Evaluation of various electrode materials for detection of oxidized low-density lipoproteins

Measurement of oxidized low-density lipoprotein (LDL) generated by oxidative stress of various kinds might be useful for evaluating the risk of cardiovascular disease. We evaluated some electrode materials to detect oxidized LDL electrochemically. Some carbon nanotube dispersions were studied as electrode materials. Native LDL was isolated from normal human serum using ultracentrifugation. Oxidized LDL was prepared by treating the native LDL with CuSO4. Electrodes were fabricated by depositing the nanotube dispersion on a gold electrode, with subsequent drying. The potential change of the electrode against a reference electrode was monitored before and after adding native LDL or oxidized LDL. Only acid-treated carbon nanotubes were able to discriminate both LDL preparations, perhaps because of the carboxylic acid groups introduced on the nanotube by acid treatment.