For more effective early-stage cancer diagnostics, there is a need to develop sensitive and specific, non- or minimally invasive, and cost-effective methods for identifying circulating nanoscale extracellular vesicles (EVs). Here, we report the utilization of a simple plasmonic scaffold composed of a microscale biosilicate substrate embedded with silver nanoparticles for surface-enhanced Raman scattering (SERS) analysis of ovarian and endometrial cancer EVs. These substrates are rapidly and inexpensively produced without any complex equipment or lithography. We extensively characterize the substrates with electron microscopy and outline a reproducible methodology for their use in analyzing EVs from in vitro and in vivo biofluids. We report effective chemical treatments for (i) decoration of metal surfaces with cysteamine to nonspecifically pull down EVs to SERS hotspots and (ii) enzymatic cleavage of extraluminal moieties at the surface of EVs that prevent localization of complementary chemical features (lipids/proteins) to the vicinity of the metal-enhanced fields. We observe a major loss of sensitivity for ovarian and endometrial cancer following enzymatic cleavage of EVs’ extraluminal domain, suggesting its critical significance for diagnostic platforms. We demonstrate that the SERS technique represents an ideal tool to assess and measure the high heterogeneity of EVs isolated from clinical samples in an inexpensive, rapid, and label-free assay.

中文翻译：

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使用细胞外囊泡进行液体活检诊断的混合纳米等离子体多孔生物材料支架。

为了更有效地进行早期癌症诊断，需要开发灵敏、特异、无创或微创且具有成本效益的方法来识别循环纳米级细胞外囊泡 (EV)。在这里，我们报告了一种简单的等离子体支架，该支架由嵌入银纳米颗粒的微尺度生物硅酸盐基板组成，用于卵巢和子宫内膜癌 EV 的表面增强拉曼散射 (SERS) 分析。这些基板无需任何复杂的设备或光刻即可快速且廉价地生产。我们用电子显微镜对底物进行了广泛的表征，并概述了一种可重复的方法，用于分析来自体外和体内生物流体的 EV。我们报告了以下有效的化学处理方法：（i）用半胱胺修饰金属表面，以非特异性地将 EV 拉下到 SERS 热点，以及（ii）酶促切割 EV 表面的腔外部分，防止互补化学特征（脂质/蛋白质）定位到金属增强场附近。我们观察到在 EV 的腔外结构域酶切后，卵巢癌和子宫内膜癌的敏感性显着下降，这表明其对诊断平台的重要意义。我们证明，SERS 技术是一种理想的工具，可以通过廉价、快速和无标签的检测来评估和测量从临床样本中分离出的 EV 的高异质性。