Tetracycline Encapsulated in Au Nanoparticle-Decorated ZnO Nanohybrids for Enhanced Antibacterial Activity

Bacterial infections instigated by antibiotic-resistant bacteria are considered perilous health threats in today’s world due to their fast-increasing nature and the fewer availability of new treatment strategies. The properties of nanomaterials triggered by external stimuli are considered an encouraging technique for the remediation of antibacterial infectious diseases by producing photoinduced reactive oxygen species (ROS). Light-mediated treatment using zinc oxide (ZnO)-based nanohybrids leads the field with high interest in terms of sensitization of antibiotics and their targeted delivery. Moreover, the dual sensitization in a hybrid system could produce more efficacy as this phenomenon has been implemented in dye sensitized solar cells and photocatalysis. However, most of those hybrids are complicated and non-biocompatible. The present study highlights a tri-hybrid by encapsulating tetracycline (TC) in Au nanoparticle-decorated ZnO nanoparticles. The composition and morphology of the samples were characterized by electron microscopy, ultrafast optical spectroscopy, and density functional theory-based techniques. The dual sensitization in the tri-hybrids leads to enhanced antimicrobial activity against Gram-positive Staphylococcus hominis bacteria due to immense ROS under white light irradiation. The Förster resonance energy transfer from TC to Au and the excited-state photo-electron transfer process in the Au_ZnO-TC tri-hybrid system trigger a huge charge separation, which enhances production of ROS. Due to such a huge ROS production capability, the tri-hybrid shows a significant antibacterial action. Moreover, the Au nanoparticle-decorated ZnO is capable of destroying excess antibiotics, which potentially reduces the chance of development of antibiotic resistance. Overall, the study demonstrates a promising aspect that could be beneficial for manifold biological applications.