Insulin-like growth factor-I (Ag_IGF-I) is a key biomarker in tumor progression. In this work, a novel label-free electrochemical impedance biosensing platform for detection of Ag_IGF-I was developed on the basis of a nanocomposite of reduced graphene oxidetin sulfide (rGO-SnS₂) loaded with gold nanoparticles (AuNPs). The rGO-SnS₂ surface serves as an interfacial matrix, exhibiting outstanding electrochemical activity because of its large surface area; meanwhile, the abundant active sites in rGO-SnS₂ promote AuNP deposition and improve antibody (Ab) immobilization. The specific recognition between IGF-I antibody (Ab_IGF-I) and antigen (Ag_IGF-I) at the interface induces changes in electrochemical impedance, which can distinguish Ag_IGF-I from a complex biological media to ensure the selectivity. Electron transfer resistance (R_ct) corresponds to the number of analytes on the interface, which serves as the basis for the design of an electrochemical impedance biosensor. Under optimized conditions, the designed biosensor exhibits a linear response range of 0.25–750.0 pg/mL and an ultralow detection limit of 0.12 pg/mL (S/N = 3), and the results based on an electrochemical method are consistent with those of enzyme-linked immunosorbent assay (ELISA). Such an electrochemical biosensor is highly effective for IGF-I sensing in human plasma samples, which broadens the application of the heterostructure AuNPs@rGO-SnS₂ nanocomposite in bioanalysis and clinical diagnosis.

胰岛素样生长因子-I (Ag _IGF-I ) 是肿瘤进展的关键生物标志物。在这项工作中，基于负载金纳米颗粒 (AuNPs)的还原氧化石墨烯硫化锡 (rGO-SnS ₂ )纳米复合材料开发了一种用于检测 Ag _{IGF-I的新型无标记电化学阻抗生物传感平台。}rGO-SnS ₂表面作为界面基质，由于其较大的表面积而表现出出色的电化学活性；_{同时，rGO-SnS 2}中丰富的活性位点促进了 AuNP 的沉积并提高了抗体 (Ab) 的固定性。IGF-I抗体（Ab _IGF-I）与抗原（Ag _{IGF- I）的特异性识别}) 在界面处引起电化学阻抗的变化，这可以将 Ag _IGF-I与复杂的生物介质区分开来，以确保选择性。电子转移电阻（R _ct）对应于界面上分析物的数量，这是设计电化学阻抗生物传感器的基础。在优化条件下，所设计的生物传感器的线性响应范围为 0.25–750.0 pg/mL，超低检测限为 0.12 pg/mL（S/N = 3），基于电化学方法的结果与酶联免疫吸附试验（ELISA）。这种电化学生物传感器对人体血浆样品中的 IGF-I 传感非常有效，拓宽了异质结构 AuNPs@rGO-SnS 的应用₂纳米复合材料在生物分析和临床诊断中的应用。