Albumin fouling-free electrochemical sensors based on polyaniline single walled carbon nanotube composites for precise purine metabolomics

Electrochemical sensors enable rapid and accurate detection of targets. However, fouling is a burden that restricts sensor performance in complex biofluids and fouling resistant or fouling-free property is paramount to guarantee the reliable operation of sensors. Single-walled carbon nanotubes (SWCNTs) possess an exceptional catalytic capability owing to the weak molecular adsorption of sp3 carbon. Poly(aniline-N-propane sulfonic acid) (PAPS) polymer dispersed SWCNTs with a high conductivity (4.184 S/cm), and hydrophilicity were prepared to circumvent the fouling issues. The length of the PAPS dispersed SWCNTs were 3.1 ± 1.0 μm and the modified screen-printed carbon electrodes (PAPS-SWCNTs/SPCEs) demonstrated efficient electro-oxidation of purines, such as, uric acid (UA), xanthine (XA), and hypoxanthine (HX) after exposure to high concentrations of a common foulant, serum albumin. The peak-to-peak separations of UA–XA, XA–HX, and UA–HX were 0.396 V, 0.352 V, and 0.748 V, respectively. The detection limits of UA, XA, and HX were 0.047, 0.049, and 0.052 μM respectively. The practical applicability of the sensor was established using human serum and synthetic urine samples. The fabricated sensor is fouling-free and could serve as a potential diagnostic device for the early detection of renal diseases, such as renal calculi, chronic kidney diseases, and renal failure in resource-limited settings, since it does not require scrupulous sample pretreatment, frequent recalibration or prolonged waiting times. Moreover, the developed sensor adheres to ASSURED criteria, which is crucial for the diagnosis of renal diseases in resource-limited settings.