Electrosynthesised CdS@ZnS quantum dots decorated multi walled carbon nanotubes for analysis of propranolol in biological fluids and pharmaceutical samples

Quantum dots (QDs) based electrochemical assays have received a great deal of attention. They preserve the outstanding characteristics of electrochemical methodologies with respect to simplicity, ease-of-use, and costeffective instrumentation. In this work, a new challenge was opened up to explore the electrochemical features of CdS@ZnS as two well-known semiconductors for analytical utilizations. Here, CdS@ZnS core-shell QDs have been prepared electrochemically and applied for electrochemical sensor development in this approach. An activated glassy carbon electrode modified with a thin film of multi walled carbon nanotube was coated with CdS@ZnS QDs (activated GCE/MWCNTs/CdS@ZnS) as a thin uniform layer for analysis and monitoring of propranolol (PRO), a non-selective beta-blocker drug. Field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectroscopy (EDX) were used to characterize the surface morphology of the developed electrodes. The results demonstrated that CdS@ZnS QDs were well-dispersed on the activated GCE/MWCNTs surface and were able to enhance the number of adsorbed analyte molecules. The electrochemical behavior of the PRO was studied at the modified electrode surface. The kinetic parameters of electron transfer coefficient (alpha) and the catalytic rate constant (kcat) for the electron transfer between PRO and the modified electrode were calculated. The electrochemical oxidation mechanism of PRO was also investigated by square wave voltammetry (SWV). Under optimal conditions, the proposed sensor demonstrated a linear response towards propranolol in the range of 0.06-27 mu mol L-1 and a detection limit of 12 nmol L-1. Furthermore, the analytical performance of the developed sensor was evaluated for measuring propranolol in biological fluids and pharmaceutical samples. The observed promising results confirm the suitability of the developed sensor for applications in measuring complex materials.