Cyclic glucose polymers

FIGURE 23.17 Both starch (a) and cellulose (b) are polymers of glucose. In starch, all the cyclic glucose units are a-D-glucose. In cellulose, all the monomer units are /3-D-glucose. 

In this paper we report the electrochemical polymerization of the PPy-GOD film on the glassy carbon (GC) electrode in enzyme solution without other supporting electrolytes and the electrochemical behavior of the synthesized PPy-GOD film electrode. Because the GOD enzyme molecules were doped into the polymer, the film electrode showed a different cyclic voltammetric behavior from that of a polypyrrole film doped with small anions. The film electrode has a good catalytic behavior to glucose, which is dependent on the film thickness and pH. The interesting result observed is that the thin PPy-GOD film electrode shows selectivity to some hydrophilic pharmaceutical drugs which may result in a new analytical application of the enzyme electrode. 

What are the structural differences between a- and /3-glucose Each of these two cyclic forms of glucose is the building block to form two different polymers. Explain. 

Figure 9. (A) The preparation of a nonordered polymeric layer of glucose oxidase electrically wired by ferrocene groups incorporated in the polymer film. (B) Cyclic voltammograms of the GOx/ferrocene-modified electrode in the absence (a) and presence (b) of glucose, 30 mM. Performed under argon, in phosphate buffer, pH 7 potential scan rate, 10 mV s. Inset calibration curve for the amperometric response to glucose at 0.35 V vs. SCE measured under N2(a) and air (b). Adapted from Ref. [90] with permission.

Cellulose is formed by elimination of water from adjacent j8-anomers of the two cyclic forms of glucose (Eq. 15.2), hence it is a dehydro polymer. 

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