In this work, a newly developed surface plasma resonance (SPR) system for the sensitive detection of M.SssI activity has been designed based on double signal amplification with DNA chain cyclic reactions and AuNPs. In the absence of M.SssI, hairpin DNA 1 (HP1) can be cleaved into s1 fragments catalyzed by HpaII. The s1 fragments can then trigger a recycling process of hairpin DNA 2 (HP2) hybridization and subsequently release massive s2 and s3 in the solution of Nt.AlwI and HPII. AuNPs-DNA can be captured on gold film by the released s2 and s3 to produce a strong SPR signal. Whereas in the presence of M.SssI, methylated HP1 cannot be cleaved by HpaII, thus produce a weak SPR signal. The SPR signals are dependent on the M.SssI concentration in the range from 0.5 to 50 U/mL. The successful detection of M.SssI activity in clinical serum samples and inhibition of M.SssI using 5-Aza and 5-Aza-dC indicate a great potential of this strategy for building new monitoring platform in bioanalysis and clinical biomedicine.

中文翻译：

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基于表面等离子体共振技术灵敏检测甲基转移酶活性的扩增策略

在这项工作中，基于 DNA 链循环反应和 AuNPs 的双信号放大，设计了一种新开发的表面等离子体共振 (SPR) 系统，用于灵敏检测 M.SssI 活性。在没有 M.SssI 的情况下，发夹 DNA 1 (HP1) 可以被 HpaII 催化切割成 s1 片段。然后，s1 片段可以触发发夹 DNA 2 (HP2) 杂交的再循环过程，随后在 Nt.AlwI 和 HPII 的溶液中释放大量 s2 和 s3。AuNPs-DNA 可以被释放的 s2 和 s3 捕获在金膜上，产生强烈的 SPR 信号。而在 M.SssI 的存在下，甲基化的 HP1 不能被 HpaII 切割，从而产生微弱的 SPR 信号。SPR 信号取决于 0.5 到 50 U/mL 范围内的 M.SssI 浓度。M的成功检测