Pyroelectric Janus nanomotors for synergistic electrodynamic-photothermal-antibiotic therapies of bacterial infections

Antibacterial electrotherapy is currently activated by external electric field or self-powered generators, but usually needs complicated power management circuits. Herein, near-infrared illumination (NIR) of pyroelectric nanoparticles (NPs) produces a built-in electric field to address the effectiveness and safety concerns in the antibacterial treatment. Janus tBT@PDA NPs were obtained by capping polydopamine (PDA) on tetragonal BaTiO3 (tBT) NPs through defining the polymerization time, followed by ciprofloxacin (CIP) loading on the PDA caps to fabricate Janus tBT@PDA-Cip NPs. NIR illumination of PDA caps creates temperature variations on tBT NPs to generate photothermal and pyroelectric effects. Finite element sim-ulation reveals a pyroelectric potential of over 1 V and sufficient reactive oxygen species (ROS) are pro-duced to exhibit pyroelectric dynamic therapy (PEDT). The elevated temperature on one side of the Janus NPs produces thermophoretic force to drive NP motion, which enhances interactions with bacteria and overcomes limitations in the short action distance and lifespan of ROS. The pyroelectric field accelerates CIP release through weakening the pi-pi stacking and electrostatic interaction with PDA and also inter-rupts membrane potentials of bacteria to enhance CIP invasion into bacteria. The synergistic antibacterial effect of pyroelectric tBT@PDA-Cip NPs causes the fully recovery of S. aureus-infected skin wounds and regeneration of intact epidermis, blood vessels and hair follicles, while no obvious pathological change or inflammatory lesion is detected in the major organs. Thus, the pyroelectric Janus nanomotors demon-strate synergistic PEDT/photothermal/antibiotic effects to enhance antibacterial efficacy while avoiding the necessity of excessive heat, ROS and antibiotic doses.

Automated summary

Antibacterial electrotherapy using near-infrared illumination of pyroelectric nanoparticles has been developed to address the effectiveness and safety concerns in the antibacterial treatment. The Janus tBT@PDA NPs, obtained by capping polydopamine on tetragonal BaTiO3 NPs followed by ciprofloxacin loading, generate photothermal and pyroelectric effects under NIR illumination. The pyroelectric Janus nanomotors demonstrate synergistic PEDT/photothermal/antibiotic effects to enhance antibacterial efficacy while avoiding excessive heat, ROS, and antibiotic doses.