Electrochemical sensor for the discrimination of bilirubin in real human blood based on Au nanoparticles/ tetrathiafulvalene -carboxylate functionalized reduced graphene oxide 0D-2D heterojunction.

In clinical practice, the excess concentration of bilirubin can trigger diseases such as neonatal jaundice, hepatic failure, septicemia, and so on. The concentration of bilirubin is one of important clinical indexes to evaluate patients with hepatic function disease in clinical practice. Therefore, it is very necessary to develop a rapid detection technique detecting the bilirubin in body fluids. Here, a new electrochemical sensor based on Au nanoparticles/tetrathiafulvalene-carboxylate functionalized reduced grapheneoxide 0D-2D heterojunction(AuNPs/TTF-COOH/RGO) was fabricated for the discrimination of bilirubin in real human blood. The TTF-COOH could effectively repair electron conductivity of RGO nanosheets, decrease interface resistance, and also enhance the dispersity of TTF-COOH/RGO nanosheets in water. What's more, the S atoms of TTF-COOH can bonding the gold nano-particles (AuNPs) to fabricate a 0D-2D heterojunction with excellent biocompatibility and enhanced specific surface area. After bilirubin oxidases were self-assembled on the surface of AuNPs, a specific recognition interface was formed as a sensor for the detection of bilirubin. The heterojunction showed enhanced interface electron transfer rate, excellent biocompatibility, and also prominent electrocatalytic activity for the high efficiency catalysis of bilirubin. The sensor shows a linear response for bilirubin from 2.66 to 83  μmol L and a low detection limit of 0.74 μmol L at 3σ. This work provides one novel approach to detection of bilirubin by functional RGO nanosheets, and broadens the application area of RGO nanosheets in selective catalysis and detection of biomolecule in biological specimens, such as blood, urine.