A paper-based dual-pad enzymatic sensor for rapid and low-cost point-of-care creatinine quantification

Abstract

The accurate and timely assessment of renal function is crucial for screening, diagnosing, and managing kidney disease, as well as preventing contrast-induced nephrotoxicity. Here, we report a dual-pad enzymatic creatinine quantification sensor (Cre-Q sensor) for rapid, low-cost, point-of-care blood creatinine measurement. The Cre-Q sensor employs a four-enzyme cascade (creatinine amidohydrolase, creatine amidinohydrolase, sarcosine oxidase, and horseradish peroxidase) to generate a colorimetric signal proportional to creatinine concentration, with ascorbate oxidase incorporated in the sample pad to eliminate ascorbic acid interference. The sensor requires 15 mu L of serum, delivers results in 10 min, at an estimated material cost of USD 0.05 per strip (excluding labor and packaging). The sensor exhibited a quadratic calibration curve (R2 = 0.99) over the 0-20 mg/dL range, a limit of detection of approximately 0.0137 mg/dL, and robust stability (<= 7% signal loss over 30 days at 4 degrees C). Clinical evaluation using 74 samples yielded R2 = 0.97 against the Cobas 8000 c702, with 100% sensitivity, 97.22% specificity, and receiver operating characteristic area under the curve (ROC AUC) of 0.9985. The low cost, ease of use, and robust analytical performance of the Cre-Q sensor support its potential application for rapid renal function testing in emergency, radiology, and resource-limited settings.