State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, PR China.
State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, PR China.
Biosens Bioelectron. 2020 Feb 15;150:111861. doi: 10.1016/j.bios.2019.111861. Epub 2019 Nov 11.
DNA methylation catalyzed by M.SssI methyltransferases (MTase) has important roles in gene expression and other cellular activities, and relates to some diseases, especially cancers. Therefore, it is important to develop a sensitive sensing platform for M.SssI MTase activity assay. Here, taking zeolitic imidazolate framework-8 (ZIF-8) polyhedra as the carriers of graphene quantum dots (GQDs), GQDs-embedded ZIF-8 polyhedra (denoted as GQDs@ZIF-8 polyhedra) were successfully prepared and used as the multi-functional signal quencher to construct a novel signal-off photoelectrochemical (PEC) biosensor for M.SssI MTase activity assay. Firstly, the indium tin oxide (ITO) slice was modified with TiO, poly(diallyldimethylammonium chloride) and CdTe quantum dots (QDs). The obtained electrode was used as the photoelectrode and labeled as ITO/TiO/CdTe QDs. Then, single-stranded DNA (S1) was anchored on the photoelectrode surface via S-Cd bond. After hybridization between S1 and biotinylated single-stranded DNA (S2), the streptavidin (SA)-labeled GQDs@ZIF-8 polyhedra were introduced to the modified electrode via the specific reaction between biotin and SA. As the signal quencher, GQDs@ZIF-8 polyhedra could not only inhibit the photocurrent signal of the ITO/TiO/CdTe QDs electrode due to the steric hindrance effect, but also act as peroxidase mimetics to catalyze precipitation reaction of 4-chloro-1-naphthol, resulting in the evident depression of the photocurrent signal. For the specially designed S1/S2 double-strand DNA, the decreased photocurrent was quantitatively correlated with the M.SssI MTase activity (linear response range, 0.005-150 U mL; detection limit, 0.004 U mL). The developed GQDs@ZIF-8 polyhedra and related PEC biosensor may have potential applications in clinical research and disease diagnosis.
M.SssI 甲基转移酶 (MTase) 催化的 DNA 甲基化在基因表达和其他细胞活动中具有重要作用，与一些疾病（特别是癌症）有关。因此，开发一种用于 M.SssI MTase 活性测定的灵敏传感平台非常重要。在这里，我们以沸石咪唑酯骨架-8 (ZIF-8) 多面体为载体，制备了嵌入石墨烯量子点 (GQDs) 的 ZIF-8 多面体 (记为 GQDs@ZIF-8 多面体)，并将其用作多功能信号猝灭剂，构建了一种用于 M.SssI MTase 活性测定的新型信号关闭光电化学 (PEC) 生物传感器。首先，将氧化铟锡 (ITO) 片用 TiO2、聚二烯丙基二甲基氯化铵和碲化镉量子点 (QDs) 修饰。得到的电极用作光电极，并标记为 ITO/TiO/CdTe QDs。然后，通过 S-Cd 键将单链 DNA (S1) 锚定在光电极表面。在 S1 和生物素化单链 DNA (S2) 杂交后，通过生物素和链霉亲和素之间的特异性反应，将标记有链霉亲和素的 GQDs@ZIF-8 多面体引入修饰电极。作为信号猝灭剂，GQDs@ZIF-8 多面体不仅由于空间位阻效应抑制了 ITO/TiO/CdTe QDs 电极的光电流信号，而且还可以作为过氧化物酶模拟物来催化 4-氯-1-萘酚的沉淀反应，导致光电流信号明显降低。对于专门设计的 S1/S2 双链 DNA，降低的光电流与 M.SssI MTase 活性呈定量相关（线性响应范围为 0.005-150 U mL；检测限为 0.004 U mL）。开发的 GQDs@ZIF-8 多面体和相关的 PEC 生物传感器可能在临床研究和疾病诊断中具有潜在的应用价值。
