Immunoassay has been widely used; however, a serious drawback
in the immunoassay of insulin is its nonspecific binding with
the coexistent biomolecules that cause imprecise detection of it [6].
In addition, high-performance liquid chromatography with ultravioletevisible
detection [4] and fluorescence detection [7] has been
used in this region, but it is time-consuming and an expensive instrument. Hence, the development of a simple, rapid, sensitive,
and inexpensive method for insulin detection is still highly desirable.
Electrochemical methods have also been proposed. Electrochemical
sensors of insulin coupled to flow systems or
chromatographic instruments can promote the analytical methodology
for this hormone. However, the use of common electrodes for
electrooxidation of insulin is not satisfactory because of slow heterogeneous
electron transfer kinetics.