Direct electron transfer: Electrochemical glucose biosensor based on hollow Pt nanosphere functionalized multiwall carbon nanotubes

Herein, a novel third-generation glucose biosensor based on unique hollow nanostructured Pt decorated multiwall carbon nanotubes (HPt-CNTs) composites was successfully constructed. The HPt-CNTs composites were successfully prepared and cast on the glassy carbon electrode (GCE) surface directly. With the help of electrostatic adsorption and covalent attachment, the negative l-cysteine (l-cys) and the positive poly(diallydimethylammonium) chloride (PDDA) protected gold nanoparticles (PDDA-Au) were modified on the resulting electrode surface subsequently, which provided further immobilization of glucose oxidase (GOD). Exploitation of the unique properties of HPt-CNTs composites led to the achievement of direct electron transfer between the electrode and the redox active centers of GOD, and the electrode exhibited a pair of well-defined reversible redox peaks with a fast heterogeneous electron transfer rate. In particular, the detection limit (4 × 10⁻⁷ M) of this biosensor was significantly lower and the linear range (1.2 μM–8.4 mM) was much wider than similar carbon nanotubes (CNTs) and Pt-based glucose biosensors. The resulted biosensor also showed high sensitivity and freedom of interference from other co-existing electroactive species, indicating that our facile procedure of immobilizing GOD exhibited better response and had potential application for glucose analysis.