Abstract The unique properties of graphene oxide (GO) nanosheets were integrated with the superparamagnetic characteristics of the CuFe2O4 nanoparticles to synthesize the magnetic graphene oxide (MGO), which was chemically modified with 3-amino propyl trimethoxy silane (APTMS) to functionalize the amine group on MGO (MGO-NH2). Afterward, MGO-NH2 was activated with glutaraldehyde (GLU) as a crosslinking agent to synthesize the functionalized MGO (fMGO) and its capability toward covalent Laccase immobilization was investigated. The comprehensive structural analysis using various characterization techniques, including Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) clearly confirmed the covalent attachment of laccase onto MGO. The response surface methodology (RSM), based on Central Composite Design (CCD), was applied to optimize the immobilized Laccase (nanobiocatalyst)-mediated biodegradation of Direct Red 23 (DR23), as an azo dye, by considering independent variables such as nanobiocatalyst dosage, dye concentration, and pH. The optimal conditions to obtain the maximum decolorization yield (95.33%) were nanobiocatalyst dosage = 290.23 mg/L, dye concentration = 19.60 mg/L, and pH = 4.23. The obtained correlation coefficient and the adjusted one of 0.9651 and 0.9336, respectively, imply the nice model fitness. Therefore, structural characterization along with the experimental decolorization results introduced the synthesized superparamagnetic GO as an environmentally friendly nanobiocatalyst for effective decolorization purposes.

中文翻译：

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超顺磁性酶-氧化石墨烯磁性纳米复合材料作为一种环境友好的生物催化剂：使用响应面法合成和生物降解染料

摘要 将氧化石墨烯 (GO) 纳米片的独特性质与 CuFe2O4 纳米颗粒的超顺磁特性相结合，合成了磁性氧化石墨烯 (MGO)，并用 3-氨基丙基三甲氧基硅烷 (APTMS) 进行化学修饰以将胺基官能化。在 MGO (MGO-NH2) 上。然后，用戊二醛 (GLU) 作为交联剂活化 MGO-NH2 以合成功能化的 MGO (fMGO)，并研究了其共价固定漆酶的能力。使用各种表征技术进行综合结构分析，包括傅里叶变换红外光谱 (FTIR)、X 射线衍射 (XRD)、振动样品磁强计 (VSM)、透射电子显微镜 (TEM)、扫描电子显微镜 (SEM) 清楚地证实了漆酶与 MGO 的共价连接。基于中心复合设计 (CCD) 的响应面方法 (RSM) 用于优化固定化漆酶 (纳米生物催化剂) 介导的直接红 23 (DR23) 作为偶氮染料的生物降解，通过考虑纳米生物催化剂等自变量剂量、染料浓度和 pH 值。获得最大脱色率 (95.33%) 的最佳条件是纳米生物催化剂用量 = 290.23 mg/L，染料浓度 = 19.60 mg/L，pH = 4.23。获得的相关系数和调整后的值分别为 0.9651 和 0.9336，表明模型拟合度很好。所以，