Quantitative Analysis of a Promising Cancer Biomarker, Calretinin, by a Biosensing System Based on Simple and Effective Immobilization Process

Calretinin (CAL) is calcium binding protein, and its levels in blood and cerebrospinal fluids are increased, since its expression is increased various cancer types. A novel biosensor system fabricated by immobilization of a specific antibody to CAL, anti-Calretinin (anti-CAL), onto a gold electrode surface via an effective covalent binding method using mercaptohexanol, epichlorohydrin, and ethanolamine was reported for the sensitive, selective, and accurate analysis of CAL. The proposed biosensor showed a linear calibration range between 1 ng/mL and 5 ng/mL. LOD and LOQ values were determined as 0.11 ng/mL and 0.38 ng/mL, respectively. The standard deviation related to the reproducibility of the new biosensor system was calculated as 3.95%. Lastly, in order to state the applicability of the biosensor to early diagnosis of CAL in practice, artificial serum samples spiked with CAL have been analyzed by the proposed biosensor.