Sensing glucose based on its affinity for concanavalin A on a glassy carbon electrode modified with a C60 fullerene nanocomposite

An ultrasensitive electrochemical glucose biosensor has been developed by depositing C-60-fullerene functionalized with tetraoctylammonium bromide (C-60-TOAB(+)) on the surface of a glassy carbon electrode (GCE). The glucose-binding protein concanavalin A (Con A) was then linked to the surface. Binding of glucose by Con A affects the electroactivity of the reversible redox couple C-60/C-60 (-), and this finding forms the basis for a quantitative glucose assay over the 10 to 10 mM concentration range and with a lower detection limit of 3.3 nM (at an S/N ratio of 3). The sensitivity of this sensor allowed glucose to be determined in saliva. This biosensor possesses excellent selectivity, outstanding reproducibility and good long-term stability.