The Effect of Reduced Graphene Oxide-Coated Biphasic Calcium Phosphate Bone Graft Material on Osteogenesis

Implications of graphene-based materials in dentistry: present and future

Since the advent of nanoscience, nanobiomaterials have been applied in the dental industry. Graphene and its derivatives have attracted the most interest of all of them due to their exceptional look, biocompatibility, multiplication differential, and antibacterial capabilities. We outlined the most recent developments about their applications to dentistry in our review. There is discussion of the synthesis processes, architectures, and characteristics of materials based on graphene. The implications of graphene and its counterparts are then meticulously gathered and described. Finally, in an effort to inspire more excellent research, this paper explores the obstacles and potential of graphene-based nanomaterials for dental aspects.

Graphene: A Multifaceted Carbon-Based Material for Bone Tissue Engineering Applications

Tissue engineering is an emerging technological field that aims to restore and replace human tissues. A significant number of individuals require bone replacement annually as a result of skeletal abnormalities or accidents. In recent decades, notable progress has been made in the field of biomedical research, specifically in the realm of sophisticated and biocompatible materials. The purpose of these biomaterials is to facilitate bone tissue regeneration. Carbon nanomaterial-based scaffolds are particularly notable due to their accessibility, mechanical durability, and biofunctionality. The scaffolds exhibit the capacity to enhance cellular proliferation, mitigate cell damage, induce bone tissue growth, and maintain biological compatibility. Therefore, they play a crucial role in the development of the bone matrix and the necessary cellular interactions required for bone tissue restoration. The attachment, growth, and specialization of osteogenic stem cells on biomaterial scaffolds play critical roles in bone tissue engineering. The optimal biomaterial should facilitate the development of bone tissue in a manner that closely resembles that of human bone. This comprehensive review encompasses the examination of graphene oxide (GO), carbon nanotubes (CNTs), fullerenes, carbon dots (CDs), nanodiamonds, and their respective derivatives. The biomaterial frameworks possess the ability to replicate the intricate characteristics of the bone microenvironment, thereby rendering them suitable for utilization in tissue engineering endeavors.

Progress in the application of graphene and its derivatives to osteogenesis

As bone and joint injuries from various causes become increasingly prominent, how to effectively reconstruct and repair bone defects presents a difficult problem for clinicians and researchers. In recent years, graphene and its derivatives have been the subject of growing body of research and have been found to promote the proliferation and osteogenic differentiation of stem cells. This provides a new idea for solving the clinical problem of bone defects. However, as as numerous articles address various aspects and have not been fully systematized, there is an urgent need to classify and summarize them. In this paper, for the first time, the effects of graphene and its derivatives on stem cells in solution, in 2D and 3D structures and in vivo and their possible mechanisms are reviewed, and the cytotoxic effects of graphene and its derivatives were summarized and analyzed. The toxicity of graphene and its derivatives is further reviewed. In addition, we suggest possible future development directions of graphene and its derivatives in bone tissue engineering applications to provide a reference for further clinical application.

Application of Graphene Oxide in Oral Surgery: A Systematic Review

The current review aims to provide an overview of the most recent research in the last 10 years on the potentials of graphene in the dental surgery field, focusing on the potential of graphene oxide (GO) applied to implant surfaces and prosthetic abutment surfaces, as well as to the membranes and scaffolds used in Guided Bone Regeneration (GBR) procedures. "Graphene oxide" and "dental surgery" and "dentistry" were the search terms utilized on the databases Scopus, Web of Science, and Pubmed, with the Boolean operator "AND" and "OR". Reviewers worked in pairs to select studies based on specific inclusion and exclusion criteria. They included animal studies, clinical studies, or case reports, and in vitro and in vivo studies. However, they excluded systematic reviews, narrative reviews, and meta-analyses. Results: Of these 293 studies, 19 publications were included in this review. The field of graphene-based engineered nanomaterials in dentistry is expanding. Aside from its superior mechanical properties, electrical conductivity, and thermal stability, graphene and its derivatives may be functionalized with a variety of bioactive compounds, allowing them to be introduced into and improved upon various scaffolds used in regenerative dentistry. This review presents state-of-the-art graphene-based dental surgery applications. Even if further studies and investigations are still needed, the GO coating could improve clinical results in the examined dental surgery fields. Better osseointegration, as well as increased antibacterial and cytocompatible qualities, can benefit GO-coated implant surgery. On bacterially contaminated implant abutment surfaces, the CO coating may provide the optimum prospects for soft tissue sealing to occur. GBR proves to be a safe and stable material, improving both bone regeneration when using GO-enhanced graft materials as well as biocompatibility and mechanical properties of GO-incorporated membranes.

A scoping review of graphene-based biomaterials for in vivo bone tissue engineering

The growing demand for more efficient materials for medical applications brought together two previously distinct fields: medicine and engineering. Regenerative medicine has evolved with the engineering contributions to improve materials and devices for medical use. In this regard, graphene is one of the most promising materials for bone tissue engineering and its potential for bone repair has been studied by several research groups. The aim of this study is to conduct a scoping review including articles published in the last 12 years (from 2010 to 2022) that have used graphene and its derivatives (graphene oxide and reduced graphene) in preclinical studies for bone tissue regeneration, searching in PubMed/MEDLINE, Embase, Web of Science, Cochrane Central, and clinicaltrials.gov (to confirm no study has started with clinical trial). Boolean searches were performed using the defined key words "bone" and "graphene", and manuscript abstracts were uploaded to Rayyan, a web-tool for systematic and scoping reviews. This scoping review was conducted based on Joanna Briggs Institute Manual for Scoping Reviews and the report follows the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses - Extension for Scoping Reviews (PRISMA-ScR) statement. After the search protocol and application of the inclusion criteria, 77 studies were selected and evaluated by five blinded researchers. Most of the selected studies used composite materials associated with graphene and its derivatives to natural and synthetic polymers, bioglass, and others. Although a variety of graphene materials were analyzed in these studies, they all concluded that graphene, its derivatives, and its composites improve bone repair processes by increasing osteoconductivity, osteoinductivity, new bone formation, and angiogenesis. Thus, this systematic review opens up new opportunities for the development of novel strategies for bone tissue engineering with graphene.

Can Graphene Pave the Way to Successful Periodontal and Dental Prosthetic Treatments? A Narrative Review

Graphene, as a promising material, holds the potential to significantly enhance the field of dental practices. Incorporating graphene into dental materials imparts enhanced strength and durability, while graphene-based nanocomposites offer the prospect of innovative solutions such as antimicrobial dental implants or scaffolds. Ongoing research into graphene-based dental adhesives and composites also suggests their capacity to improve the quality and reliability of dental restorations. This narrative review aims to provide an up-to-date overview of the application of graphene derivatives in the dental domain, with a particular focus on their application in prosthodontics and periodontics. It is important to acknowledge that further research and development are imperative to fully explore the potential of graphene and ensure its safe use in dental practices.

Effect of Porcine- and Bovine-Derived Xenografts with Hydroxypropyl Methylcellulose for Bone Formation in Rabbit Calvaria Defects

In this study, hydroxypropyl methylcellulose (HPMC) was mixed with particle-type xenografts, derived from two different species (bovine and porcine), to increase the manipulability of bone grafts and compare the bone regeneration ability. Four circular defects with a diameter of 6 mm were formed on each rabbit calvaria, and the defects were randomly divided into three groups: no treatment (control group), HPMC-mixed bovine xenograft (Bo-Hy group), and HPMC-mixed porcine xenograft (Po-Hy group). At eight weeks, micro-computed tomography (µCT) scanning and histomorphometric analyses were performed to evaluate new bone formation within the defects. The results revealed that the defects treated with the Bo-Hy and the Po-Hy showed higher bone regeneration than the control group (p < 0.05), while there was no significant difference between the two xenograft groups (p > 0.05). Within the limitations of the present study, there was no difference in new bone formation between porcine and bovine xenografts with HPMC, and bone graft material was easily moldable with the desired shape during surgery. Therefore, the moldable porcine-derived xenograft with HPMC used in this study could be a promising substitute for the currently used bone grafts as it exhibits good bone regeneration ability for bony defects.

Graphene-Based Materials in Dental Applications: Antibacterial, Biocompatible, and Bone Regenerative Properties

Graphene-based materials have been shown to have advantageous properties in biomedical and dental applications due to their high mechanical, physiochemical, antibacterial, and stem cell differentiating properties. Although graphene-based materials have displayed appropriate biocompatible properties when used in implant materials for orthopedic applications, little research has been performed to specifically test the biocompatibility of graphene for dental applications. The oral environment, compared to the body, varies greatly and must be considered when evaluating biocompatibility requirements for dental applications. This review will discuss in vitro and in vivo studies that assess graphene's cytotoxicity, antibacterial properties, and cell differentiation ability to evaluate the overall biocompatibility of graphene-based materials for dental applications. Particle shape, size, and concentration were found to be major factors that affected overall biocompatibility of graphene.

Synthetic materials in craniofacial regenerative medicine: A comprehensive overview

The state-of-the-art approach to regenerating different tissues and organs is tissue engineering which includes the three parts of stem cells (SCs), scaffolds, and growth factors. Cellular behaviors such as propagation, differentiation, and assembling the extracellular matrix (ECM) are influenced by the cell's microenvironment. Imitating the cell's natural environment, such as scaffolds, is vital to create appropriate tissue. Craniofacial tissue engineering refers to regenerating tissues found in the brain and the face parts such as bone, muscle, and artery. More biocompatible and biodegradable scaffolds are more commensurate with tissue remodeling and more appropriate for cell culture, signaling, and adhesion. Synthetic materials play significant roles and have become more prevalent in medical applications. They have also been used in different forms for producing a microenvironment as ECM for cells. Synthetic scaffolds may be comprised of polymers, bioceramics, or hybrids of natural/synthetic materials. Synthetic scaffolds have produced ECM-like materials that can properly mimic and regulate the tissue microenvironment's physical, mechanical, chemical, and biological properties, manage adherence of biomolecules and adjust the material's degradability. The present review article is focused on synthetic materials used in craniofacial tissue engineering in recent decades.

Effects of a graphene oxide-alginate sheet scaffold on rotator cuff tendon healing in a rat model

BACKGROUND

Natural polymer scaffolds used to promote rotator cuff healing have limitations in terms of their mechanical and biochemical properties. This animal study aimed to investigate the effects of combined graphene oxide (GO) and alginate scaffold and the toxicity of GO on rotator cuff healing in a rat model.

METHODS

First, the mechanical properties of a GO/alginate scaffold and a pure alginate scaffold were compared. The in vitro cytotoxicity of and proliferation of human tenocytes with the GO/alginate scaffold were evaluated by CCK-8 assay. For the in vivo experiment, 20 male rats were randomly divided into two groups (n = 10 each), and supraspinatus repair was performed: group 1 underwent supraspinatus repair alone, and group 2 underwent supraspinatus repair with the GO/alginate scaffold. Biomechanical and histological analyses were performed to evaluate the quality of tendon-to-bone healing 8 weeks after rotator cuff repair.

RESULTS

The GO/alginate scaffold exhibited an increased maximum load (p = .001) and tensile strength (p = .001). In the cytotoxicity test, the cell survival rate with the GO/alginate scaffold was 102.08%. The proliferation rate of human tenocytes was no significant difference between the GO/alginate and alginate groups for 1, 3, 5, and 7 days. Biomechanically, group 2 exhibited a significantly greater ultimate failure load (p < .001), ultimate stress (p < .001), and stiffness (p < .001) than group 1. The histological analysis revealed that the tendon-to-bone interface in group 2 showed more collagen fibers bridging, tendon-to-bone integration, longitudinally oriented collagen fibers, and fibrocartilage formation than in group 1.

CONCLUSION

A small amount of GO added to alginate improved the mechanical properties of the scaffold without evidence of cytotoxicity. At 8 weeks after rotator cuff repair, the GO/alginate scaffold improved tendon-to-bone healing without causing any signs of toxicity in a rat model.

Smart biomaterials and their potential applications in tissue engineering

Smart biomaterials have been rapidly advancing ever since the concept of tissue engineering was proposed. Interacting with human cells, smart biomaterials can play a key role in novel tissue morphogenesis. Various aspects of biomaterials utilized in or being sought for the goal of encouraging bone regeneration, skin graft engineering, and nerve conduits are discussed in this review. Beginning with bone, this study summarizes all the available bioceramics and materials along with their properties used singly or in conjunction with each other to create scaffolds for bone tissue engineering. A quick overview of the skin-based nanocomposite biomaterials possessing antibacterial properties for wound healing is outlined along with skin regeneration therapies using infrared radiation, electrospinning, and piezoelectricity, which aid in wound healing. Furthermore, a brief overview of bioengineered artificial skin grafts made of various natural and synthetic polymers has been presented. Finally, by examining the interactions between natural and synthetic-based biomaterials and the biological environment, their strengths and drawbacks for constructing peripheral nerve conduits are highlighted. The description of the preclinical outcome of nerve regeneration in injury healed with various natural-based conduits receives special attention. The organic and synthetic worlds collide at the interface of nanomaterials and biological systems, producing a new scientific field including nanomaterial design for tissue engineering.

Enhanced osseointegration of dental implants with reduced graphene oxide coating

Background

The implants of pure titanium (Ti) and its alloys can lead to implant failure because of their poor interaction with bone-associated cells during bone regeneration. Surface modification over implants has achieved successful implants for enhanced osseointegration. Herein, we report a robust strategy to implement bioactive surface modification for implant interface enabled by the combinatorial system of reduced graphene oxide (rGO)-coated sandblasted, large-grit, and acid-etched (SLA) Ti to impart benefits to the implant.

Methods

We prepared SLA Ti (ST) implants with different surface modifications [i.e., rGO and recombinant human bone morphogenetic protein-2 (rhBMP-2)] and investigated their dental tissue regenerating ability in animal models. We performed comparative studies in surface property, in vitro cellular behaviors, and in vivo osseointegration activity among different groups, including ST (control), rhBMP-2-immobilized ST (BI-ST), rhBMP-2-treated ST (BT-ST), and rGO-coated ST (R-ST).

Results

Spectroscopic, diffractometric, and microscopic analyses confirmed that rGO was coated well around the surfaces of Ti discs (for cell study) and implant fixtures (for animal study). Furthermore, in vitro and in vivo studies revealed that the R-ST group showed significantly better effects in cell attachment and proliferation, alkaline phosphatase activity, matrix mineralization, expression of osteogenesis-related genes and protein, and osseointegration than the control (ST), BI-ST, and BT-ST groups.

Conclusion

Hence, we suggest that the rGO-coated Ti can be a promising candidate for the application to dental or even orthopedic implants due to its ability to accelerate the healing rate with the high potential of osseointegration.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40824-022-00257-7.

Graphene-Based Nanomaterials for Dental Applications: Principles, Current Advances, and Future Outlook

With the development of nanotechnology, nanomaterials have been used in dental fields over the past years. Among them, graphene and its derivatives have attracted great attentions, owing to their excellent physicochemical property, morphology, biocompatibility, multi-differentiation activity, and antimicrobial activity. In our review, we summarized the recent progress about their applications on the dentistry. The synthesis methods, structures, and properties of graphene-based materials are discussed. Then, the dental applications of graphene-based materials are emphatically collected and described. Finally, the challenges and outlooks of graphene-based nanomaterials on the dental applications are discussed in this paper, aiming at inspiring more excellent studies.

Osteoinductive and antimicrobial mechanisms of graphene-based materials for enhancing bone tissue engineering

Graphene-based materials (GMs) have great application prospects in bone tissue engineering due to their osteoinductive ability and antimicrobial activity. GMs induce osteogenic differentiation through several mechanisms and pathways in bone tissue engineering. First of all, the surface and high hardness of the porous folds of graphene or graphene oxide (GO) can generate mechanical stimulation to initiate a cascade of reactions that promote osteogenic differentiation without any chemical inducers. In addition, change of the extracellular matrix (ECM), regulation of macrophage polarization, the oncostatin M (OSM) signaling pathway, the MAPK signaling pathway, the BMP signaling pathway, the Wnt/β-catenin signaling pathway, and other pathways are involved in GMs' regulation of osteogenesis. In bone tissue engineering, GMs prevent the formation of microbial biofilms mainly through preventing microbial adhesion and killing them. The former is mainly achieved by reducing surface free energy (SFE) and increasing hydrophobicity. The latter mainly includes oxidative stress and photothermal/photodynamic effects. Graphene and its derivatives (GDs) are mainly combined with bioactive ceramic materials, metal materials and macromolecular polymers to play an antimicrobial effect in bone tissue engineering. Concentration, number of layers, and type of GDs often affect the antimicrobial activity of GMs. In this paper, we reviewed relevant osteoinductive and antimicrobial mechanisms of GMs and their applications in bone tissue engineering.

Recent Advances in Graphene and Conductive Polymer Composites for Supercapacitor Electrodes: A Review

Supercapacitors (SCs) have generated a great deal of interest regarding their prospects for application in energy storage due to their advantages such as long life cycles and high-power density. Graphene is an excellent electrode material for SCs due to its high electric conductivity and highly specific surface area. Conductive polymers (CPs) could potentially become the next-generation SC electrodes because of their low cost, facile synthesis methods, and high pseudocapacitance. Graphene/CP composites show conspicuous electrochemical performance when used as electrode materials for SCs. In this article, we present and summarize the synthesis and electrochemical performance of graphene/CP composites for SCs. Additionally, the method for synthesizing electrode materials for better electrochemical performance is discussed.

Graphene Oxide: Opportunities and Challenges in Biomedicine

Desirable carbon allotropes such as graphene oxide (GO) have entered the field with several biomedical applications, owing to their exceptional physicochemical and biological features, including extreme strength, found to be 200 times stronger than steel; remarkable light weight; large surface-to-volume ratio; chemical stability; unparalleled thermal and electrical conductivity; and enhanced cell adhesion, proliferation, and differentiation properties. The presence of functional groups on graphene oxide (GO) enhances further interactions with other molecules. Therefore, recent studies have focused on GO-based materials (GOBMs) rather than graphene. The aim of this research was to highlight the physicochemical and biological properties of GOBMs, especially their significance to biomedical applications. The latest studies of GOBMs in biomedical applications are critically reviewed, and in vitro and preclinical studies are assessed. Furthermore, the challenges likely to be faced and prospective future potential are addressed. GOBMs, a high potential emerging material, will dominate the materials of choice in the repair and development of human organs and medical devices. There is already great interest among academics as well as in pharmaceutical and biomedical industries.

Applications of Ceramic/Graphene Composites and Hybrids

Research activity on ceramic/graphene composites and hybrids has increased dramatically in the last decade. In this review, we provide an overview of recent contributions involving ceramics, graphene, and graphene-related materials (GRM, i.e., graphene oxide, reduced graphene oxide, and graphene nanoplatelets) with a primary focus on applications. We have adopted a broad scope of the term ceramics, therefore including some applications of GRM with certain metal oxides and cement-based matrices in the review. Applications of ceramic/graphene hybrids and composites cover many different areas, in particular, energy production and storage (batteries, supercapacitors, solar and fuel cells), energy harvesting, sensors and biosensors, electromagnetic interference shielding, biomaterials, thermal management (heat dissipation and heat conduction functions), engineering components, catalysts, etc. A section on ceramic/GRM composites processed by additive manufacturing methods is included due to their industrial potential and waste reduction capability. All these applications of ceramic/graphene composites and hybrids are listed and mentioned in the present review, ending with the authors' outlook of those that seem most promising, based on the research efforts carried out in this field.

Development of Two-Dimensional Nanomaterials Based Electrochemical Biosensors on Enhancing the Analysis of Food Toxicants

In recent times, food safety has become a topic of debate as the foodborne diseases triggered by chemical and biological contaminants affect human health and the food industry's profits. Though conventional analytical instrumentation-based food sensors are available, the consumers did not appreciate them because of the drawbacks of complexity, greater number of analysis steps, expensive enzymes, and lack of portability. Hence, designing easy-to-use tests for the rapid analysis of food contaminants has become essential in the food industry. Under this context, electrochemical biosensors have received attention among researchers as they bear the advantages of operational simplicity, portability, stability, easy miniaturization, and low cost. Two-dimensional (2D) nanomaterials have a larger surface area to volume compared to other dimensional nanomaterials. Hence, researchers nowadays are inclined to develop 2D nanomaterials-based electrochemical biosensors to significantly improve the sensor's sensitivity, selectivity, and reproducibility while measuring the food toxicants. In the present review, we compile the contribution of 2D nanomaterials in electrochemical biosensors to test the food toxicants and discuss the future directions in the field. Further, we describe the types of food toxicity, methodologies quantifying food analytes, how the electrochemical food sensor works, and the general biomedical properties of 2D nanomaterials.

Reduced graphene oxide coating enhances osteogenic differentiation of human mesenchymal stem cells on Ti surfaces

BACKGROUND

Titanium (Ti) has been utilized as hard tissue replacement owing to its superior mechanical and bioinert property, however, lack in tissue compatibility and biofunctionality has limited its clinical use. Reduced graphene oxide (rGO) is one of the graphene derivatives that possess extraordinary biofunctionality and are known to induce osseointegration in vitro and in vivo. In this study, rGO was uniformly coated by meniscus-dragging deposition (MDD) technique to fabricate rGO-Ti substrate for orthopedic and dental implant application.

METHODS

The physicochemical characteristics of rGO-coated Ti (rGO-Ti) substrates were evaluated by atomic force microscopy, water contact angle, and Raman spectroscopy. Furthermore, human mesenchymal stem cells (hMSCs) were cultured on the rGO-Ti substrate, and then their cellular behaviors such as growth and osteogenic differentiation were determined by a cell counting kit-8 assay, alkaline phosphatase (ALP) activity assay, and alizarin red S staining.

RESULTS

rGO was coated uniformly on Ti substrates by MDD process, which allowed a decrease in the surface roughness and contact angle of Ti substrates. While rGO-Ti substrates significantly increased cell proliferation after 7 days of incubation, they significantly promoted ALP activity and matrix mineralization, which are early and late differentiation markers, respectively.

CONCLUSION

It is suggested that rGO-Ti substrates can be effectively utilized as dental and orthopedic bone substitutes since these graphene derivatives have potent effects on stimulating the osteogenic differentiation of hMSCs and showed superior bioactivity and osteogenic potential.

On the road to smart biomaterials for bone research: definitions, concepts, advances, and outlook

The demand for biomaterials that promote the repair, replacement, or restoration of hard and soft tissues continues to grow as the population ages. Traditionally, smart biomaterials have been thought as those that respond to stimuli. However, the continuous evolution of the field warrants a fresh look at the concept of smartness of biomaterials. This review presents a redefinition of the term "Smart Biomaterial" and discusses recent advances in and applications of smart biomaterials for hard tissue restoration and regeneration. To clarify the use of the term "smart biomaterials", we propose four degrees of smartness according to the level of interaction of the biomaterials with the bio-environment and the biological/cellular responses they elicit, defining these materials as inert, active, responsive, and autonomous. Then, we present an up-to-date survey of applications of smart biomaterials for hard tissues, based on the materials' responses (external and internal stimuli) and their use as immune-modulatory biomaterials. Finally, we discuss the limitations and obstacles to the translation from basic research (bench) to clinical utilization that is required for the development of clinically relevant applications of these technologies.

Nanocomposites for Enhanced Osseointegration of Dental and Orthopedic Implants Revisited: Surface Functionalization by Carbon Nanomaterial Coatings

Over the past few decades, carbon nanomaterials, including carbon nanofibers, nanocrystalline diamonds, fullerenes, carbon nanotubes, carbon nanodots, and graphene and its derivatives, have gained the attention of bioengineers and medical researchers as they possess extraordinary physicochemical, mechanical, thermal, and electrical properties. Recently, surface functionalization with carbon nanomaterials in dental and orthopedic implants has emerged as a novel strategy for reinforcement and as a bioactive cue due to their potential for osseointegration. Numerous developments in fabrication and biological studies of carbon nanostructures have provided various novel opportunities to expand their application to hard tissue regeneration and restoration. In this minireview, the recent research trends in surface functionalization of orthopedic and dental implants with coating carbon nanomaterials are summarized. In addition, some seminal methodologies for physicomechanical and electrochemical coatings are discussed. In conclusion, it is shown that further development of surface functionalization with carbon nanomaterials may provide innovative results with clinical potential for improved osseointegration after implantation.

Effect of zoledronic acid and graphene oxide on the physical and in vitro properties of injectable bone substitutes

The aim of this work was to develop injectable bone substitutes (IBS) consisting of zoledronic acid (ZOL) and graphene oxide (GO) for the treatment of osteoporosis and metastasis. The powder phase was consisting of tetra calcium phosphate (TTCP), dicalcium phosphate dihyrate (DCPD) and calcium sulfate dihyrate (CSD), while the liquid phase comprised of methylcellulose (MC), gelatin and sodium citrate dihyrate (SC), ZOL and GO. The structural analysis of IBS samples was performed by Fourier Transform Infrared Spectroscopy (FTIR). Injectability, setting time and mechanical strength were investigated. Additionally, in vitro properties of synthesized IBS were analyzed by means of bioactivity, ZOL release, degradation, pH variation, PO₄^3- ion release and cell studies. Overall, all IBS exhibited excellent injectability results with no phase separation. The setting time of the IBS was prolonged with ZOL incorporation while the prolonging effect decreased with GO incorporation. The mechanical properties decreased with ZOL addition and increased with the incorporation of GO. The maximum compressive strength was found as 25.73 MPa for 1.5GO0ZOL incorporated IBS. In vitro results showed that ZOL and GO loaded IBS also revealed clinically suitable properties with controlled release of ZOL, pH value and PO₄^3- ions. In in vitro cell studies, both the inhibitory effect of ZOL and GO loaded IBS on MCF-7 cells and proliferative effect on osteoblast cells were observed. Moreover, the prepared IBS led to proliferation, differentiation and mineralization of osteoblasts. The results are encouraging and support the conclusion that developed IBS have promising physical and in vitro properties which needs to be further validated by gene expression and in vivo studies.

Nanostructured Biomaterials for Bone Regeneration

This review article addresses the various aspects of nano-biomaterials used in or being pursued for the purpose of promoting bone regeneration. In the last decade, significant growth in the fields of polymer sciences, nanotechnology, and biotechnology has resulted in the development of new nano-biomaterials. These are extensively explored as drug delivery carriers and as implantable devices. At the interface of nanomaterials and biological systems, the organic and synthetic worlds have merged over the past two decades, forming a new scientific field incorporating nano-material design for biological applications. For this field to evolve, there is a need to understand the dynamic forces and molecular components that shape these interactions and influence function, while also considering safety. While there is still much to learn about the bio-physicochemical interactions at the interface, we are at a point where pockets of accumulated knowledge can provide a conceptual framework to guide further exploration and inform future product development. This review is intended as a resource for academics, scientists, and physicians working in the field of orthopedics and bone repair.

One-Step Preparation of an AgNP-nHA@RGO Three-Dimensional Porous Scaffold and Its Application in Infected Bone Defect Treatment

Background

Bactericidal capacity, durable inhibition of biofilm formation, and a three-dimensional (3D) porous structure are the emphases of infected bone defect (IBD) treatment via local scaffold implantation strategy.

Purpose

In this study, silver nanoparticle (AgNP)-loaded nano-hydroxyapatite (nHA)@ reduced graphene oxide (RGO) 3D scaffolds (AHRG scaffolds) were designed to alleviate bone infection, inhibit biofilm formation, and promote bone repair through the synergistic effects of AgNPs, RGO, and nHA.

Materials and Methods

AHRGs were prepared using a one-step preparation method, to create a 3D porous scaffold to facilitate a uniform distribution of AgNPs and nHA. Methicillin-resistant Staphylococcus aureus (MRSA) was used as a model-resistant bacterium, and the effects of different silver loadings on the antimicrobial activity and cytocompatibility of materials were evaluated. Finally, a rabbit IBD model was used to evaluate the therapeutic effect of the AHRG scaffold in vivo.

Results

The results showed successful synthesis of the AHRG scaffold. The ideal 3D porous structure was verified using scanning electron microscopy and transmission electron microscopy, and X-ray photoelectron spectroscopy and selected area electron diffraction measurements revealed uniform distributions of AgNP and nHA. In vitro antibacterial and cytocompatibility indicated that the 4% AHRG scaffolds possessed the most favorable balance of bactericidal properties and cytocompatibility. In vivo evaluation of the IBD model showed promising treatment efficacy of AHRG scaffolds.

Conclusion

The as-fabricated AHRG scaffolds effectively eliminated infection and inhibited biofilm formation. IBD repair was facilitated by the bactericidal properties and 3D porous structure of the AHRG scaffold, suggesting its potential in the treatment of IBDs.

Functionalized Graphene Oxide Shields Tooth Dentin from Decalcification

This in vitro study assessed the efficacy of functionalized graphene oxide (f-GO) nanocomposites on the decalcification of dentin, because dental caries of the root surface is becoming one of the new problems in aged society. Hydroxyapatite plates (HAP) and dentin slices were coated with f-GO nanocomposites by comparing them to silver diamine fluoride as a positive control, then treated with decalcification solutions such as ethylenediaminetetraacetic acid and citrate at 37°C for 24 h. Scanning electron microscopy (SEM) revealed significant protection of the surface morphology of HAP and dentin. On the other hand, a cariogenic Streptococcus mutans growth was inhibited by f-GO nanocomposites. In addition, cytotoxicity of them to epithelial cells was much less than that of povidone-iodine, which is commonly used for oral disinfectant. We synthesized 5 different f-GO nanocomposites such as GO–silver (Ag), GO-Ag–calcium fluoride (CaF2), GO-CaF2, GO-zinc, and GO–tricalcium phosphate (Ca3(PO4)2). They were standardized by evaluating under SEM, transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetry analysis (TGA), and Raman spectra after being synthesized in an aseptic technique. The abilities of GO-Ag, GO-Ag-CaF2, and GO-CaF2 nanocomposites were most preventive for decalcification. In addition, GO-Ag and GO-Ag-CaF2 almost completely inhibited S. mutans growth. However, they did not exhibit cytotoxicity to epithelial cells except at the highest concentration (0.1 w/v%) of GO-Ag and GO-Ag-CaF2. Furthermore, these f-GO nanocomposites exhibited less or no discoloration of dentin, although commonly used silver diamine fluoride causes discoloration of dentin to black. Thus, these f-GO nanocomposites are useful to protect dental caries on the tooth root that becomes a social problem in aged society.

Preparation and Characterization of Functionalized Graphene Oxide Carrier for siRNA Delivery

A successful siRNA delivery system is dependent on the development of a good siRNA carrier. Graphene oxide (GO) has gained great attention as a promising nanocarrier in recent years. It has been reported that GO could be used to deliver a series of drugs including synthetic compounds, proteins, antibodies, and genes. Our previous research indicated that functionalized GO could deliver siRNA into tumor cells and induce a gene silencing effect, to follow up the research, in this research, GO-R8/cRGDfV(GRcR) was designed and prepared for VEGF-siRNA delivery as a novel carrier. The Zeta potential and particle size of the new designed GRcR carrier was measured at (29.46 ± 5.32) mV and (135.7 ± 3.3) nm respectively, and after transfection, the VEGF mRNA level and protein expression level were down-regulated by 48.22% (p < 0.01) and 38.3% (p < 0.01) in HeLa cells, respectively. The fluorescent images of the treated BALB/c nude mice revealed that GRcR/VEGF-siRNA could conduct targeted delivery of VEGF-siRNA into tumor tissues and showed a gene silencing effect as well as a tumor growth inhibitory effect (p < 0.01) in vivo. Further studies showed that GRcR/VEGF-siRNA could effectively inhibit angiogenesis by suppressing VEGF expression. Histology and immunohistochemistry studies demonstrated that GRcR/VEGF-siRNA could inhibit tumor tissue growth effectively and have anti-angiogenesis activity, which was the result of VEGF protein downregulation. Both in vitro and in vivo results demonstrated that GRcR/VEGF-siRNA could be used as an ideal nonviral tumor-targeting vector for VEGF-siRNA delivery in gene therapy.

Graphene Family Materials in Bone Tissue Regeneration: Perspectives and Challenges

We have witnessed abundant breakthroughs in research on the bio-applications of graphene family materials in current years. Owing to their nanoscale size, large specific surface area, photoluminescence properties, and antibacterial activity, graphene family materials possess huge potential for bone tissue engineering, drug/gene delivery, and biological sensing/imaging applications. In this review, we retrospect recent progress and achievements in graphene research, as well as critically analyze and discuss the bio-safety and feasibility of various biomedical applications of graphene family materials for bone tissue regeneration.

Graphene-Based Nanocomposites as Promising Options for Hard Tissue Regeneration

Tissues are often damaged by physical trauma, infection or tumors. A slight injury heals naturally through the normal healing process, while severe injury causes serious health implications. Therefore, many efforts have been devoted to treat and repair various tissue defects. Recently, tissue engineering approaches have attracted a rapidly growing interest in biomedical fields to promote and enhance healing and regeneration of large-scale tissue defects. On the other hand, with the recent advances in nanoscience and nanotechnology, various nanomaterials have been suggested as novel biomaterials. Graphene, a two-dimensional atomic layer of graphite, and its derivatives have recently been found to possess promoting effects on various types of cells. In addition, their unique properties, such as outstanding mechanical and biological properties, allow them to be a promising option for hard tissue regeneration. Herein, we summarized recent research advances in graphene-based nanocomposites for hard tissue regeneration, and highlighted their promising potentials in biomedical and tissue engineering.

Graphene-Functionalized Biomimetic Scaffolds for Tissue Regeneration

Graphene is a two-dimensional atomic layer of graphite, where carbon atoms are assembled in a honeycombed lattice structure. Recently, graphene family nanomaterials, including pristine graphene, graphene oxide and reduced graphene oxide, have increasingly attracted a great deal of interest from researchers in a variety of science, engineering and industrial fields because of their unique structural and functional features. In particular, extensive studies have been actively conducted in the biomedical and related fields, including multidisciplinary and emerging areas, as their stimulating effects on cell behaviors have been becoming an increasing concern. Herein, we are attempting to summarize some of recent findings in the fields of tissue regeneration concerning the graphene family nanomaterial-functionalized biomimetic scaffolds, and to provide the promising perspectives for the possible applications of graphene family nanomaterial.

Development and Assessment of a 3D-Printed Scaffold with rhBMP-2 for an Implant Surgical Guide Stent and Bone Graft Material: A Pilot Animal Study

In this study, a new concept of a 3D-printed scaffold was introduced for the accurate placement of an implant and the application of a recombinant human bone morphogenetic protein-2 (rhBMP-2)-loaded bone graft. This preliminary study was conducted using two adult beagles to evaluate the 3D-printed polycaprolactone (PCL)/β-tricalcium phosphate (β-TCP)/bone decellularized extracellular matrix (bdECM) scaffold conjugated with rhBMP-2 for the simultaneous use as an implant surgical guide stent and bone graft material that promotes new bone growth. Teeth were extracted from the mandible of the beagle model and scanned by computed tomography (CT) to fabricate a customized scaffold that would fit the bone defect. After positioning the implant guide scaffold, the implant was placed and rhBMP-2 was injected into the scaffold of the experimental group. The two beagles were sacrificed after three months. The specimen block was obtained and scanned by micro-CT. Histological analysis showed that the control and experimental groups had similar new bone volume (NBV, %) but the experimental group with BMP exhibited a significantly higher bone-to-implant contact ratio (BIC, %). Within the limitations of this preliminary study, a 3D-printed scaffold conjugated with rhBMP-2 can be used simultaneously as an implant surgical guide and a bone graft in a large bone defect site. Further large-scale studies will be needed to confirm these results.

Multifaceted Biomedical Applications of Functional Graphene Nanomaterials to Coated Substrates, Patterned Arrays and Hybrid Scaffolds

Because of recent research advances in nanoscience and nanotechnology, there has been a growing interest in functional nanomaterials for biomedical applications, such as tissue engineering scaffolds, biosensors, bioimaging agents and drug delivery carriers. Among a great number of promising candidates, graphene and its derivatives-including graphene oxide and reduced graphene oxide-have particularly attracted plenty of attention from researchers as novel nanobiomaterials. Graphene and its derivatives, two-dimensional nanomaterials, have been found to have outstanding biocompatibility and biofunctionality as well as exceptional mechanical strength, electrical conductivity and thermal stability. Therefore, tremendous studies have been devoted to employ functional graphene nanomaterials in biomedical applications. Herein, we focus on the biological potentials of functional graphene nanomaterials and summarize some of major literature concerning the multifaceted biomedical applications of functional graphene nanomaterials to coated substrates, patterned arrays and hybrid scaffolds that have been reported in recent years.