Surface functionalization of graphene oxide by disodium guanosine 5′-monophosphate and its excellent performance for lipase immobilization

• Published in: Applied surface science Vol. 492; pp. 27 - 36
• Main Authors: Zhuang, Wei, Gu, Weiwei, Zhu, Qianqian, Zhu, Jiahua, Wang, Zhenfu, Niu, Huanqing, Liu, Dong, Wu, Jinglan, Chen, Yong, Li, Ming, Zhu, Chenjie, Ying, Hanjie
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 30.10.2019
• Subjects: Disodium guanosine 5′-monophosphate; Enzyme immobilization; Graphene oxide; Lipase; Surface modification; Surface modification; Graphene oxide; Enzyme immobilization; Lipase; Disodium guanosine 5′-monophosphate
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2019.05.166

In order to solve the toxic and hazardous issues of the agents in the chemical reduction process of graphene oxide (GO), disodium guanosine 5′-monophosphate (GMP-2Na) was used as an ideal reducing agent for the synthesis of functionalized GO (FGO) for lipase immobilization. At the condition of low amount adsorption of GMP-2Na indicated by the N1s spectra of X-ray photoelectron spectroscopy (XPS), the C/O atomic ratio of the FGO increased from 2.09 to 3.12, indicating the reduction of GO. As the amount of GMP-2Na increased, the intensity of the characteristic peak of GO in the XRD pattern decreased, and the ID/IG peak intensity of Raman spectra increased during the functionalization process. It was found that when the concentration of GMP-2Na is 0.20 mg/mL, the degree of hydrophobicity of FGO is conducive to the formation of optimal conformation of lipase. After immobilization, the activity of the immobilized enzyme reaches twice the value of free enzyme. At the same time, the protein loading reaches to 600 mg/g. The immobilized enzyme showed enhanced durability since no obvious decrease was observed after incubation for 8 h at pH 6.0 and pH 7.0. After storage for 35 days, the activity of GO-G@ enzyme was 54.47% higher than that of free enzyme. GO reduced by GMP-2Na provides a possibility to obtain a highly efficient lipase immobilization carrier. [Display omitted] •Graphene oxide was functionalized by guanosine 5′-monophosphate disodium (GMP-2Na).•GO reduced by GMP-2Na can be used as an efficient lipase immobilization carrier.•The activity of the immobilized enzyme reaches twice the value of free enzyme.•The storage stability of GO-G@ enzyme was better than that of free enzyme.