Bacterial Outer Membrane‐Coated Mesoporous Silica Nanoparticles for Targeted Delivery of Antibiotic Rifampicin against Gram‐Negative Bacterial Infection In Vivo

Abstract The efficacy of conventional antibiotics therapeutics has declined rapidly due to the emerged antibiotic resistance. There is an urgent need to develop novel approaches to address the problem of antibiotic shortage, particularly for Gram‐negative bacteria. Herein, a biomimetic nanodelivery system is proposed to enhance the bacterial targeting and uptake of rifampicin (Rif), a traditional antibiotic but not effective against Gram‐negative bacteria. The biomimetic nanodelivery system (Rif@MSN@OMV) is composed of outer membrane vesicles (OMVs) isolated from E. coli as shell and rifampicin‐loaded mesoporous silica nanoparticles (MSNs) as core. The OMVs greatly improve the uptake of MSNs in E. coli , but not in Gram‐positive bacteria S. aureus , owing to the homotypic targeting function of the OMVs. The Rif@MSN@OMV exhibits enhanced antimicrobial activity against E. coli and completely eradicates bacteria at an equivalent rifampicin concentration (4 µg mL −1 ) while free rifampicin shows weak bactericidal activity. Meanwhile, the Rif@MSN@OMV maintains good biocompatibility both in vitro and in vivo. More importantly, the Rif@MSN@OMV elevates survival rate of infected mice and reduces bacterial load in intraperitoneal fluid and organs. Overall, the OMVs‐coated nanodelivery system provides a novel strategy to improve the antimicrobial efficacy of conventional antibiotic or repurpose drugs for treatment of Gram‐negative bacterial infections.