Both biomarker and probe degradations cause serious false assay results. However, protecting a target or a target and a probe simultaneously has rarely been explored. Herein, MnO₂-nanosheet-powered target- and probe-protective Janus DNA nanomachines are reported. It is formed in living cells by an RNA-responsive assembly of two chemically modified DNA partzymes and one substrate probe. MnO₂ nanosheets are used to facilitate the cellular uptake of DNA reagents and generate Mn²⁺, which are indispensable DNAzyme cofactors for efficient catalytic cleavage. We find that DNA partzymes with modified sugar moieties (e.g., LNA or ones with 2′-O-methylation) protect the RNA of RNA–DNA hybrids from RNase H degradation. LNA blocks RNase H recruitment on the hybrid best because of its 2′-O, 4′-C methylene bridge structure. In contrast, modifications at DNA phosphate moieties fail to protect the RNA. RNA protection can exclude target-degradation-induced false negative results. In addition, the phosphorothioate-modified substrate probe is known to resist nuclease degradation, which minimizes false positive interference. Compared to canonical DNA systems without chemical modifications, the protective Janus nanomachine avoids false results and supports robust RNA imaging.

中文翻译：

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MnO _2-纳米片供电的保护性Janus DNA纳米机，支持强大的RNA成像。

生物标志物和探针的降解都会导致严重的错误检测结果。但是，几乎没有研究过同时保护靶标或靶标和探针。在本文中，报道了MnO _2-纳米片供电的靶标和探针保护性Janus DNA纳米机器。它是通过两种化学修饰的DNA部分酶和一个底物探针的RNA响应组装在活细胞中形成的。MnO ₂纳米片用于促进细胞对DNA试剂的吸收并产生Mn ²⁺，它们是有效催化裂解必不可少的DNAzyme辅助因子。我们发现，具有修饰的糖基的DNA部分酶（例如LNA或具有2'-O-甲基化的部分）可以保护RNA-DNA杂种的RNA免受RNase H降解。由于LNA具有2'-O，4'-C亚甲基桥结构，因此可以最好地阻止RNase H在杂交体上的募集。相反，DNA磷酸部分的修饰不能保护RNA。RNA保护可以排除靶标降解引起的假阴性结果。另外，已知硫代磷酸酯修饰的底物探针可抵抗核酸酶降解，从而将假阳性干扰降至最低。与没有化学修饰的规范DNA系统相比，Janus纳米保护机可避免错误的结果并支持可靠的RNA成像。