Shell Thickness Regulated Non-Enzymatic Au@AgNanocube Electrochemical Sensor for Sensitive and Simultaneous...

Developing plasmonic metal-based electrocatalysts for selective and sensitive biomolecular sensing remains an important research focus. Herein, a facile non-enzymatic electrochemical sensing platform based on Au@Ag_n core-shell nanocubes (NCs)-modified glassy carbon electrode is reported for the simultaneous detection of three kidney dysfunction biomarkers (KDBs): creatinine (Crn), uric acid (UA), and xanthine (Xan). Among different shell thicknesses, Au@Ag₃NC exhibited superior electrocatalytic activity, showing well-resolved diffusion-controlled oxidation peaks, enhanced current response, interference-free detection, and good long-term stability. The enhanced catalytic performance is attributed to interfacial tensile strain and electronegativity differences between the Au core and Ag shell, generating a positively charged surface which is favorable for electron rich analyte adsorption. Density functional theory (DFT) calculations further revealed enhanced charge transfer between the adsorbates (KDBs) and Au@Ag_nNC surfaces with increasing Ag-shell thickness, supporting the experimental observations. Differential pulse voltammetry (DPV) demonstrated a wide linear detection range from nM to mM concentrations with limits of detection (LOD) of 20.6, 28.0, and 34.3 nM for Crn, UA, and Xan, respectively. The proposed nanocatalytic platform also showed satisfactory recovery in human bio-fluid analysis, highlighting its potential for multiplexed kidney biomarker sensing.