Ultrasensitive sensor for detection of early stage chronic kidney disease in human

A facile label free, ultrasensitive platform for a rapid detection of chronic kidney disease has been fabricated. Early intervention in patients with chronic kidney disease has the potential to delay, or even prevent, the development of end stage renal disease and complications, leading to a marked impact on life expectancy and quality of life. Thus, a potable electrochemical diagnostic biosensor has become an attractive option as electrochemical analysis is feasible to use for on-site detection of samples. In human, Cystatin C present in human body fluids is freely filtered by the glomerulus, but reabsorbed and catabolised by the renal tubules. Trace detectable amount is eliminated in urine, giving this molecular marker an edge over serum creatinine's disadvantages. A carboxyl functionalized multiwalled carbon nanotubes screen printed electrode was immobilized with papain (cysteine protease) where amino group of papain covalently bound carboxyl group on electrode surface by EDC (1-ethyl-3-(3-dimethylaminopropyl) carbodiimide) and NHS (N-hydroxysuccinimide) chemistry. The modifications on sensor surface were characterized by field emission scanning electron microscopy. Interaction between papain and chronic kidney disease specific biomarker, Cystatin C was detected by cyclic voltammetry and differential pulse voltammetry within 10min. The sensor is highly specific to Cystatin C and showed negligible response to non-specific macromolecules present in urine. The sensitivity of the sensor was 1583.49µAcm^-2µg^-1 and lower limit of detection of Cystatin C was found 0.58ngL^-1 which presents as a promising platform for designing potable kidney disease detector.