Antioxidant mesoporous Ce-doped bioactive glass nanoparticles with anti-inflammatory and pro-osteogenic activities

In-vitro cytotoxicity of biosynthesized nanoceria using Eucalyptus camaldulensis leaves extract against MCF-7 breast cancer cell line

Cerium oxide nanoparticles possess unique properties that make them promising candidates in various fields, including cancer treatment. Among the proposed synthesis methods for CNPs, biosynthesis using natural extracts, offers an eco-friendly and convenient approach for producing CNPs, particularly for biomedical applications. In this study, a novel method of biosynthesis using the aqueous extract of Eucalyptus camaldulensis leaves was used to synthesize CNPs. Scanning electron microscopy and Transmission electron microscopy (TEM) techniques revealed that the synthesized CNPs exhibit a flower-like morphology. The particle size of CNPs obtained using Powder X-ray diffraction peaks and TEM as 13.43 and 39.25 nm. Energy-dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy confirmed the effect of biomolecules during the synthesis process and the formation of CNPs. The cytotoxicity of biosynthesized samples was evaluated using the MTT method demonstrating the potential of these samples to inhibit MCF-7 cancerous cells. The viability of the MCF-7 cell line conducted by live/dead imaging assay confirmed the MTT cytotoxicity method and indicated their potential to inhibit cancerous cells. Furthermore, the successful uptake of CNPs by MCF-7 cancer cells, as demonstrated by confocal microscopy, provides evidence that the intracellular pathway contributes to the anticancer activity of the CNPs. In general, results indicate that the biosynthesized CNPs exhibit significant cytotoxicity against the MCF-7 cancerous cell line, attributed to their high surface area.

Multifunctional Sr,Mg-Doped Mesoporous Bioactive Glass Nanoparticles for Simultaneous Bone Regeneration and Drug Delivery

Mesoporous bioactive glass nanoparticles (MBGNs) doped with therapeutical ions present multifunctional systems that enable a synergistic outcome through the dual delivery of drugs and ions. The aim of this study was to evaluate influence of co-doping with strontium and magnesium ions (SrMg-MBGNs) on the properties of MBGNs. A modified microemulsion-assisted sol-gel synthesis was used to obtain particles, and their physicochemical properties, bioactivity, and drug-loading/release ability were evaluated. Indirect biological assays using 2D and 3D cell culture models on human bone marrow-derived mesenchymal stem cells (hBM-MSCs) and endothelial EA.hy926 cells, respectively, were used to determine biocompatibility of MBGNs, their influence on alkaline phosphatase (ALP) production, calcium deposition, and cytoskeletal organization. Results showed that Sr,Mg-doping increased pore volume and solubility, and changed the mesoporous structure from worm-like to radial-dendritic, which led to a slightly accelerated drug release compared to pristine MBGNs. Biological assays confirmed that particles are biocompatible, and have ability to slightly induce ALP production and calcium deposition of hBM-MSCs, as well as to significantly improve the proliferation of EA.hy926 compared to biochemical stimulation via vascular endothelial growth factor (VEGF) administration or regular media. Fluorescence staining revealed that SrMg-MBGNs had a similar effect on EA.hy926 cytoskeletal organization to the VEGF group. In conclusion, Sr,Mg-MBGNs might be considered promising biomaterial for biomedical applications.

Cerium doping of 45S5 bioactive glass improves redox potential and cellular bioactivity

45S5 Bioglass (BG) is composed of a glass network with silicate based on the component and can be doped with various therapeutic ions for the enhancement of hard tissue therapy. Nanoceria (CeO2) has been shown to indicate redox reaction and enhance the biological response. However, few studies focus on the proportion of CeO2-doped and its effect on the cellular bioactivity of CeO2-doped BG (CBG). In this study, we synthesized the CBG series with increasing amounts of doping CeO2 ranging (1 to 12) wt.%. The synthesized CBG series examined the characterization, mineralization capacity, and cellular activity against BG. Our results showed that the CBG series exhibited a glass structure and indicated the redox states between Ce3+ and Ce4+, thus they showed the antioxidant activity by characterization of Ce. The CBG series had a stable glass network structure similar to BG, which showed the preservation of bioactivity by exhibiting mineralization on the surface. In terms of biological response, although the CBG series showed the proliferative activity of pre-osteoblastic cells similar to BG, the CBG series augmented not only the alkaline phosphatase activity but also the osteogenic marker in the mRNA level. As stimulated the osteogenic activity, the CBG series improved the biomineralization. In conclusion, the CBG series might have a potential application for hard tissue therapeutic purposes.

Bifunctional mesoporous glasses for bone tissue engineering: Biological effects of doping with cerium and polyphenols in 2D and 3D in vitro models

This study evaluates the cytocompatibility of cerium-doped mesoporous bioactive glasses (Ce-MBGs) loaded with polyphenols (Ce-MBGs-Poly) for possible application in bone tissue engineering after tumour resection. We tested MBGs powders and pellets on 2D and 3D in vitro models using human bone marrow-derived mesenchymal stem cells (hMSCs), osteosarcoma cells (U2OS), and endothelial cells (EA.hy926). Promisingly, at a low concentration in culture medium, Poly-loaded MBGs powders containing 1.2 mol% of cerium inhibited U2OS metabolic activity, preserved hMSCs viability, and had no adverse effects on EA.hy926 migration. Moreover, the study discussed the possible interaction between cerium and Poly, influencing anti-cancer effects. In summary, this research provides insights into the complex interactions between Ce-MBGs, Poly, and various cell types in distinct 2D and 3D in vitro models, highlighting the potential of loaded Ce-MBGs for post-resection bone tissue engineering with a balance between pro-regenerative and anti-tumorigenic activities.

Anti-inflammatory cerium-containing nano-scaled mesoporous bioactive glass for promoting regenerative capability of dental pulp cells

AIMS

This study aimed to investigate the anti-inflammatory and odontoblastic effects of cerium-containing mesoporous bioactive glass nanoparticles (Ce-MBGNs) on dental pulp cells as novel pulp-capping agents.

METHODOLOGY

Ce-MBGNs were synthesized using a post-impregnation strategy based on the antioxidant properties of Ce ions and proposed the first use of Ce-MBGNs for pulp-capping application. The biocompatibility of Ce-MBGNs was analysed using the CCK-8 assay and apoptosis detection. Additionally, the reactive oxygen species (ROS) scavenging ability of Ce-MBGNs was measured using the 2,7-Dichlorofuorescin Diacetate (DCFH-DA) probe. The anti-inflammatory effect of Ce-MBGNs on THP-1 cells was further investigated using flow cytometry and quantitative real-time polymerase chain reaction (RT-qPCR). Moreover, the effect of Ce-MBGNs on the odontoblastic differentiation of the dental pulp cells (DPCs) was assessed by combined scratch assays, RT-qPCR, western blotting, immunocytochemistry, Alizarin Red S staining and tissue-nonspecific alkaline phosphatase staining. Analytically, the secretions of tumour necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were detected with enzyme-linked immunosorbent assay (ELISA).

RESULTS

Ce-MBGNs were confirmed to effectively scavenge ROS in THP-1-derived macrophages and DPCs. Flow cytometry and RT-qPCR assays revealed that Ce-MBGNs significantly inhibited the M1 polarization of macrophages (Mφ). Furthermore, the protein levels of TNF-α and IL-1β were downregulated in THP-1-derived macrophages after stimulation with Ce-MBGNs. With a step-forward virtue of promoting the odontoblastic differentiation of DPCs, we further confirmed that Ce-MBGNs could regulate the formation of a conductive immune microenvironment with respect to tissue repair in DPCs, which was mediated by macrophages.

CONCLUSIONS

Ce-MBGNs protected cells from self-produced oxidative damage and exhibited excellent immunomodulatory and odontoblastic differentiation effects on DPCs. As a pulp-capping agent, this novel biomaterial can exert anti-inflammatory effects and promote restorative dentine regeneration in clinical treatment. We believe that this study will stimulate further correlative research on the development of advanced pulp-capping agents.

Systematic review of the osteogenic effect of rare earth nanomaterials and the underlying mechanisms

Rare earth nanomaterials (RE NMs), which are based on rare earth elements, have emerged as remarkable biomaterials for use in bone regeneration. The effects of RE NMs on osteogenesis, such as promoting the osteogenic differentiation of mesenchymal stem cells, have been investigated. However, the contributions of the properties of RE NMs to bone regeneration and their interactions with various cell types during osteogenesis have not been reviewed. Here, we review the crucial roles of the physicochemical and biological properties of RE NMs and focus on their osteogenic mechanisms. RE NMs directly promote the proliferation, adhesion, migration, and osteogenic differentiation of mesenchymal stem cells. They also increase collagen secretion and mineralization to accelerate osteogenesis. Furthermore, RE NMs inhibit osteoclast formation and regulate the immune environment by modulating macrophages and promote angiogenesis by inducing hypoxia in endothelial cells. These effects create a microenvironment that is conducive to bone formation. This review will help researchers overcome current limitations to take full advantage of the osteogenic benefits of RE NMs and will suggest a potential approach for further osteogenesis research.

Effect of Modified Bioceramic Mineral Trioxide Aggregate Cement with Mesoporous Nanoparticles on Human Gingival Fibroblasts

The ion doping of mesoporous silica nanoparticles (MSNs) has played an important role in revolutionizing several materials applied in medicine and dentistry by enhancing their antibacterial and regenerative properties. Mineral trioxide aggregate (MTA) is a dental material widely used in vital pulp therapies with high success rates. The aim of this study was to investigate the effect of the modification of MTA with cerium (Ce)- or calcium (Ca)-doped MSNs on the biological behavior of human gingival fibroblasts (hGFs). MSNs were synthesized via sol-gel, doped with Ce and Ca ions, and mixed with MTA at three ratios each. Powder specimens were characterized using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Biocompatibility was evaluated using a 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay following hGFs' incubation in serial dilutions of material eluates. Antioxidant status was evaluated using Cayman's antioxidant assay after incubating hGFs with material disc specimens, and cell attachment following dehydration fixation was observed through SEM. Material characterization confirmed the presence of mesoporous structures. Biological behavior and antioxidant capacity were enhanced in all cases with a statistically significant increase in CeMTA 50.50. The application of modified MTA with cerium-doped MSNs offers a promising strategy for vital pulp therapies.

Chitosan/MWCNTs nanocomposite coating on 3D printed scaffold of poly 3-hydroxybutyrate/magnetic mesoporous bioactive glass: A new approach for bone regeneration

The utilization of 3D printing has become increasingly common in the construction of composite scaffolds. In this study, magnetic mesoporous bioactive glass (MMBG) was incorporated into polyhydroxybutyrate (PHB) to construct extrusion-based 3D printed scaffold. After fabrication of the PHB/MMBG composite scaffolds, they were coated with chitosan (Cs) and chitosan/multi-walled carbon nanotubes (Cs/MWCNTs) solutions utilizing deep coating method. FTIR was conducted to confirm the presence of Cs and MWCNTs on the scaffolds' surface. The findings of mechanical analysis illustrated that presence of Cs/MWCNTs on the composite scaffolds increases compressive young modulus significantly, from 16.5 to 42.2 MPa. According to hydrophilicity evaluation, not only MMBG led to decrease the contact angle of pure PHB but also scaffolds surface modification utilization of Cs and MWCNTs, the contact angle decreased significantly from 82.34° to 54.15°. Furthermore, investigation of cell viability, cell metabolism and inflammatory cytokines such as interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) and interleukin-10 (IL-10) and transforming growth factor-beta (TGF-β) proved that the scaffolds not only do not stimulate the immune system, but also polarize macrophage cells from M1 phase to M2 phase. The present study highlights the suitability of 3D printed scaffold PHB/MMBG with Cs/MWCNTs coating for bone tissue engineering.

Lithium and cobalt co-doped mesoporous bioactive glass nanoparticles promote osteogenesis and angiogenesis in bone regeneration

Healing of severe fractures and bone defects involves many complex biological processes, including angiogenesis and osteogenesis, presenting significant clinical challenges. Biomaterials used for bone tissue engineering often possess multiple functions to meet these challenges, including proangiogenic, proosteogenic, and antibacterial properties. We fabricated lithium and cobalt co-doped mesoporous bioactive glass nanoparticles (Li-Co-MBGNs) using a modified sol-gel method. Physicochemical analysis revealed that the nanoparticles had high specific surface areas (>600 m2/g) and a mesoporous structure suitable for hydroxyapatite (HA) formation and sustained release of therapeutic ions. In vitro experiments with Li-Co-MBGNs showed that these promoted angiogenic properties in HUVECs and pro-osteogenesis abilities in BMSCs by releasing Co2+ and Li+ ions. We observed their antibacterial activity against Staphylococcus aureus and Escherichia coli, indicating their potential applications in bone tissue engineering. Overall, our findings indicate the feasibility of its application in bone tissue engineering.

The Preparation and Effects of Organic-Inorganic Antioxidative Biomaterials for Bone Repair

Reactive oxygen species (ROS) has great influence in many physiological or pathological processes in organisms. In the site of bone defects, the overproduced ROS significantly affects the dynamic balance process of bone regeneration. Many antioxidative organic and inorganic antioxidants showed good osteogenic ability, which has been widely used for bone repair. It is of great significance to summarize the antioxidative bone repair materials (ABRMs) to provide guidance for the future design and preparation of osteogenic materials with antioxidative function. Here, this review introduced the major research direction of ABRM at present in nanoscale, 2-dimensional coating, and 3-dimensional scaffolds. Moreover, the referring main active substances and antioxidative properties were classified, and the positive roles of antioxidative materials for bone repair have also been clearly summarized in signaling pathways, antioxidant enzymes, cellular responses and animal levels.

The Impact of 45S5-Bioactive Glass on Synovial Cells in Knee Osteoarthritis-An In Vitro Study

Synovial inflammation in osteoarthritis (OA) is characterized by the release of cartilage-degrading enzymes and inflammatory cytokines. 45S5-bioactive glass (45S5-BG) can modulate inflammation processes; however, its influence on OA-associated inflammation has hardly been investigated. In this study, the effects of 45S5-BG on the release of cartilage-degrading metalloproteinases and cytokines from synovial membrane cells (SM) isolated from patients with knee OA was assessed in vitro. SM were cultivated as SM monocultures in the presence or absence of 45S5-BG. On day 1 (d1) and d7 (d7), the concentrations of Matrix Metalloproteinases (MMPs) and cytokines were assessed. In 45S5-BG-treated SM cultures, MMP9 concentration was significantly reduced at d1 and d7, whilst MMP13 was significantly increased at d7. Concentrations of interleukin (IL)-1B and C-C motif chemokine ligand 2 (CCL2) in 45S5-BG-treated SM cultures were significantly increased at both time points, as were interferon gamma (IFNG) and IL-6 at d7. Our data show an effect of 45S5-BG on SM activity, which was not clearly protective, anti-inflammatory, or pro-inflammatory. The influence of 45S5-BG on MMP release was more suggestive of a cartilage protective effect, but 45S5-BG also increased the release of pro-inflammatory cytokines. Further studies are needed to analyze the effect of BGs on OA inflammation, including the anti-inflammatory modification of BG compositions.

Mesenchymal stem cells-derived extracellular vesicles protect against oxidative stress-induced xenogeneic biological root injury via adaptive regulation of the PI3K/Akt/NRF2 pathway

Xenogeneic extracellular matrices (xECM) for cell support have emerged as a potential strategy for addressing the scarcity of donor matrices for allotransplantation. However, the poor survival rate or failure of xECM-based organ transplantation is due to the negative impacts of high-level oxidative stress and inflammation on seed cell viability and stemness. Herein, we constructed xenogeneic bioengineered tooth roots (bio-roots) and used extracellular vesicles from human adipose-derived mesenchymal stem cells (hASC-EVs) to shield bio-roots from oxidative damage. Pretreatment with hASC-EVs reduced cell apoptosis, reactive oxygen species generation, mitochondrial changes, and DNA damage. Furthermore, hASC-EV treatment improved cell proliferation, antioxidant capacity, and odontogenic and osteogenic differentiation, while significantly suppressing oxidative damage by activating the phosphatidylinositol 3-kinase (PI3K)/Akt pathway and nuclear factor erythroid 2 (NFE2)-related factor 2 (NRF2) nuclear translocation via p62-associated Kelch-like ECH-associated protein 1 (KEAP1) degradation. Inhibition of PI3K/Akt and Nrf2 knockdown reduced antioxidant capacity, indicating that the PI3K/Akt/NRF2 pathway partly mediates these effects. In subcutaneous grafting experiments using Sprague-Dawley rats, hASC-EV administration significantly enhanced the antioxidant effect of the bio-root, improved the regeneration efficiency of periodontal ligament-like tissue, and maximized xenograft function. Conclusively, therefore, hASC-EVs have the potential to be used as an immune modulator and antioxidant for treating oxidative stress-induced bio-root resorption and degradation, which may be utilized for the generation and restoration of other intricate tissues and organs.

Recent advances in nano-scaffolds for tissue engineering applications: Toward natural therapeutics

Among the promising methods for repairing or replacing tissue defects in the human body and the hottest research topics in medical science today are regenerative medicine and tissue engineering. On the other hand, nanotechnology has been expanded into different areas of regenerative medicine and tissue engineering due to its essential benefits in improving performance in various fields. Nanotechnology, a helpful strategy in tissue engineering, offers new solutions to unsolved problems. Especially considering the excellent physicochemical properties of nanoscale structures, their application in regenerative medicine has been gradually developed, and a lot of research has been conducted in this field. In this regard, various nanoscale structures, including nanofibers, nanosheets, nanofilms, nano-clays, hollow spheres, and different nanoparticles, have been developed to advance nanotechnology strategies with tissue repair goals. Here, we comprehensively review the application of the mentioned nanostructures in constructing nanocomposite scaffolds for regenerative medicine and tissue engineering. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Implantable Materials and Surgical Technologies > Nanotechnology in Tissue Repair and Replacement Diagnostic Tools > Biosensing.

Reactive X (where X = O, N, S, C, Cl, Br, and I) species nanomedicine

Reactive oxygen, nitrogen, sulfur, carbonyl, chlorine, bromine, and iodine species (RXS, where X = O, N, S, C, Cl, Br, and I) have important roles in various normal physiological processes and act as essential regulators of cell metabolism; their inherent biological activities govern cell signaling, immune balance, and tissue homeostasis. However, an imbalance between RXS production and consumption will induce the occurrence and development of various diseases. Due to the considerable progress of nanomedicine, a variety of nanosystems that can regulate RXS has been rationally designed and engineered for restoring RXS balance to halt the pathological processes of different diseases. The invention of radical-regulating nanomaterials creates the possibility of intriguing projects for disease treatment and promotes advances in nanomedicine. In this comprehensive review, we summarize, discuss, and highlight very-recent advances in RXS-based nanomedicine for versatile disease treatments. This review particularly focuses on the types and pathological effects of these reactive species and explores the biological effects of RXS-based nanomaterials, accompanied by a discussion and the outlook of the challenges faced and future clinical translations of RXS nanomedicines.

Reduced Sodium Portions Favor Osteogenic Properties and Cytocompatibility of 45S5-Based Bioactive Glass Particles

Besides its favorable biological properties, the release of sodium (Na) from the well-known 45S5-bioactive glass (BG) composition (in mol%: 46.1, SiO2, 24.5 CaO, 24.5 Na2O, 6.0 P2O5) can hamper its cytocompatibility. In this study, particles of Na-reduced variants of 45S5-BG were produced in exchange for CaO and P2O5 via the sol-gel-route resulting in Na contents of 75%, 50%, 25% or 0% of the original composition. The release of ions from the BGs as well as their impact on the cell environment (pH values), viability and osteogenic differentiation (activity of alkaline phosphatase (ALP)), the expression of osteopontin and osteocalcin in human bone-marrow-derived mesenchymal stromal cells in correlation to the Na-content and ion release of the BGs was assessed. The release of Na-ions increased with increasing Na-content in the BGs. With decreasing Na content, the viability of cells incubated with the BGs increased. The Na-reduced BGs showed elevated ALP activity and a pro-osteogenic stimulation with accelerated osteopontin induction and a pronounced upregulation of osteocalcin. In conclusion, the reduction in Na-content enhances the cytocompatibility and improves the osteogenic properties of 45S5-BG, making the Na-reduced variants of 45S5-BG promising candidates for further experimental consideration.

Development and Characterization of Electrospun Composites Built on Polycaprolactone and Cerium-Containing Phases

The current study reports on the fabrication of composite scaffolds based on polycaprolactone (PCL) and cerium (Ce)-containing powders, followed by their characterization from compositional, structural, morphological, optical and biological points of view. First, CeO2, Ce-doped calcium phosphates and Ce-substituted bioglass were synthesized by wet-chemistry methods (precipitation/coprecipitation and sol-gel) and subsequently loaded on PCL fibres processed by electrospinning. The powders were proven to be nanometric or micrometric, while the investigation of their phase composition showed that Ce was present as a dopant within the crystal lattice of the obtained calcium phosphates or as crystalline domains inside the glassy matrix. The best bioactivity was attained in the case of Ce-containing bioglass, while the most pronounced antibacterial effect was visible for Ce-doped calcium phosphates calcined at a lower temperature. The scaffolds were composed of either dimensionally homogeneous fibres or mixtures of fibres with a wide size distribution and beads of different shapes. In most cases, the increase in polymer concentration in the precursor solution ensured the achievement of more ordered fibre mats. The immersion in SBF for 28 days triggered an incipient degradation of PCL, evidenced mostly through cracks and gaps. In terms of biological properties, the composite scaffolds displayed a very good biocompatibility when tested with human osteoblast cells, with a superior response for the samples consisting of the polymer and Ce-doped calcium phosphates.

3D printing of piezoelectric and bioactive barium titanate-bioactive glass scaffolds for bone tissue engineering

Bone healing is a complex process orchestrated by various factors, such as mechanical, chemical and electrical cues. Creating synthetic biomaterials that combine several of these factors leading to tailored and controlled tissue regeneration, is the goal of scientists worldwide. Among those factors is piezoelectricity which creates a physiological electrical microenvironment that plays an important role in stimulating bone cells and fostering bone regeneration. However, only a limited number of studies have addressed the potential of combining piezoelectric biomaterials with state-of-the-art fabrication methods to fabricate tailored scaffolds for bone tissue engineering. Here, we present an approach that takes advantage of modern additive manufacturing techniques to create macroporous biomaterial scaffolds based on a piezoelectric and bioactive ceramic-crystallised glass composite. Using binder jetting, scaffolds made of barium titanate and 45S5 bioactive glass are fabricated and extensively characterised with respect to their physical and functional properties. The 3D-printed ceramic-crystallised glass composite scaffolds show both suitable mechanical strength and bioactive behaviour, as represented by the accumulation of bone-like calcium phosphate on the surface. Piezoelectric scaffolds that mimic or even surpass bone with piezoelectric constants ranging from 1 to 21 pC/N are achieved, depending on the composition of the composite. Using MC3T3-E1 osteoblast precursor cells, the scaffolds show high cytocompatibility coupled with cell attachment and proliferation, rendering the barium titanate/45S5 ceramic-crystallised glass composites promising candidates for bone tissue engineering.

Cellular Uptake of Modified Mesoporous Bioactive Glass Nanoparticles for Effective Intracellular Delivery of Therapeutic Agents

Introduction

There has recently been a surge of interest in mesoporous bioactive glass nanoparticles (MBGNs) as multi-functional nanocarriers for application in bone-reconstructive and -regenerative surgery. Their excellent control over their structural and physicochemical properties renders these nanoparticles suitable for the intracellular delivery of therapeutic agents to combat degenerative bone diseases, such as bone infection, or bone cancer. Generally, the therapeutic efficacy of nanocarriers strongly depends on the efficacy of their cellular uptake, which is determined by numerous factors including cellular features and the physicochemical characteristics of nanocarriers, particularly surface charge. In this study, we have systematically investigated the effect of the surface charge of MBGNs doped with copper as a model therapeutic agent on cellular uptake by both macrophages and pre-osteoblast cells involved in bone healing and bone infections to guide the future design of MBGN-based nanocarriers.

Methods

Cu-MBGNs with negative, neutral, and positive surface charges were synthesized and their cellular uptake efficiency was assessed. Additionally, the intracellular fate of internalized nanoparticles along with their ability to deliver therapeutic cargo was studied in detail.

Results

The results showed that both cell types internalized Cu-MBGNs regardless of their surface charge, indicating that cellular uptake of nanoparticles is a complex process influenced by multiple factors. This similarity in cellular uptake was attributed to the formation of a protein corona surrounding the nanoparticles when exposed to protein-rich biological media, which masks the original nanoparticle surface. Once internalized, the nanoparticles were found to mainly colocalize with lysosomes, exposing them to a more compartmentalized and acidic environment. Furthermore, we verified that Cu-MBGNs released their ionic components (Si, Ca, and Cu ions) in both acidic and neutral environments, leading to the delivery of these therapeutic cargos intracellularly.

Conclusion

The effective internalization of Cu-MBGNs and their ability to deliver cargos intracellularly highlight their potential as intracellular delivery nanocarriers for bone-regenerative and -healing applications.

Ce-MBGs Loaded with Gentamicin: Characterization and In Vitro Evaluation

Mesoporous Bioactive Glasses (MBGs) are biomaterials widely used in tissue engineering, particularly for hard tissue regeneration. One of the most frequent postoperative complications following a biomaterial surgical implant is a bacterial infection, which usually requires treatment by the systemic administration of drugs (e.g., antibiotics). In order to develop biomaterials with antibiotic properties, we investigated cerium-doped MBGs (Ce-MBGs) as in situ-controlled drug delivery systems (DDSs) of gentamicin (Gen), a wide spectrum antibiotic commonly employed against bacteria responsible of postoperative infections. Here we report the optimization of Gen loading on MBGs and the evaluation of the antibacterial properties and of retention of bioactivity and antioxidant properties of the resulting materials. The Gen loading (up to 7%) was found to be independent from cerium content, and the optimized Gen-loaded Ce-MBGs retain significant bioactivity and antioxidant properties. The antibacterial efficacy was verified up to 10 days of controlled release. These properties make Gen-loaded Ce-MBGs interesting candidates for simultaneous hard tissue regeneration and in situ antibiotic release.

Mesoporous Bioactive Nanoparticles for Bone Tissue Applications

Research in nanomaterials with applications in bone regeneration therapies has experienced a very significant advance with the development of bioactive mesoporous nanoparticles (MBNPs). These nanomaterials consist of small spherical particles that exhibit chemical properties and porous structures that stimulate bone tissue regeneration, since they have a composition similar to that of conventional sol-gel bioactive glasses and high specific surface area and porosity values. The rational design of mesoporosity and their ability to incorporate drugs make MBNPs an excellent tool for the treatment of bone defects, as well as the pathologies that cause them, such as osteoporosis, bone cancer, and infection, among others. Moreover, the small size of MBNPs allows them to penetrate inside the cells, provoking specific cellular responses that conventional bone grafts cannot perform. In this review, different aspects of MBNPs are comprehensively collected and discussed, including synthesis strategies, behavior as drug delivery systems, incorporation of therapeutic ions, formation of composites, specific cellular response and, finally, in vivo studies that have been performed to date.

Unraveling the mechanisms of inhibition of silver-doped bioactive glass-ceramic particles

Infections are a major concern in orthopedics. Antibacterial agents such as silver ions are of great interest as broad-spectrum biocides and have been incorporated into bioactive glass-ceramic particles to control the release of ions within a therapeutic concentration and provide tissue regenerative properties. In this work, the antibacterial capabilities of silver-doped bioactive glass (Ag-BG) microparticles were explored to reveal the unedited mechanisms of inhibition against methicillin-resistant Staphylococcus aureus (MRSA). The antibacterial properties were not limited to the delivery of silver ions but rather a combination of antibacterial degradation by-products. For example, nano-sized debris punctured holes in bacteria membranes, osmotic effects, and reactive oxygen species causing oxidative stress and almost 40% of the inhibition. Upon successive Ag-BG treatments, MRSA underwent phenotypic and genomic mutations which were not only insufficient to develop resistance but instead, the clones became more sensitive as the treatment was re-delivered. Additionally, the unprecedented restorative functionality of Ag-BG allowed the effective use of antibiotics that MRSA resists. The synergy mechanism was mainly identified for combinations targeting cell-wall activity and their action was proven in biofilm-like and virulent conditions. Unraveling these mechanisms may offer new insights into how to tailor healthcare materials to prevent or debilitate infections and join the fight against antibiotic resistance in clinical cases.

Melaleuca armillaris Essential Oil as an Antibacterial Agent: The Use of Mesoporous Bioactive Glass Nanoparticles as Drug Carrier

Bioactive glasses have been proposed for bone tissue engineering due to their excellent biocompatibility and osteo-inductive behaviour. The generation of mesoporous bioactive glass (nano) particles adds a high surface area for the dissolution and release of bioactive ions, and the possibility to load them with different drugs for antibacterial purposes. Essential oils (EO) are an interesting resource for alternative medical therapy, providing antimicrobial compounds that come from organic/natural resources like aromatic plants. Also, a biological polymer, such as chitosan, could be used to control the release of active agents from mesoporous bioactive glass (MBG) loaded particles. This work presents MBG particles with nominal composition (in mol) 60% SiO2, 30% CaO and 10% P2O5, loaded with essential oil of Melaleuca armillaris, which contains 1,8-cineol as the main active component, with an inhibitory in vitro activity against several bacterial species. Also, co-loading with a broad-spectrum antibiotic, namely gentamicin, was investigated. The MBG particles were found to be of around 300nm in diameter and to exhibit highly porous open structure. The release of EO from the particles reached 72% of the initial content after the first 24 h, and 80% at 48 h of immersion in phosphate buffered solution. Also, the MBG particles with EO and EO-gentamicin loading presented in vitro apatite formation after 7 days of immersion in simulated body fluid. The antibacterial tests indicated that the main effect, after 24 h of contact with the bacteria, was reached either for the MBG EO or MBG EO-gentamicin particles against E. coli, while the effect against S. aureus was less marked. The results indicate that MBG particles are highly bioactive with the tested composition and loaded with EO of Melaleuca armillaris. The EO, also combined with gentamicin, acts as an antibacterial agent but with different efficacy depending on the bacteria type.

Biocompatibility, Bioactivity, and Antibacterial Behaviour of Cerium-Containing Bioglass®

The main reason for the increased use of dental implants in clinical practice is associated with aesthetic parameters. Implants are also presented as the only technique that conserves and stimulates natural bone. However, there are several problems associated with infections, such as peri-implantitis. This disease reveals a progressive inflammatory action that affects the hard and soft tissues surrounding the implant, leading to implant loss. To prevent the onset of this disease, coating the implant with bioactive glasses has been suggested. In addition to its intrinsic function of promoting bone regeneration, it is also possible to insert therapeutic ions, such as cerium. Cerium has several advantages when the aim is to improve osseointegration and prevent infectious problems with dental implant placement. It promotes increased growth and the differentiation of osteoblasts, improves the mechanical properties of bone, and prevents bacterial adhesion and proliferation that may occur on the implant surface. This antibacterial effect is due to its ability to disrupt the cell wall and membrane of bacteria, thus interfering with vital metabolic functions such as respiration. In addition, its antioxidant effect reverses oxidative stress after implantation in bone. In this work, Bioglass 45S5 with CeO₂ with different percentages (0.25, 0.5, 1, and 2 mol%) was developed by the melt-quenching method. The materials were analyzed in terms of morphological, structural, and biological (cytotoxicity, bioactivity, and antibacterial activity) properties. The addition of cerium did not promote structural changes to the bioactive glass, which shows no cytotoxicity for the Saos-2 cell line up to 25 mg/mL of extract concentration for all cerium contents. For the maximum cerium concentration (2 mol%) the bioactive glass shows an evident inhibitory effect for Escherichia coli and Streptococcus mutans bacteria. Furthermore, all samples showed the beginning of the deposition of a CaP-rich layer on the surface of the material after 24 h.

Achievements in Mesoporous Bioactive Glasses for Biomedical Applications

Nowadays, mesoporous bioactive glasses (MBGs) are envisaged as promising candidates in the field of bioceramics for bone tissue regeneration. This is ascribed to their singular chemical composition, structural and textural properties and easy-to-functionalize surface, giving rise to accelerated bioactive responses and capacity for local drug delivery. Since their discovery at the beginning of the 21st century, pioneering research efforts focused on the design and fabrication of MBGs with optimal compositional, textural and structural properties to elicit superior bioactive behavior. The current trends conceive MBGs as multitherapy systems for the treatment of bone-related pathologies, emphasizing the need of fine-tuning surface functionalization. Herein, we focus on the recent developments in MBGs for biomedical applications. First, the role of MBGs in the design and fabrication of three-dimensional scaffolds that fulfil the highly demanding requirements for bone tissue engineering is outlined. The different approaches for developing multifunctional MBGs are overviewed, including the incorporation of therapeutic ions in the glass composition and the surface functionalization with zwitterionic moieties to prevent bacterial adhesion. The bourgeoning scientific literature on MBGs as local delivery systems of diverse therapeutic cargoes (osteogenic/antiosteoporotic, angiogenic, antibacterial, anti-inflammatory and antitumor agents) is addressed. Finally, the current challenges and future directions for the clinical translation of MBGs are discussed.

Application of bioactive metal ions in the treatment of bone defects

The treatment of bone defects is an important problem in clinical practice. The rapid development of bone tissue engineering (BTE) may provide a new method for bone defect treatment. Metal ions have been widely studied in BTE and demonstrated a significant effect in promoting bone tissue growth. Different metal ions can be used to treat bone defects according to specific conditions, including promoting osteogenic activity, inhibiting osteoclast activity, promoting vascular growth, and exerting certain antibacterial effects. Multiple studies have confirmed that metal ions-modified composite scaffolds can effectively promote bone defect healing. By studying current extensive research on metal ions in the treatment of bone defects, this paper reviews the mechanism of metal ions in promoting bone tissue growth, analyzes the loading mode of metal ions, and lists some specific applications of metal ions in different types of bone defects. Finally, this paper summarizes the advantages and disadvantages of metal ions and analyzes the future research trend of metal ions in BTE. This article can provide some new strategies and methods for future research and applications of metal ions in the treatment of bone defects.

Antioxidant Effects of Bioactive Glasses (BGs) and Their Significance in Tissue Engineering Strategies

Elevated levels of oxidative stress are usually observed following injuries, leading to impaired tissue repair due to oxidation-related chronic inflammation. Several attempts have been made to manage this unfavorable situation, and the use of biomaterials with antioxidant activity is showing great promise in tissue engineering and regenerative medicine approaches. Bioactive glasses (BGs) are a versatile group of inorganic substances that exhibit an outstanding regenerative capacity for both hard and soft damaged tissues. The chemical composition of BGs provides a great opportunity for imparting specific biological activities to them. On this point, BGs may easily become antioxidant substances through simple physicochemical modifications. For example, particular antioxidant elements (mostly cerium (Ce)) can be added to the basic composition of the glasses. On the other hand, grafting natural antioxidant substances (e.g., polyphenols) on the BG surface is feasible for making antioxidant substitutes with promising results in vitro. Mesoporous BGs (MBGs) were demonstrated to have unique merits compared with melt-derived BGs since they make it possible to load antioxidants and deliver them to the desired locations. However, there are actually limited in vivo experimental studies on the capability of modified BGs for scavenging free radicals (e.g., reactive oxygen species (ROS)). Therefore, more research is required to determine the actual potential of BGs in decreasing oxidative stress and subsequently improving tissue repair and regeneration. The present work aims to highlight the potential of different types of BGs in modulating oxidative stress and subsequently improving tissue healing.

Coatings of hydroxyapatite-bioactive glass microparticles for adhesion to biological tissues

Adsorption of particles across interfaces has been proposed as a way to create adhesion between hydrogels and biological tissues. Here, we explore how this particle bridging approach can be applied to attach a soft polymer substrate to biological tissues, using bioresorbable and nanostructured hydroxyapatite-bioactive glass microparticles. For this, microparticles of aggregated flower-like hydroxyapatite and bioactive glass (HA-BG) were synthesized via a bioinspired route. A deposition technique using suspension spreading was developed to tune the coverage of HA-BG coatings at the surface of weakly cross-linked poly(beta-thioester) films. By varying the concentration of the deposited suspensions, we produced coatings having surface coverages ranging from 4% to 100% and coating densities ranging from 0.02 to 1.0 mg cm-2. The progressive dissolution of these coatings within 21 days in phosphate-buffered saline was followed by SEM. Ex vivo peeling experiments on pig liver capsules demonstrated that HA-BG coatings produce an up-to-two-fold increase in adhesion energy (9.8 ± 1.5 J m-2) as compared to the uncoated film (4.6 ± 0.8 J m-2). Adhesion energy was found to increase with increasing coating density until a maximum at 0.2 mg cm-2, well below full surface coverage, and then it decreased for larger coating densities. Using microscopy observations during and after peeling, we show that this maximum in adhesion corresponds to the appearance of particle stacks, which are easily separated and transferred onto the tissue. Such bioresorbable HA-BG coatings give the possibility of combining particle bridging with the storage and release of active compounds, therefore offering opportunities to design functional bioadhesive surfaces.

A 3D Printed Bone Tissue Engineering Scaffold Composed of Alginate Dialdehyde-Gelatine Reinforced by Lysozyme Loaded Cerium Doped Mesoporous Silica-Calcia Nanoparticles

A novel biomaterial comprising alginate dialdehyde-gelatine (ADA-GEL) hydrogel augmented by lysozyme loaded mesoporous cerium doped silica-calcia nanoparticles (Lys-Ce-MSNs) was 3D printed to create bioactive scaffolds. Lys-Ce-MSNs raised the mechanical stiffness of the hydrogel composite scaffold and induced surface apatite mineralization, when the scaffold was immersed in simulated body fluid (SBF). Moreover, the scaffolds could co-deliver bone healing (Ca and Si) and antioxidant ions (Ce), and Lys to achieve antibacterial (and potentially anticancer) properties. The nanocomposite hydrogel scaffolds could hold and deliver Lys steadily. Based on the in vitro results, the hydrogel nanocomposite containing Lys assured improved pre-osteoblast cell (MC3T3-E1) proliferation, adhesion, and differentiation, thanks to the biocompatibility of ADA-GEL, bioactivity of Ce-MSNs, and the stabilizing effect of Lys on the scaffold structure. On the other hand, the proliferation level of MG63 osteosarcoma cells decreased, likely due to the anticancer effect of Lys. Last but not least, cooperatively, alongside gentamicin (GEN), Lys brought about a proper antibacterial efficiency to the hydrogel nanocomposite scaffold against gram-positive and gram-negative bacteria. Taken together, ADA-GEL/Lys-Ce-MSN nanocomposite holds great promise for 3D printing of multifunctional hydrogel BTE scaffolds, able to induce bone regeneration, address infection, and potentially inhibit tumor formation and growth. This article is protected by copyright. All rights reserved.

Polymeric biomaterials for wound healing applications: a comprehensive review

Chronic wounds have been a global health threat over the past few decades, requiring urgent medical and research attention. The factors delaying the wound-healing process include obesity, stress, microbial infection, aging, edema, inadequate nutrition, poor oxygenation, diabetes, and implant complications. Biomaterials are being developed and fabricated to accelerate the healing of chronic wounds, including hydrogels, nanofibrous, composite, foam, spongy, bilayered, and trilayered scaffolds. Some recent advances in biomaterials development for healing both chronic and acute wounds are extensively compiled here. In addition, various properties of biomaterials for wound-healing applications and how they affect their performance are reviewed. Based on the recent literature, trilayered constructs appear to be a convincing candidate for the healing of chronic wounds and complete skin regeneration because they mimic the full thickness of skin: epidermis, dermis, and the hypodermis. This type of scaffold provides a dense superficial layer, a bioactive middle layer, and a porous lower layer to aid the wound-healing process. The hydrophilicity of scaffolds aids cell attachment, cell proliferation, and protein adhesion. Other scaffold characteristics such as porosity, biodegradability, mechanical properties, and gas permeability help with cell accommodation, proliferation, migration, differentiation, and the release of bioactive factors.

Cerium-Containing Mesoporous Bioactive Glasses (MBGs)-Derived Scaffolds with Drug Delivery Capability for Potential Tissue Engineering Applications

Finding innovative solutions to improve the lives of people affected by trauma, bone disease, or aging continues to be a challenge worldwide. Tissue engineering is the most rapidly growing area in the domain of biomaterials. Cerium-containing MBG-derived biomaterials scaffolds were synthesized using polymethyl methacrylate (PMMA) as a sacrificial template. The obtained scaffolds were characterized by X-ray powder diffraction (XRPD), infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The Ce4+/Ce3+ ratio in the scaffolds was estimated. In vitro testing revealed good cytocompatibility of the investigated scaffolds in mouse fibroblast cell line (NCTC clone L929). The results obtained regarding bioactivity, antibacterial activity, and controlled drug delivery functions recommend these scaffolds as potential candidates for bone tissue engineering applications.

Co-doping of iron and copper ions in nanosized bioactive glass by reactive laser fragmentation in liquids

Bioactive glass (BG) is a frequently used biomaterial applicable in bone tissue engineering and known to be particularly effective when applied in nanoscopic dimensions. In this work, we employed the scalable reactive laser fragmentation in liquids method to produce nanosized 45S5 BG in the presence of light-absorbing Fe and Cu ions. Here, the function of the ions was twofold: (i) increasing the light absorption and thus causing a significant increase in laser fragmentation efficiency by a factor of 100 and (ii) doping the BG with bioactive metal ions up to 4 wt%. Our findings reveal an effective downsizing of the BG from micrometer-sized educts into nanoparticles having average diameters of <50 nm. This goes along with successful element-specific incorporation of the metal ions into the BG, inducing co-doping of Fe and Cu ions as verified by energy-dispersive X-ray spectroscopy (EDX). In this context, the overall amorphous structure is retained, as evidenced by X-ray powder diffraction (XRD). We further demonstrate that the level of doping for both elements can be adjusted by changing the BG/ion concentration ratio during laser fragmentation. Consecutive ion release experiments using inductively-coupled plasma mass spectrometry (ICP-MS) were conducted to assess the potential bioactivity of the doped nanoscopic BG samples, and cell culture experiments using MG-63 osteoblast-like cells demonstrated their cytocompatibility. The elegant method of in situ co-doping of Fe and Cu ions during BG nanosizing may provide functionality-advanced biomaterials for future studies on angiogenesis or bone regeneration, particularly as the level of doping may be adjusted by ion concentrations and ion type in solution.

Cerium-Containing Bioactive Glasses Promote In Vitro Lymphangiogenesis

The lymphatic system is crucial for the regeneration of many tissues due to its fundamental role in immune cell trafficking, protein transport, and tissue homeostasis maintenance. Strategies stimulating lymphangiogenesis can provide new therapeutic approaches for tissue repair and regeneration (e.g., chronic wound healing). Here, we explored the effects of cerium-containing mesoporous bioactive glass nanoparticles (Ce-MBGNs) on lymphangiogenesis. The results showed that the extracts of Ce-MBGNs (1, 5, or 10 wt/v%) were non-cytotoxic toward lymphatic endothelial cells (LECs), while they enhanced the proliferation of LECs. Moreover, as evidenced by the scratch wound healing and Transwell migration assays, conditioned media containing the extract of Ce-MBGNs (1 wt/v%) could enhance the migration of LECs in comparison to the blank control and the media containing vascular endothelial growth factor-C (VEGF-C, 50 ng/mL). Additionally, a tube-formation assay using LECs showed that the extract of Ce-MBGNs (1 wt/v%) promoted lymphatic vascular network formation. Western blot results suggested that Ce-MBGNs could induce lymphangiogenesis probably through the HIF-1α/VEGFR-3 pathway. Our study for the first time showed the effects of Ce-MBGNs on stimulating lymphangiogenesis in vitro, highlighting the potential of Ce-MBGNs for wound healing.

Mesoporous Bioactive Glasses in Cancer Diagnosis and Therapy: Stimuli-Responsive, Toxicity, Immunogenicity, and Clinical Translation

Cancer is one of the top life-threatening dangers to the human survival, accounting for over 10 million deaths per year. Bioactive glasses have developed dramatically since their discovery 50 years ago, with applications that include therapeutics as well as diagnostics. A new system within the bioactive glass family, mesoporous bioactive glasses (MBGs), has evolved into a multifunctional platform, thanks to MBGs easy-to-functionalize nature and tailorable textural properties-surface area, pore size, and pore volume. Although MBGs have yet to meet their potential in tumor treatment and imaging in practice, recently research has shed light on the distinguished MBGs capabilities as promising theranostic systems for cancer imaging and therapy. This review presents research progress in the field of MBG applications in cancer diagnosis and therapy, including synthesis of MBGs, mechanistic overview of MBGs application in tumor diagnosis and drug monitoring, applications of MBGs in cancer therapy ( particularly, targeted delivery and stimuli-responsive nanoplatforms), and immunological profile of MBG-based nanodevices in reference to the development of novel cancer therapeutics.

ROS-Scavenging Therapeutic Hydrogels for Modulation of the Inflammatory Response

Although reactive oxygen species (ROS) are essential for cellular processes, excessive ROS could be a major cause of various inflammatory diseases because of the oxidation of proteins, DNA, and membrane lipids. It has recently been suggested that the amount of ROS could thus be regulated to treat such physiological disorders. A ROS-scavenging hydrogel is a promising candidate for therapeutic applications because of its high biocompatibility, 3D matrix, and ability to be modified. Approaches to conferring antioxidant properties to normal hydrogels include embedding ROS-scavenging catalytic nanoparticles, modifying hydrogel polymer chains with ROS-adsorbing organic moieties, and incorporating ROS-labile linkers in polymer backbones. Such therapeutic hydrogels can be used for wound healing, cardiovascular diseases, bone repair, ocular diseases, and neurodegenerative disorders. ROS-scavenging hydrogels could eliminate oxidative stress, accelerate the regeneration process, and show synergetic effects with other drugs or therapeutic molecules. In this review, the mechanisms by which ROS are generated and scavenged in the body are outlined, and the effects of high levels of ROS and the resulting oxidative stress on inflammatory diseases are described. Next, the mechanism of ROS scavenging by hydrogels is explained depending on the ROS-scavenging agents embedded within the hydrogel. Lastly, the recent achievements in the development of ROS-scavenging hydrogels to treat various inflammation-associated diseases are presented.

Bioactive glasses incorporating less-common ions to improve biological and physical properties

Bioactive glasses (BGs) have been a focus of research for over five decades for several biomedical applications. Although their use in bone substitution and bone tissue regeneration has gained important attention, recent developments have also seen the expansion of BG applications to the field of soft tissue engineering. Hard and soft tissue repair therapies can benefit from the biological activity of metallic ions released from BGs. These metallic ions are incorporated in the BG network not only for their biological therapeutic effects but also in many cases for influencing the structure and processability of the glass and to impart extra functional properties. The "classical" elements in silicate BG compositions are silicon (Si), phosphorous (P), calcium (Ca), sodium (Na), and potassium (K). In addition, other well-recognized biologically active ions have been incorporated in BGs to provide osteogenic, angiogenic, anti-inflammatory, and antibacterial effects such as zinc (Zn), magnesium (Mg), silver (Ag), strontium (Sr), gallium (Ga), fluorine (F), iron (Fe), cobalt (Co), boron (B), lithium (Li), titanium (Ti), and copper (Cu). More recently, rare earth and other elements considered less common or, some of them, even "exotic" for biomedical applications, have found room as doping elements in BGs to enhance their biological and physical properties. For example, barium (Ba), bismuth (Bi), chlorine (Cl), chromium (Cr), dysprosium (Dy), europium (Eu), gadolinium (Gd), ytterbium (Yb), thulium (Tm), germanium (Ge), gold (Au), holmium (Ho), iodine (I), lanthanum (La), manganese (Mn), molybdenum (Mo), nickel (Ni), niobium (Nb), nitrogen (N), palladium (Pd), rubidium (Rb), samarium (Sm), selenium (Se), tantalum (Ta), tellurium (Te), terbium (Tb), erbium (Er), tin (Sn), tungsten (W), vanadium (V), yttrium (Y) as well as zirconium (Zr) have been included in BGs. These ions have been found to be particularly interesting for enhancing the biological performance of doped BGs in novel compositions for tissue repair (both hard and soft tissue) and for providing, in some cases, extra functionalities to the BG, for example fluorescence, luminescence, radiation shielding, anti-inflammatory, and antibacterial properties. This review summarizes the influence of incorporating such less-common elements in BGs with focus on tissue engineering applications, usually exploiting the bioactivity of the BG in combination with other functional properties imparted by the presence of the added elements.

Incorporation of Zinc into Binary SiO2-CaO Mesoporous Bioactive Glass Nanoparticles Enhances Anti-Inflammatory and Osteogenic Activities

During the healing and repair of bone defects, uncontrolled inflammatory responses can compromise bone regeneration. Biomaterials with anti-inflammatory activity are favorable for bone tissue regeneration processes. In this work, multifunctional Zn-containing mesoporous bioactive glass nanoparticles (Zn-MBGs) exhibiting favorable osteogenic and anti-inflammatory activities were produced employing a sol-gel method. Zn-MBGs exhibited a mesoporous spherical shape and nanoscale particle size (100 ± 20 nm). They were degradable in cell culture medium, and could release Si, Ca, and Zn in a sustained manner. Zn-MBGs also exhibited a concentration-dependent cellular response. The extract of Zn-MBGs obtained by incubation at 0.1 mg/mL (in culture medium) for 24 h could enhance in vitro mineralization, alkaline phosphatase activity, the expression of osteogenesis-related genes, and the production of intracellular protein osteocalcin of rat bone marrow stromal cells (BMSCs). Moreover, the extract of Zn-MBGs at 0.1 mg/mL could significantly downregulate the expression of inflammatory genes and the production of inducible nitric oxide in RAW 264.7 cells, particularly under stimulation of inflammatory signals interferon-γ (IFN-γ) and lipopolysaccharide (LPS). Zn-MBGs also inhibited the pro-inflammatory M1 polarization of RAW264.7 cells induced by LPS and IFN-γ. In summary, we successfully synthesized Zn-MBGs with concentration-dependent osteogenic and anti-inflammatory activities. Zn-MBGs show their great potential in immunomodulation strategies for bone regeneration, representing a multifunctional biomaterial that can be applied to regenerate bone defects under inflammatory conditions.

Polyelectrolyte-Coated Mesoporous Bioactive Glasses via Layer-by-Layer Deposition for Sustained Co-Delivery of Therapeutic Ions and Drugs

In the field of bone regeneration, considerable attention has been addressed towards the use of mesoporous bioactive glasses (MBGs), as multifunctional therapeutic platforms for advanced medical devices. In fact, their extremely high exposed surface area and pore volume allow to load and the release of several drugs, while their framework can be enriched with specific therapeutic ions allowing to boost the tissue regeneration. However, due to the open and easily accessible mesopore structure of MBG, the release of the incorporated therapeutic molecules shows an initial burst effect leading to unsuitable release kinetics. Hence, a still open challenge in the design of drug delivery systems based on MBGs is the control of their release behavior. In this work, Layer-by-layer (LbL) deposition of polyelectrolyte multi-layers was exploited as a powerful and versatile technique for coating the surface of Cu-substituted MBG nanoparticles with innovative multifunctional drug delivery systems for co-releasing of therapeutic copper ions (exerting pro-angiogenic and anti-bacterial effects) and an anti-inflammatory drug (ibuprofen). Two different routes were investigated: in the first strategy, chitosan and alginate were assembled by forming the multi-layered surface, and, successively, ibuprofen was loaded by incipient wetness impregnation, while in the second approach, alginate was replaced by ibuprofen, introduced as polyelectrolyte layer. Zeta-potential, TGA and FT-IR spectroscopy were measured after the addition of each polyelectrolyte layer, confirming the occurrence of the stepwise deposition. In addition, the in vitro bioactivity and the ability to modulate the release of the cargo were evaluated. The polyelectrolyte coated-MBGs were proved to retain the peculiar ability to induce hydroxyapatite formation after 7 days of soaking in Simulated Body Fluid. Both copper ions and ibuprofen were co-released over time, showing a sustained release profile up to 14 days and 24 h, respectively, with a significantly lower burst release compared to the bare MBG particles.

Anti-inflammatory and antibacterial activities of cerium-containing mesoporous bioactive glass nanoparticles for drug-free biomedical applications

Mesoporous bioactive glass nanoparticles (MBGNPs) are attracting significant attention as suitable materials for multifunctional biomedical applications. In this study, cerium was incorporated into MBGNPs using two different approaches. In the first approach, cerium was added to the glass system directly during the synthesis, while in the second approach, cerium was added to the as-synthesized MBGNPs via the template ion-exchange method. The influence of the method of synthesis on the physicochemical properties of nanoparticles was examined by SEM, TEM, XRD, FTIR, and N₂ adsorption-desorption analyses. The MBGNPs exhibited spheroidal morphology and disordered mesoporous structure. XRD analysis confirmed the amorphous nature of the nanoparticles. The chemical composition was determined by the acid digestion method using ICP-OES. The influence of the synthesis method on the specific surface area, mesoporosity, and solubility of synthesized nanoparticles in Tris/HCl (pH 7.4) and acetate (pH 4.5) buffer has also been studied. The obtained Ce containing MBGNPs were non-cytotoxic toward ​preosteoblast MC3T3-E1 cells in contact with nanoparticles in a concentration of up to 100 ​μg/mL. The anti-inflammatory effect of Ce containing MBGNPs was tested with lipopolysaccharides (LPS)-induced proinflammatory RAW 264.7 macrophage cells. Ce containing MBGNPs decreased the release of nitric oxide, indicating the anti-inflammatory response of macrophage cells. Ce containing MBGNPs also showed antibacterial activity against S. aureus and E. coli. The mentioned features of the obtained MBGNPs make them useful in a variety of biomedical applications, considering their biocompatibility, anti-inflammatory response, and enhanced antibacterial effect.

Poly(tannic acid) nanocoating based surface modification for construction of multifunctional composite CeO2NZs to enhance cell proliferation and antioxidative viability of preosteoblasts

Ceria (CeO₂) based materials possess many antioxidant enzyme-like activities and unique properties for bone repair, but their free radical scavenging function is still insufficient. In order to deal with the complex oxidative stress environment in bone repair, multifunctional composite CeO₂ nanozymes (CeO₂NZs), featuring multiple antioxidative properties, were constructed via surface modification on CeO₂NZs with nanoscale poly(tannic acid) (PTA) coatings. Moreover, we adjusted pH conditions (ranging from 4 to 9) to effectively control the formation and antioxidative properties of PTA coatings on CeO₂NZ surfaces. Here, the physical properties of this novel inorganic and organic composite antioxidant, such as surface morphology, particle size, crystal structure, surface charge and element composition, were thoroughly characterized. The PTA/CeO₂NZs showed obvious coating morphology under weak acid conditions (pH = 5-6), and the PTA layer at pH = 5 is about 1 nm in thickness. Compared with untreated CeO₂NZs, the PTA/CeO₂NZs showed stronger SOD-like activity and obviously higher free radical scavenging rate (for both ABTS⁺˙ and DPPH˙).Notably, this composite antioxidative nanozyme not only exhibited favorable cell proliferation of preosteoblasts (MC3T3-E1) but also provided strong antioxidative property to maintain cell vitality against H₂O₂ induced oxidative damage. In particular, this study provides new insights into the designing of surface polyphenolic coatings at the nanoscale, and these multiple antioxidative properties shown by PTA coated CeO₂NZs make them suitable for protecting cells under the oxidative stress environment.

Quercetin-Loaded Ceria Nanocomposite Potentiate Dual-Directional Immunoregulation via Macrophage Polarization against Periodontal Inflammation

Macrophage polarization toward M1 phenotype (pro-inflammation) is closely associated with the destructive phase of periodontal inflammation. Nanoceria is verified to inhibit M1 polarization of macrophages by the favorable ability of reactive oxygen species (ROS) scavenging. However, the function of nanoceria on macrophage polarization toward M2 phenotype (anti-inflammation) in reparative phase of periodontal inflammation is quite limited. In this work, by introducing an antioxidant drug quercetin onto nano-octahedral ceria, synergistic and intense regulation of host immunity against periodontal disease is realized. Such nanocomposite can control the phenotypic switch of macrophages by not only inhibition of M1 polarization for suppressing the damage in the destructive phase but also promotion of M2 polarization for regenerating the surrounding tissues in reparative phase of periodontal disease. As-prepared nanocomposite can effectively increase the M2/M1 ratio of macrophage polarization in inflammatory cellular models by lipopolysaccharide stimulation. More importantly, the nanocomposite also exerts an improved therapeutic potential against local inflammation by significant downregulation of pro-inflammatory cytokines and upregulation of anti-inflammatory cytokines in an animal model with periodontal inflammation. Therefore, this newly developed nanomedicine is efficient in ROS scavenging and driving pro-inflammatory macrophages to the anti-inflammatory phenotype to eliminate inflammation, thereby providing a promising candidate for treating periodontal inflammation.

Porous Nanomaterials Targeting Autophagy in Bone Regeneration

Porous nanomaterials (PNMs) are nanosized materials with specially designed porous structures that have been widely used in the bone tissue engineering field due to the fact of their excellent physical and chemical properties such as high porosity, high specific surface area, and ideal biodegradability. Currently, PNMs are mainly used in the following four aspects: (1) as an excellent cargo to deliver bone regenerative growth factors/drugs; (2) as a fluorescent material to trace cell differentiation and bone formation; (3) as a raw material to synthesize or modify tissue engineering scaffolds; (4) as a bio-active substance to regulate cell behavior. Recent advances in the interaction between nanomaterials and cells have revealed that autophagy, a cellular survival mechanism that regulates intracellular activity by degrading/recycling intracellular metabolites, providing energy/nutrients, clearing protein aggregates, destroying organelles, and destroying intracellular pathogens, is associated with the phagocytosis and clearance of nanomaterials as well as material-induced cell differentiation and stress. Autophagy regulates bone remodeling balance via directly participating in the differentiation of osteoclasts and osteoblasts. Moreover, autophagy can regulate bone regeneration by modulating immune cell response, thereby modulating the osteogenic microenvironment. Therefore, autophagy may serve as an effective target for nanomaterials to facilitate the bone regeneration process. Increasingly, studies have shown that PNMs can modulate autophagy to regulate bone regeneration in recent years. This paper summarizes the current advances on the main application of PNMs in bone regeneration, the critical role of autophagy in bone regeneration, and the mechanism of PNMs regulating bone regeneration by targeting autophagy.

Cerium Containing Bioactive Glasses: A Review

Bioactive glasses (BGs) for biomedical applications are doped with therapeutic inorganic ions (TIIs) in order to improve their performance and reduce the side effects related to the surgical implant. Recent literature in the field shows a rekindled interest toward rare earth elements, in particular cerium, and their catalytic properties. Cerium-doped bioactive glasses (Ce-BGs) differ in compositions, synthetic methods, features, and in vitro assessment. This review provides an overview on the recent development of Ce-BGs for biomedical applications and on the evaluation of their bioactivity, cytocompatibility, antibacterial, antioxidant, and osteogenic and angiogenic properties as a function of their composition and physicochemical parameters.

Incorporation of cerium oxide into zirconia toughened alumina ceramic promotes osteogenic differentiation and osseointegration

Due to its high wear resistance and good biocompatibility, zirconia toughened alumina (ZTA) is an ideal material used as load-bearing implant. However, ZTA needs to be modified to overcome its bio-inert and thus improve osseointegration. Cerium oxide, which has been proved to be a bone-friendly ceramic, might be a desired material to enhance the bioactivity of ZTA. In this study, ZTA and cerium oxide doped ZTA (ZTAC) were prepared via sintering method. The in vitro study showed that the addition of cerium oxide promoted MC3T3-E1 cell adhesion and spreading through upregulating ITG α5 and ITG β1. In addition, the incorporation of cerium oxide enhanced cell proliferation, ALP activity, and ECM mineralization capacity. Moreover, the incorporation of cerium oxide promoted the expressions of osteogenesis related genes, such as ALP, Col-I, and OCN. The in vivo implantation test via a SD rat model showed that the incorporation of cerium oxide promoted new bone formation and bone-implant integration. In summary, this study provided a new strategy to fabricate bioactive ZTA implant for potential application in orthopedics field.

Effect of Artemisinin-Loaded Mesoporous Cerium-Doped Calcium Silicate Nanopowder on Cell Proliferation of Human Periodontal Ligament Fibroblasts

Ion doping has rendered mesoporous structures important materials in the field of tissue engineering, as apart from drug carriers, they can additionally serve as regenerative materials. The purpose of the present study was the synthesis, characterization and evaluation of the effect of artemisinin (ART)-loaded cerium-doped mesoporous calcium silicate nanopowders (NPs) on the hemocompatibility and cell proliferation of human periodontal ligament fibroblasts (hPDLFs). Mesoporous NPs were synthesized in a basic environment via a surfactant assisted cooperative self-assembly process and were characterized using Scanning Electron Microscopy (SEM), X-ray Fluorescence Spectroscopy (XRF), Fourier Transform Infrared Spectroscopy (FT-IR), X-ray Diffraction Analysis (XRD) and N2 Porosimetry. The loading capacity of NPs was evaluated using Ultrahigh Performance Liquid Chromatography/High resolution Mass Spectrometry (UHPLC/HRMS). Their biocompatibility was evaluated with the MTT assay, and the analysis of reactive oxygen species was performed using the cell-permeable ROS-sensitive probe 2′,7′-dichlorodihydrofluorescein diacetate (H2DCFDA). The synthesized NPs presented a mesoporous structure with a surface area ranging from 1312 m²/g for undoped silica to 495 m²/g for the Ce-doped NPs, excellent bioactivity after a 1-day immersion in c-SBF, hemocompatibility and a high loading capacity (around 80%). They presented ROS scavenging properties, and both the unloaded and ART-loaded NPs significantly promoted cell proliferation even at high concentrations of NPs (125 μg/mL). The ART-loaded Ce-doped NPs with the highest amount of cerium slightly restricted cell proliferation after 7 days of culture, but the difference was not significant compared with the control untreated cells.

Investigation on the antimicrobial properties of cerium-doped bioactive glasses

Cerium‐doped bioactive glasses (Ce‐BGs) are implant materials that present high biocompatibility, modulate the levels of reactive oxygen species, and exert antimicrobial activity. The potential of BGs, 45S5, and K50S derived glasses doped with CeO₂ (1.2, 3.6, and 5.3 mol%) to inhibit the growth of pathogen microbes was thoroughly investigated according to the ISO 22196:2011 method properly adapted. A significant reduction of the E. coli charge was detected in all glasses, including the BGs without cerium. The evolution of pH of the medium not inoculated following the immersion of the Ce‐BGs was monitored. The presence of cerium did not affect markedly the pH trend, which increased rapidly for both compositions. The change of pH was strongly mitigated by the presence of 200 mM phosphate buffer pH 7.0 (PB) in the medium. In media buffered by PB, the growth of E. coli, Pseudomonas aeruginosa, Listeria monocytogenes, Staphylococcus aureus, and C. albicans was not affected by the presence of BGs doped or not with cerium, suggesting that the antibacterial activity of Ce‐BGs is linked to the increase of environmental pH rather than to specific ion effects. However, Ce‐BGs resulted promising biomaterials that associate low toxicity to normal cells to a considerable antimicrobial effect, albeit the latter is not directly associated with the presence of cerium.

Combination of Selective Etching and Impregnation toward Hollow Mesoporous Bioactive Glass Nanoparticles

In this study, binary SiO2-CaO hollow mesoporous bioactive glass nanoparticles (HMBGNs) are prepared by combing selective etching and impregnation strategies. Spherical silica particles (SiO2 NPs) are used as hard cores to assemble cetyltrimethylammonium bromide (CTAB)/silica shells, which are later removed by selective etching to generate a hollow structure. After the removal of CTAB by calcination, the mesoporous shell of particles is formed. Calcium (Ca) is incorporated into the particles using impregnation by soaking the etched SiO2 NPs in calcium nitrate aqueous solution. The amount of incorporated Ca is tailorable by controlling the ratio of SiO2 NPs:calcium nitrate in the soaking solution. The produced HMBGNs are bioactive, as indicated by the rapid formation of hydroxyapatite on their surfaces after immersion in simulated body fluid. In a direct culture with MC3T3-E1 cells, HMBGNs were shown to exhibit concentration-dependent cytotoxicity and can stimulate osteogenic differentiation of MC3T3-E1 cells at concentrations of 1, 0.5, and 0.25 mg/mL. Our results indicate that the combination of selective etching and impregnation is a feasible approach to produce hierarchical HMBGNs. The produced hollow particles have potential in drug delivery and bone tissue regeneration applications, and should be further investigated in detailed in vitro and in vivo studies.

Multi-functional silica-based mesoporous materials for simultaneous delivery of biologically active ions and therapeutic biomolecules

Mesoporous silica-based materials, especially mesoporous bioactive glasses (MBGs), are being highly considered for biomedical applications, including drug delivery and tissue engineering, not only because of their bioactivity and biocompatibility but also due to their tunable composition and potential use as drug delivery carriers owing to their controllable nanoporous structure. Numerous researches have reported that MBGs can be doped with various therapeutic ions (strontium, copper, magnesium, zinc, lithium, silver, etc.) and loaded with specific biomolecules (e.g., therapeutic drugs, antibiotics, growth factors) achieving controllable loading and release kinetics. Therefore, co-delivery of ions and biomolecules using a single MBG carrier is highly interesting as this approach provides synergistic effects toward improved therapeutic outcomes in comparison to the strategy of sole drug or ion delivery. In this review, we discuss the state-of-the-art in the field of mesoporous silica-based materials used for co-delivery of ions and therapeutic drugs with osteogenesis/cementogenesis, angiogenesis, antibacterial and anticancer properties. The analysis of the literature reveals that specially designed mesoporous nanocarriers can release multiple ions and drugs at therapeutically safe and relevant levels, achieving the desired biological effects (in vivo, in vitro) for specific biomedical applications. It is expected that this review on the ion/drug co-delivery concept using MBG carriers will shed light on the advantages of such co-delivery systems for clinical use. Areas for future research directions are identified and discussed. STATEMENT OF SIGNIFICANCE: Many studies in literature focus on the potential of single drug or ion delivery by mesoporous silica-based materials, exploiting the bioactivity, biocompatibility, tunable composition and controllable nanoporosity of these materials. Recenlty, studies have adopted the "dual-delivery" concept, by designing multi-functional mesoporous silica-based systems which are capable to deliver both biologically active ions and biomolecules (growth factors, drugs) simultaneously in order to achieve synergy of their complementary therapeutic activities. This review summarizes the state of the art in the field, with focus on osteogenesis/cementogenesis, angiogenesis, antibacterial and anticancer properties, and discusses the challenges and prospects for further progress in this area, expecting to generate broader interest in the technology for applications in disease treatment and regenerative medicine.

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.

Tailoring Materials for Modulation of Macrophage Fate

Human immune system acts as a pivotal role in the tissue homeostasis and disease progression. Immunomodulatory biomaterials that can manipulate innate immunity and adaptive immunity hold great promise for a broad range of prophylactic and therapeutic purposes. This review is focused on the design strategies and principles of immunomodulatory biomaterials from the standpoint of materials science to regulate macrophage fate, such as activation, polarization, adhesion, migration, proliferation, and secretion. It offers a comprehensive survey and discussion on the tunability of material designs regarding physical, chemical, biological, and dynamic cues for modulating macrophage immune response. The range of such tailorable cues encompasses surface properties, surface topography, materials mechanics, materials composition, and materials dynamics. The representative immunoengineering applications selected herein demonstrate how macrophage-immunomodulating biomaterials are being exploited for cancer immunotherapy, infection immunotherapy, tissue regeneration, inflammation resolution, and vaccination. A perspective on the future research directions of immunoregulatory biomaterials is also provided.