Immobilization of methotrexate (MTX) anticancer drug onto the graphene surface is reported through three methods, including either covalent linkage via (a) EDC/NHS organic activators and (b) electrografting of MTX diazonium salt, or (c) noncovalent bonding, resulting in three different systems. To evaluate the interaction ability of the immobilized MTX with biological species, calf thymus DNA (ctDNA), mouse 4T1 breast tumor, and Human foreskin fibroblast (hFF) cells as models of the primary intracellular target of anticancer drugs, cancer and normal cells, respectively, are examined. The features of the constructed systems and their interactions with ctDNA are followed by surface analysis techniques and electrochemical methods. The results indicate that (i) the amount of the immobilized MTX on the graphene surface is affected by type of the immobilization method; and a maximum value of (Γ = 9.3 ± 0.9 pmol cm⁻²) is found via electrografting method, (ii) graphene-modified-MTX has high affinity for ctDNA in a wide dynamic range of concentrations, and (iii) the nature of the interaction is of electrostatic and/or hydrogen bonding type, formed most probably between OH, NH and CO groups of MTX and different DNA functions. Finally, electrochemical impedance spectroscopy results approved the high affinity of the systems for 4T1 cancer cells.

通过三种方法报道了甲氨蝶呤（MTX）抗癌药在石墨烯表面的固定化，包括通过（a）EDC / NHS有机活化剂的共价键合和（b）MTX重氮盐的电接枝，或（c）非共价键合，导致三种不同的系统。为了评估固定化MTX与生物物种，小牛胸腺DNA（ctDNA），小鼠4T1乳腺肿瘤和人包皮成纤维细胞（hFF）细胞的相互作用能力，分别作为抗癌药物，癌细胞和正常细胞的主要细胞内靶标模型，被检查。构造系统的功能并通过表面分析技术和电化学方法研究了它们与ctDNA的相互作用。结果表明：（i）固定在石墨烯表面的MTX的量受固定方法类型的影响；并且通过电接枝方法发现（Γ= 9.3±0.9 pmol cm ^-2）的最大值，（ii）石墨烯修饰的MTX在宽的动态浓度范围内对ctDNA具有高亲和力，并且（iii）相互作用是静电和/或氢键型的，最有可能在MTX的O H，NH和C O基团与不同的DNA功能之间形成。最终，电化学阻抗谱结果证实了该系统对4T1癌细胞的高度亲和力。