Nanostructured sensor devices for kidney disease biomarkers in sweat

Chronic Kidney Disease (CKD) is a complex condition, representing the third fastest-growing cause of death globally. Clinical diagnosis depends on glomerular filtration rate (GFR), which reflect the kidney’s filtering efficiency. GFR is estimated by monitoring creatinine, cystatin C, and urea levels in blood. The development of a sweat-based sensing platform would allow for a minimally invasive strategy for frequent therapy assessment, improving patient management and reducing hospitalization rates.

To establish a sensing platform for remote patients monitoring, we developed three sensors for simultaneous detection of creatinine, cystatin C, and urea in human sweat. The cystatin C device was an aptasensor built on a titanium carbide (Ti₃C₂) MXene-based substrate, integrating the high specificity of the aptamer with the superior conductive property of MXenes. The creatinine sensor depended on the electro-oxidation of the copper–creatinine complex exploiting titanium carbide–copper quantum dots (Ti₃C₂-Cu QDs). The urea sensor consisted of a composite of metal hydroxide nanoparticles tailored for selective interaction with urea. Electrochemical impedance spectroscopy was used to evaluate the response of all three sensors to the specific analyte.

The cystatin C aptasensor achieved a limit of detection (LOD) of 3.1 ng/mL with an RMSE of 8% over the clinically relevant range of 2–18.5 ng/mL. In the 10–100 µM range, the creatinine biosensor had an LOD of 1 µM and an RMSE of 10%. The urea sensor had an LOD of 36 mM and an RMSE of 15% over the range of 50–200 mM. These results agreed with the clinical requirements for CKD assessment. Ongoing advancements are underway to integrate these sensors into a wearable platform for remote kidney function monitoring.

This work was supported by The European Union through the Horizon Europe EIC programme (Grant Agreement project 101115504).