Bifunctional nano-Ag₃PO₄ with capabilities of enhancing ceftazidime for sterilization and removing residues

Since the efficacy of antibiotics towards bacteria is decreasing over time, the rising of antibiotic emission has become an increasingly grave issue. In this study, we proposed an integrated antibacterial nanotechnology without pollution residues, which synergistically enhances the antibacterial activity of ceftazidime by using the inorganic nano-Ag₃PO₄, and subsequently removes drug residues by photocatalysis. Ag₃PO₄ were synthesized using a simple ion-exchange method without any reducing agent or protectant. The combined antibacterial activity of Ag₃PO₄ and 22 kinds of antibiotics against Escherichia coli was first studied. The results showed that Ag₃PO₄ and ceftazidime exhibited the best synergistic effect. Next, the synergy mechanism was proposed, the non-chemical bond forces between Ag₃PO₄ and ceftazidime was determined by zeta potential analyzer, X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (IR). The interaction between antimicrobials and bacteria was further demonstrated by surface plasma resonance spectroscopy (SPR), scanning electron microscopy (SEM) and propidium iodide (PI) staining. In addition, the production of reactive oxygen species (ROS), the induction of oxidative stress and dissolution of silver ions in Ag₃PO₄ were studied and found out that only under light, could the ROS be generated. In conclusion, the synergistic effect of Ag₃PO₄ and ceftazidime is responsible for the joint destruction of cell wall.