L-arginine proliferative actions are a direct link to the onset of breast cancer in the presence of low nitric oxide levels (Singh et al., 2000). As a predictive biomarker for breast cancer, detecting L-arginine at a level of high sensitivity and accuracy is important. In previous research, metal nanoparticles have been used as catalysts, because of their ability to increase measurement sensitivity (Durst et al., 1997). With our electrode surfaces, we chose to modify it two ways with copper nanoparticles, either embedded into a polyaniline film (Cu-PANI) or in a hexacyanoferrate structure (Casella et al., 1996; Chen et al., 2007). We first tested the sensitivity of the Cu-PANI on a glassy carbon electrode, providing preliminary data indicating the removal of copper from the PANI surface. Through the use of an electrochemical quartz crystal microbalance (eQCM), I was able to validate our preliminary observation. The eQCM is helpful in measuring mass changes by monitoring the quartz frequency changes that occur on the quartz surface. Our concerns with the Cu-PANI stability prompted further examination to understand the reasons for the delamination. In the end, we were able to confirm four factors that increased the speed of the delamination process including pH, flow rate, voltage, and concentration. Ultimately, the factors had little affect on the copper hexacyanoferrate and, in comparison to Cu-PANI, had less copper removal. Our focus on the modification’s stability will continue for the purposes of detection of L-arginine for later comparison of stability versus the sensitivity.
Casella, I.G., Cataldi, T.R.I., Guerrieri, A., and Desimoni, E. (1996). Copper dispersed into polyaniline films as an amperometric sensor in alkaline solutions of amino acids and polyhydric compounds. Anal. Chim. Acta 335, 217–225.
Chen, S.-M., Li, S.-H., and Thiagarajan, S. (2007). Preparation of Bilayer Platinum and Copper Hexacyanoferrate Hybrid Film Modified Electrode and Its Electrocatalytic Properties. J. Electrochem. Soc. 154, E123.
Durst, R.A., Baumner, A.J., Murray, R.W., Buck, R.P., and Andrieux, C.P. (1997). Chemically modified electrodes: Recommended terminology and definitions. Pure Appl. Chem. 69, 1317–1323.
Singh, R., Pervin, S., Karimi, A., Cederbaum, S., and Chaudhuri, G. (2000). Arginase activity in human breast cancer cell lines: N(omega)-hydroxy-L-arginine selectively inhibits cell proliferation and induces apoptosis in MDA-MB-468 cells. Cancer Res. 60, 3305–3312.