Table 4.

The advantages and disadvantages of the common metal oxide nanostructured materials for glucose biosensors.

Metal Oxide	Advantages	Disadvantages	References
ZnO	Good chemical stability Good biocompatibility Non-toxic Good electrochemical activity Fast electron transfer rate High isoelectric point (IEP = 9.5)	Require relatively high potential for operation might cause oxidation of interfering agents Poor stability, easy to be removed from electrode	[169,170]
CuO/Cu2O	Abundance Low production cost Good electrochemical and catalytic properties Stable in air and solutions High isoelectric point (IEP = 9.5)	Performance dependent on size and morphology Toxic in some cases Air-sensitive Cu substrate causes big sensor-to-sensor variation	[164,165]
Fe3O4	Good biocompatibility High electrical conductivity Superparamagnetic Low toxicity Low cost for large scale production	Easy to aggregate and agglomerate Require surface functionalization Intermediate IEP (3–7)	[110,171]
MnO2	Abundance Low toxicity High catalytic activity Low cost Environmental friendly	Low sensitivity in glucose detection Poor selectivity thus induces interfering effect Low IEP (4–5)	[168,172]