Control of the total cholesterol level in the body plays an important role for preventing these life-style related diseases. Now, the measurement of cholesterol level in the clinical institution is carried out by using absorption photometer with the enzymatic reaction. However, the conventional method is troublesome due to the necessity of going to a hospital for invasive-collecting blood and using the enzyme reaction through many procedures. On contrary, about 11 % of the body's cholesterol is found in the skin at the same rate as in blood, according to the United States FDA. Therefore, we focus on a simple electrochemical detection and non-invasive measurement of skin cholesterol using the molecularly imprinted self-assembled monolayer electrode (MISAM).
A gold electrode was immersed in ethanol solution, containing cholesterol and stearyl mercaptan (n=18), and then washed in ethanol in order to extract cholesterol as a template molecule. The extraction of cholesterol molecules has created the shape-complementary cavities on the MISAM. A detection of the electroinactive cholesterol has been achieved by electrochemical method with a potassium ferrocyanide as a redox marker. The change of the oxidation peak current (Ia) has shown a linear relationship with the concentration of cholesterol. The Ia related to the cavity concentration for the mass-transport of redox marker on the
MISAM. When the cholesterol-sensitive MISAM recognizes cholesterol, the Ia decreases due to the rejection of diffusion of the marker to the gold electrode surface. On the contrary, when the MISAM extracts cholesterol, the marker diffuses to the electrode surface, and the Ia increases.
Sensing property of MISAM, such as sensitivity, selectivity, and reproducibility, has been examined and it has been applied for simple and speedy electrochemical sensor development.
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