Development of Electrochemical Sensing Platforms: Detection of Therapeutic Drugs and Heavy Metal Ions

Abstract

The sensitivity characteristics of the electrode can be enhanced by modifying its surface with suitable modifiers. The surface assisted electron transfer platforms are particularly useful for pharmaceutical analysis and detection of water toxins. The primary objective of the current work is to modify the electrode surface in a way that could significantly boost its sensitivity for medical and environmental applications. Four electrode modifiers including bis-triazole appended calix[4] arene (BTC), Bis (imidazo [4, 5-f][1, 10] phenanthroline) appended bis-triazolo calix[4] arene (BPTC), FeCoSe2 and CoPd@Al2O3 were synthesized and characterized by various electrochemical, structural, and morphological techniques. The synthesized materials were immobilized individually onto the electrode surface and modification was ensured by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and square wave anodic stripping voltammetry (SWASV). In the designed nanosensors, FeCoSe2 nano-rods and CoPd@Al2O3 were used as receptors for the sensing of Isoniazid (INZ) and Venlafaxine (VEN) drugs in biological fluids. For real sample analysis the labelled claims of INZ and VEN in tablets were validated and the detection limits of 0.12 nM and 1.86 pM were evaluated by square wave anodic stripping voltammetry. It was observed that the signals of the drugs remained intense even in the presence of interfering agents such as citric acid, uric acid, ascorbic acid, glucose, sucrose, Ca2+, Mg2+ and NH4+ ions with concentration higher than INZ and VEN. For the sensing of heavy metal ions, Zn (II), Pb (II), Cd (II), As (III), and Hg (II), BTC and BPBTC were used as receptors on the transducer’s surface. The platforms were then used for the detection of metal ions. The selected metal ions were found to interact with the electron rich functionalities of the recognition layers and the resulting host guest complexation led to increase in the oxidation signals, about 5 times at the fabricated electrode as compare to bare GCE. To check the performance of the sensing platforms, EIS, CV, and SWASV were utilized. Conditions were optimized to achieve the highest possible current response of the target analytes. The validity of the modified electrodes for practical applications was verified by testing them with real samples. Results indicated that the designed electrochemical platforms possess the qualities of sensitivity, selectivity, reproducibility, and stability.