Molecularly imprinted interdigitated capacitive sensor for highly sensitive and selective detection of creatinine in human serum

Creatinine is a critical biomarker for kidney function assessment, requiring sensitive and selective detection in clinical samples. This study develops an interdigitated capacitive (IDC) sensor comprising a molecularly imprinted poly(methacrylic acid-co-ethylene glycol dimethacrylate) recognition layer for highly sensitive and selective sensing of creatinine in human serum samples. The structural features of molecularly imprinted polymer (MIP) and non-imprinted polymer (NIP) are characterized by Fourier transform infrared (FTIR) spectroscopy, while their surface morphology is studied by atomic force microscopy (AFM). The differential capacitance response (ΔC) of MIP and NIP-coated IDC was recorded as a function of increasing creatinine concentration. The sensor exhibited linear response in the concentration range of 100-1000 ppb of creatinine with R2 of 0.976 and sensitivity of 0.0065 nF ppb-1. The calculated limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.168 ppb and 0.509 ppb, respectively. The sensor exhibited at least seven-fold higher response for creatinine compared to interfering analytes such as uric acid, tryptophan, guanine, ascorbic acid, and arginine. Measurements for creatinine analysis in human serum samples revealed that despite a modest reduction in linearity, the sensor retained comparable sensitivity in serum, demonstrating its potential for label-free, real-time creatinine detection in clinical diagnostics.