From Solution to Biointerface: Graphene Self-Assemblies of Varying Lateral Sizes and Surface Properties for Biofilm Control and Osteodifferentiation

Abstract

Bringing multifunctional graphene out of solution through facile self-assembly to form 2D surface nanostructures, with control over the lateral size and surface properties, would be an intriguing accomplishment, especially in biomedical fields where biointerfaces with functional diversity are in high demand. Guided by this goal, in this work, we built such graphene-based self-assemblies on orthopedic titanium, attempting to selectively regulate bacterial activities and osteoblastic functions, which are both crucial in bone regeneration. Briefly, large-area graphene oxide (GO) sheets and functionalized reduced GO (rGO) micro-/nanosheets were self-assembled spontaneously and controllably onto solid Ti, through an evaporation-assisted electrostatic assembly process and a mussel-inspired one-pot assembly process, respectively. The resultant layers were characterized in terms of topological structure, chemical composition, hydrophilicity, and protein adsorption properties. The antibacterial efficacies of the assemblies were examined by challenging them with pathogenic Staphylococcus aureus (S. aureus) bacteria that produce biofilms, whereby around 50% antiadhesion effects and considerable antibiofilm activities were observed for both layer types but through dissimilar modes of action. Their cytocompatibility and osteogenic potential were also investigated. Interfaced with MC3T3-E1 cells, the functionalized rGO sheets evoked better cell adhesion and growth than GO sheets, whereas the latter elicited higher osteodifferentiation activity throughout a 28-day in vitro culture. In this work, we showed that it is technically possible to construct graphene interface layers of varying lateral dimensions and surface properties and confirmed the concept of using the obtained assemblies to address the two major challenges facing orthopedic clinics. In addition, we determined fundamental implications for understanding the surface-biology relationship of graphene biomaterials, in efforts to better design and more safely use them for future biomedicine.

Graphene Materials in Antimicrobial Nanomedicine: Current Status and Future Perspectives

“…For instance, Chen et al described an osteogenic and antibacterial composite made of ZnO and carboxylated GO. [111] Bioactive and antibacterial properties of GMs and GM-based nanocomposites are also promising for dental applications. In another interesting recent study (Figure 6c), polydopamine-GO-coated Ti substrates were shown to have the capacity of triggering osteogenic differentiation (Figure 6d) and biofilm inhibition (Figure 6e) simultaneously.…”

“…[117] They found that GO coatings can reduce the bacterial adhesion significantly (64% and 85% for S. aureus and P. aeruginosa, respectively) together with platelet adhesion reduction. [111] Copyright 2016, American Chemical Society. Podila et al have demonstrated that GM-coated nitinol surfaces show lower blood clotting (thrombosis) rate due to greater affinity of GMs toward albumin than fibrinogen.…”

Polydopamine-assisted functionalization of heparin and vancomycin onto microarc-oxidized 3D printed porous Ti6Al4V for improved hemocompatibility, osteogenic and anti-infection potencies

“…For antibacterial assays, TS, TS-M and TS-M/P/V (50 μg mL −1 ) samples were incubated respectively with 1 mL of bacterial suspensions at a concentration of 10 8 CFU mL −1 per well for 4 and 24 h. The antibacterial rates (Ra) of different samples against planktonic (Rap) and adhered (Raa) bacteria were quantitatively evaluated using a Microbial Viability Assay Kit-WST (Dojindo, Japan) according to the manufacturer's directions, which can calorimetrically detect bacteria metabolic activities that correspond well with the living bacterial amounts [34]. Briefly, at the end of incubation, the remaining culture media were collected, and the scaffolds were rinsed thoroughly to remove the none-adherent bacteria.…”

“…Interestingly, dopamine is capable of adaptively forming crosslinked strongly adhesive PD nanolayer onto virtually any substrate of any material/ shape at alkaline conditions, proving an advantageous platform for diverse surface design of biomaterials [32,33]. PD is rich in reactive quinone, carboxy, amino, imine, and phenol groups [34]. In particular, because of the coupling between the amine groups of heparin and quinone species in PD, heparin have been covalently immobilized onto various PD-modified substrates [35,36].…”

Graphene‐Oxide‐Decorated Microporous Polyetheretherketone with Superior Antibacterial Capability and In Vitro Osteogenesis for Orthopedic Implant

“…These abundant epoxide, hydroxyl, and carboxylic groups on the GO basal plane and edges provide enormous reactive sites for chemical functionalization, which can substantially improve its interplay with proteins through hydrophobic and electrostatic interactions, and contribute to potentially enhance the osteogenic differentiation of stem cells . Furthermore, GO nanosheets display apparent antimicrobial capabilities for Gram‐negative and Gram‐positive bacteria . Hence, GO has been widely applied in various biotechnologies and biomedical applications such as biosensor, cellular imaging, nanoprobe, drug delivery, and tissue engineering .…”