Using hydrothermal method to prepare reduced graphene-hemin electrochemical biosensor for tyrosine detection

Hemin immobilized reduced graphene(HGN) has been investigated to be an outstanding enzymatic catalysis in detection important molecular recently. In this work, two "clean" methods to prepare HGN through π- π stack were charactered by UV-vis spectra, TEM images, and 5- potential. The enzymatic catalysis of both materials was compared by catalytic hydrogen peroxide to oxidize pyrogallol. The colorimetric result shows HGN attached before reduction has stronger catalytic ability than the one after reduction. The optimized HGN was then used as an electrochemical biosensor to determine L-tyrosine levels. The cyclic voltammetry (CV) tests were carried out for the bare glass carbon electrode (GCE), and the optimized hemin-reduced graphene electrode (HGN1/GCE). The HGN1/GCE based biosensor exhibits a Tyrosine detection linear range from 5× 10^-7 M to 4×10^-5 M with a detection limitation of 7.5× 10^-8 M at signal noise ratio (S/N) of 3. In comparison with other biosensor, electrochemical biosensors are easy-fabricated, easy-controlled, and cost-effective. Compared with other materials, the hemin- reduced graphene based biosensors demonstrate higher stability, a broader detection linear range, and better detection sensitivity. The study of oxidation scheme reveals that reduced graphene enhanced the electron transfer between electrode and hemin. Meanwhile, the hemin groups effectively electrocatalyzed the oxidation of tyrosine. This study contributes to a widespread clinical application of nanomaterial based biosensor devices with a broader detection linear range, improved stability, enhanced sensitivity, and reduced costs.