Dopamine Binding and Analysis in Undiluted Human Serum and Blood by the RNA-Aptamer Electrode

TY - JOUR

T1 - Dopamine Binding and Analysis in Undiluted Human Serum and Blood by the RNA-Aptamer Electrode

AU - Álvarez-Martos, Isabel

AU - Møller, Arne

AU - Ferapontova, Elena E.

PY - 2019

Y1 - 2019

N2 - Specific analysis of such neurotransmitters as dopamine by the aptamer electrodes in biological fluids is detrimentally affected by nonspecific 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 nonspecific interfacial adsorption of serum and blood components. We demonstrate that nonspecific 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) × 10 4 M -1 s -1 was comparable to the (3.7 ± 0.3) × 10 4 M -1 s -1 found in PBS, and the dopamine oxidation signal linearly depended on the dopamine concentration, providing a sensitivity of analysis of 73 ± 3 nA μM -1 cm -2 and a 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, otherwise most pronounced at positive electrode potentials used for dopamine detection, and assist in designing more efficient antifouling strategies for biomedical applications.

AB - Specific analysis of such neurotransmitters as dopamine by the aptamer electrodes in biological fluids is detrimentally affected by nonspecific 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 nonspecific interfacial adsorption of serum and blood components. We demonstrate that nonspecific 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) × 10 4 M -1 s -1 was comparable to the (3.7 ± 0.3) × 10 4 M -1 s -1 found in PBS, and the dopamine oxidation signal linearly depended on the dopamine concentration, providing a sensitivity of analysis of 73 ± 3 nA μM -1 cm -2 and a 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, otherwise most pronounced at positive electrode potentials used for dopamine detection, and assist in designing more efficient antifouling strategies for biomedical applications.

KW - Blood

KW - Chronoamperometry

KW - Dopamine

KW - Electrochemical Impedance

KW - Flow-through cell

KW - Human serum

KW - RNA aptamer electrode

KW - Surface fouling

UR - http://www.scopus.com/inward/record.url?scp=85063228867&partnerID=8YFLogxK

U2 - 10.1021/acschemneuro.8b00616

DO - 10.1021/acschemneuro.8b00616

M3 - Journal article

C2 - 30605601

AN - SCOPUS:85063228867

SN - 1948-7193

VL - 10

SP - 1706

EP - 1715

JO - ACS Chemical Neuroscience

JF - ACS Chemical Neuroscience

IS - 3

ER -