Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA.
Analyst. 2021 Nov 8;146(22):6780-6787. doi: 10.1039/d1an01132d.
Three-dimensional (3D) dried blood spheroids form when whole blood is deposited onto hydrophobic paper and allowed to dry in ambient air. The adsorbed 3D dried blood spheroid present at the surface of the hydrophobic paper is observed to offer enhanced stability for labile analytes that would otherwise degrade if stored in the traditional two-dimensional (2D) dried blood spot method. The protective mechanism for the dried blood spheroid microsampling platform was studied using scanning electron microscopy (SEM), which revealed the presence of a passivation thin film at the surface of the spheroid that serves to stabilize the interior of the spheroid against environmental stressors. Through time-course experiments based on sequential SEM analyses, we discovered that the surface protective thin film forms through the self-assembly of red blood cells following the evaporation of water from the blood sample. The bridging mechanism of red blood cell aggregation is evident in our experiments, which leads to the distinct rouleau conformation of stacked red blood cells in less than 60 min after creating the blood spheroid. The stack of self-assembled red blood cells at the exterior of the spheroid subsequently lyse to afford the surface protective layer detected to be approximately 30 μm in thickness after three weeks of storage in ambient air. We applied this mechanistic insight to plasma and serum to enhance stability when stored under ambient conditions. In addition to physical characterization of these thin biofilms, we also used paper spray (PS) mass spectrometry (MS) to examine chemical changes that occur in the stored biofluid. For example, we present stability data for cocaine spiked in whole blood, plasma, and serum when stored under ambient conditions on hydrophilic and hydrophobic paper substrates.
当全血沉积在疏水性纸上并在环境空气中干燥时，会形成三维（3D）干燥血球。在疏水性纸上表面观察到吸附的 3D 干燥血球为不稳定分析物提供了增强的稳定性，否则如果储存在传统的二维（2D）干燥血斑方法中，这些不稳定分析物会降解。使用扫描电子显微镜（SEM）研究了干燥血球微采样平台的保护机制，SEM 揭示了在血球表面存在一层钝化薄膜，该薄膜可稳定血球内部免受环境胁迫物的影响。通过基于顺序 SEM 分析的时间过程实验，我们发现表面保护薄膜是通过在血样中的水分蒸发后，红细胞自组装形成的。在不到 60 分钟的时间内，我们的实验中就观察到了红细胞聚集的桥接机制，导致堆叠的红细胞呈现明显的滚动构象，从而形成了血球。随后，血球外部的自组装红细胞破裂，形成我们在三周的环境空气储存后检测到的约 30 μm 厚的表面保护层。我们将这种机制上的认识应用于等离子体和血清中，以增强在环境条件下储存时的稳定性。除了对这些薄膜生物膜进行物理特性描述外，我们还使用纸喷雾（PS）质谱（MS）来检查储存的生物流体中发生的化学变化。例如，我们展示了在亲水和疏水性纸上基片在环境条件下储存时，可卡因在全血、血浆和血清中的稳定性数据。
