利用等离激元纳米腔对单肽链中单一氨基酸残基的SERS识别
SERS discrimination of single amino acid residue in single peptide by plasmonic nanocavities
AI总结：
针对蛋白质SERS光谱被芳香族残基主导而难以分析序列的问题，本研究利用电等离激元纳米腔实现单分子水平SERS，成功识别短肽链中单一氨基酸残基，为单蛋白质测序提供了新方法。
摘要：
表面增强拉曼光谱（SERS）是一种灵敏的无标记光学方法，能够提供DNA、氨基酸和蛋白质等生物分子的指纹拉曼光谱。尽管单DNA分子的SERS近期已被实现，但单蛋白质序列的拉曼分析仍不可行，因为蛋白质的SERS光谱通常被芳香族氨基酸残基的信号所主导。在此，我们采用电等离激元方法将单个金纳米颗粒捕获于纳米孔中，从而在捕获的纳米颗粒与纳米孔壁之间产生等离激元纳米腔。纳米腔中产生的巨型场极为灵敏且高度局域化，使得在单分子水平上对10种不同氨基酸进行SERS识别成为可能。所得光谱被用于分析由9个氨基酸短序列组成的2种生物标志物（加压素和催产素）的光谱。值得注意的是，我们展示了在单条短肽链中识别单一非芳香族氨基酸残基，以及区分在2个特定氨基酸上序列有别的两种肽链。我们的结果证明了该方法在识别蛋白质链中单一氨基酸残基方面的高灵敏度，并在蛋白质组学和单蛋白质测序中具有进一步应用的潜力。
英文摘要：
Surface-enhanced Raman spectroscopy (SERS) is a sensitive label-free optical method that can provide fingerprint Raman spectra of biomolecules such as DNA, amino acids and proteins. While SERS of single DNA molecule has been recently demonstrated, Raman analysis of single protein sequence was not possible because the SERS spectra of proteins are usually dominated by signals of aromatic amino acid residues. Here, we used electroplasmonic approach to trap single gold nanoparticle in a nanohole for generating a plasmonic nanocavity between the trapped nanoparticle and the nanopore wall. The giant field generated in the nanocavity was so sensitive and localized that it enables SERS discrimination of 10 distinct amino acids at single-molecule level. The obtained spectra are used to analyze the spectra of 2 biomarkers (Vasopressin and Oxytocin) made of a short sequence of 9 amino-acids. Significantly, we demonstrated identification of single non-aromatic amino acid residues in a single short peptide chain as well as discrimination between two peptides with sequences distinguishable in 2 specific amino-acids. Our result demonstrate the high sensitivity of our method to identify single amino acid residue in a protein chain and a potential for further applications in proteomics and single-protein sequencing.
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