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Photo-refreshable electrochemical sensor based on composite electrode of carbon nanotubes and TiO2 nanoparticles
摘要： Surface fouling and passivation on the electrode during electrochemical process is a major challenge for the practical applications of electrochemical sensors. Herein, a photo-refreshable electrochemical sensor was presented based on carbon nanotubes/TiO2 nanoparticles (CNTs/TiO2-NPs) composite electrode, which not only exhibits high electrochemical activity towards the determination of 5-hydroxytryptamine and dopamine, but also displays excellent reproducibility in the surface electrochemical monitoring without damaging microstructure. The linear range for 5-hydroxytryptamine determination is 0.5-400 μM (R=0.991) under UV light irradiation with a detection limit of 0.47 μM (S/N=3). The CNTs/TiO2-NPs electrode also shows excellent response to dopamine, with the linear range of 0.05 μM to 100 μM and a detection limit of 0.022 μM (S/N =3). The high performance of this photo-refreshable electrochemical sensor should be attributed to the excellent photocatalytic activity of the TiO2-NPs and the high electrochemical activity of CNTs.
关键词： carbon nanotubes,photocatalysis,TiO2 nanoparticles,electrochemical sensors,surface fouling
更新于2025-09-23 15:22:29
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Dopamine Binding and Analysis in Undiluted Human Serum and Blood by the RNA-Aptamer Electrode
摘要： Specific analysis of such neurotransmitters as dopamine by the aptamer electrodes in biological fluids is detrimentally affected by non-specific adsorption of media, particularly pronounced at positive charges of the electrode surface at which dopamine oxidizes. Here, we show that dopamine analysis at the RNA-aptamer/cysteamine-modified electrodes is strongly inhibited in undiluted human serum and blood due to non-specific interfacial adsorption of serum and blood components. We demonstrate that non-specific adsorption of serum proteins (but not of blood components) could be minimized when analysis is performed in a flow and injections of serum samples are followed by washing steps in a phosphate buffer solution (PBS) carrier. Under those conditions, the dopamine-aptamer binding affinity in whole human serum of (1.9±0.3)×104 M-1 s-1 was comparable to (3.7±0.3)×104 M-1 s-1 found in PBS, and the dopamine oxidation signal linearly depended on the dopamine concentration, providing the sensitivity of analysis of 73 ± 3 nA μM-1 cm-2 and the LOD of 114 ± 8 nM. The flow-injection apatmer-electrode system was used for direct analysis of basal levels of dopamine in undiluted human serum samples, without using any physical separators (membranes) or filtration procedures. The results suggest a simple strategy for combatting biosurface fouling most pronounced at positive electrode potentials and assist in designing more efficient antifouling strategies for biomedical applications.
关键词： Human serum,Blood,Surface fouling,RNA aptamer electrode,Dopamine,Chronoamperometry,Electrochemical Impedance,Flow-through cell
更新于2025-09-23 15:22:29