Characterization and modification of reduced graphene oxide nanoparticle for horseradish peroxidase immobilization

Horseradish peroxidase (HRP) was immobilized onto modified reduced graphene oxide (RGO) nanoparticles (NPs) through physical adsorption. RGO can interact to HRP primarily through electrostatic interactions and hydrogen bonding because this nanoparticle contains greater amounts of O-containing functional groups. Surface morphology of the modified RGO nanoparticles was characterized by field emission scanning electron microscopy (SEM). The surface functionalities of RGO were further analyzed by a Fourier transform infrared spectroscopy (FTIR) in the range of 4000-400 cm-1. Zeta potentials were measured by the electrophoretic mobility using Zeta PALS. The enlarged structures of functionalized RGO NPs and HRP@RGO nanocomposit demonstrated that the average diameters of the NPs before and after immobilization are about 70 nm and 99 nm, respectively. FT-IR spectra analysis was performed to identify the functional groups of HRP, modified RGO NPs, and HRP@RGO. The peaks around 1600-1700 cm-1 and 1450-1600 cm-1 are attributed to the amides І and ІІ in HRP. For functionalized RGO NPs, the peaks around 1530 cm-1 and 1430 cm-1 were observed owing to N-H bending and C-N stretch, respectively. After immobilization of HRP, the intensity of the band in the ranges of amides, N-H bending and C-N stretch increases, suggesting successful adsorption of the HRP at the NPs. Zeta potential (

کلیدواژه ها:

Horseradish peroxidase ، Physical adsorption ، Reduced graphene oxide ، Modification