Target-Imprinted Polyaniline/Nb₂O₅ Nanoparticles as Electrochemical Interfaces for Monitoring Kidney Function

Timely detection of creatinine (Cre), a biomarker for kidney function and muscle health, is crucial for the diagnosis of chronic kidney disease (CKD), particularly in point-of-care (POC) settings. In this study, we present the design of Cre-imprinted, conductive polyaniline/Nb2O5 nanostructures, termed Cre-PAni/Nb2O5, as an electrochemical interface for the rapid quantification of Cre in human saliva. Cre-PAni/Nb2O5 is synthesized via in situ oxidative polymerization of diphenylamine-cross-linked aniline on the surface of monoclinic Nb2O5 nanoparticles and fabricated on screen-printed Au disposable electrodes to develop cost-efficient Cre-PAni/Nb2O5 sensors. The microscopic characterizations of the Cre-PAni/Nb2O5 sensor demonstrate the composite architecture of the synthesized Cre-PAni/Nb2O5 nanoparticles and a granular surface morphology with irregular spherical shapes. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) reveal that Cre-PAni/Nb2O5 possesses outstanding electrocatalytic properties, with lower interfacial resistance and superior electron transfer kinetics, compared to pristine, nonimprinted PAni and PAni/Nb2O5 as well as Cre-PAni sensors. Differential pulse voltammetry (DPV) confirms an increase in the electrooxidation current with rising Cre concentrations (0–1000 nM). Notably, the Cre-PAni/Nb2O5 sensor displays 3.68 μAcm–2 nM–1 sensitivity, with detection and quantification limits of 127 pM and 385 pM, respectively. Furthermore, the sensor exhibits remarkable Cre selectivity and 97.41 ± 2.83% Cre recovery in real saliva samples. Hence, disposable Cre-PAni/Nb2O5 sensors enable routine monitoring of kidney function and early CKD diagnosis through economical, noninvasive POC testing.