Biosensor based on self-assembling glucose oxidase and dendrimer-encapsulated Pt nanoparticles on carbon nanotubes for glucose detection

A novel amperometric glucose biosensor based on layer-by-layer (LbL) electrostatic adsorption of glucose oxidase (GOx) and dendrimer-encapsulated Pt nanoparticles (Pt-DENs) on multiwalled carbon nanotubes (CNTs) was described. Anionic GOx was immobilized on the negatively charged CNTs surface by alternatively assembling a cationic Pt-DENs layer and an anionic GOx layer. Transmission electron microscopy images and zeta-potentials proved the formation of layer-by-layer nanostructures on carboxyl-functionalized CNTs. LbL technique provided a favorable microenvironment to keep the bioactivity of GOx and prevent enzyme molecule leakage. The excellent electrocatalytic activity of CNTs and Pt-DENs toward H2O2 and special three-dimensional structure of the enzyme electrode resulted in good characteristics such as a low detection limit of 2.5 mu M, a wide linear range of 5 mu M - 0.65 mM, a short response time (within 5 s), and high sensitivity (30.64 mu A mM(-1) cm(-2)) and stability (80% remains after 30 days).