Polymyxin B-Modified Fosfomycin Liposomes Target Gram-Negative Bacteria and Exert Synergistic Antibacterial Effect.

Bacterial infection has always been one of the most serious threats faced by humans. Bacterial targeting is a promising strategy to enhance treatment efficacy and reduce the emergence of drug resistance. However, the traditional antibiotic targeting efficiency is poor, and it is challenging to achieve therapeutic concentrations of both drugs simultaneously in the same tissue due to differences in drug metabolism. This study aims to construct bacteria-targeted liposomes to enhance antibiotic delivery. In this study, anionic liposomes were constructed using the thin-film dispersion method, and the cationic antimicrobial peptide polymyxin B (PMB) was adsorbed onto the liposome surface through anionic-cationic electrostatic interaction as a carrier for fosfomycin (FOS), enabling bacteria-targeted drug delivery. The targeted effect of polymyxin B liposomes (PMB-Lipo) on Acinetobacter baumannii was evaluated in vitro and in vivo. The bactericidal activity of polymyxin B adsorbed fosfomycin liposomes (PMB-FOS-Lipo) in vitro and in vivo was compared with PMB and FOS mixture solution (PMB-FOS-Solution), and the anti-infection and anti-inflammatory effects were assessed. We also explored the issue of PMB nephrotoxicity using a series of biochemical indicators in mice. In vitro and in vivo experiments showed that PMB-Lipo effectively targeted Acinetobacter baumannii. PMB-FOS-Lipo exhibited better therapeutic efficacy compared to free PMB and FOS. Finally, adsorbing polymyxin B onto the liposome surface significantly reduced its severe nephrotoxicity. PMB-Lipo can effectively target Acinetobacter baumannii, and the encapsulated fosfomycin in liposomes synergizes with polymyxin B, enhancing antibacterial efficacy and reducing adverse drug reactions. We believe this antibacterial strategy can provide new insights into bacteria-targeted treatment.

Core-Shell Microspheres Prepared Using Coaxial Electrostatic Spray for Local Chemotherapy of Solid Tumors.

Local chemotherapy is an alternative therapeutic strategy that involves direct delivery of drugs to the tumor site. This approach avoids adverse reactions caused by the systemic distribution of drugs and enhances the tumor-suppressing effect by concentrating the drugs at the tumor site. Drug-loaded microspheres are injectable sustained-release drug carriers that are highly suitable for local chemotherapy. However, a complex preparation process is one of the main technical difficulties limiting the development of microsphere formulations. In this study, core-shell structured microspheres loaded with paclitaxel (PTX; with a core-shell structure, calcium alginate outer layer, and a poly (lactic acid-co-glycolic acid) copolymer inner layer, denoted as PTX-CA/PLGA-MS) were prepared using coaxial electrostatic spray technology and evaluated in vitro and in vivo. PTX-CA/PLGA-MS exhibited a two-stage drug release profile and enhanced anti-tumor effect in animal tumor models. Importantly, the preparation method reported in this study is simple and reduces the amount of organic solvent(s) used substantially.