Cactus-mimetic ZnO nanohybrids: Topography-engineered high efficiency of mechanical bactericidal activity

A crystal-interface-engineering guided imperfect-orientation mechanism is developed to regulate the fabrication of cactus-mimetic ZnO nanohybrids. • The as-prepared cactus-mimetic nanohybrids exhibit topography-governed ultrafast mechanical bactericidal activity. Mechanical bactericidal strategies based on biomimetic micro/nanostructures have emerged as a green and sustainable disinfection approach, owing to their low tendency to induce microbial mutation and resistance, as well as the absence of chemical-related side effects and toxic byproducts. However, current mechanical bactericidal surfaces predominantly rely on single nanostructures (e.g., nanopillars, nanosheets, or nanocones), whose bactericidal efficacy is often constrained by the inherent limitations of a single action mode. Inspired by the hierarchical structure of cacti, which integrates both blade-like sheets and sharp spines, we herein report a cactus-mimetic ZnO nanohybrid featuring nanosheets decorated with epitaxially grown nanoneedles, fabricated via a crystal-interface-engineering strategy under ambient conditions. The growth mechanism involves dislocations generated by imperfect oriented attachment between crystals, which serve as secondary nucleation sites. An ultrafast mechanical bactericidal activity evaluation platform was designed for the subsequent mechanical bactericidal tests. This unique hierarchical architecture enables a synergistically enhanced mechanical bactericidal mechanism, which mainly involves concurrent actions of stress-stretching, edge-cutting and needle-piercing at multi-scaled contact interfaces, as well as their cooperative effects. The synergistic integration of these mechanical actions enables ultrafast bacterial inactivation, achieving a 99.99% bactericidal efficiency against both Escherichia coli and Staphylococcus aureus (10 6  CFU/mL, 300 μL) within just 1 min of contact, demonstrating a significantly outperforming pristine ZnO nanosheets. This work provides a new design paradigm for high-performance mechanical bactericidal materials by harnessing synergistic multi-mechanism actions, offering a rapid and sustainable solution for water disinfection and infection control applications. Download: Download high-res image (138KB) Download: Download full-size image