Corrosion Behaviour and J774A.1 Macrophage Response to Hyaluronic Acid Functionalization of Electrochemically Reduced Graphene Oxide on Biomedical Grade CoCr

Macrophage proteomic analysis of covalent immobilization of hyaluronic acid and graphene oxide on CoCr alloy in a tribocorrosive environment

In this work, a sequential covalent immobilization of graphene oxide (GO) and hyaluronic acid (HA) is performed to obtain a biocompatible wear-resistant nanocoating on the surface of the biomedical grade cobalt-chrome (CoCr) alloy. Nanocoated CoCr surfaces were characterized by Raman spectroscopy and electrochemical impedance spectroscopy (EIS) in 3 g/L HA electrolyte. Tribocorrosion tests of the nanocoated CoCr surfaces were carried out in a pin on flat tribometer. The biological response of covalently HA/GO biofunctionalized CoCr surfaces with and without wear-corrosion processes was studied through the analysis of the proteome of macrophages. Raman spectra revealed characteristic bands of GO and HA on the functionalized CoCr surfaces. The electrochemical response by EIS showed a stable and protective behavior over 23 days in the simulated biological environment. HA/GO covalently immobilized on CoCr alloy is able to protect the surface and reduce the wear volume released under tribocorrosion tests. Unsupervised classification analysis of the macrophage proteome via hierarchical clustering and principal component analysis (PCA) revealed that the covalent functionalization on CoCr enhances the macrophage biocompatibility in vitro. On the other hand, disruption of the HA/GO nanocoating by tribocorrosion processes induced a macrophage proteome which was differently clustered and was distantly located in the PCA space. In addition, tribocorrosion induced an increase in the percentage of upregulated and downregulated proteins in the macrophage proteome, revealing that disruption of the covalent nanocoating impacts the macrophage proteome. Although macrophage inflammation induced by tribocorrosion of HA/GO/CoCr surfaces is observed, it is ameliorated by the covalently grafting of HA, which provides immunomodulation by eliciting downregulations in characteristic pro-inflammatory signaling involved in inflammation and aseptic loosening of CoCr joint arthroplasties. Covalent HA/GO nanocoating on CoCr provides potential applications for in vivo joint prostheses led a reduced metal-induced inflammation and degradation by wear-corrosion.

Wettability, Corrosion Resistance, and Osteoblast Response to Reduced Graphene Oxide on CoCr Functionalized with Hyaluronic Acid

The durability of metal-metal prostheses depends on achieving a higher degree of lubrication. The beneficial effect of hyaluronic acid (HA) on the friction and wear of both natural and artificial joints has been reported. For this purpose, graphene oxide layers have been electrochemically reduced on CoCr surfaces (CoCrErGO) and subsequently functionalized with HA (CoCrErGOHA). These layers have been evaluated from the point of view of wettability and corrosion resistance in a physiological medium containing HA. The wettability was analyzed by contact angle measurements in phosphate buffer saline-hyaluronic acid (PBS-HA) solution. The corrosion behavior of functionalized CoCr surfaces was studied with electrochemical measurements. Biocompatibility, cytotoxicity, and expression of proteins related to wound healing and repair were studied in osteoblast-like MC3T3-E1 cell cultures. All of the reported results suggest that HA-functionalized CoCr surfaces, through ErGO layers in HA-containing media, exhibit higher hydrophilicity and better corrosion resistance. Related to this increase in wettability was the increase in the expressions of vimentin and ICAM-1, which favored the growth and adhesion of osteoblasts. Therefore, it is a promising material for consideration in trauma applications, with improved properties in terms of wettability for promoting the adhesion and growth of osteoblasts, which is desirable in implanted materials used for bone repair.

Effect of Olibanum Extract/Graphene Oxide on Differentiation of Bone Marrow Mesenchymal Stem Cells into Neuron-Like Cells on Freeze Dried Scaffolds

BACKGROUND

One of the challenges in using stem cells to neural repair is to induce their differentiation into neurons and lack of glial formation.

OBJECTIVES

Mesenchymal stem cells have revealed great potential for neural reorganization and renewal by taking advantage of differentiation capabilities. Here we explored the potential use of olibanum extract in freeze-dried scaffolds for induction of stem cells differentiation.

MATERIALS AND METHODS

In this study, gelatin/ collagen/olibanum/ graphene oxide (GEL/COL/OL/GO) freeze-dried scaffolds were synthesized and then adult rat bone marrow mesenchymal stem cells (BMMSCs) were seeded on scaffolds. The viability of cells was evaluated using MTT test on days 1, 3 and 5. The morphology of the cells seeded on scaffolds was studied using SEM and specific protein expression detected by immunohistochemical analysis. Real-time PCR was applied to detect the expression of Chat, Pax6, Hb-9, Nestin, Islet-1, and neurofilament-H (NF-H). The data were analyzed using Tukey test and one-way ANOVA and the means difference was considered significant at P<0.05, P<0.01, and P<0.001.

RESULTS

Showed that the pore size is increased in GEL/COL/OL/GO scaffolds compared with GO-free scaffolds and higher attachment and proliferation of BMMSCs on GEL/COL/OL /1.5% GO scaffolds compared to GEL/COL/OL/3% GO scaffolds. The cell viability results after 5 days of incubation showed the significant biocompatibility of GEL/COL/OL /1.5% GO freeze-dried scaffold. The results of immunohistochemical and PCR analysis revealed positive role of GEL/COL/OL/1.5% GO scaffolds in upregulation of neuron-specific markers.

CONCLUSION

These results reveal the great potential of GEL/COL/OL/GO scaffolds for nerve regeneration. Our data suggested that both OL extract and GO can regulate the MSCs differentiation into neurons.

Surface Engineering of Metals and Alloys

Nowadays, the surface treatments of metals and alloys allow us to obtain from them the films or coatings with different physical and chemical properties from the substrate [...]