Synergies in antimicrobial treatment by a levofloxacin-loaded halloysite and gold nanoparticles with a conjugation to a cell-penetrating peptide

Herein, a novel designed antimicrobial therapeutic drug delivery system is presented, in which halloysite nanotubes (HNTs) encapsulate a determined dosage of levofloxacin (lvx). Moreover, gold nanoparticles (AuNPs) have been embedded into the structure for plasmonic heating under irradiation of the green LED light (7 W, 526 nm). It was revealed that the plasmonic heating of the AuNPs leads to a controlled trend in the lvx release process. Also, a synergistic effect on the antimicrobial activity of the prepared therapeutic system has been observed through photothermal heating of the structure. To enhance the cell adhesion, a cell-penetrating peptide sequence (CPP) is conjugated to the surfaces. This CPP has led to quick co-localization of the prepared nano-cargo (denoted as lvx@HNT/Au-CPP) with the bacterial living cells and further attachment (confirmed by confocal microscopy). Concisely, the structure of the designed nano-cargo has been investigated by various methods, and the in vitro cellular experiments (zone of inhibition and colony-counting) have disclosed that the antimicrobial activity of the lvx is significantly enhanced through incorporation into the HNT/Au-CPP delivery system (drug content: 16 wt%), in comparison with the individual lvx with the same dosage. Hence, it can be stated that the bacterial resistance against antibiotics and the toxic effects of the chemical medications are reduced through the application of the presented strategy.