The detection of methylation level in O⁶-methylguanine-DNA methyltransferase (MGMT) gene is of great significance for diagnosis, prognosis and treatment of glioblastoma. Herein, we proposed an electrochemical immunosensor for detection of MGMT gene methylation. Graphene oxide-magnetic nanoparticles-β-cyclodextrin (GO-Fe₃O₄-β-CD) nanocomposite was covered on electrode, and then anti-5-methylcytosine (5mC) antibody was immobilized on modified electrode via host–guest interaction with β-CD. The immobilized antibody specifically recognized and directly captured 5mC on DNA containing MGMT promoter sequence (MGMT-DNA). The methylation level in MGMT-DNA could be evaluated using Ru(NH₃)₆³⁺ as an electrochemical signal indicator. The redox recycling of Ru(NH₃)₆³⁺ was triggered by Fe(CN)₆³⁻ and further amplified current response. A detection limit as low as 0.0825 pM was obtained. Finally, this electrochemical method was successfully applied to analysis of methylated MGMT-DNA in biological sample and detection of other methylation modifications, such as N6-methyladenosine in RNA.

检测O ⁶ -甲基鸟嘌呤-DNA甲基转移酶(MGMT)基因甲基化水平对胶质母​​细胞瘤的诊断、预后和治疗具有重要意义。在此，我们提出了一种用于检测 MGMT 基因甲基化的电化学免疫传感器。将氧化石墨烯-磁性纳米粒子-β-环糊精（GO-Fe ₃ O ₄ -β-CD）纳米复合材料覆盖在电极上，然后通过与β的主客体相互作用将抗5-甲基胞嘧啶（5mC）抗体固定在修饰电极上-光盘。固定化抗体特异性识别并直接捕获含有 MGMT 启动子序列 (MGMT-DNA) 的 DNA 上的 5mC。_{可以使用 Ru(NH 3} ) ₆ ³⁺评估 MGMT-DNA 中的甲基化水平作为电化学信号指示剂。_{Ru(NH 3} ) ₆ ³⁺的氧化还原循环由 Fe(CN) ₆ ^3-触发并进一步放大电流响应。检测限低至 0.0825 pM。最后，该电化学方法成功应用于生物样品中甲基化 MGMT-DNA 的分析和其他甲基化修饰的检测，例如 RNA 中的 N6-甲基腺苷。