Multi-Responsive Lanthanide-Based Hydrogel with Encryption, Naked Eye Sensing, Shape Memory, Self-Healing, and Antibacterial Activity

In this work, we reported a multi-responsive luminescent hydrogel with properties of encryption, naked eye sensing of glucose, shape memory, self-healing, and antibacterial activity. The hydrogel (GA/CCS/DNSA/Eu3+) was obtained by mixing phenylboronic acid-modified gelatin (GA-DBA), catechol-modified carboxymethyl chitosan (CCS-PCA), 3,5-dinitrosalicylic acid (DNSA), and Eu3+ ions through a facile heating–cooling process. The resultant hydrogel exhibits reversible luminescence and color and phase changes in response to temperature, acid/base, salt, and redox stimuli. Based on the multiple responsiveness, information encryption and decryption, naked eye sensing of glucose, remarkable shape memory, and enhanced mechanical properties of the as-prepared hydrogel were realized. In addition, the self-healing capacity was also achieved due to the dynamic bonds in GA/CCS/DNSA/Eu3+ hydrogels. Specifically, the GA/CCS/DNSA/Eu3+ hydrogels possess antibacterial activity owing to the bacteriostasis of the CCS-PCA and DNSA/Eu3+ complex. Thus, GA/CCS/DNSA/Eu3+ hydrogels have potential applications in the fields of anticounterfeiting, wearable devices, biomedicine, sensing, etc.