Microstructure regulation of hollow AuAg alloy nanobowls toward high-performance electrochemical urea biosensing

AuAg alloys possess excellent electrical conductivity and biocompatibility. AuAg alloy nanobowls (AuAg NBs) were fabricated using a self-assembled polystyrene microsphere film as the template via an in situ galvanic replacement reaction between Ag and HAuCl4. The AuAg NBs exhibited a hierarchical hollow architecture consisting of large bowl-like structures containing smaller bowls. By employing the AuAg NBs as an electrode-modifying material and integrating them with urease, we constructed a glassy carbon electrode (GCE)/AuAg NBs/urease electrochemical sensor for the detection of urea. The unique hierarchical nanobowl structure provides a large electrochemically accessible surface area for urease immobilization, while density functional theory (DFT) calculations using a simplified Gly-His model indicate a favorable local adsorption tendency on AuAg NBs. In addition, the excellent biocompatibility of the AuAg alloy helps preserve the bioactivity of urease, enabling the specific recognition and catalytic hydrolysis of urea. The as-prepared sensor exhibited a good linear response with a detection limit as low as 6.7 μM. The GCE/AuAg NBs/urease electrode exhibited a 135.5% higher potential response than the GCE/AuAg NPs/urease electrode. Urea in tear fluid is a potential biomarker for the diagnosis of dry eye disease (DED). Furthermore, the AuAg NBs were applied to screen-printed electrodes, demonstrating the potential of this platform for tear-based urea sensing and future point-of-care applications related to DED screening.