A portable sweat biosensor for multiple chronic kidney diseases biomarkers detection

Continuous and quantitative measurement of toxin biomarkers in biological fluids constitutes a significant advancement in the proactive management of chronic kidney diseases (CKD). Although sweat analysis presents a promising non-invasive strategy, conventional detection methods suffer from inherent limitations, including low sensitivity, poor specificity, high cost, and inadequate long-term durability. Herein, we constructed a novel molecularly imprinted portable biosensor that can simultaneously detect three critical biomarkers (urea, creatinine, and uric acid) for CKD in human sweat. The sensor was fabricated on flexible polyethylene terephthalate (PET) film using screen-printing technology to form a five-electrode array consisting of one counter electrode, one reference electrode and three working electrodes. The ternary composite electrodes (NiCoMOF/MWCNTs/NCDs) were designed as sensing substrate, the porous structure derived from metal-organic frameworks provides abundant active sites for analyte sensing and in synergy with the conductivity of MWCNTs and NCDs, endows the ternary composite electrode with a high electrochemically active surface area (A) of 0.062 cm 2 , a rapid electron transfer rate ( k 0 ) of 6.685 × 10 −3  cm s −1 , and a low electron transfer resistance of 52.79 Ω, significantly enhancing its electrochemical properties (Bare carbon, A: 0.0161 cm 2 , k 0 : 0.613 × 10 −3  cm s −1 ). Molecular imprinting technology generates highly specific recognition cavities with enhanced rebinding efficiency by removing template molecules from each working electrode. The portable sensing platform exhibits sensitivities of 6.2 μA mM −1  cm −2 , 134 nA μM −1  cm −2 , and 1870 nA μM −1  cm −2 for the detection of urea, creatinine, and uric acid, respectively, with detection limits of 0.048 mM, 0.032 μM, and 0.024 μM. The linear ranges encompass the physiological concentrations of these analytes in sweat, with corresponding correlation coefficients (R 2 ) of 0.9959, 0.9952, and 0.9981. The non-enzymatic mechanism ensures that the signal retention rate remains above 95.8 % after 60 days of storage. The results from various scenario tests demonstrated that the sensing system successfully achieved synchronous dynamic monitoring of three biomarkers in sweat samples. Hence, this work shows high development prospects for a continuous, convenient, non-invasive sensing platform for point-of-care diagnosis and personalized management of chronic kidney diseases.