Israelsen Nathan D, Wooley Donald, Hanson Cynthia, Vargis Elizabeth
Department of Biological Engineering, Utah State University, 4105 Old Main Hill, Logan, UT 84322 USA.
J Biol Eng. 2016 Jan 7;10:2. doi: 10.1186/s13036-015-0023-y. eCollection 2016.
Surface-enhanced Raman scattering (SERS) is a powerful light scattering technique that can be used for sensitive immunoassay development and cell labeling. A major obstacle to using SERS is the complexity of fabricating SERS probes since they require nanoscale characterization and optical uniformity. The light scattering response of SERS probes may also be modulated by the substrate used for SERS analysis. A typical SERS substrate such as quartz can be expensive. Polystyrene is a cheaper substrate option but can decrease the SERS response due to interfering Raman emission peaks and high background fluorescence. The goal of this research is to develop an optimized process for fabricating Raman-labeled nanoparticles for a SERS-based immunoassay on a polystyrene substrate.
We have developed a method for fabricating SERS nanoparticle probes for use in a light scattering immunoassay on a polystyrene substrate. The light scattering profile of both spherical gold nanoparticle and gold nanorod SERS probes were characterized using Raman spectroscopy and optical absorbance spectroscopy. The effects of substrate interference and autofluorescence were reduced by selecting a Raman reporter with a strong light scattering response in a spectral region where interfering substrate emission peaks are minimized. Both spherical gold nanoparticles and gold nanorods SERS probes used in the immunoassay were detected at labeling concentrations in the low pM range. This analytical sensitivity falls within the typical dynamic range for direct labeling of cell-surface biomarkers using SERS probes.
SERS nanoparticle probes were fabricated to produce a strong light scattering signal despite substrate interference. The optical extinction and inelastic light scattering of these probes was detected by optical absorbance spectroscopy and Raman spectroscopy, respectively. This immunoassay demonstrates the feasibility of analyzing strongly enhanced Raman signals on polystyrene, which is an inexpensive yet non-ideal Raman substrate. The assay sensitivity, which is in the low pM range, suggests that these SERS probe particles could be used for Raman labeling of cell or tissue samples in a polystyrene tissue culture plate. With continued development, this approach could be used for direct labeling of multiple cell surface biomarkers on strongly interfering substrate platforms.
表面增强拉曼散射（SERS）是一种强大的光散射技术，可用于灵敏免疫分析的开发和细胞标记。使用SERS的一个主要障碍是制造SERS探针的复杂性，因为它们需要纳米级表征和光学均匀性。SERS探针的光散射响应也可能受到用于SERS分析的底物的调制。典型的SERS底物如石英可能很昂贵。聚苯乙烯是一种较便宜的底物选择，但由于干扰拉曼发射峰和高背景荧光，可能会降低SERS响应。本研究的目标是开发一种优化的方法，用于在聚苯乙烯底物上制造用于基于SERS的免疫分析的拉曼标记纳米颗粒。
我们开发了一种制造SERS纳米颗粒探针的方法，用于在聚苯乙烯底物上进行光散射免疫分析。使用拉曼光谱和光吸收光谱对球形金纳米颗粒和金纳米棒SERS探针的光散射轮廓进行了表征。通过选择在干扰底物发射峰最小化的光谱区域具有强光散射响应的拉曼报告分子，减少了底物干扰和自发荧光的影响。免疫分析中使用的球形金纳米颗粒和金纳米棒SERS探针在低pM范围内的标记浓度下均被检测到。这种分析灵敏度属于使用SERS探针直接标记细胞表面生物标志物的典型动态范围。
制造了SERS纳米颗粒探针，尽管存在底物干扰，但仍能产生强光散射信号。这些探针的光消光和非弹性光散射分别通过光吸收光谱和拉曼光谱进行检测。这种免疫分析证明了在聚苯乙烯上分析强增强拉曼信号的可行性，聚苯乙烯是一种廉价但非理想的拉曼底物。在低pM范围内的分析灵敏度表明，这些SERS探针颗粒可用于在聚苯乙烯组织培养板中对细胞或组织样本进行拉曼标记。随着不断发展，这种方法可用于在强干扰底物平台上直接标记多种细胞表面生物标志物。
