Acidic and Basic Functionalized Carbon Nanomaterials as Electrical Bridges in Enzyme Loaded Chitosan/Poly(styrene sulfonate) Self-Assembled Layer-by-Layer Glucose Biosensors

Glucose oxidase (GOx) was incorporated in a self-assembled multilayer modified gold electrode, based on electrostatic interaction between positively charged chitosan polymer, containing GOx, and negatively charged poly(styrene sulfonate). Good electronic communication between electrode and enzyme was ensured by carbon nanomaterials (CN), graphene (G) or carbon nanotubes (CNT) functionalised in either HNO3 or KOH, immobilized together with the enzyme. Cyclic voltammetry and electrochemical impedance spectroscopy enabled identification of the glucose biosensor assemblies with the best functionalized CN, KOH_G and HNO3_CNT, confirmed by fixed potential amperometry at -0.3V vs. Ag/AgCl, these glucose biosensors exhibiting the highest sensitivities and lowest detection limits.