Multifunctional poly(sulfobetaine acrylamide) hydrogel integrating robust mechanical properties, pH-triggered multicolor fluorescence, and antibacterial efficacy

This study reports the development of a multicolor fluorescence zwitterionic hydrophobic association hydrogel based on sulfobetaine acrylamide (SBAA) for advanced wound care applications. Initially, the mechanical properties and self-healing capabilities of hydrophobically associated poly(sulfobetaine methacrylate) (polySBMA) and polySBAA hydrogels were systematically compared. Owing to the presence of amide bonds in SBAA, which promote additional hydrogen bonding interactions, the polySBAA hydrogel exhibited significantly improved mechanical strength, fatigue resistance, and self-healing efficiency—achieving nearly 100 % recovery within 90 s, compared to approximately 75 % for polySBMA. Next, tris(2,6-pyridinedicarboxylato)lanthanide(III) complexes (Ln(PDAc)₃) were incorporated into the hydrogel matrix. By adjusting the Eu(PDAc)₃/Tb(PDAc)₃ ratio, the hydrogel exhibited tunable multicolor fluorescence. Furthermore, pH-responsive fluorescence behavior was achieved through the protonation–deprotonation equilibrium of PDAc ligands under varying pH conditions. In the physiologically relevant pH range of 5.5–8.0, the hydrogel demonstrated distinct fluorescence changes, allowing for intuitive and real-time monitoring of bacterial contamination. In addition, ciprofloxacin (CIP) was loaded into the hydrogel to impart antimicrobial functionality. Inhibition zone assays confirmed strong bactericidal activity against E. coli and S. aureus, which was further validated using an ex vivo infected pig skin model. Overall, the engineered hydrogel integrates enhanced mechanical properties, rapid self-healing, pH-responsive fluorescent sensing, and potent antibacterial efficacy, highlighting its potential as a smart wound dressing capable of simultaneous infection diagnosis and treatment.