Functionalization of Nitrogen-Doped Carbon Nanotubes by 1-Pyrenebutyric Acid and Its Application for Biosensing

The homogeneous nanocomposites of 1-pyrene butyric acid modified nitrogen-doped carbon nanotubes (PBA/NCNTs) are synthesized for the immobilization of enzymes and glucose biosensing. Through the aqueous carbodiimide coupling chemistry, glucose oxidase (GOD) is covalently immobilized on the surface of the as-prepared PBA/NCNTs with high enzyme loading (1.986 nmol · cm^-2). Fast direct electron transfer between GOD and the electrode is observed with the electron transfer rate constant (ks) of 2.43 s^-1. Besides, the GOD/PBA/NCNTs-based biosensor exhibits a linear response to glucose concentrations ranging from 2 μM to 0.2 mM with the detection limit of 1.33 μM and the high sensitivity of 179.76 μA·mM^-1 · cm^-2. Furthermore, this biosensor is also applied to detect glucose in the human serum samples with high accuracy. These results demonstrate that the PBA/NCNTs nanocomposites can be a promising platform for immobilizing biomolecules and biosensing application.