How it works? What is its basic/simplified operation principle?
Glucose oxidase (GOx) catalyses the oxidation of glucose (removal of an electron) into Glucono delta-lactone:
Glucose -- GOx_catalyst --> Glucono delta-lactone + e-
In the glucose sensor, this electron then, instead of being consumed by an oxygen molecule to produce hydrogen proxide (H2O2), is being transferred to an electrode in the electrochemical cell due to applied potential, thereby producing a current. This current can then be detected and related to the concentrations of glucose.
Further detailed explanation from Wiki:
"At pH 7, glucose exists in solution in cyclic hemiacetal form as 63.6% β-D-glucopyranose and 36.4% α-D-glucopyranose, the proportion of linear and furanose form being negligible. The glucose oxidase binds specifically to β-D-glucopyranose and does not act on α-D-glucose. It is able to oxidise all of the glucose in solution because the equilibrium between the α and β anomers is driven towards the β side as it is consumed in the reaction.[3]
Glucose oxidase catalyzes the oxidation of β-D-glucose into D-glucono-1,5-lactone, which then hydrolyzes to gluconic acid.
In order to work as a catalyst, GOx requires a cofactor, flavin adenine dinucleotide (FAD). FAD is a common component in biological oxidation-reduction (redox reactions). Redox reactions involve a gain or loss of electrons from a molecule. In the GOx-catalyzed redox reaction, FAD works as the initial electron acceptor and is reduced to FADH2. Then FADH2 is oxidized by the final electron acceptor, molecular oxygen (O2), which can do so because it has a higher reduction potential. O2 is then reduced to hydrogen peroxide (H2O2).
Enzymatic glucose biosensors use an electrode instead of O2 to take up the electrons needed to oxidize glucose and produce an electronic current in proportion to glucose concentration.[11] This is the technology behind the disposable glucose sensor strips used by diabetics to monitor serum glucose levels."
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