Bispecific antibody vesicles: a multifunctional bioactive drug delivery platform for the treatment of Pseudomonas aeruginosa infection

Pseudomonas aeruginosa (P. aeruginosa) is a major pulmonary pathogen that establishes chronic infection through Psl polysaccharide-mediated adhesion and biofilm formation, while accelerating acute disease via toxin injection through the type III secretion system (T3SS) PcrV protein. Conventional small-molecule antibiotics show poor target specificity, limited biofilm penetration and insufficient toxin neutralization, thereby compromising therapeutic efficacy. Here, we developed a bioactive nano delivery system that integrates a bispecific antibody (BsAb) with a nano-antibiotic for P. aeruginosa infection. Specifically, an anti-Psl single-chain variable fragment (scFv) was linked with an anti-PcrV monoclonal antibody (mAb) to generate the BsAb, which was subsequently displayed on cellular outer membranes and harvested as nanoscale membrane vesicles displaying BsAb (BsAb-MVs). Gentamicin (Gen)-loaded poly (lactic-co-glycolic acid) nanoparticles (GNPs) were coated with BsAb-MVs to form BsAb-functionalized GNPs (BsAb-GNPs). By leveraging high-affinity recognition of bacterial surface antigens and enhanced antibiotic penetration, BsAb-GNPs showed robust bactericidal activity by precisely targeting planktonic bacteria and biofilms, imposing effective local drug concentration. Moreover, BsAb-MVs retained antibody-mediated adhesion neutralization and host-cell invasion blockade, thereby mitigating toxin-induced tissue damage. In vitro biofilm assays and a murine pneumonia model confirmed the precise targeting and potent antibacterial efficacy of BsAb-GNPs. Collectively, this antibody-antibiotic system integrated multifunctional antibody-antibiotic therapeutic strategy for biofilm-associated infections and offers immunological advantages, which may provide a scalable and translational strategy against P. aeruginosa biofilm infections. Schematic illustration of the BsAb-GNP mechanism of action in a murine model of P. aeruginosa pneumonia infection.