Biopolymer Nano-Network for Antimicrobial Peptide Protection and Local Delivery.

Antimicrobial resistance (AMR) develops when bacteria no longer respond to conventional antimicrobial treatment. The limited treatment options for resistant infections result in a significantly increased medical burden. Antimicrobial peptides offer advantages for treatment of resistant infections, including broad-spectrum activity and lower risk of resistance development. However, sensitivity to proteolytic cleavage often limits their clinical application. Here, a moldable and biodegradable colloidal nano-network is presented that protects bioactive peptides from enzymatic degradation and delivers them locally. An antimicrobial peptide, PA-13, is encapsulated electrostatically into positively and negatively charged nanoparticles made of chitosan and dextran sulfate without requiring chemical modification. Mixing and concentration of oppositely charged particles form a nano-network with the rheological properties of a cream or injectable hydrogel. After exposure to proteolytic enzymes, the formed nano-network loaded with PA-13 eliminates Pseudomonas aeruginosa during in vitro culture and in an ex vivo porcine skin model while the unencapsulated PA-13 shows no antibacterial effect. This demonstrates the ability of the nano-network to protect the antimicrobial peptide in an enzyme-challenged environment, such as a wound bed. Overall, the nano-network presents a useful platform for antimicrobial peptide protection and delivery without impacting peptide bioactivity.