Development, characterization, and in vitro evaluation of co-drug encapsulated, targeted theranostic liposomes for osteomyelitis

Osteomyelitis is a bone infection marked by inflammation and swelling, with persistent challenges in diagnosis and treatment, especially in chronic and therapy-resistant pediatric cases. Within the scope of the study, targeted, PEGylated nano-sized, co-drug (Fusidic acid (FA) and Levofloxacin (LEV)) encapsulated, ⁶⁸Ga-labeled, theranostic liposomes were formulated for osteomyelitis. Asp-DPPE and DOTA-Bn-DSPE were synthesized and confirmed by mass spectrometry, HPLC, FTIR-ATR, and XPS. The characterization of liposomes was carried out by assessing the particle size, zeta potential, encapsulation efficiency, obtaining CTEM images, drug release profiles, stability, and hydroxyapatite binding percentage. Additionally, in vitro antimicrobial activity was evaluated. Asp-Lipo/LEV/FA liposomes were developed nanosized (220,31 ± 2,40 nm) with sufficient encapsulation efficiencies (8,62 ± 1,27 for LEV and 31,20 ± 2,04 for FA). The highest ⁶⁸Ga-labeling yield was obtained at 60 °C, pH 4.5, and 5 min for Asp-Lipo/LEV/FA. All liposomes were stable at 4 °C for 30 days. Asp-Lipo/LEV/FA had significantly lower MIC values than Lipo/LEV/FA, and single-drug encapsulated liposomes for both E. Coli and S. aureus strains.