Electrochemical grafting of 4-aminobenzoic acid onto toray carbon – Interfacial investigation and fabrication of non-enzymatic bilirubin sensor

Abstract

In this work, non-enzymatic electrochemical detection of bilirubin (BR) has been demonstrated using chemically functionalized toray carbon (TC) fiber electrode. Electrografting method is used for the functionalization of 4-aminobenzoic acid (4-ABA) onto TC fiber electrode represented as TC/ABA. For this purpose, potential dynamic cycles are carried out in aqueous solution containing in-situ generated diazonium cation from 4-ABA at ambient temperature. The functionalized TC electrodes have been characterized using cyclic voltammetry (CV), contact angle measurements, electrochemical impedance spectroscopy (EIS), attenuated total reflection FTIR (ATR –FTIR) and atomic force microscopy (AFM) studies. Further, TC/ABA electrode has been evaluated for the electro-oxidation of free BR and investigated the sensor performance under realistic situation. From our results, we find that TC/ABA electrode showed a wide linear concentration range, better sensitivity and lower limit of detection for BR sensor. At physiological concentration, the interference study performed in presence of other analytes showed a higher selectivity towards BR at 0.27 V. Interestingly the proposed sensor selectively detects BR not only in the absence of albumin but also it produces a response in presence of human serum albumin and hence the sensor exhibits a direct measure of free BR. Moreover, this biosensor has been utilized for the determination of BR in real sample analysis and for the assessment of diseases along with organs failure.