐sensitized Förster resonance energy transfer (TS‐FRET) with fluorescent dyes further enables tunable multi‐color afterglow under multi‐wavelength excitation (254/312/365 nm). The composites retain the inherent antibacterial activity of the embedded antibiotics, achieving high inhibition of Escherichia coli and Staphylococcus aureus . Formulated as water‐soluble antibacterial security inks, the films allow transparent coatings on training banknotes for time‐resolved anti‐counterfeiting demonstration while providing enhanced hygiene. This work not only demonstrates antibiotic‐polysaccharide composites as an efficient antibacterial p‐RTP platform for advanced security applications, but also provides insights into the RTP properties of other bioactive molecules and their potential applications in related fields.