Biochemically Responsive Bacterial Codes Enabled by Photodynamic AIE Nanoparticles for Advanced Information Encryption

Abstract With the escalating risk of information leakage, the development of advanced, high‐security encryption technologies has become increasingly critical. Herein, a novel multilevel information encryption platform is reported based on biochemically responsive bacterial codes, enabled by high‐resolution photodynamic patterning. This system employs positively charged photodynamic nanoparticles, which can form strong electrostatic interactions with negatively charged bacteria; simultaneously, the photosensitizing performance of aggregation‐induced emission photosensitizers is markedly enhanced by restricted intramolecular motions through encapsulation in natural saturated fatty acids. These nanoparticles not only exhibit potent, broad‐spectrum antibacterial activity but also enable precise, high‐contrast bacterial patterning on mixed cellulose membranes. Importantly, the resulting patterns can be reliably transferred across diverse culture media, with exceptional spatial fidelity and functional stability. By harnessing the inherent and unique metabolic characteristics of different bacterial species, a wide spectrum of visible and fluorescent bacterial patterns is generated without the need for genetic modification. This capability allows the construction of biochemically responsive 1D Morse codes, 2D QR codes, and 3‐/4D bacterial codes with reconfigurable and time‐gated features—including “code‐in‐code” architectures that require sequential decoding. By integrating high‐resolution photodynamic control with the biochemical complexity of living systems, this work establishes a versatile platform for secure information storage and anti‐counterfeiting strategies.