Graphene Surfaces Interaction with Proteins, Bacteria, Mammalian Cells, and Blood Constituents: The Impact of Graphene Platelet Oxidation and Thickness

Abstract

Graphene-based materials (GBMs) have been increasingly explored for biomedical applications. However, interaction between GBMs-integrating surfaces and bacteria, mammalian cells, and blood components, that is, the major biological systems in our body, is still poorly understood. In this study, we systematically explore the features of GBMs that most strongly impact the interactions of GBMs films with plasma proteins and biological systems. Films produced by vacuum filtration of GBMs with different oxidation degree and thickness depict different surface features: graphene oxide (GO) and fewlayer GO (FLGO) films are more oxidized, smoother, and hydrophilic, while reduced GO (rGO) and few-layer graphene (FLG) are less or nonoxidized, rougher, and more hydrophobic. All films promote glutathione oxidation, although in a lower extent by rGO, indicating their potential to induce oxidative stress in biological systems. Human plasma proteins, which mediate most of the biological interactions, adsorb less to oxidized films than to rGO and FLG. Similarly, clinically relevant bacteria, Staphylococcus epidermidis, Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli, adhere less to GO and FLGO films, while rGO and FLG favor bacterial adhesion and viability. Surface features caused by the oxidation degree and thickness of the GBMs powders within the films have less influence toward human foreskin fibroblasts; all materials allow cell adhesion, proliferation and viability up to 14 days, despite less on rGO surfaces. Blood cells adhere to all films, with higher numbers in less or nonoxidized surfaces, despite none having caused hemolysis (<5%). Unlike thickness, oxidation degree of GBMs platelets strongly impact surface morphology/ topography/chemistry of the films, consequently affecting protein adsorption and thus bacteria, fibroblasts and blood cells response. Overall, this study provides useful guidelines regarding the choice of the GBMs to use in the development of surfaces for an envisioned application. Oxidized materials appear as the most promising for biomedical applications that require low bacterial adhesion without being cytotoxic to mammalian cells.

Using Graphene-Based Materials for Stiff and Strong Poly(ethylene glycol) Hydrogels

“…Both the FLGO and GO composites showed hydrophilicity comparable to that of the neat PEG hydrogels with a water contact angle <20 • . It has been reported that the FLGO and GO films produced by vacuum filtration present water contact angles of 42 • and 33 • , respectively [53]. The maintenance of high hydrophilicity in composite hydrogels may be explained by the fact that GBM are encapsulated within the hydrogel matrix, with almost no sheets or sharp edges exposed at the surface (as shown in SEM images).…”

Tunable, bacterio-instructive scaffolds made from functional graphenic materials

“…Graphenic materials are capable of adsorbing proteins and ions onto their surface through van der Waals, π-π, electrostatic, and hydrogen bonding interactions. [50][51][52] Zeta potential of our FGMs in bacterial culture media (LB Miller and Trypticase Soy broth) demonstrates this phenomenon: the zeta potential of all FGMs becomes indiscriminately negative in media, which is likely due to adsorption of media components…”

“…Quantification of the green and red fluorescence reveals that CG has significantly fewer total cells (Green FL + Red FL) than either of the PLL n -G materials ( p < 0.05, "#" symbol). Further, PLL 6 -G fosters more live cells (Green FL) than PLL 50…”

Toward the Specificity of Bare Nanomaterial Surfaces for Protein Corona Formation

“…Therefore, graphene surfaces can be produced with different wettability and roughness by controlling the degree of oxidation. Protein adsorption can be predicted and modulated by the intertwining of these factors [ 52 ]. As an example, single-layer graphene oxide (GO) and few-layer graphene oxide can form smooth hydrophilic and anti-fouling surfaces, which significantly resisted unspecific protein adsorption.…”