A disposable label-free MXene/graphene-based aptasensor for the electrochemical detection of Cystatin C in human sweat

Cystatin C is a key biomarker for assessing kidney disease since its level increases in response to renal dysfunction. Current techniques detect Cystatin C in plasma, saliva, and urine, but the detection in sweat has not been explored. This paper describes a disposable label-free 2D nanomaterial-based aptasensor for assessing Cystatin C levels in human sweat. The aptasensor consisted of an aptamer immobilized on a Ti3C2–rGO layer for the non-invasive label-free electrochemical detection of Cystatin C. Electrochemical Impedance Spectroscopy showed that the aptasensor had a limit of detection of about 1 ng/mL (linear range 2–25 ng/mL) and can thus possibly help better discriminating among the five stages of kidney disease when combined with the measurement of creatinine. Potential sweat-specific interferents such as NaCl, urea, lactate, glucose and ascorbic acid did not affect the aptasensor response. This aptasensor proved the detection of Cystatin C in human sweat and may offer a promising alternative for the real-time monitoring of renal disease.