Multiple lipid nanoparticles as antimicrobial drug delivery systems

The present work aimed at investigating formulations based on multiple lipid nanoparticles (MLNs) containing carvacrol (CAR) and vancomycin hydrochloride (VAN) co-loaded (CAR-VAN-MLNs) as therapeutical strategy useful to improve the antibiotic activity of VAN. Drug-loaded MLNs were prepared by the ultra-sonication technique and investigated for both physico-chemical and antimicrobial properties. Results revealed that all the formulations possessed particle size lower than 150 nm and negatively charged surfaces, as suggested by the ζ-potential values. The encapsulation efficiencies were higher than 70% and 21% for CAR and VAN, respectively. Moreover, differential scanning calorimetry analysis confirmed the effective drug loading, while stability studies indicated that the prepared formulations remained stable for about one month when stored at 4 °C. Finally, in vitro studies revealed a sustained drug release during the time. The morphological MLNs characterization, performed by transmission electron microscopy analysis, showed a spherical shape of the produced nanoparticles. Antimicrobial studies suggested that the co-encapsulation improved VAN antibiotic activity against Staphylococcus aureus with a possible greater advantage during systemic therapies.