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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
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Multifaceted Protocol in Biotechnology || Characterization of Electrochemical Transducers for Biosensor Applications
摘要： Biosensors are devices that detect and report the presence or quantity of a particular analyte. Among the biosensor components, a physicochemical transducer measures physical and chemical changes from analyte-recognition interactions where products, by-products, intermediates, or physical changes are converted into a measurable signal. The character of the transducer determines the performance of a biosensor; hence the characterization of the transduction is crucial in the design of a biosensor. This chapter describes electrochemical characterization of the transducer layer of a biosensor via cyclic voltammetry.
关键词： Effective surface area,Randles-Sevcik,Electrochemical transducer,Cyclic voltammetry,Chronoamperometry,Biosensors
更新于2025-09-19 17:15:36
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Raman Spectroscopy as an Assay to Disentangle Zinc Oxide Carbon Nanotube Composites for Optimized Uric Acid Detection
摘要： Refluxed zinc oxide (ZnO) nanoparticles (NPs) were prepared and attached to carboxylic acid functionalized multi-walled carbon nanotubes (COOH-MWNTs) via sonication. Practical optimization of electrocatalysts using sonication to disentangle a carbon nanotube composite for monitoring uric acid (UA) is shown. Monitoring UA is important for the management of medical disorders. Selection of sonication time is a crucial step in producing the desired composite. We report, for the first time, the practical use of Raman spectroscopy to tune the sonication involved in tethering ZnO NPs to the multi-walled carbon nanotube (MWNT) surface. Maximum current for detecting UA, using chronoamperometry and cyclic voltammetry, correlated with the highest sp2-hybridized carbon signal, as seen in the integrated Raman G band peak areas denoting maximum COOH-MWNT disentanglement. An array of ZnO/COOH-MWNT composites were prepared ranging from 60 to 240 min sonication times. Optimum sonication (150 min) corresponded with both maximum measured current and MWNT disentanglement. The sensor was able to quantitatively and selectively measure UA at clinically relevant concentrations (100–900 μM) with rapid current response time (< 5 s).
关键词： chronoamperometry,zinc oxide nanoparticles,Raman spectroscopy,cyclic voltammetry,multi-walled carbon nanotubes,electrochemical sensing
更新于2025-09-19 17:15:36