Preparation of a Highly Sensitive Electrochemical Aptasensor for Measuring Epirubicin Based on a Gold Electrode Boosted with Carbon Nano-Onions and MB

Epirubicin is prescribed as an essential drug for treating breast, prostate, uterine, and gastrointestinal cancers. It has many side effects, such as heart failure, mouth inflammation, abdominal pain, fever, and shortness of breath. Its measurement is necessary by straightforward and cheap methods. The application of aptamer-based electrochemical sensors is accounted as a selective option for measuring different compounds. In this work, a thiol-modified aptamer was self-assembled on the surface of the gold electrode (AuE) boosted with carbon nano-onions (CNOs), and coupled with methylene blue (MB) as an electroactive tracker to achieve a sensitive and selective aptasensor. In the absence of the epirubicin, CNOs binds to the aptamer through a π-π interaction enhancing the MB electrochemical signal. When epirubicin binds to the aptamer, the adsorption of CNOs and MB to the aptamer is not well established, so the electrochemical signal is reduced, consequently, the epirubicin value can be measured. The prepared aptasensor demonstrated an excellent sensitivity with a curve slope of 0.36 μI/nM, and 3 nM limit of detection in the linear concentration range of 1–75 nM. The prepared aptasensor was accurately capable of measuring epirubicin in blood serum samples

An efficient electrochemical sensor based on CeVO4-CuWO4 nanocomposite for methyldopa

A novel modified electrode based on cerium vanadate and copper tungstate (CeVO _4 -CuWO _4 ) nanocomposite was prepared as a sensitive sensor for the methyldopa. The prepared nanocomposite was characterized by x-ray diffraction (XRD), energy dispersive x-ray spectroscope (EDX), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM) methods. The cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques were applied for the evaluation of the electrochemical performance of the sensor. The enhanced active surface area, electro-catalytic activity, and expedient conductivity provided by the CeVO _4 -CuWO _4 nanocomposite led to the peak current increment with a well-resolved anodic peak for methyldopa in the presence of potential interferences. The CeVO _4 -CuWO _4 nanocomposite-based modified electrode successfully measured methyldopa over a wide concentration range of 0.02–400 μ M with the low limit of detection (LOD) of 0.006 μ M. The findings of the methyldopa sensing in human serum samples verified the proper efficiency of the proposed sensor

High electrochemical detection of dopamine based on Cu doped single phase hexagonally ZnO plates

Dopamine is a chemical that plays a key role in various neurological diseases such as Parkinson's, depression, and some types of cancer. Hence, sensitive detection methods of dopamine are necessary for early discernment of diseases related to abnormal levels. In this study, Cu doped ZnO (Cu/ZnO) nanostructures, immobilized onto the surface of glassy carbon electrode (GCE), have been investigated as a highly efficient electrode material for the electrochemical detection of dopamine (DA). A simple hydrothermal process was used for the synthesis of the ZnO and Cu/ZnO nanostructures. Detailed characterization revealed that addition of Cu on the ZnO changed the morphology of ZnO creating a highly microporous nanostructure. The electrochemical response of DA on the Cu/ZnO/GC electrodes, determined using cyclic voltammetry (CV) and differential pulsed voltammetry (DPV), indicated that on these materials it is possible to achieve lower over-potentials for the DA oxidation and higher catalytic activity. Furthermore, the GCE modified with 50 % Cu doped ZnO showed the most promising performance with high stability in wide range of pH values (2–8 pH), and linear response for DA from 0.1–20 μM with high sensitivity of 2630 nA/μM and detection limit as low as 55 nM. The analytical performance of the developed sensor showed its potential capability for the DA quantification in complex biological systems