β-Cyclodextrin-modified AuBi metallic aerogels enable efficient peroxidase mimicking for colorimetric sensing of urease-positive pathogenic bacteria

The detection of pathogenic bacteria with improved accessibility, reduced analysis time, and increased sensitivity is of great importance for diagnosing the infected disease. Nanozymes have attracted rising attention in the bioassay field. Designing a model nanozyme needs the combined merit of sensible nanostructures and a large specific surface area to guarantee exceptional enzyme-mimic activity. Herein, a β-cyclodextrin modified AuBi aerogel is prepared by a one-pot reduction strategy. The introduction of β-cyclodextrin (featured with a hydrophobic cavity and hydrophilic surface) enhances the catalytic activity of AuBi aerogels by engendering host–guest complex and improving dispersity/stability. Based on the specific urea hydrolysis, which could produce NH₃ to raise pH by urease, the pH up-regulation would inhibit the peroxidase-mimicking performances of β-cyclodextrin/AuBi aerogels. Therefore, the sensitive colorimetric detection platform for urease activity could be constructed. Moreover, the sensing platform can detect straightforwardly urease-positive Proteus mirabilis in urine circumstances with a wide detection range and a low limit of detection (LOD) of 4 colony-forming unit (CFU)·mL⁻¹. The reproducibility, stability, and specificity of this approach are verified to be satisfactory. Also, as an inhibitor of urease activity, the fluoride ion could be detected by the constructed sensing platform sensitively and specifically. Overall, this work provides a blueprint for designing an ideal nanozyme and paves a new roadway for detecting pathogenic bacteria.