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.
Sensors (Basel). 2018 Aug 16;18(8):2696. doi: 10.3390/s18082696.
To better understand detection and monitoring of the important neurotransmitter adenosine at physiological levels, this study combines quantum chemical density functional modeling and ultrasensitive surface-enhanced Raman spectroscopic (SERS) measurements. Combined simulation results and experimental data for an analyte concentration of about 10 molar indicate the presence of all known molecular forms resulting from adenosine's complex redox-reaction. Detailed analysis presented here, besides assessing potential Raman signatures of these adenosinic forms, also sheds light on the analytic redox process and voltammetric detection. Examples of adenosine Raman fingerprints for different molecular orientations with respect to the SERS substrate are the vibrational line around 920 ± 10 cm for analyte physisorption through the carbinol moiety and around 1600 ± 20 cm for its fully oxidized form. However, both hydroxyl/oxygen sites and NH₂/nitrogen sites contribute to molecule's interaction with the SERS environment. Our results also reveal that contributions of partially oxidized adenosine forms and of the standard form are more likely to be detected with the first recorded voltammetric oxidation peak. The fully oxidized adenosine form contributes mostly to the second peak. Thus, this comparative theoretical⁻experimental investigation of adenosine's vibrational signatures provides significant insights for advancing its detection, and for future development of opto-voltammetric biosensors.
为了更好地理解生理水平下重要神经递质腺苷的检测和监测，本研究将量子化学密度泛函建模与超灵敏表面增强拉曼光谱（SERS）测量相结合。对于约 10 摩尔浓度的分析物，结合模拟结果和实验数据表明存在所有已知的分子形式，这些形式源自腺苷的复杂氧化还原反应。这里提出的详细分析，除了评估这些腺苷形式的潜在拉曼特征外，还揭示了分析氧化还原过程和伏安检测。不同分子取向相对于 SERS 衬底的腺苷拉曼指纹的示例是围绕 920 ± 10 cm 的振动线，用于通过甲醇部分进行分析物物理吸附，以及围绕 1600 ± 20 cm 的完全氧化形式。然而，羟基/氧位和 NH₂/氮位都有助于分子与 SERS 环境的相互作用。我们的结果还表明，部分氧化的腺苷形式和标准形式的贡献更有可能通过第一个记录的伏安氧化峰来检测到。完全氧化的腺苷形式主要贡献于第二个峰。因此，对腺苷振动特征的这种理论⁻实验比较研究为其检测以及未来光电伏安生物传感器的发展提供了重要的见解。
