Aptamer-based Nanosensors: Juglone as an Attached-Redox Molecule for Detection of Codeine

Among several biosensing approaches, electrochemical-based procedures have been described as one of the most common and useful methods for sensing because of their simplicity, sensitivity, accuracy, and low cost. The electroactive species, which called redox, play a main role in the electrochemical-based approaches. Of several redox molecules used for electrochemical experiments, ferrocene is one of the commonly used redox molecules. However, instability of ferrocenium ion in the chloride containing solutions appeared to be weakness of this redox molecule limiting its utilization. In the current study, Juglone was attached (using EDC/NHS coupling method) to the 3'-amino-modified terminus of the immobilized specific aptamer of codeine, which was successfully used in a cyclic electrochemical voltammetry procedure. The cyclic voltammogram peak of aptamer-attached Juglone was observed in the potential range of +0.4 to +0.9 V and the fabricated aptamer-based sensor was used for detection of different concentrations of codeine in the phosphate buffer 0.1 M solution containing 2 M NaCl. Based on these findings, it can be suggested that the new aptamer-attached Juglone could be considered as an effective alternative redox molecule in particular with oligonucleotide-based sensing systems.