A Dual Role of Graphene Oxide Sheet Deposition on Titanate Nanowire Scaffolds for Osteo-implantation: Mechanical Hardener and Surface Activity Regulator

Abstract

Scaffold biomaterials with open pores and channels are favourable for cell growth and tissue regeneration, however the inherent poor mechanical strength and low surface activity limit their applications as load-bearing bone grafts with satisfactory osseointegration. In this study, macroporous graphene oxide (GO) modified titanate nanowire scaffolds with desirable surface chemistry and tunable mechanical properties were prepared through a simple hydrothermal process followed by electrochemical deposition of GO nanosheets. The interconnected and porous structure of the GO/titanate nanowire scaffolds provides a large surface area for cellular attachment and migration and displays a high compressive strength of approximately 81.1 MPa and a tunable Young's modulus over the range of 12.4-41.0 GPa, which satisfies site-specific requirements for implantation. Surface chemistry of the scaffolds was modulated by the introduction of GO, which endows the scaffolds flexibility in attaching and patterning bioactive groups (such as -OH, -COOH and -NH 2 ). In vitro cell culture tests suggest that the GO/titanate nanowire scaffolds act as a promising biomaterial candidate, in particular the one terminated with -OH groups, which demonstrates improved cell viability, and proliferation, differentiation and osteogenic activities.Considering the ageing population, and the giant number of osteoporosis and traffic accident victims, it is a pressing need to design, develop and commercialize synthetic materials for bone repair and replacement, in particular at heavy load bearing sites, such as hip and joints 1-2 . The gold criteria in terms of design of manmade biomaterial grafts, emphasize the compatibility with a high degree to those of natural bone tissues, including structure, morphology, topography, chemistry, mechanical properties and biological functionalities [3][4][5] . Of all existing and being developed biomaterials, scaffolds are the most favourable components for tissue regeneration and replacement, owing to their intriguing structural characteristics, which elicit resemble mechanical performances and functionalities to those of the human bones for satisfactory host-implant interactions, osteoconductivity, and integration [6][7] . The porous structure of tissue-engineering scaffolds provides cells with essential space as residence, facilitates exchange of nutrients with metabolic wastes between internal and external environments efficiently 8 , and promotes tissue ingrowth and regeneration [9][10] . Meanwhile, adequate mechanical strength is essential to establish a favourable stress environment for the growth of neo-tissues 11 , providing sustainable supports, resisting cell contractile forces and minimizing wear and shrinkage, both in vitro and in vivo 12 . Matching the mechanical properties well to the site-specific requirements of scaffolds will promote engineering techniques for high yields of robust tissues 13 . The high porosity (up to 95%) of the synthetic scaffolds gives rise to both enhanced cellular activities and...

In vitro effect of graphene structures as an osteoinductive factor in bone tissue engineering: A systematic review

“…Five articles 13, 83-86 used osteoblasts. Immortalized mouse embryonic fibroblasts (iMEFs), immortalized mouse adipose-derived cells (iMADs), immortalized mouse calvarial cells (iCALs)87 and human osteosarcoma cell line hMG63 34,[88][89][90][91][92] were other types of the cells used.…”

“…Graphene has unique physiochemical features, especially its potential for osteogenic induction of stem cells, that make it a promising material for promoting surface modification and bioactive character of metal-based composites. 48 Several studies 13,26,28,45,47,50,65,69,71,76,86,89,92 raised a debate regarding the influential role of metals combined with graphene on cell proliferation and viability.…”

“…50 Recently, a surface modification of Ti-based materials and promotion of their biological activities has gained attention of researchers in the field of biomaterial engineering. 28 A study performed by Dong et al 92 represented that by grafting GO on Ti by functional terminal groups, including -COOH, -NH2, and -OH, the GO/Titanate OH-grafted composite was found to significantly improve cell viability. This increase in viability is likely due to the fact that -OH groups play a crucial role in modifying the surface to allow attachment of growth factors, proteins, or other biological molecules.…”

Biomaterials and scaffolds in the medical-surgical area

“…The interconnected and porous structure of the macroporous-nanowire titanium graphene oxide scaffolds provides a large surface for cell attachment and migration, as well as showing a high compressive strength of about 81.1 MPa, in addition to a Young's modulus tunable in the range of 12.4 to 41.0 GPa, meeting site-specific requirements for implantation. Cellular affinity is improved with this combination of biomaterials, allowing a unique environment that facilitates vascularization, exhibiting cellular viability with adequate proliferation, differentiation and osteogenic activity, helping tissue regeneration and support of constant loading, main functions necessary for a biomaterial that tries to replace the bone (Dong et al, 2015).…”

Biocompatibility of Subcutaneously Implanted Plant-Derived Cellulose Biomaterials

“…After several week or months, the implanted scaffold will be resorbed leaving behind a completely natural healthy tissue [26,29,50,51]. Although this is an ideal approach, many non-resorbable biomaterials (ceramic, titanium) have been successfully employed in clinical settings and play a major role in numerous therapies [2,49,[52][53][54][55][56][57]. Importantly, resorbable biomaterials suffer from the fact that regenerated tissues often collapse and become deformed due to the loss of structure [58][59][60][61][62].…”