Transparent and flexible glucose biosensor via layer-by-layer assembly of multi-wall carbon nanotubes and glucose oxidase

This paper reports a transparent and flexible glucose biosensor of which multi-wall carbon nanotubes (MWNTs) and glucose oxidase (GOx) is layer-by-layer (LBL) self-assembled on a polymer substrate. A thin Ti and Au layers is firstly deposited on the polymer substrate through plasma immersion ion implantation (PIII) and sputtering, respectively. An organic monolayer then forms on the gold surface using thiol chemistry. Subsequently, negatively charged MWNTs and GOx are stably LBL assembled on the modified Au surface, respectively, via alternative electrostatic interaction of the positively charged polyelectrolyte with the oppositely charged MWNTs and GOx. Electrochemical studies show that the multilayer membrane exhibits remarkable electrocatalytic activity to detect glucose molecule. The biosensor displays a linear response range of 0.02–2.2 mM (a correlation coefficient of 0.998) with a low detection limit of 10 μM. This remarkable performance, combined with the large area preparation process, demonstrates this CNT-based multilayer biosensor is well suited for commercial applications.