Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA.
Department of Materials Science and Engineering, Texas A&M University, College Station, TX 77843, USA.
Biosensors (Basel). 2024 Feb 2;14(2):81. doi: 10.3390/bios14020081.
One aim of personalized medicine is to use continuous or on-demand monitoring of metabolites to adjust prescription dosages in real time. Surface-enhanced spatially offset Raman spectroscopy (SESORS) is an optical technique capable of detecting surface-enhanced Raman spectroscopy (SERS)-active targets under a barrier, which may enable frequent metabolite monitoring. Here we investigate how the intensity of the signal from SERS-active material varies spatially through tissue, both experimentally and in a computational model. Implant-sized, SERS-active hydrogel was placed under different thicknesses of contiguous tissue. Emission spectra were collected at the air-tissue boundary over a range of offsets from the excitation site. New features were added to the Monte Carlo light-tissue interaction model to modify the optical properties after inelastic scattering and to calculate the distribution of photons as they exit the model. The Raman signals were detectable through all barrier thicknesses, with strongest emission for the case of 0 mm offset between the excitation and detector. A steep decline in the signal intensities occurred for offsets greater than 2 mm. These results did not match published SORS work (where targets were much larger than an implant). However, the model and experimental results agree in showing the greatest intensities at 0 mm offset and a steep gradient in the intensities with increasing offset. Also, the model showed an increase in the number of photons when the new, longer wavelengths were used following the Stokes shift for scattering and the graphical display of the exiting photons was helpful in the determination and confirmation of the optimal offset.
个性化医疗的目标之一是利用代谢物的连续或按需监测来实时调整处方剂量。表面增强空间偏移拉曼光谱（SESORS）是一种光学技术，能够在屏障下检测表面增强拉曼光谱（SERS）活性靶标，这可能使频繁的代谢物监测成为可能。在这里，我们研究了 SERS 活性材料的信号强度如何在组织中进行空间变化，包括实验和计算模型。将植入物大小的 SERS 活性水凝胶放置在不同厚度的连续组织下。在从激发点的一系列偏移处收集空气中的组织边界处的发射光谱。向蒙特卡罗光组织相互作用模型中添加了新功能，以在非弹性散射后修改光学特性，并计算光子作为它们离开模型时的分布。通过所有的屏障厚度都可以检测到拉曼信号，在激发和探测器之间的偏移为 0mm 的情况下，发射最强。对于大于 2mm 的偏移，信号强度急剧下降。这些结果与已发表的 SORS 工作（其中目标远大于植入物）不匹配。然而，模型和实验结果一致，表明在 0mm 偏移处强度最大，并且随着偏移增加强度急剧增加。此外，当根据散射的斯托克斯位移使用新的更长波长时，模型显示出更多的光子数量增加，并且退出光子的图形显示有助于确定和确认最佳偏移。
