Biofilm-associated bacterial infection remains a major challenge in chronic wound healing, largely because dense extracellular matrices hinder drug penetration and protect bacteria from conventional antibiotics. Developing smart antibacterial nanoplatforms that can actively move, penetrate biofilms, and deliver therapeutics in deep regions is therefore highly desirable. Polydopamine (PDA), inspired by mussel adhesive proteins, has attracted broad interest owing to its strong adhesion, good biocompatibility, and versatile surface chemistry. However, pristine PDA generally suffers from limited stimuli-responsive functionality and insufficient morphological complexity, which restricts its use in intelligent antibacterial systems.
Recently, Prof. Yong Wang (Zhejiang University), together with Lianhui Wang (Nanjing University of Posts and Telecommunications), Prof. Ruizheng Liang (Beijing University of Chemical Technology), and their collaborators, demonstrated a one-pot polyoxometalate (POM)-directed interfacial assembly strategy to construct anisotropy-tunable hybrid mesoporous PDA nanostructures. By using silicotungstic acid as a multifunctional interfacial regulator, the POMs guide the co-assembly of P123, TMB, and dopamine at emulsion interfaces. During this process, POMs simultaneously stabilize composite micelles, regulate interfacial tension, direct PDA growth, and become molecularly dispersed within the PDA framework. As a result, the morphology of HMPs can be precisely programmed from isotropic hollow nanospheres to open hollow architectures with tunable opening degrees, providing a powerful route to integrate shape anisotropy and functional activity in a single PDA-based platform.
The POMs play a dual role in this system. Structurally, they enable controllable interfacial assembly and anisotropic cavity formation. Functionally, their redox-active and oxygen-rich metal–oxide cluster structure endows the PDA matrix with intrinsic antibacterial activity. This overcomes the limited responsiveness of pristine PDA and transforms the material from a passive carrier into an active functional nanoplatform.
To further exploit the anisotropic geometry, Pt nanoparticles were loaded into the HMPs to construct HMPM nanomotors. Pt catalyzes the decomposition of hydrogen peroxide, generating local oxygen concentration gradients that drive autonomous motion. The opening degree of the hollow cavity regulates the propulsion behavior, trajectory, and speed of the nanomotors. Simulations of oxygen distribution and flow fields further reveal that the asymmetric cavity structure modulates local catalytic reactions and propulsion-force generation, providing a mechanistic basis for active transport and biofilm penetration.
In antibacterial applications, the optimized HMPM-1.5 nanomotors combine POM-derived intrinsic antibacterial activity, anisotropic open hollow morphology, Pt-driven self-propulsion, and high drug-loading capacity. After loading daptomycin, HMPM-1.5 enables active drug delivery, enhanced bacterial contact, and deep penetration into methicillin-resistant Staphylococcus aureus biofilms. This integrated design leads to 97.8% antibacterial efficiency and 97.2% biofilm eradication, demonstrating near-complete destruction of drug-resistant bacterial biofilms.
Overall, this work highlights a POM-mediated interfacial assembly strategy for synchronizing morphology control, functional integration, and autonomous motion in mesoporous PDA nanostructures. The resulting anisotropy-tunable PDA nanomotors provide a versatile and intelligent platform for active antibacterial therapy, with potential applications in chronic wound treatment, biofilm-associated infections, and advanced biomedical nanodevices.
National Science Review
Experimental study