Department of Physics, University of Texas at El Paso, El Paso, TX 79968, USA.
Department of Biomedical Engineering, University of Texas at El Paso, El Paso, TX 79968, USA.
Biosensors (Basel). 2017 Sep 28;7(4):43. doi: 10.3390/bios7040043.
A combined theoretical and experimental analysis of dopamine (DA) is presented in this work with the objective of achieving more accurate detection and monitoring of this neurotransmitter at very low concentrations, specific to physiological levels. Surface-enhanced Raman spectroscopy on silver nanoparticles was employed for recording DA concentrations as low as 10 molar. Quantum chemical density functional calculations were carried out using Gaussian-09 analytical suite software. Relatively good agreement between the simulated and experimentally determined results indicates the presence of different DA molecular forms, such as uncharged DA, anionic DA, and dopaminequinone. Disappearance of the strongest bands of dopamine around 750 cm and 790 cm, which suggests its adsorption onto the metallic surface, is not only consistent with all of these DA configurations, but also provides additional information about the analyte's redox process and voltammetric detection. On the other hand, occurrence of the abovementioned Raman lines could indicate the formation of multilayers of DA or its presence in a cationic DA⁺ form. Thus, through coordinated experiment and theory, valuable insights into changes observed in the vibrational signatures of this important neurotransmitter can be achieved for a better understanding of its detection at physiological levels, which is crucial if further optovoltammetric medical device development is envisioned.
本文对多巴胺（DA）进行了理论和实验联合分析，旨在实现对这种神经递质的更精确检测和监测，尤其是在生理水平下的检测和监测。实验采用银纳米粒子的表面增强拉曼光谱技术，对低至 10 毫摩尔的 DA 浓度进行记录。使用 Gaussian-09 分析套件软件进行量子化学密度泛函计算。模拟和实验结果之间的相对较好的一致性表明存在不同的 DA 分子形式，例如中性 DA、阴离子 DA 和多巴胺醌。在 750 cm 和 790 cm 左右，多巴胺最强谱带的消失表明其吸附在金属表面上，这不仅与所有这些 DA 构型一致，而且还提供了有关分析物的氧化还原过程和伏安检测的附加信息。另一方面，上述拉曼线的出现可能表明 DA 形成了多层或其以阳离子 DA⁺形式存在。因此，通过实验和理论的协调，可以深入了解这种重要神经递质的振动特征的变化，从而更好地理解其在生理水平下的检测，这对于进一步开发光电压医疗设备至关重要。
