Huang Lu, Huang Hanbing, Zhang Zhuomin, Li Gongke
School of Chemistry, Sun Yat-sen University, Guangzhou 510006, China.
Anal Chem. 2024 Jul 15. doi: 10.1021/acs.analchem.4c01006.
Monitoring changes in the expression of marker proteins in biological fluids is essential for biomarker-based disease diagnosis. Epithelial cell adhesion molecule (EpCAM) has been identified as a broad-spectrum biomarker for various chronic diseases and as a therapeutic target. However, the development of simple and reliable methods for quantifying EpCAM changes in biological fluids faces challenges due to the variability of its expression across different diseases, the presence of soluble forms, and matrix effects. In this paper, a surface-enhanced Raman scattering (SERS)-fluorescence (FL) dual-mode sensing method was established for quantification of trace EpCAM in biological fluids based on bimetallic Au@Ag nanoparticles and nitrogen-doped quantum dots encapsulated DNA hydrogel hybrid with graphene oxide (Au@Ag-NQDs/GO). The DNA hydrogel was constructed based on three-dimensional (3D) structure DNA-mediated strategy using an aptamer DNA (AptDNA) linker. The interaction of the AptDNA with EpCAM triggered the disassembly of the DNA hydrogel. Consequently, the release of Au@Ag nanoparticles induced an "on-off" switch in the SERS signal while the weakened FL quenching effect in Au@Ag-NQDs/GO system achieved "off-on" switch of FL signal, enabling the simultaneous SERS-FL quantification of EpCAM. The established dual-mode method exhibited outstanding sensitivity and stability in quantifying EpCAM in the range of 0.5-60.0 pg/mL, with the limits of detection (LODs) of SERS and FL as 0.17 and 0.35 pg/mL, respectively. When applied for real sample analysis, the method showed satisfactory specificity and recoveries in cancer cells lysate, serum, and urine samples with RSDs of 2.8-6.3%, 4.0-6.3%, and 2.8-5.7%, respectively. The developed SERS-FL sensing method offered a sensitive, reliable, and practical quantification strategy for trace EpCAM in diverse biological fluid samples, which would benefit the early diagnosis of disease and further health management.
监测生物体液中标志物蛋白表达的变化对于基于生物标志物的疾病诊断至关重要。上皮细胞粘附分子（EpCAM）已被确定为多种慢性疾病的广谱生物标志物以及治疗靶点。然而，由于其在不同疾病中的表达存在变异性、存在可溶性形式以及基质效应，开发简单可靠的方法来定量生物体液中EpCAM的变化面临挑战。本文基于双金属Au@Ag纳米颗粒和氮掺杂量子点包裹的DNA水凝胶与氧化石墨烯的复合物（Au@Ag-NQDs/GO），建立了一种表面增强拉曼散射（SERS）-荧光（FL）双模传感方法，用于定量生物体液中的痕量EpCAM。DNA水凝胶基于三维（3D）结构DNA介导策略，使用适配体DNA（AptDNA）接头构建。AptDNA与EpCAM的相互作用触发了DNA水凝胶的解体。因此，Au@Ag纳米颗粒的释放导致SERS信号的“开-关”切换，而Au@Ag-NQDs/GO系统中减弱的荧光猝灭效应实现了荧光信号的“关-开”切换，从而能够同时对EpCAM进行SERS-FL定量。所建立的双模方法在0.5-60.0 pg/mL范围内定量EpCAM时表现出出色的灵敏度和稳定性，SERS和FL的检测限分别为0.17和0.35 pg/mL。当应用于实际样品分析时，该方法在癌细胞裂解液、血清和尿液样品中显示出令人满意的特异性和回收率，相对标准偏差分别为2.8-6.3%、4.0-6.3%和2.8-5.7%。所开发的SERS-FL传感方法为多种生物体液样品中的痕量EpCAM提供了一种灵敏、可靠且实用的定量策略，这将有利于疾病的早期诊断和进一步的健康管理。
