Effects of graphene oxide and graphene oxide quantum dots on the osteogenic differentiation of stem cells from human exfoliated deciduous teeth

Recent advances in targeting cancer stem cells by using nanomaterials

Cancer stem cells (CSCs) are a special group of cells that start, regenerate, and maintain the growth of tumors. Cancer stem cells (CSCs) contribute to the dissemination of tumors, their recurrence following treatment, and the mechanisms by which cancers develop resistance to therapies. CSCs reside in a unique microenvironment influenced by a variety of factors from their immediate surroundings. These factors include low oxygen levels, too much new blood vessel growth, a shift in how cells use energy from breathing oxygen to breaking down glucose, and an increase in certain markers and signals related to stem cells that help remove drugs from the body. Antibodies and special molecules that focus on the unique features keeping the environment stable are used to deliver cancer treatments to CSCs. As a result, nanoparticles are extremely effective in delivering drugs that combat cancer directly to cancer stem cells. Right now, stem cell nanotechnology is a new and interesting area of study. Some experiments on how stem cells interact with tiny structures or materials have shown good results. The importance of tiny structures and materials in creating treatments using stem cells for diseases and injuries has been clearly understood. The way nanomaterials are built and their characteristics influence how stem cells grow and change. This area of study is a new and exciting field where material science meets medicine. This review talks about the biology of CSCs and new ways to create nanoparticles (NPs) that can deliver cancer drugs specifically to these CSCs. This review talks about the creation of different types of tiny particles, including synthetic and natural polymer particles, lipid particles, inorganic particles, protein particles that can assemble themselves, combined antibody-drug particles, and small bubbles called nanovesicles, all aimed at targeting cancer stem cells. This paper talks about recent progress and opinions on using nanotechnology in stem cell research and therapy. It also covers how nanoparticles can help track, control, and improve the retention of stem cells.

The impact of graphene quantum dots on osteogenesis potential of Wharton's jelly mesenchymal stem cells in fibrin hydrogel scaffolds

Bone tissue engineering is a promising approach to overcome the limitations of traditional autograft bone transplantation. Graphene quantum dots (GQDs) have been suggested as an enhancement for osteogenic differentiation. This study aimed to investigate the ability of the fibrin hydrogel scaffold in the presence of graphene quantum dots to promote osteogenic differentiation of human Wharton's jelly-derived mesenchymal stem cells (hWJ-MSCs). The hWJ-MSCs were isolated from the Wharton's jelly of the human umbilical cord using a mechanical method. Fibrin hydrogel scaffolds were prepared by mixing 15 µl of thrombin solution with fibrinogen solution. GQDs were incorporated into the scaffolds at concentrations of 0, 5, and 10 µg/ml. Cell viability was determined through DAPI staining and the MTT assay. Osteogenic differentiation was assessed by measuring alkaline phosphatase (ALP) activity, quantifying calcium deposition using Alizarin Red S staining, and analyzing the gene expression of BGLAP, COL1A1, Runx-2 and ALP via qPCR. Scanning electron microscopy (SEM) was employed to analyze the scaffold architecture. SEM analysis revealed that the fibrin hydrogel exhibited a suitable architecture for tissue engineering, and DAPI staining confirmed cell viability. The MTT results indicated that the GQDs and fibrin hydrogel scaffold exhibited no cytotoxic effects. Furthermore, the incorporation of GQDs at a concentration of 10 µg/ml significantly enhanced ALP activity, calcium deposition, and the expression of osteogenesis-related genes compared to the control. The findings suggest that the combination of fibrin hydrogel and GQDs can effectively promote the osteogenic differentiation of hWJ-MSCs, contributing to the advancement of bone tissue engineering.

Processing and properties of graphene-reinforced polylactic acid nanocomposites for bioelectronic and tissue regenerative functions

An in-situ polymer-solution-processing approach enables the efficient production of uniform graphene-reinforced polylactic acid (G-PLA) nanocomposites with notable physical and biomedical properties. The approach effectively enhances the interfacial bonding between graphene and PLA by creating graphene dangling bonds and defects during exfoliation. As a result, an 182 % increase in Young's modulus and an 85 % increase in tensile strength can be achieved in G-PLA. Only 0.5 wt% graphene addition can reduce the contact angle of the composite from 75.3 to 70.4 and reduce its oxygen permeability by 23 %. The improved hydrophilicity, hermeticity, and mechanical properties make G-PLA an excellent encapsulation material for implantable bioelectronics. Moreover, the composite surface attributes and cell behaviors at the material-tissue interface are investigated histologically through the culture of stem cells on as-synthesized G-PLA. G-PLA composites can significantly boost cell proliferation and regulate cell differentiation towards vascular endothelium, offering tissue regeneration at the surface of implants to recover the injured tissues. The degradation rate of G-PLA nanocomposite can also be regulated since the graphene slows down the autocatalytic chain splitting induced by the terminal carboxylic acid groups of PLA. Therefore, such G-PLA nanocomposites with physical and biomedical properties regulated by graphene loading enable the development of next-generation implantable electronic systems providing both sensing and tissue engineering functions for complicated applications such as implanted sensors monitoring the healing of fractured bones or intracranial pressure.

Honeycomb Bionic Graphene Oxide Quantum Dot/Layered Double Hydroxide Composite Nanocoating Promotes Osteoporotic Bone Regeneration via Activating Mitophagy

Abnormal osteogenic and remodeling microenvironment due to osteoblast apoptosis are the primary causes of delayed fracture healing in osteoporotic patients. Magnesium (Mg) alloys exhibit biodegradability and appropriate elastic moduli for bone defects in osteoporosis, but the effect on the local bone remodeling disorder is still insufficient. Inspired by the "honeycomb," layered double hydroxide (LDH) with regular traps with graphene oxide quantum dots (GOQDs) inlayed is constructed by pulsed electrodeposition to generate GOQD/LDH composite nanocoatings on the surfaces of Mg alloy substrates. The honeycomb bionic multi-layer stereoscopic structure shows good regulation of the degradation of Mg alloy for the support of healing time required for osteoporotic bone defect. Within its lattice, the local microenvironment conducive to osteogenesis is provided by both the rescue effect of GOQD and LDH. The osteoblast apoptosis is rescued due to the activation of mitophagy to clear dysfunctional mitochondria, where the upregulation of BNIP3 phosphorylation played a key role. The osteoporotic rat model of femoral defects confirmed the improvement of bone regeneration and osseointegration of GOQD/LDH coating. In summary, honeycomb bionic composite nanocoatings with controllable degradation and excellent pro-osteogenic performance demonstrated a promising design strategy on Mg alloy implants in the therapy of osteoporotic bone defects.

Graphene Oxide Quantum Dots-Preactivated Dental Pulp Stem Cells/GelMA Facilitates Mitophagy-Regulated Bone Regeneration

Background

In bone tissue engineering (BTE), cell-laden scaffolds offer a promising strategy for repairing bone defects, particularly when host cell regeneration is insufficient due to age or disease. Exogenous stem cell-based BTE requires bioactive factors to activate these cells. Graphene oxide quantum dots (GOQDs), zero-dimensional derivatives of graphene oxide, have emerged as potential osteogenic nanomedicines. However, constructing biological scaffolds with GOQDs and elucidating their biological mechanisms remain critical challenges.

Methods

We utilized GOQDs with a particle size of 10 nm, characterized by a surface rich in C-O-H and C-O-C functional groups. We developed a gelatin methacryloyl (GelMA) hydrogel incorporated with GOQDs-treated dental pulp stem cells (DPSCs). These constructs were transplanted into rat calvarial bone defects to estimate the effectiveness of GOQDs-induced DPSCs in repairing bone defects while also investigating the molecular mechanism underlying GOQDs-induced osteogenesis in DPSCs.

Results

GOQDs at 5 μg/mL significantly enhanced the osteogenic differentiation of DPSCs without toxicity. The GOQDs-induced DPSCs showed active osteogenic potential in three-dimensional cell culture system. In vivo, transplantation of GOQDs-preactivated DPSCs/GelMA composite effectively facilitated calvarial bone regeneration. Mechanistically, GOQDs stimulated mitophagy flux through the phosphatase-and-tensin homolog-induced putative kinase 1 (PINK1)/Parkin E3 ubiquitin ligase (PRKN) pathway. Notably, inhibiting mitophagy with cyclosporin A prevented the osteogenic activity of GOQDs.

Conclusion

This research presents a well-designed bionic GOQDs/DPSCs/GelMA composite scaffold and demonstrated its ability to promote bone regeneration by enhancing mitophagy. These findings highlight the significant potential of this composite for application in BTE and underscore the crucial role of mitophagy in promoting the osteogenic differentiation of GOQDs-induced stem cells.

Graphene-Based Photodynamic Therapy and Overcoming Cancer Resistance Mechanisms: A Comprehensive Review

Photodynamic therapy (PDT) is a non-invasive therapy that has made significant progress in treating different diseases, including cancer, by utilizing new nanotechnology products such as graphene and its derivatives. Graphene-based materials have large surface area and photothermal effects thereby making them suitable candidates for PDT or photo-active drug carriers. The remarkable photophysical properties of graphene derivates facilitate the efficient generation of reactive oxygen species (ROS) upon light irradiation, which destroys cancer cells. Surface functionalization of graphene and its materials can also enhance their biocompatibility and anticancer activity. The paper delves into the distinct roles played by graphene-based materials in PDT such as photosensitizers (PS) and drug carriers while at the same time considers how these materials could be used to circumvent cancer resistance. This will provide readers with an extensive discussion of various pathways contributing to PDT inefficiency. Consequently, this comprehensive review underscores the vital roles that graphene and its derivatives may play in emerging PDT strategies for cancer treatment and other medical purposes. With a better comprehension of the current state of research and the existing challenges, the integration of graphene-based materials in PDT holds great promise for developing targeted, effective, and personalized cancer treatments.

Graphene quantum dots enhance the osteogenic differentiation of PDLSCs in the inflammatory microenvironment

BACKGROUND AND OBJECTIVE

Graphene quantum dots (GQDs), a type of carbon-based nanomaterial, have remarkable biological, physical, and chemical properties. This study investigated the biological mechanisms of the proliferation and osteogenic differentiation of human periodontal ligament stem cells (PDLSCs) induced by GQDs in an inflammatory microenvironment.

MATERIALS AND METHODS

PDLSCs were cultured in osteogenic-induced medium with various concentrations of GQDs in standard medium or medium mimicking a proinflammatory environment. The effects of GQDs on the proliferation and osteogenic differentiation activity of PDLSCs were tested by CCK-8 assay, Alizarin Red S staining, and qRT‒PCR. In addition, Wnt/β-catenin signalling pathway-related gene expression was measured by qRT‒PCR.

RESULTS

Compared with the control group, the mRNA expression levels of ALP, RUNX2, and OCN and the number of mineralized nodules were all increased in PDLSCs after treatment with GQDs. Moreover, during the osteogenic differentiation of PDLSCs, the expression levels of LRP6 and β-catenin, which are Wnt/β-catenin signalling pathway-related genes, were upregulated.

CONCLUSION

In the inflammatory microenvironment, GQDs might promote the osteogenic differentiation ability of PDLSCs by activating the Wnt/β-catenin signalling pathway.

Graphene and its derivatives: "one stone, three birds" strategy for orthopedic implant-associated infections

Orthopedic implants provide an avascular surface for microbial attachment and biofilm formation, impeding the entry of immune cells and the diffusion of antibiotics. The above is an important cause of dental and orthopedic implant-associated infection (IAI). For the prevention and treatment of IAI, the drawbacks of antibiotic resistance and surgical treatment are increasingly apparent. Due to their outstanding biological properties such as biocompatibility, immunomodulatory effects, and antibacterial properties, graphene-based nanomaterials (GBNs) have been applied to bone tissue engineering to deal with IAI, and in particular have great potential application in drug/gene carriers, multi-functional platforms, and coating forms. Here we review the latest research progress and achievements in GBNs for the prevention and treatment of IAI, mainly including their biomedical applications for antibacterial and immunomodulation effects, and for inducing osteogenesis. Furthermore, the biosafety of graphene family materials in bone tissue regeneration and the feasibility of clinical application are critically analyzed and discussed.

3D-Printing Graphene Scaffolds for Bone Tissue Engineering

Graphene-based materials have recently gained attention for regenerating various tissue defects including bone, nerve, cartilage, and muscle. Even though the potential of graphene-based biomaterials has been realized in tissue engineering, there are significantly many more studies reporting in vitro and in vivo data in bone tissue engineering. Graphene constructs have mainly been studied as two-dimensional (2D) substrates when biological organs are within a three-dimensional (3D) environment. Therefore, developing 3D graphene scaffolds is the next clinical standard, yet most have been fabricated as foams which limit control of consistent morphology and porosity. To overcome this issue, 3D-printing technology is revolutionizing tissue engineering, due to its speed, accuracy, reproducibility, and overall ability to personalize treatment whereby scaffolds are printed to the exact dimensions of a tissue defect. Even though various 3D-printing techniques are available, practical applications of 3D-printed graphene scaffolds are still limited. This can be attributed to variations associated with fabrication of graphene derivatives, leading to variations in cell response. This review summarizes selected works describing the different fabrication techniques for 3D scaffolds, the novelty of graphene materials, and the use of 3D-printed scaffolds of graphene-based nanoparticles for bone tissue engineering.

Effects of Low-Concentration Graphene Oxide Quantum Dots on Improving the Proliferation and Differentiation Ability of Bone Marrow Mesenchymal Stem Cells through the Wnt/β-Catenin Signaling Pathway

Graphene oxide quantum dots (GOQDs) are considered to be a new method for regulating the proliferation and differentiation of bone marrow mesenchymal stem cells (BMSCs). However, there are few reports on such regulation with different concentrations of GOQDs, and the molecular mechanism has not been fully elucidated. The purposes of this study were, first, to explore the effects of GOQDs on the proliferation and differentiation of BMSCs in vitro and in vivo, and, second, to provide a theoretical basis for the repair of bone defects. Live/Dead staining, EdU staining, immunofluorescence staining, alkaline phosphatase (ALP), western blotting, and qT-PCR were used for detecting the proliferation and differentiation of BMSCs after coculture with GOQDs of different concentrations. Hematoxylin and eosin (HE) staining and Van Gieson (VG) staining were used to detect new bone regeneration in vivo. The results showed that low-concentration GOQDs (0.1 and 1 μg/mL) promoted the proliferation and differentiation of BMSCs. Compared with the 1 μg/mL GOQD group, the 0.1 μg/mL GOQD group had better ability to promote the proliferation and differentiation of BMSCs. HE and VG staining results showed the greatest proportion of new bone area on sandblasted, large-grit, and acid-etched (SLA)/GOQD scaffolds. Furthermore, the ratio of active β-catenin and the phosphorylation level of GSK-3β (p-GSK-3β) increased after BMSCs treatment with 0.1 μg/mL GOQDs. Low concentrations of GOQDs improved the osteogenic differentiation ability of BMSCs by activating the Wnt/β-catenin signaling pathway.

A Chirality-Based Quantum Leap

There is increasing interest in the study of chiral degrees of freedom occurring in matter and in electromagnetic fields. Opportunities in quantum sciences will likely exploit two main areas that are the focus of this Review: (1) recent observations of the chiral-induced spin selectivity (CISS) effect in chiral molecules and engineered nanomaterials and (2) rapidly evolving nanophotonic strategies designed to amplify chiral light-matter interactions. On the one hand, the CISS effect underpins the observation that charge transport through nanoscopic chiral structures favors a particular electronic spin orientation, resulting in large room-temperature spin polarizations. Observations of the CISS effect suggest opportunities for spin control and for the design and fabrication of room-temperature quantum devices from the bottom up, with atomic-scale precision and molecular modularity. On the other hand, chiral-optical effects that depend on both spin- and orbital-angular momentum of photons could offer key advantages in all-optical and quantum information technologies. In particular, amplification of these chiral light-matter interactions using rationally designed plasmonic and dielectric nanomaterials provide approaches to manipulate light intensity, polarization, and phase in confined nanoscale geometries. Any technology that relies on optimal charge transport, or optical control and readout, including quantum devices for logic, sensing, and storage, may benefit from chiral quantum properties. These properties can be theoretically and experimentally investigated from a quantum information perspective, which has not yet been fully developed. There are uncharted implications for the quantum sciences once chiral couplings can be engineered to control the storage, transduction, and manipulation of quantum information. This forward-looking Review provides a survey of the experimental and theoretical fundamentals of chiral-influenced quantum effects and presents a vision for their possible future roles in enabling room-temperature quantum technologies.

Development of Graphene-Based Materials in Bone Tissue Engineaering

Bone regeneration-related graphene-based materials (bGBMs) are increasingly attracting attention in tissue engineering due to their special physical and chemical properties. The purpose of this review is to quantitatively analyze mass academic literature in the field of bGBMs through scientometrics software CiteSpace, to demonstrate the rules and trends of bGBMs, thus to analyze and summarize the mechanisms behind the rules, and to provide clues for future research. First, the research status, hotspots, and frontiers of bGBMs are analyzed in an intuitively and vividly visualized way. Next, the extracted important subjects such as fabrication techniques, cytotoxicity, biodegradability, and osteoinductivity of bGBMs are presented, and the different mechanisms, in turn, are also discussed. Finally, photothermal therapy, which is considered an emerging area of application of bGBMs, is also presented. Based on this approach, this work finds that different studies report differing opinions on the biological properties of bGBMS due to the lack of consistency of GBMs preparation. Therefore, it is necessary to establish more standards in fabrication, characterization, and testing for bGBMs to further promote scientific progress and clinical translation.

Genetic profiling of human bone marrow and adipose tissue-derived mesenchymal stem cells reveals differences in osteogenic signaling mediated by graphene

BACKGROUND

In the last decade, graphene surfaces have consistently supported osteoblast development of stem cells, holding promise as a therapeutic implant for degenerative bone diseases. However, until now no study has specifically examined the genetic changes when stem cells undergo osteogenic differentiation on graphene.

RESULTS

In this study, we provide a detailed overview of gene expressions when human mesenchymal stem cells (MSCs) derived from either adipose tissue (AD-MSCs) or bone marrow (BM-MSCs), are cultured on graphene. Genetic expressions were measured using osteogenic RT² profiler PCR arrays and compared either over time (7 or 21 days) or between each cell source at each time point. Genes were categorized as either transcriptional regulation, osteoblast-related, extracellular matrix, cellular adhesion, BMP and SMAD signaling, growth factors, or angiogenic factors. Results showed that both MSC sources cultured on low oxygen graphene surfaces achieved osteogenesis by 21 days and expressed specific osteoblast markers. However, each MSC source cultured on graphene did have genetically different responses. When compared between each other, we found that genes of BM-MSCs were robustly expressed, and more noticeable after 7 days of culturing, suggesting BM-MSCs initiate osteogenesis at an earlier time point than AD-MSCs on graphene. Additionally, we found upregulated angiogenic markers in both MSCs sources, suggesting graphene could simultaneously attract the ingrowth of blood vessels in vivo. Finally, we identified several novel targets, including distal-less homeobox 5 (DLX5) and phosphate-regulating endopeptidase homolog, X-linked (PHEX).

CONCLUSIONS

Overall, this study shows that graphene genetically supports differentiation of both AD-MSCs and BM-MSCs but may involve different signaling mechanisms to achieve osteogenesis. Data further demonstrates the lack of aberrant signaling due to cell-graphene interaction, strengthening the application of specific form and concentration of graphene nanoparticles in bone tissue engineering.

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.

The effectiveness of hydroxyapatite-beta tricalcium phosphate incorporated into stem cells from human exfoliated deciduous teeth for reconstruction of rat calvarial bone defects

OBJECTIVE

To investigate the effects of stem cells from the pulp of human exfoliated deciduous teeth (SHED) on biphasic calcium phosphate granules (BCP) to repair rat calvarial defects as compared to autogenous bone grafting.

MATERIALS AND METHODS

A defect with a 6-mm diameter was produced on the calvaria of 50 rats. BCP granules were incorporated into SHED cultures grown for 7 days in conventional (CM) or osteogenic (OM) culture media. The animals were allocated into 5 groups of 10, namely: clot, autogenous bone, BCP, BCP+SHED in CM (BCP-CM), and BCP+SHED in OM (BCP-OM). The presence of newly formed bone and residual biomaterial particles was assessed by histometric analysis after 4 and 8 weeks.

RESULTS

The autogenous group showed the largest newly formed bone area at week 8 and in the entire experimental period, with a significant difference in relation to the other groups (P < 0.05). At week 8, BCP-CM and BCP-OM groups showed homogeneous new bone formation (P = 0.13). When considering the entire experimental period, the BCP group had the highest percentage of residual particle area, with no significant difference from the BCP-CM group (P = 0.06) and with a significant difference from the BCP-OM group (P = 0.01). BCP-CM and BCP-OM groups were homogeneous throughout the experimental period (P = 0.59).

CONCLUSIONS

BCP incorporated into SHED cultures showed promising outcomes, albeit less pronounced than autogenous grafting, for the repair of rat calvarial defects.

CLINICAL RELEVANCE

BCP incorporated into SHED cultures showed to be an alternative in view of the disadvantages to obtain autogenous bone graft.

Application of nanoparticles in bone tissue engineering; a review on the molecular mechanisms driving osteogenesis

The introduction of nanoparticles into bone tissue engineering strategies is beneficial to govern cell fate into osteogenesis and the regeneration of large bone defects. The present study explored the role of nanoparticles to advance osteogenesis with a focus on the cellular and molecular pathways involved. Pubmed, Pubmed Central, Embase, Scopus, and Science Direct databases were explored for those published articles relevant to the involvement of nanoparticles in osteogenic cellular pathways. As multifunctional compounds, nanoparticles contribute to scaffold-free and scaffold-based tissue engineering strategies to progress osteogenesis and bone regeneration. They regulate inflammatory responses and osteo/angio/osteoclastic signaling pathways to generate an osteogenic niche. Besides, nanoparticles interact with biomolecules, enhance their half-life and bioavailability. Nanoparticles are promising candidates to promote osteogenesis. However, the interaction of nanoparticles with the biological milieu is somewhat complicated, and more considerations are recommended on the employment of nanoparticles in clinical applications because of NP-induced toxicities.

Graphene Oxide Quantum Dots Promote Osteogenic Differentiation of Stem Cells from Human Exfoliated Deciduous Teeth via the Wnt/β-Catenin Signaling Pathway

Graphene oxide quantum dots (GOQDs) are a carbon nanomaterial with broad potential for application in the field of nanomaterial biomedicine. Stem cells from human exfoliated deciduous teeth (SHEDs) play an important role in tissue engineering and regenerative medicine. This study investigated the effects of GOQDs on SHED osteogenic differentiation. GOQDs were synthesized; then, the proliferation of SHEDs incubated in GOQDs at different concentrations was evaluated; and the live cells were observed. We observed that live SHEDs incubated in GOQDs emitted green fluorescence in the absence of chemical dyes, and 1, 10, and 50 μg/mL GOQDs significantly promoted SHED proliferation. Culture with the osteogenic induction medium containing 10 μg/mL GOQDs induced calcium nodule formation, increased alkaline phosphatase (ALP) activity, and upregulated SHED mRNA and protein levels of OCN, RUNX2, COL I, and β-catenin. With the addition of Dickkopf 1 (DKK-1) or β-catenin knockdown, expression levels of the above mRNAs and proteins were decreased in GOQD-treated SHEDs. In summary, at a concentration of 10 μg/mL, GOQDs promote SHED proliferation and osteogenic differentiation via the Wnt/β-catenin signaling pathway. This work provides new ideas and fundamental information on interactions between GOQDs and SHEDs that are relevant for the biomedical engineering field.

Applications of Graphene and Its Derivatives in Bone Repair: Advantages for Promoting Bone Formation and Providing Real-Time Detection, Challenges and Future Prospects

During continuous innovation in the preparation, characterization and application of various bone repair materials for several decades, nanomaterials have exhibited many unique advantages. As a kind of representative two-dimensional nanomaterials, graphene and its derivatives (GDs) such as graphene oxide and reduced graphene oxide have shown promising potential for the application in bone repair based on their excellent mechanical properties, electrical conductivity, large specific surface area (SSA) and atomic structure stability. Herein, we reviewed the updated application of them in bone repair in order to present, as comprehensively, as possible, their specific advantages, challenges and current solutions. Firstly, how their advantages have been utilized in bone repair materials with improved bone formation ability was discussed. Especially, the effects of further functionalization or modification were emphasized. Then, the signaling pathways involved in GDs-induced osteogenic differentiation of stem cells and immunomodulatory mechanism of GDs-induced bone regeneration were discussed. On the other hand, their applications as contrast agents in the field of bone repair were summarized. In addition, we also reviewed the progress and related principles of the effects of GDs parameters on cytotoxicity and residues. At last, the future research was prospected.

Poly(Ethylene Glycol) Functionalized Graphene Oxide in Tissue Engineering: A Review on Recent Advances

Owing to the unique physical, chemical, mechanical and electrical properties, graphene and its derivatives have been extensively researched for diverse biomedical applications including in tissue engineering since the past decade. Tunable chemical functionalities of graphene oxide (GO), a graphene derivative, allow easy surface functionalization. Functionalization of GO with poly(ethylene glycol) (PEG) (PEG-GO) has received significant attention as it offers superior solubility, stability, and biocompatibility. Besides being an attractive candidate for drug delivery, PEG-GO can aid in the attachment, proliferation, and differentiation of stem cells, thereby augmenting tissue engineering. PEG-GO has shown excellent antibacterial efficacy, which could be an added advantage to minimize implant-associated infections. This review describes the synthesis techniques, properties, and biological potential of PEG-GO towards mammalian and bacterial cells. Studies wherein these nanomaterials have been explored for engineering various tissues are reviewed along with future opportunities in this field.

Synergistic effect of graphene oxide and zoledronic acid for osteoporosis and cancer treatment

Zoledronic acid (ZOL) is a third generation bisphosphonate which can be used as a drug for the treatment of osteoporosis and metastasis. In this study, graphene oxide (GO) is conjugated with ZOL, and the nanostructured material is evaluated in terms viability, proliferation and differentiation. Furthermore, the associated morphological changes of bone marrow-derived mesenchymal stem cells (BM-MSC), and Michigan Cancer Foundation-7 (MCF-7) breast cancer cells, as well as the effect of the drugs on mineralization of BM-MSCs are investigated using a variety of characterization techniques including Fourier Transform Infrared Spectroscopy (FTIR), scanning electron microscopy (SEM) as well as alamar blue, acridine orange, and alizarin red assays. Nanostructured ZOL-GO with an optimum performance is synthesized using ZOL and GO suspensions with the concentration of 50 µM and 2.91 ng/ml, respectively. ZOL-GO nanostructures can facilitate the mineralization of BM-MSC cells, demonstrated by the formation of clusters around the cells. The results obtained confirm the performance of ZOL-GO nanostructures as promising drug complexes for the treatment of osteoporosis and metastasis.

Bone Tissue Engineering via Carbon-Based Nanomaterials

Bone tissue engineering (BTE) has received significant attention due to its enormous potential in treating critical-sized bone defects and related diseases. Traditional materials such as metals, ceramics, and polymers have been widely applied as BTE scaffolds; however, their clinical applications have been rather limited due to various considerations. Recently, carbon-based nanomaterials attract significant interests for their applications as BTE scaffolds due to their superior properties, including excellent mechanical strength, large surface area, tunable surface functionalities, high biocompatibility as well as abundant and inexpensive nature. In this article, recent studies and advancements on the use of carbon-based nanomaterials with different dimensions such as graphene and its derivatives, carbon nanotubes, and carbon dots, for BTE are reviewed. Current challenges of carbon-based nanomaterials for BTE and future trends in BTE scaffolds development are also highlighted and discussed.

Multi-lineage differentiation and clinical application of stem cells from exfoliated deciduous teeth

Stem cells from human exfoliated deciduous teeth (SHED) have now been considered one of the most promising sources of stem cells for tissue engineering and stem cell therapies due to their stemness and potential to differentiate into other cell lines. The high proliferation rate, the differentiation capacity, the easy access and less ethical concerns make SHED a brilliant solution for many diseases. The purpose of this review is to describe current knowledge of SHED's capability of differentiation, applications and immune status and to draw attention to further research on the mechanism and the dependability of stem cell therapy with SHED.

Use of nanoparticles in skeletal tissue regeneration and engineering

Bone and osteochondral defects represent one of the major causes of disabilities in the world. Derived from traumas and degenerative pathologies, these lesions cause severe pain, joint deformity, and loss of joint motion. The standard treatments in clinical practice present several limitations. By producing functional substitutes for damaged tissues, tissue engineering has emerged as an alternative in the treatment of defects in the skeletal system. Despite promising preliminary clinical outcomes, several limitations remain. Nanotechnologies could offer new solutions to overcome those limitations, generating materials more closely mimicking the structures present in naturally occurring systems. Nanostructures comparable in size to those appearing in natural bone and cartilage have thus become relevant in skeletal tissue engineering. In particular, nanoparticles allow for a unique combination of approaches (e.g. cell labelling, scaffold modification or drug and gene delivery) inside single integrated systems for optimized tissue regeneration. In the present review, the main types of nanoparticles and the current strategies for their application to skeletal tissue engineering are described. The collection of studies herein considered confirms that advanced nanomaterials will be determinant in the design of regenerative therapeutic protocols for skeletal lesions in the future.

Kaolin alleviates the toxicity of graphene oxide for mammalian cells

The development of novel nanoscale vehicles for drug delivery promotes the growth of interest in investigations of interaction between nanomaterials. In this paper, we report the in vitro studies of eukaryotic cell physiological response to incubation with graphene oxide and planar kaolin nanoclay. Graphene family materials, including graphene oxide (GO), hold promise for numerous applications due to their unique electronic properties. However, graphene oxide reveals toxicity to some cell lines through an unidentified mechanism. Thus, methods and agents reducing the toxicity of graphene oxide can widen its practical application. We used a colorimetric test, flow cytometry and cell index assay methods to evaluate the effects of separate and combined application of graphene oxide and kaolin on mammalian cells. We have shown that the joint application of graphene oxide and kaolin reduced the negative effects of graphene by almost 20%, most likely because of coagulation of the nanoparticles with each other, which was detected by atomic force microscopy.