Enzymeless electrochemical biosensor platform utilizing Cu2O-Au nanohybrids for point-of-care creatinine testing in complex biological fluids

Abstract

Herein, we developed a novel, enzyme-free electrochemical biosensor that can directly quantify creatinine within complex biological fluids in a highly specific and sensitive manner. Our approach utilizes the synergistic effects of zwitterion-functionalized Cu2O-Au core satellite nanohybrids with sophisticated 3D granular structures, which were synthesized via a rapid room-temperature combinatory protocol. Through nanoscale zwitterion surface engineering, outstanding antifouling capabilities were obtained and interferents were effectively eliminated by generating a pseudo proton exchange membrane (PEM). This pseudo-PEM can potentially serve as an alternative to traditional methods of removing interference; thus, analytes can be directly detected in untreated biofluids. The optimized biosensor platform demonstrated a linear response to creatinine with exceptional reproducibility and an excellent limit of detection (LOD) in the following sensing ranges: (i) 10.0–200 µM (R2 =0.99, RSD=1.22 %, n = 10, LOD=0.72 µM) and (ii) 1.00–35.0 mM (R2 =0.99, RSD=1.32 %, n = 10, LOD=2.41 mM). These ranges are clinically relevant and cover the entire physiological range of creatinine in human serum and urine, respectively. Furthermore, we successfully detected creatinine directly in untreated human urine samples and observed a high correlation with clinically determined values (r = 0.98). Overall, our proposed biosensor platform offers significant improvements over existing methods and provides a reliable and efficient approach for practical point-of-care (POC) creatinine quantification.