Interfacial microenvironment for lipase immobilization: Regulating the heterogeneity of graphene oxide

Strain-boosted hyperoxic graphene oxide efficiently loading and improving performances of microcystinase

“…FTIR spectroscopy revealed a characteristic N-H peak (1,536 cm −1 ) for HGO 5 @CMlrA, indicating that CMlrA was successfully loaded onto HGO 5 ( Figure 2 A). C- O -C antisymmetric tensile vibration bands (1,220 cm −1 ) were observed in both the HGO 5 and HGO 5 @CMlrA, corresponding to the characteristic peaks for C=C (1,616 cm −1 ), C=O (1,720 cm −1 ), -OH, (3,500 cm −1 ), as previously reported in other studies ( Zhuang et al., 2020 ; Chaudhary et al., 2021 ). Thus, most of the functional groups and the skeleton structure of HGO 5 were not damaged after CMlrA immobilization.…”

“…In addition, XRD analysis revealed that the characteristic diffraction peak of the GO (001) crystal plane at 2θ of 10.7° in HGO 5 @CMlrA disappeared and an amorphous peak appeared at 2θ of 20-30° that may be caused by crystal structure changes of HGO 5 immobilizing CMlrA ( Figure 2 B). Specifically, the energy-dispersive X-ray spectroscopy (EDS) analysis revealed that the corresponding N element mapping of HGO 5 @CMlrA was obviously higher than that of HGO 5 , further confirming that HGO 5 @CMlrA was successfully prepared ( Figure 2 D) ( Zhuang et al., 2020 ; Chaudhary et al., 2021 ). Fluorescein isothiocyanate (FITC)-labeled CMlrA (F-CMlrA) and HGO 5 @F-CMlrA exhibited higher fluorescence intensities, while HGO 5 and CMlrA did not exhibit any measurable fluorescence intensity ( Figure S13 ).…”

“…Moreover, when comparing materials prepared using the same adsorption synthesis method, the loading capacity of HGO 5 for CMlrA (up to 1,559 mg·g −1 ) was 17 times higher than that of CysGO (89.77 mg·g −1 ) ( Wu et al., 2020 ). The loading capacities were also significantly higher than those of other modified GO derivatives for their respective enzymes (e.g., Glu-r3h-GO for lipase and PEGA-GOMNP for xylanase, 217 mg·g −1 and 273 mg·g −1 , respectively) ( Zhuang et al., 2020 ; Mehnati-Najafabadi et al., 2018 ), and also five times higher than that of HGO 0 (303 mg·g −1 ) ( Tables S1 and S2 ). These results suggest that the HGO 5 @CMlrA composite may be assembled through a new mechanism differing from that of other modified GO derivatives that simply absorb enzymes on their surfaces ( Zhuang et al., 2020 ; Mehnati-Najafabadi et al., 2018 ; Wu et al., 2020 ).…”

“…Physical adsorption is widely used for enzyme immobilization because it is typically simple to conduct and minimally affects enzyme activity. Covalent binding generally leads to higher loading capacity and stability of nanomaterials than physical adsorption, although it may be a more complex process and considerably affects enzyme activities ( Zhuang et al., 2020 ; Monajati et al., 2018 ; Chaudhary et al., 2021 ). The assembly conditions of the two methods for the HGO 5 @CMlrA composites were also optimized ( Figures S11 and S12 ).…”

Surface Modulation of Graphene Oxide for Amidase Immobilization with High Loadings for Efficient Biocatalysis

“…Although there are some cases of other enzymes (such as horseradish peroxidase, glucose oxidase, lipase, etc.) immobilized on GO [20][21][22][23][24][25], immobilization of amidases on GO has not been reported yet and their catalytic performance needs to be investigated [5,19].…”