A Label-Free Electrochemical Biosensor Based on Carbon Paste Electrode Modified with Graphene and ds-DNA for the Determination of the Anti-Cancer Drug Tamoxifen

In nanotechnology and biosensor technology, DNA serves as an excellent building block for the construction of new devices since being stable, low-cost, and easily adaptable [1]. In rational design of drugs, a structural guideline can be attained via the interaction between DNA and small molecules, which contributes to an improved synthesis of new drugs with higher selective activities and clinical efficacy and lower toxicities. Drug binding interactions with DNA have been investigated through various techniques. The interaction mechanism can be evidenced through observing DNA electrochemical signals before and after interacting with its targeted drug. Also, these drugs can be quantified by this interaction besides determining new drugs targeting DNA [2]. As an oral nonsteroidal antiestrogen drug, Tamoxifen has been widely utilized and developed via several methods for the prevention and treatment of breast cancer [3]. In this study, we constructed a carbon paste electrode modified with graphene and ds-DNA and studied the electrochemical interaction of ds-DNA and Tamoxifen. The DPV response to ds-DNA-GPE to various tamoxifen concentrations, as well as a calibration curve for tamoxifen detection with the help of the proposed biosensor under the optimal experimental conditions. A linear relationship was exhibited to exist between the tamoxifen concentration over the range of 8.0×10-7– 8.5×10-5 M and the peak current at ds-DNA-GPE by the calibration graph. Furthermore, the proposed method was applied to tamoxifen determination in human blood serum and urine samples.