Mn-doped ZnS synthesis in DABCO based ionic liquid: Morphology and electrochemical sensing performance for isoprenaline analysis

Electron transfer-chemical reaction-electron transfer study of dobutamine, isoprenaline, droxidopa, and methyldopa with carbon nanotube-based electrode

The electrochemical behavior of catecholamines involves an electron transfer-chemical reaction-electron transfer (ECE) mechanism, characterized by two reversible redox reactions interspersed with an irreversible chemical reaction. Previously, we reported ECE studies on dopamine and norepinephrine. In this work, we extend our study to catecholamine drugs including dobutamine, isoprenaline, droxidopa, and methyldopa, using a carbon nanotube electrode. These drugs exhibit significantly faster intramolecular cyclization rates compared to dopamine and norepinephrine. This accelerated cyclization is attributed to (1) the presence of more complex substituents in these drugs and (2) the fact that dobutamine and isoprenaline are secondary amines, while dopamine and norepinephrine are primary amines. This study enhances the understanding of catecholamines and offers valuable insights for the development of novel electrochemical sensing strategies for catecholamine drugs.

Regulating the nitrogen content in graphene to modify manganese dioxide for the sensitive detection of dopamine in biological samples

A 3D neural network-shaped nitrogen-doped graphene-coated MnO2 composite (N@Gr-MnO2) was successfully prepared by hydrothermal method. The nitrogen content in graphene is effectively regulated by changing the amount of urea added. Upon achieving a graphene oxide (GO) to urea mass proportion of 1/200, the resultant N@Gr exhibited maximal nitrogen concentration. Moreover, XPS analyses confirmed that this configuration led to an apex in the total abundance of both pyridinic nitrogen and graphitic nitrogen, elements pivotal for catalytic proficiency. The N@Gr-MnO2 was prepared by the combination of N@Gr (at the mass ratio of 1/200) and manganese dioxide and was used to construct an electrochemical sensor (N@Gr/α-MnO2/GCE) to detect dopamine. There are two linear relationships between the current response of the sensor to DA concentration: the first section is 0.01 to 8.79 μmol·L-1, the corresponding linear equation and correlation coefficient (R2) are I (μA) = 7439.5 C (mmol·L-1) + 2.27 and 0.986, respectively, and the sensitivity is 16,907.9 μA (mmol·L-1) -1 cm-2. The second section of concentration is 11-104 μmol·L-1, and the corresponding linear equation and correlation coefficient (R2) are I (μA) = 2883.9 C (mmol·L-1) + 45.5 and 0.995. The detection limit (S/N) of DA by N@Gr/α-MnO2/GCE is 1.7 nmol·L-1. The sensor can be applied to the quantification detection of dopamine in human serum and urine, with a recovery percentage of 92%, confirming its significant potential for real-world implementation.

Direct and Sensitive Electrochemical Detection of Bisphenol A in Complex Environmental Samples Using a Simple and Convenient Nanochannel-Modified Electrode

Rapid, convenient, and sensitive detection of Bisphenol A (BPA) in complex environmental samples without the need for tedious pre-treatment is crucial for assessing potential health risks. Herein, we present an electrochemical sensing platform using a simple nanochannel-modified electrode, which enables the direct and sensitive detection of BPA in complex samples. A vertically ordered mesoporous silica-nanochannel film (VMSF) with high-density nanochannels is rapidly and stably grown on the surface of a electrochemically activated glassy carbon electrode (p-GCE) by using the electrochemically assisted self-assembly (EASA) method. The high antifouling capability of the VMSF/p-GCE sensor is proven by investigating the electrochemical behavior of BPA in the presence of model coexisting interfering molecules including amylum, protein, surfactant, and humic acid. The VMSF/p-GCE sensor can sensitively detect BPA ranged from 50 to 1.0 μM and 1.0–10.0 μM, with low detection limits (15 nM). Owing to the electrocatalytic performance and high potential resolution of p-GCE, the sensor exhibits high selectivity for BPA detection in the presence of common environmental pollutants, including bisphenol S (BPS), catechol (CC), hydroquinone (HQ), and 4-nitrophenol (4-NP). In combination with the good antifouling property of the VMSF, direct detection of BPA in environmental water samples and soil leaching solution (SLS) is also realized without separation pretreatment. The developed VMSF/p-GCE sensor demonstrated advantages of simple structure, high sensitivity, good antifouling performance, and great potential in direct electroanalysis of endocrine-disrupting compounds in complex samples.