Dual-Functionalized Graphene Oxide Based siRNA Delivery System for Implant Surface Biomodification with Enhanced Osteogenesis

Osseointegration, antimicrobial capacity and cytotoxicity of implant materials coated with graphene compounds: A systematic review

The use of graphecs excellent mechanical properties. However, it is necessary to evaluate the biological effects of this material. This systematic review aimed to observe and understand through studies the current state of the art regarding osseointegration, antimicrobial capacity, and the cytotoxicity of graphene coating applied to the surface of dental implant materials. Searches in PubMed, Embase, Science Direct, Web of Science, and Google Scholar databases were conducted between June and July 2021 and updated in May 2022 using the keywords: graphene, graphene oxide, dental implants, zirconium, titanium, peek, aluminum, disilicate, methyl-methacrylate, cytotoxicity, osseointegration, and bone regeneration. The criteria included in vivo and in vitro studies that evaluated antimicrobial capacity and/or osseointegration and/or cytotoxicity of dental implant materials coated with graphene compounds. The risk of bias for in vitro studies was assessed by the JBI tool, and for in vivo studies, Syrcle's risk of bias tool for animal studies was used. The database search resulted in 176 articles. Of the 18 articles selected for full reading, 16 remained in this systematic review. The use of graphene compounds as coatings on the surface of implant materials is promising because it promotes osseointegration and has antimicrobial capacity. However, further studies are needed to ensure its cytotoxic potential.

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.

Functional Graphene for Peritumoral Brain Microenvironment Modulation Therapy in Glioblastoma

Peritumoral brain invasion is the main target to cure glioblastoma. Chemoradiotherapy and targeted therapies fail to combat peritumoral relapse. Brain inaccessibility and tumor heterogeneity explain this failure, combined with overlooking the peritumor microenvironment. Reduce graphene oxide (rGO) provides a unique opportunity to modulate the local brain microenvironment. Multimodal graphene impacts are reported on glioblastoma cells in vitro but fail when translated in vivo because of low diffusion. This issue is solved by developing a new rGO formulation involving ultramixing during the functionalization with polyethyleneimine (PEI) leading to the formation of highly water-stable rGO-PEI. Wide mice brain diffusion and biocompatibility are demonstrated. Using an invasive GL261 model, an anti-invasive effect is observed. A major unexpected modification of the peritumoral area is also observed with the neutralization of gliosis. In vitro, mechanistic investigations are performed using primary astrocytes and cytokine array. The result suggests that direct contact of rGO-PEI_UT neutralizes astrogliosis, decreasing several proinflammatory cytokines that would explain a bystander tumor anti-invasive effect. rGO also significantly downregulates several proinvasive/protumoral cytokines at the tumor cell level. The results open the way to a new microenvironment anti-invasive nanotherapy using a new graphene nanomaterial that is optimized for in vivo brain delivery.

The paradigm of miRNA and siRNA influence in Oral-biome

Short nucleotide sequences like miRNA and siRNA have attracted a lot of interest in Oral-biome investigations. miRNA is a small class of non-coding RNA that regulates gene expression to provide effective regulation of post-transcription. On contrary, siRNA is 21-25 nucleotide dsRNA impairing gene function post-transcriptionally through inhibition of mRNA for homologous dependent gene silencing. This review highlights the application of miRNA in oral biome including oral cancer, dental implants, periodontal diseases, gingival fibroblasts, oral submucous fibrosis, radiation-induced oral mucositis, dental Pulp, and oral lichenoid disease. Moreover, we have also discussed the application of siRNA against the aforementioned disease along with the impact of miRNA and siRNA to the various pathways and molecular effectors pertaining to the dental diseases. The influence of upregulation and downregulation of molecular effector post-treatment with miRNA and siRNA and their impact on the clinical setting has been elucidated. Thus, the mentioned details on application of miRNA and siRNA will provide a novel gateway to the scholars to not only mitigate the long-lasting issue in dentistry but also develop new theragnostic approaches.

Gene-activated titanium implants for gene delivery to enhance osseointegration

Osseointegration is the direct and intimate contact between mineralized tissue and titanium implant at the bone-implant interface. Early establishment and stable maintenance of osseointegration is the key to long-term implant success. However, in patients with compromised conditions such as osteoporosis and patients beginning early load-bearing activities such as walking, lower osseointegration around titanium implants is often observed, which might result in implant early failure. Gene-activated implants show an exciting prospect of combining gene delivery and biomedical implants to solve the problems of poor osseointegration formation, overcoming the shortcomings of protein therapy, including rapid degradation and overdose adverse effects. The conception of gene-activated titanium implants is based on "gene-activated matrix" (GAM), which means scaffolds using non-viral vectors for in situ gene delivery to achieve a long-term and efficient transfection of target cells. Current preclinical studies in animal models have shown that plasmid DNA (pDNA), microRNA (miRNA), and small interference RNA (siRNA) functionalized titanium implants can enhance osseointegration with safety and efficiency, leading to the expectation of applying this technique in dental and orthopedic clinical scenarios. This review aims to comprehensively summarize fabrication strategies, current applications, and futural outlooks of gene-activated implants, emphasizing nucleic acid targets, non-viral vectors, implant surface modification techniques, nucleic acid/vector complexes loading strategies.

Carbon-based Nanomaterials for delivery of small RNA molecules: a focus on potential cancer treatment applications

BACKGROUND

Nucleic acid-mediated therapy holds immense potential in the treatment of recalcitrant human diseases such as cancer. This is underscored by advances in understanding the mechanisms of gene regulation. In particular, the endogenous protective mechanism of gene silencing known as RNA interference (RNAi) has been extensively exploited.

METHODS

We review here the developments from 2011 to 2021, in the use of nanographene oxide, carbon nanotubes, fullerenes, carbon nanohorns, carbon nanodots and nanodiamonds for the delivery of therapeutic small RNA molecules.

RESULTS

Appropriately designed effector molecules such as small interfering RNA (siRNA), can, in theory, silence the expression of any disease-causing gene. Alternatively, siRNA can be generated in vivo through the introduction of plasmid-based short hairpin RNA (shRNA) expression vectors. Other small RNAs such as micro RNA (miRNA) also function in post-transcriptional gene regulation and are aberrantly expressed under disease conditions. The miRNA-based therapy involves either restoration of miRNA function through the introduction of miRNA mimics; or the inhibition of miRNA function by delivering anti-miRNA oligomers. However, the large size, hydrophilicity, negative charge and nuclease-sensitivity of nucleic acids necessitate an appropriate carrier for their introduction as medicine into cells.

CONCLUSION

While numerous organic and inorganic materials have been investigated for this purpose, the perfect carrier agent remains elusive. In recent years, carbon-based nanomaterials have received widespread attention in biotechnology due to their tunable surface characteristics, mechanical, electrical, optical and chemical properties.

The effect of QiangGuYin on osteoporosis through the AKT/mTOR/autophagy signaling pathway mediated by CKIP-1

Osteoporosis is a systemic bone disease characterized by decreased bone mass and deterioration of bone microstructure, which leads to increased bone fragility and increased risk of fractures. Casein kinase 2 interacting protein 1 (CKIP-1, also known as PLEKHO1) is involved in the biological process of bone formation, differentiation and apoptosis, and is a negative regulator of bone formation. QiangGuYin (QGY) is a famous TCM formula that has been widely used in China for the clinical treatment of postmenopausal osteoporosis for decades, but the effect in regulating CKIP-1 on osteoporosis is not fully understood. This study aimed to explore the potential mechanism of CKIP-1 participating in autophagy in bone cells through the AKT/mTOR signaling pathway and the regulatory effect of QGY. The results in vivo showed that QGY treatment can significantly improve the bone quality of osteoporotic rats, down-regulate the expression of CKIP-1, LC3II/I and RANKL, and up-regulated the expression of p62, p-AKT/AKT, p-mTOR/mTOR, RUNX2 and OPG. It is worth noting that the results in vitro confirmed that CKIP-1 interacts with AKT. By up-regulating the expression of Atg5 and down-regulating the p62, the level of LC3 (autophagosome) is increased, and the cells osteogenesis and differentiation are inhibited. QGY inhibits the combination of CKIP-1 and AKT in osteoblasts, activates the AKT/mTOR signaling pathway, inhibits autophagy, and promotes cell differentiation, thereby exerting an anti-osteoporosis effect. Therefore, QGY targeting CKIP-1 to regulate the AKT/mTOR-autophagy signaling pathway may represent a promising drug candidate for the treatment of osteoporosis.

Collagen-based biocomposites inspired by bone hierarchical structures for advanced bone regeneration: ongoing research and perspectives

Bone is a hard-connective tissue composed of matrix, cells and bioactive factors with a hierarchical structure, where the matrix is mainly composed of type I collagen and hydroxyapatite. Collagen fibers assembled by collagen are the template for mineralization and make an important contribution to bone formation and the bone remodeling process. Therefore, collagen has been widely clinically used for bone/cartilage defect regeneration. However, pure collagen implants, such as collagen scaffolds or sponges, have limitations in the bone/cartilage regeneration process due to their poor mechanical properties and osteoinductivity. Different forms of collagen-based composites prepared by incorporating natural/artificial polymers or bioactive inorganic substances are characterized by their interconnected porous structure and promoting cell adhesion, while they improve the mechanical strength, structural stability and osteogenic activities of the collagen matrix. In this review, various forms of collagen-based biocomposites, such as scaffolds, sponges, microspheres/nanoparticles, films and microfibers/nanofibers prepared by natural/synthetic polymers, bioactive ceramics and carbon-based materials compounded with collagen are reviewed. In addition, the application of collagen-based biocomposites as cytokine, cell or drug (genes, proteins, peptides and chemosynthetic) delivery platforms for proangiogenesis and bone/cartilage tissue regeneration is also discussed. Finally, the potential application, research and development direction of collagen-based biocomposites in future bone/cartilage tissue regeneration are discussed.

Selenomethionine-Modified Polyethylenimine-Based Nanoparticles Loaded with miR-132-3p Inhibitor-Biofunctionalized Titanium Implants for Improved Osteointegration

Titanium and its alloys have been widely used as bone implants, but for reduced treatment span, improvements are urgently needed to achieve faster and better osteointegration. In this study, we found that miR-132-3p inhibited bone-marrow-derived stem cell (BMSC) osteogenic differentiation via targeting BMP2, and that inhibiting miR-132-3p could significantly improve the osteogenic capability of BMSCs. Moreover, we fabricated a biocompatible selenomethionine (SEMET)-modified polyethylene glycol (PEG)/polyethylenimine (PEI) nanoparticle (SeNP) cross-linked with 0.2% gelatin solutions and delivered miR-132-3p inhibitor to biofunctionalize alkali heat-treated titanium implants, resulting in the development of a novel coating for reverse transfection. The biological performances of PEG/PEI/miR-132-3p inhibitor and SeNP/miR-132-3p inhibitor-biofunctionalized titanium were compared. The biological effects, including cell viability, cytotoxicity, adhesion, cellular uptake, and osteogenic capacity of SeNP/miR-132-3p inhibitor-biofunctionalized titanium implants, were then assessed. Results showed that SeNPs presented appropriate morphology, diameter, and positive zeta potential for efficient gene delivery. The transfection efficiency of the SeNP/miR-132-3p inhibitor was comparable to that of the PEG/PEI/miR-132-3p inhibitor, but the former induced less reactive oxygen species (ROS) production and lower apoptosis rates. Confocal laser scanning microscopy (CLSM) demonstrated that SeNP/miR-132-3p inhibitor nanoparticles released from the titanium surfaces and were taken up by adherent BMSCs. In addition, the release profile showed that transfection could obtain a long-lasting silencing effect for more than 2 weeks. The cell viability, cytotoxicity, and cell spreading of SeNP/miRNA-132-3p inhibitor-biofunctionalized titanium were comparable with those of untreated titanium and the SeNP/miRNA-132-3p inhibitor negative control (NC)-biofunctionalized titanium but resulted in higher ALP activity and osteogenic gene expression levels. In vivo animal studies further certified that SeNP/miRNA-132-3p inhibitor nanoparticles from titanium surfaces promoted osteointegration, which was revealed by microcomputed tomography (micro-CT) and histological observations. Taken together, these findings suggested that selenomethionine-modified PEI-based nanoparticles could achieve better biocompatibility. Moreover, titanium implants biofunctionalized by SeNP/miRNA-132-3p inhibitor nanoparticles might have significant clinical potential for more effective osteointegration.

Potential of Carbon-Based Nanocomposites for Dental Tissue Engineering and Regeneration

While conventional dental implants focus on mechanical properties, recent advances in functional carbon nanomaterials (CNMs) accelerated the facilitation of functionalities including osteoinduction, osteoconduction, and osseointegration. The surface functionalization with CNMs in dental implants has emerged as a novel strategy for reinforcement and as a bioactive cue due to their potential for mechanical reinforcing, osseointegration, and antimicrobial properties. Numerous developments in the fabrication and biological studies of CNMs have provided various opportunities to expand their application to dental regeneration and restoration. In this review, we discuss the advances in novel dental implants with CNMs in terms of tissue engineering, including material combination, coating strategies, and biofunctionalities. We present a brief overview of recent findings and progression in the research to show the promising aspect of CNMs for dental implant application. In conclusion, it is shown that further development of surface functionalization with CNMs may provide innovative results with clinical potential for improved osseointegration after implantation.

A High-Resolution Ternary Model Demonstrates How PEGylated 2D Nanomaterial Stimulates Integrin αv β8 on Cell Membrane

Bio-nano interfaces are integral to all applications of nanomaterials in biomedicine. In addition to peptide-ligand-functionalized nanomaterials, passivation on 2D nanomaterials has emerged as a new regulatory factor for integrin activation. However, the mechanisms underlying such ligand-independent processes are poorly understood. Here, using graphene oxide passivated with polyethylene glycol (GO-PEG) as a test bed, a ternary simulation model is constructed that also includes a membrane and both subunits of integrin αv β8 to characterize GO-PEG-mediated integrin activation on the cell membrane in a ligand-independent manner. Combined with the experimental findings, production simulations of the ternary model show a three-phase mechanotransduction process in the vertical interaction mode. Specifically, GO-PEG first induces lipid aggregation-mediated integrin proximity, followed by transmembrane domain rotation and separation, leading to the extension and activation of extracellular domains. Thus, this study presents a complete picture of the interaction between passivated 2D nanomaterials and cell membranes to mediate integrin activation, and provides insights into the potential de novo design and rational use of novel desirable nanomaterials at diverse bio-nano interfaces.

The construction of a novel xenograft bovine bone scaffold, (DSS)6-liposome/CKIP-1 siRNA/calcine bone and its osteogenesis evaluation on skull defect in rats

Background

Xenograft bone scaffolds have advantages such as mechanical strength, sufficient source and safety. Combined with siRNA properly targeting CKIP-1, a negative regulator of osteogenesis, may contribute to the repair result of calcine bone alone.

Methods

Herein, we constructed a novel xenograft bovine bone scaffold namely (DSS)6-liposome/CKIP-1 siRNA/calcine bone, the characteristics of which were investigated by confirming the effect of (DSS)6-liposome, observing the appearance and testing mechanical strength of calcine bone, and observing the combined result of CKIP-1 siRNA by FAM immunofluorescence. In addition, cytotoxicity by CCK-8 and LDH activity of L929 ​cells and MC3T3-E1 osteoblasts cultured with the scaffold were tested in vitro, primary osteoblasts proliferation, the mRNA expressions of CKIP-1, ALP, COL1-α and OCN, the protein expressions of CKIP-1, BMP-2, COL-1 and Runx2 and calcium nodules were also determined by CCK-8, RT-qPCR, western-blot and Alizarin Red staining in vitro. Then, we successively established the skull defect model for evaluating the repair result of the novel scaffold by HE staining of 2, 4, 8 and 12 weeks, immumohistochemical stainings of 2, 4, 8 and 12 weeks such as ALP, COL-1α and OCN, Mirco-CT scanning of 4 and 12 weeks and the relative parameters and so on in vivo.

Results

It indicated that (DSS)6-liposome/CKIP-1 siRNA/calcine bone could successfully knock down the CKIP-1 mRNA and protein expressions, promote osteoblasts proliferation with the little cytotoxicity in vitro, increase the protein expressions of BMP-2, COL-1 and Runx2 in vitro, increase mRNA expressions of ALP, COL-1α and OCN in vitro and in vivo, and have a better bone defect repair effect with few side effects in rats after 12 weeks.

Conclusion

Our research indicates (DSS)6-liposome/CKIP-1 siRNA/calcine bone could repair skull defects well in rats, and it may lay the foundation of applicating the novel xenograft bone scaffold in the clinical.

The Translational potential of this article

These findings provide evidence that (DSS)6- liposome/CKIP-1 siRNA/calcine bone could be used as a novel xenograft bone scaffold for osteogenesis with the good safety.

Nanocarrier Mediated siRNA Delivery Targeting Stem Cell Differentiation

Stem cell-based regenerative medicine holds exceptional therapeutic potential and hence the development of efficient techniques to enhance control over the rate of differentiation has been the focus of active research. One of the strategies to achieve this involves delivering siRNA into stem cells and exploiting the RNA interference (RNAi) mechanism. Transport of siRNA across the cell membrane is a challenge due to its anionic property, especially in primary human cells and stem cells. Moreover, naked siRNA incites immune responses, may cause off-target effects, exhibits low stability and is easily degraded by endonucleases in the bloodstream. Although siRNA delivery using viral vectors and electroporation has been used in stem cells, these methods demonstrate low transfection efficiency, cytotoxicity, immunogenicity, events of integration and may involve laborious customization. With the advent of nanotechnology, nanocarriers which act as novel gene delivery vehicles designed to overcome the problems associated with safety and practicality are being developed. The various nanomaterials that are currently being explored and discussed in this review include liposomes, carbon nanotubes, quantum dots, protein and peptide nanocarriers, magnetic nanoparticles, polymeric nanoparticles, etc. These nanodelivery agents exhibit advantages such as low immunogenic response, biocompatibility, design flexibility allowing for surface modification and functionalization, and control over the surface topography for achieving the desired rate of siRNA delivery and improved gene knockdown efficiency. This review also includes discussion on siRNA co-delivery with imaging agents, plasmid DNA, drugs etc. to achieve combined diagnostic and enhanced therapeutic functionality, both for in vitro and in vivo applications.

Chitosan-miRNA functionalized microporous titanium oxide surfaces via a layer-by-layer approach with a sustained release profile for enhanced osteogenic activity

BACKGROUND

The biofunctionalization of titanium implants for high osteogenic ability is a promising approach for the development of advanced implants to promote osseointegration, especially in compromised bone conditions. In this study, polyelectrolyte multilayers (PEMs) were fabricated using the layer-by-layer approach with a chitosan-miRNA (CS-miRNA) complex and sodium hyaluronate (HA) as the positively and negatively charged polyelectrolytes on microarc-oxidized (MAO) Ti surfaces via silane-glutaraldehyde coupling.

METHODS

Dynamic contact angle and scanning electron microscopy measurements were conducted to monitor the layer accumulation. RiboGreen was used to quantify the miRNA loading and release profile in phosphate-buffered saline. The in vitro transfection efficiency and the cytotoxicity were investigated after seeding mesenchymal stem cells (MSCs) on the CS-antimiR-138/HA PEM-functionalized microporous Ti surface. The in vitro osteogenic differentiation of the MSCs and the in vivo osseointegration were also evaluated.

RESULTS

The surface wettability alternately changed during the formation of PEMs. The CS-miRNA nanoparticles were distributed evenly across the MAO surface. The miRNA loading increased with increasing bilayer number. More importantly, a sustained miRNA release was obtained over a timeframe of approximately 2 weeks. In vitro transfection revealed that the CS-antimiR-138 nanoparticles were taken up efficiently by the cells and caused significant knockdown of miR-138 without showing significant cytotoxicity. The CS-antimiR-138/HA PEM surface enhanced the osteogenic differentiation of MSCs in terms of enhanced alkaline phosphatase, collagen production and extracellular matrix mineralization. Substantially enhanced in vivo osseointegration was observed in the rat model.

CONCLUSIONS

The findings demonstrated that the novel CS-antimiR-138/HA PEM-functionalized microporous Ti implant exhibited sustained release of CS-antimiR-138, and notably enhanced the in vitro osteogenic differentiation of MSCs and in vivo osseointegration. This novel miRNA-functionalized Ti implant may be used in the clinical setting to allow for more effective and robust osseointegration.

Recent progress of graphene oxide as a potential vaccine carrier and adjuvant

Vaccine is one of the most effective strategies for preventing and controlling infectious diseases and some noninfectious diseases, especially cancers. Adjuvants and carriers have been appropriately added to the vaccine formulation to improve the immunogenicity of the antigen and induce long-lasting immunity. However, there is an urgent need to develop new all-purpose adjuvants because some adjuvants approved for human use have limited functionality. Graphene oxide (GO), widely employed for the delivery of biomolecules, excels in loading and delivering antigen and shows the potentiality of activating the immune system. However, GO aggregates in biological liquid and induces cell death, and it also exhibits poor biosolubility and biocompatibility. To address these limitations, various surface modification protocols have been employed to integrate aqueous compatible substances with GO to effectively improve its biocompatibility. More importantly, these modifications render functionalized-GO with superior properties as both carriers and adjuvants. Herein, the recent progress of physicochemical properties and surface modification strategies of GO for its application as both carriers and adjuvants is reviewed. STATEMENT OF SIGNIFICANCE: Due to its unique physicochemical properties, graphene oxide is widely employed in medicine for purposes of photothermal treatment of cancer, drug delivery, antibacterial therapy, and medical imaging. Our work describes the surface modification of graphene oxide and for the first time summarizes that functionalized graphene oxide serves as a vaccine carrier and shows significant adjuvant activity in activating cellular and humoral immunity. In the future, it is expected to be introduced into vaccine research to improve the efficacy of vaccines.

The non-viral vectors and main methods of loading siRNA onto the titanium implants and their application

Surface modification of titanium implants by siRNA is quite efficient for improving implant osseointegration. Loading siRNA onto their surface is a crucial factor for siRNA-functionalized implants to realize their biological function. Direct binding of siRNA to implants has low siRNA binding and releasing rate, so usually it needs to be mediated by vectors. Polymeric, nonmaterial-mediated and lipid-based vectors are types of non-viral vectors which are commonly used for delivering siRNA. Three major methods of loading process, namely simple physical adsorption, layer-by-layer assembly and electrodeposition, are also summarized. A brief introduction, the basic principle and the general procedure of each method are included. The loading efficiency, which can be measured both qualitatively and quantitatively, together with gene knockdown efficiency, cytotoxicity assay and osteogenesis of the three methods are compared. A good many applications in osteogenesis have also been described in this review.

Surfce Functionalized via AdLAMA3 Multilayer Coating for Re-epithelization Around Titanium Implants

The peri-implant epithelium (PIE) forms a crucial seal between the oral environment and the implant surface. Compared with the junctional epithelium (JE), the biological sealing of PIE is fragile, which lacks hemidesmosomes (HDs) and internal basal lamina (extracellular matrix containing laminin332, IBL) on the upper part of the interface. In the study, we aim to prepare a coating with good biocompatibility and ability to immobilize the recombinant adenovirus vector of LAMA3 (AdLAMA3) for promoting the re-epithelization of PIE. The titanium surface functionalized with AdLAMA3 was established via layer-by-layer assembly technique and antibody-antigen specific binding. The biological evaluations including cell adhesion and the re-epithelization of PIE were investigated. The results in vitro demonstrated that the AdLAMA3 coating could improve epithelial cell attachment and cell spreading in the early stage. In vivo experiments indicated that the AdLAMA3 coating on the implant surface has the potential to accelerate the healing of the PIE, and could promote the expression of laminin α3 and the formation of hemidesmosomes. This study might provide a novel approach and experimental evidence for the precise attachment of LAMA3 to titanium surfaces. The process could improve the re-epithelization of PIE.

Surface modification via plasmid-mediated pLAMA3-CM gene transfection promotes the attachment of gingival epithelial cells to titanium sheets in vitro and improves biological sealing at the transmucosal sites of titanium implants in vivo

Although titanium implants have been applied in dental clinics to replace lost teeth and to restore masticatory function for decades, strategies to design the surface of the transmucosal sites of implants to achieve ideal and predictable biological sealing following implantation remain to be optimized. In this study, we hypothesized that gingival epithelial cell (GEC) adhesion and new tissue attachment to titanium sheets/implants could be promoted by the release of plasmid pLAMA3-CM (encoding a motif of the C-terminal globular domain of LAMA3) from a titanium surface. To test this hypothesis, a chitosan/collagen (Chi/Col) coating was immobilized on the surfaces of titanium substrates with nanotube topography (NT-Ti) through cathodic electrophoretic deposition; it was found that pLAMA3-CM could be released from the coating in a highly sustained manner. After culturing on titanium with nanotube topography coated by Chi/Col with the plasmid pLAMA3-CM (Chi/Col/pLAMA3-CM-Ti), human GECs (hGECs) were found to effectively uptake the incorporated plasmids, which resulted in improved attachment, as evidenced by morphological and immunofluorescence analyses. In addition, Chi/Col/pLAMA3-CM-Ti induced better biological sealing at transmucosal sites following immediate implantation into Sprague-Dawley rats. Our findings indicate that the modification of titanium implants by plasmid-mediated pLAMA3-CM gene transfection points to a practical strategy for optimizing biological sealing around the transmucosal sites of implants.

Electrospun Chitosan/Poly (Vinyl Alcohol)/Graphene Oxide Nanofibrous Membrane with Ciprofloxacin Antibiotic Drug for Potential WoundDressing Application

In this paper, nanofibrous membranes based on chitosan (CS), poly (vinyl alcohol) (PVA) and graphene oxide (GO) composites, loaded with antibiotic drugs, such as Ciprofloxacin (Cip) and Ciprofloxacin hydrochloride (CipHcl) were prepared via the electrospinning technique. The uniform and defect-free CS/PVA nanofibers were obtained and GO nanosheets, shaping spindle and spherical, were partially embedded into nanofibers. Besides, the antibiotic drugs were effectively loaded into the nanofibers and part of which were absorbed into GO nanosheets. Intriguingly, the release of the drug absorbed in GO nanosheets regulated the drug release profile trend, avoiding the "burst" release of drug at the release initial stage, and the addition of GO slightly improved the drug release ratio. Nanofibrous membranes showed the significantly enhanced antibacterial activity against Escherichia coli, Staphylococcus aureus and Bacillus subtilis after the addition of antibiotic drug. Moreover, the drug-loaded nanofibrous membranes exhibited excellent cytocompatibility with Melanoma cells, indicative to the great potential potential for applications in wound dressing.

Exposure to graphene oxide sheets alters the expression of reference genes used for real-time RT-qPCR normalization

Studies unraveling the interactions between graphene oxide (GO) and the biological milieu, including cells and tissues, are multiplying quickly as the biomedical applications of this and other 2D materials continue to be explored. Many of such studies rely on real-time RT-qPCR as a powerful yet simple technique to assess gene expression. However, a systematic investigation of potential GO-induced changes in the expression of reference genes, crucial for appropriate qPCR data normalization, is still lacking. We aimed to cover this gap investigating the stability of the expression of ten candidate reference genes upon exposure to increasing, but subtoxic, GO concentrations, with two established algorithms (Bestkeeper and NormFinder). The study was performed in a human cancer cell line (MCF7) and in mouse, non-cancerous, primary cells (mouse embryonic fibroblasts, MEFs), to assess different behaviors between cell types. Both algorithms evidenced significant deviations in the expression of various reference genes. Ribosomal proteins scored among the most significantly dysregulated in both cell types. ACTB and GAPDH, the most frequent calibrators in real-time RT-qPCR, were also affected, although differences existed between cell lines. This study illustrates the need to validate reference genes for appropriate real-time RT-qPCR normalization, according to specific experimental conditions, when GO-cell interactions occur.

Glycyrrhetinic acid-modified graphene oxide mediated siRNA delivery for enhanced liver-cancer targeting therapy

Graphene oxide (GO) has attracted huge attention in biomedical field in recent years. However, limited attempts have been invested in utilizing GO on active targeted delivery for gene therapy in liver cancer treatments. Glycyrrhetinic acid (GA) has been reported to be widely used as a targeting ligand to functionalize nanomaterials to treat hepatocellular carcinoma. In this article, GA is employed as a liver targeting ligand to construct GA, polyethylene glycol (PEG), polyamidoamine dendrimer (Dendrimer) and nano-graphene oxide (NGO) conjugate (GA-PEG-NGO-Dendrimer, GPND) for siRNA delivery for the first time. As we expected, GPND exhibited excellent stability, low toxicity, negligible hemolytic activity and remarkably high transfection efficiency in vitro. We also found effective VEGFa gene silencing in both mRNA and protein level in HepG2 cells. Notably, siRNA efficiently gathered in liver tumor tissues by the delivery of GPND, and eventually the growth of tumor tissues were inhibited with enhanced targeting capability and no obvious pathological changes. Moreover, histopathological results preliminarily support the high in vivo safety of GPND/anti-VEGFa siRNA nanocomplex. Collectively, GPND/siRNA nanocomplex, with high safety, targeting and transfection as well as prolonged half-life, is a promising nanomedicine and may provide a new direction for highly-specific targeted gene therapy.

Graphene oxide as a 2D platform for complexation and intracellular delivery of siRNA

The development of efficient and safe nucleic acid delivery vectors remains an unmet need holding back translation of gene therapy approaches to the bedside. Graphene oxide (GO) could help bypass such bottlenecks, thanks to its large surface area, versatile chemistry and biocompatibility, which could overall enhance transfection efficiency while abolishing some of the limitations linked to the use of viral vectors. Here, we aimed to assess the capacity of bare GO, without any further surface modification, to complex a short double-stranded nucleic acid of biological relevance (siRNA) and mediate its intracellular delivery. GO formed stable complexes with siRNA at 10 : 1, 20 : 1 and 50 : 1 GO : siRNA mass ratios. Complexation was further corroborated by atomistic molecular dynamics simulations. GO : siRNA complexes were promptly internalized in a primary mouse cell culture, as early as 4 h after exposure. At this time point, intracellular siRNA levels were comparable to those provided by a lipid-based transfection reagent that achieved significant gene silencing. The time-lapse tracking of internalized GO and siRNA evidenced a sharp decrease of intracellular siRNA from 4 to 12 h, while GO was sequestered in large vesicles, which may explain the lack of biological effects (i.e. gene silencing) achieved by GO : siRNA complexes. This study underlines the potential of non-surface modified GO flakes to act as 2D siRNA delivery platforms, without the need for cationic functionalization, but warrants further vector optimization to allow the effective release of the nucleic acid and achieve efficient gene silencing.

Collagen Functionalized With Graphene Oxide Enhanced Biomimetic Mineralization and in Situ Bone Defect Repair

Biomimetic mineralization using simulated body fluid (SBF) can form a bonelike apatite (Ap) on the natural polymers and enhance osteoconductivity and biocompatibility, and reduce immunological rejection. Nevertheless, the coating efficiency of the bonelike apatite layer on natural polymers still needs to be improved. Graphene oxide (GO) is rich in functional groups, such as carbonyls (-COOH) and hydroxyls (-OH), which can provide more active sites for biomimetic mineralization and improve the proliferation of the rat bone marrow stromal cells (r-BMSCs). In this study, we introduced 0%, 0.05%, 0.1%, and 0.2% w/v concentrations of GO into collagen (Col) scaffolds and immersed the fabricated scaffolds into SBF for 1, 7, and 14 days. In vitro environment scanning electron microscopy (ESEM), energy-dispersive spectrometry (EDS), thermogravimetric analysis (TGA), micro-CT, calcium quantitative analysis, and cellular analysis were used to evaluate the formation of bonelike apatite on the scaffolds. In vivo implantation of the scaffolds into the rat cranial defect was used to analyze the bone regeneration ability. The resulting GO-Col-Ap scaffolds exhibited a porous and interconnected structure coated with a homogeneous distribution of bonelike apatite on their surfaces. The Ca/P ratio of 0.1% GO-Col-Ap group was equal to that of natural bone tissue on the basis of EDS analysis. More apatites were observed in the 0.1% GO-Col-Ap group through TGA analysis, micro-CT evaluation, and calcium quantitative analysis. Furthermore, the 0.1% GO-Col-Ap group showed significantly higher r-BMSCs adhesion and proliferation in vitro and more than 2-fold higher bone formation than the Col-Ap group in vivo. Our study provides a new approach of introducing graphene oxide into bone tissue engineering scaffolds to enhance biomimetic mineralization.

Effects of constrained dynamic loading, CKIP‑1 gene knockout and combination stimulations on bone loss caused by mechanical unloading

Mechanical stimulation plays an important role in maintaining the growth and normal function of the skeletal system. Mechanical unloading occurs, for example, in astronauts spending long periods of time in space or in patients on prolonged bed rest, and causes a rapid loss of bone mass. Casein kinase 2‑interacting protein‑1 (CKIP‑1) is a novel negative bone regulation factor that has been demonstrated to reduce bone loss and enhance bone formation. The aim of this study was to investigate the effect of constrained dynamic loading (Loading) in combination with CKIP‑1 gene knockout (KO) on unloading‑induced bone loss in tail‑suspension mice. The blood serum metabolism index [alkaline phosphatase (ALP) activity and osteocalcin (OCN) levels], tibia mechanical behavior (including bone trabecular microstructure parameters and tibia biomechanical properties), osteoblast‑related gene expression [ALP, OCN, collagen I and bone morphogenetic protein‑2 and osteoprotegerin (OPG)] and osteoclast‑related gene expression [receptor activators of NF‑kB ligand (RANKL)] were measured. The results demonstrated that mice experienced a loss of bone mass after four weeks of tail suspension compared with a wild type group. The mechanical properties, microarchitecture and mRNA expression were significantly increased in mice after Loading + KO treatment (P<0.05). Furthermore, compared with loading or KO alone, the ratio of OPG/RANKL was increased in the combined treatment group. The combined effect of Loading + KO was greater than that observed with loading or KO alone (P<0.05). The present study demonstrates that Loading + KO can counter unloading‑induced bone loss, and combining the two treatments has an additive effect. These results indicate that combined therapy could be a novel strategy for the clinical treatment of disuse osteoporosis associated with space travel or bed rest.

Engineering functional inorganic-organic hybrid systems: advances in siRNA therapeutics

Cancer treatment still faces a lot of obstacles such as tumor heterogeneity, drug resistance and systemic toxicities. Beyond the traditional treatment modalities, exploitation of RNA interference (RNAi) as an emerging approach has immense potential for the treatment of various gene-caused diseases including cancer. The last decade has witnessed enormous research and achievements focused on RNAi biotechnology. However, delivery of small interference RNA (siRNA) remains a key challenge in the development of clinical RNAi therapeutics. Indeed, functional nanomaterials play an important role in siRNA delivery, which could overcome a wide range of sequential physiological and biological obstacles. Nanomaterial-formulated siRNA systems have potential applications in protection of siRNA from degradation, improving the accumulation in the target tissues, enhancing the siRNA therapy and reducing the side effects. In this review, we explore and summarize the role of functional inorganic-organic hybrid systems involved in the siRNA therapeutic advancements. Additionally, we gather the surface engineering strategies of hybrid systems to optimize for siRNA delivery. Major progress in the field of inorganic-organic hybrid platforms including metallic/non-metallic cores modified with organic shells or further fabrication as the vectors for siRNA delivery is discussed to give credit to the interdisciplinary cooperation between chemistry, pharmacy, biology and medicine.