Treating bacterial biofilm infections on implanted materials remains challenging in clinical practice, as bacteria can be resistant by weakening the host defense from immune cells like macrophages. Herein, a metal-piezoelectric hetero-nanostructure with mechanical energy-driven antimicrobial property is in situ constructed on the Ti implant. Under ultrasonic irradiation, the formed piezotronic Ti (piezoTi) can promote the generation of reactive oxygen species (ROS) by facilitating local charge transfer at the surface, thus leading to piezodynamic killing of Staphylococcus aureus (S. aureus) while downregulating biofilm-forming genes. In addition, the stimulated macrophages on piezoTi display potent phagocytosis and anti-bacterial activity through the activation of PI3K-AKT and MAPK pathway. As a demonstration, one-time ultrasound irradiation of piezoTi pillar implanted in an osteomyelitis model efficiently eliminates the S. aureus biofilm infection and rescues the implant with enhanced osteointegration. By the synergistic effect of ultrasound-driven piezodynamic therapy and immuno-regulation, the proposed piezoelectric nanostructured surface can endow Ti implants with highly efficient antibacterial performance in an antibiotic-free, noninvasive, and on-demand manner.
Piezocatalysis in aqueous medium has shown great potential for various applications, however the efficiency of piezocatalytic nanoparticles is harmed by the limited utilization of piezoelectric charge and the lack of active catalytic interface. In this study, BaTiO3@Metal (BTO@M, M=Pt, Pd and Au) hetero‐nanostructures were synthesized by using a piezodeposition method. The deposited metal cocatalysts significantly promote the separation and migration of piezogenerated charge, consequently enhancing the piezocatalytic reactions on different metal cocatalyst interfaces. Specifically, BTO@Au under ultrasonic vibrations exhibited most efficient generation of reactive oxidative species via a two‐electron reduction pathway in the presence of dissolved oxygen, while BTO@Pt showed promoted hydrogen evolution in the absence of oxygen. The metal‐piezoelectric hetero‐nanostructures proposed in this work highlight the key role of noble metal as cocatalysts for piezoelectricity‐driven oxygen reduction and hydrogen evolution reactions, which could further advance piezocatalysis in the field of clean energy, water disinfection and biomedicine.
Improving bioavailability of orally delivered drugs is still challenging, as conventional drug delivery systems suffer from non-specific drug delivery in the gastrointestinal (GI) tract and limited drug absorption efficiency. Gastric drug delivery is even more difficult due to the harsh microenvironment, short retention time, and physiologic barriers in the stomach. Here, an oral drug delivery microcapsule system was developed for gastric drug delivery, which consists of ionic liquid (IL) as the inner carrier and metal-phenolic network (MPN) as the microcapsule shell. The IL@MPN microcapsules are prepared by interfacial self-assembly of Fe III and quercetin at the interface of hydrophobic IL ([EMIM][NTf 2 ]) and water. The formation of MPN shell could improve the stability of IL droplets in water and endow the system with pH-response drug release properties, while the encapsulated IL core could efficiently load the drug and enhance the drug tissue permeability. The IL@MPN microcapsules showed enhanced drug absorption in the stomach after oral administration in a rat model, where the microcapsules are disassembled in gastric acid, and the released IL could reduce the viscosity of mucus gel and increase the drug transport rate across endothelial cells. This work presents a simple yet efficient strategy for oral drug delivery to the stomach. Given the diversity and versatility of both MPN and IL, the proposed self-assembled microcapsules could expand the toolbox of drug delivery systems with enhanced oral drug bioavailability.
Implant-associated infections (IAI) are great challenges to medical healthcare and human wellness, yet current clinical treatments are limited to the use of antibiotics and physical removal of infected tissue or the implant. Inspired by the protein/membrane complex structure and its generation of reactive oxygen species in the mitochondria respiration process of immune cells during bacteria invasion, we herein propose a metal/piezoelectric nanostructure embedded on the polymer implant surface to achieve efficient piezocatalysis for combating IAI. The piezoelectricity-enabled local electron discharge and the induced oxidative stress generated at the implant−bacteria interface can efficiently inhibit the activity of the attachedStaphylococcus aureusby cell membrane disruption and sugar energy exhaustion, possess high biocompatibility, and eliminate the subcutaneous infection by simply applying the ultrasound stimulation. For further demonstration, the treatment of root canal reinfection with simplified procedures has been achieved by using piezoelectric gutta-percha implanted in ex vivo human teeth. This surface-confined piezocatalysis antibacterial strategy, which takes advantage of the limited infection interspace, easiness of polymer processing, and noninvasiveness of sonodynamic therapy, has potential applications in IAI treatment.
The Cover Feature highlights the key role of noble metal as cocatalysts for piezoelectricity‐driven oxygen reduction and hydrogen evolution reactions. In their Research Article, W. Wang, J. Li and co‐workers synthesized BaTiO3@Metal (BTO@M, M=Pt, Pd and Au) hetero‐nanostructures by using a piezodeposition method. The deposited metal cocatalysts significantly promote the separation and migration of piezogenerated charge, consequently enhancing the piezocatalytic reactions on different metal cocatalyst interfaces. Specifically, BTO@Au under ultrasonic vibrations exhibited most efficient generation of reactive oxidative species via a two‐electron reduction pathway in the presence of dissolved oxygen, while BTO@Pt showed promoted hydrogen evolution in the absence of oxygen. This work could further advance piezocatalysis in the field of clean energy, water disinfection and biomedicine. More information can be found in the Research Article by W. Wang, J. Li and co‐workers.
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