Dual-Layer Living Hydrogel Enables On-Demand Delivery of Phages and Probiotics for Synergistic Wound Infection Therapy

Abstract

Wound infections caused by multidrug-resistant pathogens such as Pseudomonas aeruginosa remain a major clinical challenge due to biofilm formation and the limited efficacy of conventional antibiotics. Living therapeutics, including bacteriophages and probiotics, provide alternative antibacterial effects but face individual limitations. This study investigates the antibacterial synergy of phages and probiotics and develops ProΦGel, a pathogen-responsive dual-layer hydrogel designed to coordinate their sequential activity. The inner layer contains Lactobacillus plantarum encapsulated in alginate microbeads generated by aerodynamically assisted jetting, whereas the outer gelatin-PEG hydrogel incorporates phages through mild Schiff-base crosslinking. This gentle fabrication process preserves the viability of both agents. Taking advantage of gelatin's pathogen-degradable nature, phages are released on-demand at infection sites to provide rapid antibacterial action, followed by delayed probiotic release from microbeads to modulate the wound microenvironment and suppress phage-resistant variants. This sequential delivery achieves significant eradication of P. aeruginosa and biofilm disruption in vitro and in an ex vivo human skin model. Beyond infection control, the probiotic component enhances fibroblast migration, underscoring the system's intrinsic pro-healing potential. Thus, the ProΦGel represents a rational material strategy for coordinating multi-component living therapeutics through responsive and sequential release for advanced wound-infection therapy.