Biological relevance of oxidative debris present in as-prepared graphene oxide

Abstract

The influence of oxidative debris (OD) present in as-prepared graphene oxide (GO) suspensions on proteins and its toxicity to human embryonic kidney cells (HEK-293T) are reported here. The OD was removed by repeated washing with aqueous ammonia to produce the corresponding base-washed GO (bwGO). The loading (w/w) of bovine serum albumin (BSA) was increased by 85% after base washing, whereas the loading of hemoglobin (Hb) and lysozyme (Lyz), respectively, was decreased by 160% and 100%. The secondary structures of 13 different proteins bound to bwGO were compared with the corresponding proteins bound to GO using the UV circular dichroism spectroscopy. There was a consistent loss of protein secondary structure with bwGO when compared with proteins bound to GO, but no correlation between either the isoelectric point or hydrophobicity of the protein and the extent of structure loss was observed. All enzymes bound to bwGO and GO indicated significant activities, and a strong correlation between the enzymatic activity and the extent of structure retention was noted, regardless of the presence or absence of OD. At low loadings (<100 μg/mL) both GO and bwGO showed excellent cell viability but substantial cytotoxicity (~40% cell death) was observed at high loadings (>100 μg/mL). In control studies, OD by itself did not alter the growth rate even after a 48-h incubation. Thus, the presence of OD in GO played a very important role in controlling the chemical and biological nature of the protein-GO interface and the presence of OD in GO improved its biological compatibility when compared to bwGO.

Kitchen Chemistry 101: Multigram Production of High Quality Biographene in a Blender with Edible Proteins

“…The intrinsic hydrophobicity of carbon nanomaterials limits their bioprocessability . The availability of hydrophilic graphene is largely restricted to GO, which was shown to have structural defects, oxidative debris, and metallic impurities limiting its biological use . The biofunctionalized graphene, reported here, was highly stable in water at various pHs and room temperature, which was not demonstrated in previous studies.…”

Nanoarmoring: strategies for preparation of multi-catalytic enzyme polymer conjugates and enhancement of high temperature biocatalysis

“…These improvements in catalytic activities of AP and Lip conjugates may be attributed to the exposure of the active sites to the substrate. 42,43 Contribution of volumetric changes to the catalytic activity profile after conjugation to polymer in single and multi-enzyme fashion is minimal due to the excessive volume of the buffer used during catalysis. The total volume of PAA and all enzymes is small when compared to the volume of the buffer.…”

Elucidating the Role of Oxidative Debris in the Antimicrobial Properties of Graphene Oxide

“…For instance, GO sheets with smaller lateral size have shown higher toxicity against bacteria. , In the context of antimicrobial applications, none of these studies consider the existence of oxidative debris on GO structure or its effect on the antibacterial properties of graphene. Removing debris changes the electrochemical properties and biocompatibility of GO sheets. Realizing that debris has an impact on several physicochemical properties of GO, the question arises: does oxidative debris have an inherent effect on the antimicrobial properties of GO?…”