The electrochemical oxidation of ketamine as an analgesia and anesthesia drug and its interaction with DNA was studied at carbon paste electrode (CPE) using voltammetric techniques. Ketamine showed one irreversible oxidation peak nearly around +1.14 V vs. Ag|AgCl|KCl (3 M) only in Britton buffer (pH 7.00). The effect of scan rate on the cyclic voltammetric behavior of ketamine was investigated at the CPE and binding constant of ketamine and DNA was also calculated. The binding mode of DNA and ketamine was elucidated by differential pulse voltammetry and UV–vis spectroscopy techniques. Based on these results, interaction between ketamine and single-stranded DNA was of electrostatic mode, while between double-stranded DNA and ketamine was of groove binding. Ketamine showed a special affinity toward guanine bases of DNA. Also, ketamine was employed as an electrochemical indicator for detection of DNA hybridization. The difference between the oxidation peak current of the DNA probe modified CPE in the presence and absence of ketamine (∆I) was enhanced with increasing ketamine concentration and a detection limit of 1.98 nM was evaluated. To further investigate the selectivity of this biosensor, some noncomplementary sequences were used. Finally, the proposed method was successfully used for voltammetric determination of ketamine in real samples.
