Porous bioactive glass micro- and nanospheres with controlled morphology: developments, properties and emerging biomedical applications

The influence of copper-doped mesoporous bioactive nanospheres on the temperature rise during polymerization, polymer cross-linking density, monomer release and embryotoxicity of dental composites

OBJECTIVES

Composites with copper-doped mesoporous bioactive nanospheres (Cu-MBGN) were developed to prevent secondary caries by imparting antimicrobial and ion-releasing/remineralizing properties.

METHODS

Seven experimental composites containing 1, 5 or 10 wt% Cu-MBGN, the corresponding inert controls (silica) and bioactive controls (bioactive glass 45S5) were prepared. The temperature rise during light curing, cross-linking density by ethanol softening test, monomer elution and their potential adverse effects on the early development of zebrafish Danio rerio was investigated.

RESULTS

Materials combining Cu-MBGN and silica showed the highest resistance to ethanol softening, as did the bioactive controls. Cu-MBGN composites showed significant temperature rise and reached maximum temperature in the shortest time. Bisphenol A was not detected, while bis-GMA was found only in the control materials and TEGDMA in the eluates of all materials. There was no increase in zebrafish mortality and abnormality rates during exposure to the eluates of any of the materials.

CONCLUSIONS

The composite with 5 wt% Cu-MBGN combined with nanosilica fillers showed the lowest ethanol softening, indicating the polymer's highest durability and cross-linking density. Despite the TEGDMA released from all tested materials, no embryotoxic effect was observed.

Dermaseptin B2 bioactive gene's potential for anticancer and anti-proliferative effect is linked to the regulation of the BAX/BBC3/AKT pathway

Dermaseptin B2 (DrsB2) is an antimicrobial peptide with anticancer and angiostatic properties. We aimed to assess the in vitro inhibitory effect of pDNA/DrsB2 on the growth of breast cancer cells and its impact on the expression of genes involved in the BAX/BBC3/AKT pathway. The nucleic acid sequence of DrsB2 was artificially synthesized and inserted into the pcDNA3.1( +) Mammalian Expression Plasmid. PCR testing and enzyme digesting procedures evaluated the accuracy of cloning. The vectors were introduced into cells using LipofectamineTM2000 transfection reagent. The breast cancer cells were assessed by flow cytometry, MTT assessment, soft agar colony method, and wound healing investigation. The gene's transcription was evaluated using real-time PCR with a significance level of P < 0.05. The recombinant plasmid harboring the pDNA/DrsB2 vector was effectively produced, and the gene sequence showed absolute homogeneity (100% similarity) with the DrsB2 gene. The transfection effectiveness of MCF-7 and MCF-10A cells was 79% and 68%, respectively. The findings are measured using the growth inhibition 50% (GI50) metric, which indicates the concentration of pDNA/DrsB2 that stops 50% of cell growth. The proportions of early apoptosis, late apoptosis, necrosis, and viable MCF-7 cells in the pDNA/DrsB2 group were 40.50%, 2.31%, 1.69%, and 55.50%, respectively. The results showed a 100% increase in gene expression in programmed cell death following treatment with pDNA/DrsB2 (**P < 0.01). To summarize, the results described in this work offer new possibilities for treating cancer by targeting malignancies via pDNA/DrsB2 and activating the BAX/BBC3/AKT signaling pathways.

Engineering mesoporous bioactive glasses for emerging stimuli-responsive drug delivery and theranostic applications

Mesoporous bioactive glasses (MBGs), which belong to the category of modern porous nanomaterials, have garnered significant attention due to their impressive biological activities, appealing physicochemical properties, and desirable morphological features. They hold immense potential for utilization in diverse fields, including adsorption, separation, catalysis, bioengineering, and medicine. Despite possessing interior porous structures, excellent morphological characteristics, and superior biocompatibility, primitive MBGs face challenges related to weak encapsulation efficiency, drug loading, and mechanical strength when applied in biomedical fields. It is important to note that the advantageous attributes of MBGs can be effectively preserved by incorporating supramolecular assemblies, miscellaneous metal species, and their conjugates into the material surfaces or intrinsic mesoporous networks. The innovative advancements in these modified colloidal inorganic nanocarriers inspire researchers to explore novel applications, such as stimuli-responsive drug delivery, with exceptional in-vivo performances. In view of the above, we outline the fabrication process of calcium-silicon-phosphorus based MBGs, followed by discussions on their significant progress in various engineered strategies involving surface functionalization, nanostructures, and network modification. Furthermore, we emphasize the recent advancements in the textural and physicochemical properties of MBGs, along with their theranostic potentials in multiple cancerous and non-cancerous diseases. Lastly, we recapitulate compelling viewpoints, with specific considerations given from bench to bedside.

Zinc-doped bioactive glass-functionalized polyetheretherketone to enhance the biological response in bone regeneration

Polyether ether ketone (PEEK) is gaining recognition as a highly promising polymer for orthopedic implants, attributed to its exceptional biocompatibility, ease of processing, and radiation resistance. However, its long-term in vivo application faces challenges, primarily due to suboptimal osseointegration from postimplantation inflammation and immune reactions. Consequently, biofunctionalization of PEEK implant surfaces emerges as a strategic approach to enhance osseointegration and increase the overall success rates of these implants. In our research, we engineered a multifaceted PEEK implant through the in situ integration of chitosan-coated zinc-doped bioactive glass nanoparticles (Zn-BGNs). This novel fabrication imbues the implant with immunomodulatory capabilities while bolstering its osseointegration potential. The biofunctionalized PEEK composite elicited several advantageous responses; it facilitated M2 macrophage polarization, curtailed the production of inflammatory mediators, and augmented the osteogenic differentiation of bone marrow mesenchymal stem cells. The experimental findings underscore the vital and intricate role of biofunctionalized PEEK implants in preserving normal bone immunity and metabolism. This study posits that utilizing chitosan-BGNs represents a direct and effective method for creating multifunctional implants. These implants are designed to facilitate biomineralization and immunomodulation, making them especially apt for orthopedic applications.

Surface engineering of mesoporous bioactive glass nanoparticles with bacteriophages for enhanced antibacterial activity

Binary SiO2-CaO mesoporous bioactive glass nanoparticles (MBGNs) are multifunctional biomaterials able to promote osteogenic, angiogenic, and immunomodulatory activities. MBGNs have been applied in a variety of tissue regeneration strategies. However, MBGNs lack strong antibacterial activity and current strategies (loading of antibacterial ions or antibiotics) toward enhanced antibacterial activity may cause cytotoxicity or antibiotic resistance. Here we engineered MBGNs using bacteriophages (phages) to enhance the antibacterial activity. Salmonella Typhimurium (S. T) phage PFPV25.1 that can infect Salmonella enterica serovar Typhimurium strain LT2 was used as a model phage to engineer MBGNs. MBGNs were first modified with amine groups to enhance the affinity between phages and MBGNs surfaces. Afterward, the physicochemical and antibacterial activity of phage-engineered MBGNs was evaluated. The results showed that S. T phage PFPV25.1 was successfully bound onto MBGNs surfaces without losing their bioactivity. A higher quantity of phages could be bounded onto amine-functionalized MBGNs than onto non-functionalized MBGNs. Phages on amine-functionalized MBGNs exhibited higher antibacterial activity. The stability test showed that phages could remain on amine-functionalized MBGNs for over 28 days. This work provides valuable information on developing phage-modified MBGNs as a new and effective antibacterial system for biomedical applications.

An injectable gel based on photo-cross-linkable hyaluronic acid and mesoporous bioactive glass nanoparticles for periodontitis treatment

Guided bone regeneration (GBR) is an effective strategy to promote periodontal tissue repair. The current study aimed to develop an injectable gel for GBR, composed of photo-cross-linkable hyaluronic acid and mesoporous bioactive glass nanoparticles (MBGNs) loaded with antibacterial minocycline hydrochloride (MNCl). Hyaluronic acid modified with methacrylic anhydride (MHA) that could be cross-linked under UV irradiation was first synthesized. Dynamic rheological evaluation of MHA under UV was carried out to determine its in-situ gelling feasibility and stability. Morphological and mechanical characterization was performed to determine the optimal concentration of MHA gels. Sol-gel derived MBGNs loaded with MNCl were further incorporated into MHA gels to obtain the injectable drug-loaded MBGN-MNCl/MHA gels. In vitro antibacterial, anti-inflammatory and osteogenic effects of this gel were evaluated. It was shown that the MHA gel obtained from 3 % MHA under UV treatment of 30s exhibited a suitable porous structure with a compressive strength of 100 kPa. MBGNs with particle size of ∼120 nm and mesopores were confirmed by TEM and SEM. MBGNs had a loading capacity of ∼120 mg/g for MNCl, exhibiting a sustained release behavior. The MBGN-MNCl/MHA gel was shown to effectively inhibit the proliferation of Streptococcus mutans and the expression of pro-inflammatory factors IL-6 and TNF-α by macrophages. It could on the other hand significantly promote the expression of osteogenic-related genes ALP, Runx2, OPN, and osterix of MC3T3-E1 cells. In conclusion, the current design using photo-crosslinkable MHA gel embedded with MNCl loaded MBGNs can serve as a promising injectable formulation for GBR treatment of irregular periodontal defects.

Extracellular and intracellular effects of bioactive glass nanoparticles on osteogenic differentiation of bone marrow mesenchymal stem cells and bone regeneration in zebrafish osteoporosis model

Bioactive glass nanoparticles (BGNs) are well-recognized multifunctional biomaterials for bone tissue regeneration due to their capability to stimulate various cellular processes through released biologically active ions. Understanding the correlation between BGN composition and cellular responses is key to developing clinically usable BGN-based medical devices. This study investigated the influence of CaO content of binary SiO2-CaO BGNs (CaO ranging from 0 to 10 mol%) on osteogenic differentiation of rat bone marrow mesenchymal stem cells (rBMSCs) and in vivo bone regeneration in zebrafish osteoporosis model. The results showed that BGNs could promote osteogenic differentiation of rBMSCs by indirectly releasing active ions or directly interacting with rBMSCs by internalization. In both situations, BGNs of a higher CaO content could promote the osteogenic differentiation of rBMSCs to a greater extent. The internalized BGNs could activate the transcription factors RUNX2 and OSX, leading to the expression of osteogenesis-related genes. The results in the zebrafish osteoporosis model indicated that the presence of BGNs of higher CaO contents could enhance bone regeneration and rescue dexamethasone-induced osteoporosis to a greater extent. These findings demonstrate that BGNs can stimulate osteogenic differentiation of rBMSCs by releasing active ions or internalization. A higher CaO content facilitates osteogenesis and bone regeneration of zebrafish as well as relieving dexamethasone-induced osteoporosis. The zebrafish osteoporosis model can be a potent tool for evaluating the in vivo bone regeneration effects of bioactive materials. STATEMENT OF SIGNIFICANCE: Bioactive glass nanoparticles (BGNs) are increasingly used as fillers of nanocomposites or as delivery platforms of active ions to regenerate bone tissue. Various studies have shown that BGNs can enhance osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) by releasing active ions. However, the correlation between BGN composition and cellular responses and in vivo bone regeneration effect has still not been well investigated. Establishment of a suitable in vivo animal model for investigating this correlation is also challenging. The present study reports the influence of CaO content in binary SiO2-CaO BGNs on osteogenic differentiation of BMSCs extracellularly and intracellularly. This study also demonstrates the suitability of zebrafish osteoporosis model to investigate in vivo bone regeneration effect of BGNs.

Opportunities for Bioactive Glass in Gastrointestinal Conditions: A Review of Production Methodologies, Morphology, Composition, and Performance

Bioactive glasses (BGs) are widely used in orthopedic and dental applications for their ability to stimulate endogenous bone formation and regeneration. BG applications more recently broadened to include soft tissue conditions, based on their ability to stimulate angiogenesis, soft tissue regeneration, and wound healing. Sol-gel synthesis has helped facilitate this expansion, allowing formulators to tailor the morphological characteristics of the BG matrix. The effectiveness of BGs in skin wound healing is viewed as a gateway for their use as both a therapeutic and drug delivery platform in other soft tissue applications, notably gastrointestinal (GI) applications, which form the focus of this review. Recent changes in international guidelines for GI conditions shifted clinical objectives from symptom management to mucosal wound healing. The additional scrutiny of proton pump inhibitor (PPI) safety, increasing burden of disease, and financial costs associated with gastroesophageal reflux disease (GERD), peptic ulcer disease (PUD), and inflammatory bowel disease (IBD) open new clinical possibilities for BG. This narrative literature review intersects materials engineering, formulation science, and clinical practice, setting it apart from prior literature. Broadly, current evidence for BG applications in GI conditions is sparse and under-developed, which this review directly addresses. It explores and synthesizes evidence that supports the potential use of sol-gel-derived BG for the efficacious treatment of soft tissue applications, with specific reference to GI conditions. An overview with comparative analysis of current BG synthesis techniques and associated challenges is presented, and influences of composition, biologically active ions, and morphological characteristics in soft tissue applications are explored. To contextualize this, sol-gel-derived BGs are proposed as a dual, tailorable therapeutic and drug delivery platform for upper and lower GI conditions. Future directions for this largely untapped area of translational research are also proposed, based on extant literature.

AuNP-Loaded Electrospinning Membrane Cooperated with CDs for Periodontal Tissue Engineering

BACKGROUND

Guided bone regeneration (GBR) is commonly used to regenerate periodontal tissue. However, the bone inductivity and antibacterial properties of the GBR membranes currently in use are severely limited. This issue can be resolved by loading growth factors and antibiotics. Bioactive substitutes, such as Au nanoparticles (AuNPs) and carbon quantum dots (CDs), were proposed to prevent the denaturation of osteogenic growth factors and the induction of antibacterial drug resistance.

METHODS

Ornidazole was initially used as the raw material to prepare the CDs, followed by the incorporation of an optimal ratio of nanoparticles to produce the electrospun membrane doped with AuNPs and novel traceable antibacterial CDs. The morphology of the membrane was characterized. The adhesion, proliferation, and osteogenic differentiation of cells on the membrane were evaluated in vitro. The antimicrobial characteristics of the membrane were also investigated. The electrospun membrane was implanted into a rat skull defect model in vivo to investigate its osteogenic potential.

RESULTS

The blending of nanomaterials did not affect the micro morphology of the fiber, resulting in enhanced mechanical properties. Membranes doped with AuNPs and CDs exhibited excellent biocompatibility, increased ALP activity, improved calcified nodules, and increased expression of osteogenic-associated proteins, in addition to pronounced antibacterial effects. The membrane also demonstrated excellent osteogenic characteristics in rat models.

CONCLUSION

The synergistic effect of loaded AuNPs electrospun fiber membrane with CDs can promote periodontal bone regeneration and exert antibacterial activity.

Nanocore-Shell Bone Filler Contained Mesoporous Silica Modified with Hydroxyapatite Precursors; Wrapped in a Natural Metal-Phenolic Network

Various therapeutic strategies have been developed to address bone diseases caused by aging society and skeletal defects caused by trauma or accidental events. One such approach is using bone fillers, such as hydroxyapatite (HA) and bioactive glasses. Although they have provided effective osteogenesis, infection and inflammation due to the surgical procedure and uncontrolled ion release can hinder the efficiency of bone regeneration. In response to these challenges, immobilizing a neutral metal-phenolic network on the surface of osteoconductive nanoparticles would be the master key to achieving a gradual, controlled release during the mineralization period and reducing infection and inflammation through biological pathways. In this regard, a mesoporous silica nanocomposite modified by an HA precursor was synthesized to enhance bone regeneration. In addition, to improve the therapeutic effects, its surface was wrapped with a magnesium-phenolic network made from pomegranate extract, which can simultaneously produce anti-inflammatory and antibacterial effects. The obtained core-shell nanocomposite was characterized by its physicochemical properties, biocompatibility, and bioactivity. The in vitro studies revealed that the synthesized nanocomposite exhibits higher osteogenic activity than the control groups, as confirmed by alizarin red staining. Moreover, the nanocomposite maintained low toxicity as measured by the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay and increased antibacterial activity against Staphylococcus aureus and Escherichia coli compared with the control groups. Therefore, this research presents a promising strategy for bone regeneration, combining the advantages of mesoporous silica nanocomposite modified by an HA precursor with the beneficial effects of a magnesium-phenolic network.

Bulk and transparent supramolecular glass from evaporation-induced noncovalent polymerization of nucleosides

Understanding the nature of glass is one of the most important challenges in chemistry, physics, and materials science. In this study, transparent bulk supramolecular glasses with excellent optical behaviors and good mechanical properties were fabricated via the non-covalent polymerization of nucleosides. Hydrogen bonding is the main driving force in the formation of bulk supramolecular glasses. The directional and saturated character of hydrogen bonding enables the formation of a short-range ordered structure, while the weak nature and reversibility of hydrogen bonds allow for the asymmetric and random connections of the short-range ordered structure into a long-range disordered network. Various relaxations, including β, γ, and δ relaxations, are observed at temperatures below the glass transition temperature, demonstrating the metastable nature of bulk supramolecular glasses. This investigation offers supramolecular insights into the nature of glass materials.

Citric Acid Catalyst-Assisted Bioactive Glass with Hydrogen Peroxide for In Vitro Bioactivity and Biodegradability Using Sol-Gel Method

In this study, carbon-free and completely soluble hydrogen peroxide (H2O2) was utilized in place of conventional surfactants as a pore-forming agent. Citric acid was also used in low concentration for the hydrolysis reaction. A sol-gel method was used to prepare bioactive glass (BG) specimens of H2O2-untreated BG, 1M, 2M, and 3M H2O2-treated BGs. X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), energy-dispersive spectroscopy (EDS), and nitrogen adsorption/desorption isotherm with the Brunauer-Emmett-Teller (BET) method were used for analyzing the samples' phase, surface morphology, chemical composition, constituent composition, pore size, and specific surface area respectively. In vitro bioactivity, as well as biodegradability tests, was performed on samples by immersing them in simulated body fluid (SBF) solution. According to the results, BG particles treated with 2 M H2O2 exhibited higher specific surface area (SSA), which is 189.55 cc/g, and better in vitro bioactivity and biodegradability.

Synergistic effect of ion-releasing fillers on the remineralization and mechanical properties of resin-dentin bonding interfaces

In modern restorative dentistry, adhesive resin materials are vital for achieving minimally invasive, esthetic, and tooth-preserving restorations. However, exposed collagen fibers are found in the hybrid layer of the resin-dentin bonding interface due to incomplete resin penetration. As a result, the hybrid layer is susceptible to attack by internal and external factors such as hydrolysis and enzymatic degradation, and the durability of dentin bonding remains limited. Therefore, efforts have been made to improve the stability of the resin-dentin interface and achieve long-term clinical success. New ion-releasing adhesive resin materials are synthesized by introducing remineralizing ions such as calcium and phosphorus, which continuously release mineral ions into the bonding interface in resin-bonded restorations to achieve dentin biomimetic remineralization and improve bond durability. As an adhesive resin material capable of biomimetic mineralization, maintaining excellent bond strength and restoring the mechanical properties of demineralized dentin is the key to its function. This paper reviews whether ion-releasing dental adhesive materials can maintain the mechanical properties of the resin-dentin bonding interface by supplementing the various active ingredients required for dentin remineralization from three aspects: phosphate, silicate, and bioactive glass.

Correlating the Effect of Composition and Textural Properties on Bioactivity for Pristine and Copper-Doped Binary Mesoporous Bioactive Glass Nanoparticles

Multifunctional substitutes for bone tissue engineering have gained significant interest in recent years in the aim to address the clinical challenge of treating large bone defects resulting from surgical procedures. Sol-gel mesoporous bioactive glass nanoparticles (MBGNs) have emerged as a promising solution due to their high reactivity and versatility. The effect of calcium content on MBGNs textural properties is well known. However, the relationship between their composition, textural properties, and reactivity has not yet been thoroughly discussed in existing studies, leading to divergent conclusions. In this study, pristine and copper-doped binary MGBNs were synthesized by a modified Stöber method, using a cationic surfactant as pore-templating agent. An opposite evolution between calcium content (12-26 wt%) and specific surface area (909-208 m2/g) was evidenced, while copper introduction (8.8 wt%) did not strongly affect the textural properties. In vitro bioactivity assessments conducted in simulated body fluid (SBF) revealed that the kinetics of hydroxyapatite (HAp) crystallization are mainly influenced by the specific surface area, while the composition primarily controls the quantity of calcium phosphate produced. The MBGNs exhibited a good bioactivity within 3 h, while Cu-MBGNs showed HAp crystallization after 48 h, along with a controlled copper release (up to 84 ppm at a concentration of 1 mg/mL). This comprehensive understanding of the interplay between composition, textural properties, and bioactivity, offers insights for the design of tailored MBGNs for bone tissue regeneration with additional biological and antibacterial effects.

Bi-lineage inducible and immunoregulatory electrospun fibers scaffolds for synchronous regeneration of tendon-to-bone interface

Facilitating regeneration of the tendon-to-bone interface can reduce the risk of postoperative retear after rotator cuff repair. Unfortunately, undesirable inflammatory responses following injury, difficulties in fibrocartilage regeneration, and bone loss in the surrounding area are major contributors to suboptimal tendon-bone healing. Thus, the development of biomaterials capable of regulating macrophage polarization to a favorable phenotype and promoting the synchronous regeneration of the tendon-to-bone interface is currently a top priority. Here, strontium-doped mesoporous bioglass nanoparticles (Sr-MBG) were synthesized through a modulated sol-gel method and Bi-lineage Inducible and Immunoregulatory Electrospun Fibers Scaffolds (BIIEFS) containing Sr-MBG were fabricated. The BIIEFS were biocompatible, showed sustained release of multiple types of bioactive ions, enhanced osteogenic and chondrogenic differentiation of mesenchymal stem cells (MSCs), and facilitated macrophage polarization towards the M2 phenotype in vitro. The implantation of BIIEFS at the torn rotator cuff resulted in greater numbers of M2 macrophages and the synchronous regeneration of tendon, fibrocartilage, and bone at the tendon-to-bone interface, leading to a significant improvement in the biomechanical strength of the supraspinatus tendon-humerus complexes. Our research offers a feasible strategy to fabricate immunoregulatory and multi-lineage inducible electrospun fibers scaffolds incorporating bioglass nanoparticles for the regeneration of soft-to-hard tissue interfaces.

Injectable mesoporous bioactive glass/sodium alginate hydrogel loaded with melatonin for intervertebral disc regeneration

Intervertebral disc degeneration (IDD) is a major contributing factor to both lower back and neck pain. As IDD progresses, the intervertebral disc (IVD) loses its ability to maintain its disc height when subjected to axial loading. This failure in the weight-bearing capacity of the IVD is a characteristic feature of degeneration. Natural polymer-based hydrogel, derived from biological polymers, possesses biocompatibility and is able to mimic the structure of extracellular matrix, enabling them to support cellular behavior. However, their mechanical performance is relatively poor, thus limiting their application in IVD regeneration. In this study, we developed an injectable composite hydrogel, namely, Mel-MBG/SA, which is similar to natural weight-bearing IVD. Mesoporous bioactive glasses not only enhance hydrogels, but also act as carriers for melatonin (Mel) to suppress inflammation during IDD. The Mel-MBG/SA hydrogel further provides a mixed system with sustained Mel release to alleviate IL-1β-induced oxidative stress and relieve inflammation associated with IDD pathology. Furthermore, our study shows that this delivery system can effectively suppress inflammation in the rat tail model, which is expected to further promote IVD regeneration. This approach presents a novel strategy for promoting tissue regeneration by effectively modulating the inflammatory environment while harnessing the mechanical properties of the material.

3D Bioprinting of a Bioactive Composite Scaffold for Cell Delivery in Periodontal Tissue Regeneration

Hydrogels have been widely applied to the fabrication of tissue engineering scaffolds via three-dimensional (3D) bioprinting because of their extracellular matrix-like properties, capacity for living cell encapsulation, and shapeable customization depending on the defect shape. However, the current hydrogel scaffolds show limited regeneration activity, especially in the application of periodontal tissue regeneration. In this study, we attempted to develop a novel multi-component hydrogel that possesses good biological activity, can wrap living cells for 3D bioprinting and can regenerate periodontal soft and hard tissue. The multi-component hydrogel consisted of gelatin methacryloyl (GelMA), sodium alginate (SA) and bioactive glass microsphere (BGM), which was first processed into hydrogel scaffolds by cell-free 3D printing to evaluate its printability and in vitro biological performances. The cell-free 3D-printed scaffolds showed uniform porous structures and good swelling capability. The BGM-loaded scaffold exhibited good biocompatibility, enhanced osteogenic differentiation, apatite formation abilities and desired mechanical strength. The composite hydrogel was further applied as a bio-ink to load with mouse bone marrow mesenchymal stem cells (mBMSCs) and growth factors (BMP2 and PDGF) for the fabrication of a scaffold for periodontal tissue regeneration. The cell wrapped in the hydrogel still maintained good cellular vitality after 3D bioprinting and showed enhanced osteogenic differentiation and soft tissue repair capabilities in BMP2- and PDGF-loaded scaffolds. It was noted that after transplantation of the cell- and growth factor-laden scaffolds in Beagle dog periodontal defects, significant regeneration of gingival tissue, periodontal ligament, and alveolar bone was detected. Importantly, a reconstructed periodontal structure was established in the treatment group eight weeks post-transplantation of the scaffolds containing the cell and growth factors. In conclusion, we developed a bioactive composite bio-ink for the fabrication of scaffolds applicable for the reconstruction and regeneration of periodontal tissue defects.

Mussel-Inspired Polydopamine Composite Mesoporous Bioactive Glass Nanoparticles: An Exploration of Potential Metal-Ion Loading Platform and In Vitro Bioactivity

Exploring new approaches to realize the possibility of incorporating biologically active elements into mesoporous silicate bioactive glass nanoparticles (MBG NPs) and guaranteeing their meso- structural integrity and dimensional stability has become an attractive and interesting challenge in biomaterials science. We present a postgrafting strategy for introducing different metal elements into MBG NPs. This strategy is mediated by polydopamine (PDA) coating, achieving uniform loading of copper or copper-cobalt on the particles efficiently and ensuring the stability of MBG NPs in terms of particle size, mesoporous structure, and chemical structure. However, the PDA coating reduced the ion-binding free energy of the MBG NPs for calcium and phosphate ions, resulting in the deposition of minimal CaP clusters on the PDA@MBG NP surface when immersed for 7 days in simulated body fluid, indicating the absence of hydroxyapatite mineralization.

Smart Dental Materials Intelligently Responding to Oral pH to Combat Caries: A Literature Review

Smart dental materials are designed to intelligently respond to physiological changes and local environmental stimuli to protect the teeth and promote oral health. Dental plaque, or biofilms, can substantially reduce the local pH, causing demineralization that can then progress to tooth caries. Progress has been made recently in developing smart dental materials that possess antibacterial and remineralizing capabilities in response to local oral pH in order to suppress caries, promote mineralization, and protect tooth structures. This article reviews cutting-edge research on smart dental materials, their novel microstructural and chemical designs, physical and biological properties, antibiofilm and remineralizing capabilities, and mechanisms of being smart to respond to pH. In addition, this article discusses exciting and new developments, methods to further improve the smart materials, and potential clinical applications.

Hydrothermally reinforcing hydroxyaptatite and bioactive glass on carbon nanofiber scafold for bone tissue engineering

As a bone tissue engineering scaffold, the objective of this study was to design hierarchical bioceramics based on an electrospun composite of carbon nanofibers (CNF) reinforced with hydroxyapatite (HA) and bioactive glasses (BGs) nanoparticles. The performance of the nanofiber as a scaffold for bone tissue engineering was enhanced by reinforcing it with hydroxyapatite and bioactive glass nanoparticles through a hydrothermal process. The influence of HA and BGs on the morphology and biological properties of carbon nanofibers was examined. The prepared materials were evaluated for cytotoxicity in vitro using the water-soluble tetrazolium salt assay (WST-assay) on Osteoblast-like (MG-63) cells, and oste-ocalcin (OCN), alkaline phosphatase (ALP) activity, total calcium, total protein, and tar-trate-resistant acid phosphatase (TRAcP) were measured. The WST-1, OCN, TRAcP, total calcium, total protein, and ALP activity tests demonstrated that scaffolds reinforced with HA and BGs had excellent in vitro biocompatibility (cell viability and proliferation) and were suitable for repairing damaged bone by stimulating bioactivity and biomarkers of bone cell formation.

Targeting Endogenous Reactive Oxygen Species Removal and Regulating Regenerative Microenvironment at Annulus Fibrosus Defects Promote Tissue Repair

The excessive reactive oxygen species (ROS) level, inflammation, and weak tissue regeneration ability after annulus fibrosus (AF) injury constitute an unfavorable microenvironment for AF repair. AF integrity is crucial for preventing disc herniation after discectomy; however, there is no effective way to repair the AF. Herein, a composite hydrogel integrating properties of antioxidant, anti-inflammation, and recruitment of AF cells is developed through adding mesoporous silica nanoparticles modified by ceria and transforming growth factor β3 (TGF-β3) to the hydrogels. The nanoparticle loaded gelatin methacrylate/hyaluronic acid methacrylate composite hydrogels eliminate ROS and induce anti-inflammatory M2 type macrophage polarization. The released TGF-β3 not only plays a role in recruiting AF cells but is also responsible for promoting extracellular matrix secretion. The composite hydrogels can be solidified in situ in the defect area to effectively repair AF in rats. The strategies targeting endogenous ROS removal and improving the regenerative microenvironment by the nanoparticle-loaded composite hydrogels have potential applications in AF repair and intervertebral disc herniation prevention.

Extensive Investigation on the Effect of Niobium Insertion on the Physical and Biological Properties of 45S5 Bioactive Glass for Dental Implant

Dental implants have emerged as one of the most consistent and predictable treatments in the oral surgery field. However, the placement of the implant is sometimes associated with bacterial infection leading to its loss. In this work, we intend to solve this problem through the development of a biomaterial for implant coatings based on 45S5 Bioglass® modified with different amounts of niobium pentoxide (Nb2O5). The structural feature of the glasses, assessed by XRD and FTIR, did not change in spite of Nb2O5 incorporation. The Raman spectra reveal the Nb2O5 incorporation related to the appearance of NbO4 and NbO6 structural units. Since the electrical characteristics of these biomaterials influence their osseointegration ability, AC and DC electrical conductivity were studied by impedance spectroscopy, in the frequency range of 102–106 Hz and temperature range of 200–400 K. The cytotoxicity of glasses was evaluated using the osteosarcoma Saos-2 cells line. The in vitro bioactivity studies and the antibacterial tests against Gram-positive and Gram-negative bacteria revealed that the samples loaded with 2 mol% Nb2O5 had the highest bioactivity and greatest antibacterial effect. Overall, the results showed that the modified 45S5 bioactive glasses can be used as an antibacterial coating material for implants, with high bioactivity, being also non-cytotoxic to mammalian cells.

Fabrication of submillimeter-sized spherical self-oscillating gels and control of their isotropic volumetric oscillatory behaviors

In this study, we established a fabrication method and analyzed the volumetric self-oscillatory behaviors of submillimeter-sized spherical self-oscillating gels. We validated that the manufactured submillimeter-sized spherical self-oscillating gels exhibited isotropic volumetric oscillations during the Belousov-Zhabotinsky (BZ) reaction. In addition, we experimentally elucidated that the volumetric self-oscillatory behaviors (i.e., period and amplitude) and the oscillatory profiles depended on the following parameters: (1) the molar composition of N-(3-aminopropyl)methacrylamide hydrochloride (NAPMAm) in the gels and (2) the concentration of Ru(bpy)₃-NHS solution containing an active ester group on conjugation. These clarified relationships imply that controlling the amount of Ru(bpy)₃ in the gel network could influence the gel volumetric oscillation during the BZ reaction. These results of submillimeter-sized and spherical self-oscillating gels bridge knowledge gaps in the current field because the gels with corresponding sizes and shapes have not been systematically explored yet. Therefore, our study could be a cornerstone for diverse applications of (self-powered) gels in various scales and shapes, including soft actuators exhibiting life-like functions.

Synthesis of Hierarchically Porous Bioactive Glass and Its Mineralization Activity

Mesoporous bioactive glass is a promising biomaterial for bone tissue engineering due to its good biocompatibility and bioactivity. In this work, we synthesized a hierarchically porous bioactive glass (HPBG) using polyelectrolyte-surfactant mesomorphous complex as template. Through the interaction with silicate oligomers, calcium and phosphorus sources were successfully introduced into the synthesis of hierarchically porous silica, and HPBG with ordered mesoporous and nanoporous structures was obtained. The morphology, pore structure and particle size of HPBG can be controlled by adding block copolymer as co-template or adjusting the synthesis parameters. The ability to induce hydroxyapatite deposition in simulated body fluids (SBF) demonstrated the good in vitro bioactivity of HPBG. Overall, this work provides a general method for the synthesis of hierarchically porous bioactive glasses.

Triple-functional bone adhesive with enhanced internal fixation, bacteriostasis and osteoinductive properties for open fracture repair

At present, effective fixation and anti-infection implant materials represent the mainstay for the treatment of open fractures. However, external fixation can cause nail tract infections and is ineffective for fixing small fracture fragments. Moreover, closed reduction and internal fixation during the early stage of injury can lead to potential bone infection, conducive to bone nonunion and delayed healing. Herein, we designed a bone adhesive with anti-infection, osteogenic and bone adhesion fixation properties to promote reduction and fixation of open fractures and subsequent soft tissue repair. It was prepared by the reaction of gelatin (Gel) and oxidized starch (OS) with vancomycin (VAN)-loaded mesoporous bioactive glass nanoparticles (MBGNs) covalently cross-linked with Schiff bases. Characterization and adhesion experiments were conducted to validate the successful preparation of the Gel-OS/VAN@MBGNs (GOVM-gel) adhesive. Meanwhile, in vitro cell experiments demonstrated its good antibacterial effects with the ability to stimulate bone marrow mesenchymal stem cell (BMSCs) proliferation, upregulate the expression of alkaline phosphatase (ALP) and osteogenic proteins (RunX2 and OPN) and enhance the deposition of calcium nodules. Additionally, we established a rat skull fracture model and a subcutaneous infection model. The histological analysis showed that bone adhesive enhanced osteogenesis, and in vivo experiments demonstrated that the number of inflammatory cells and bacteria was significantly reduced. Overall, the adhesive could promote early reduction of fractures and antibacterial and osteogenic effects, providing the foothold for treatment of this patient population.

Biomineralization inspired 3D printed bioactive glass nanocomposite scaffolds orchestrate diabetic bone regeneration by remodeling micromilieu

Type II diabetes mellitus (TIIDM) remains a challenging clinical issue for both dentists and orthopedists. By virtue of persistent hyperglycemia and altered host metabolism, the pathologic diabetic micromilieu with chronic inflammation, advanced glycation end products accumulation, and attenuated biomineralization severely impairs bone regeneration efficiency. Aiming to "remodel" the pathologic diabetic micromilieu, we 3D-printed bioscaffolds composed of Sr-containing mesoporous bioactive glass nanoparticles (Sr-MBGNs) and gelatin methacrylate (GelMA). Sr-MBGNs act as a biomineralization precursor embedded in the GelMA-simulated extracellular matrix and release Sr, Ca, and Si ions enhancing osteogenic, angiogenic, and immunomodulatory properties. In addition to angiogenic and anti-inflammatory outcomes, this innovative design reveals that the nanocomposites can modulate extracellular matrix reconstruction and simulate biomineralization by activating lysyl oxidase to form healthy enzymatic crosslinked collagen, promoting cell focal adhesion, modulating osteoblast differentiation, and boosting the release of OCN, the noncollagenous proteins (intrafibrillar mineralization dependent), and thus orchestrating osteogenesis through the Kindlin-2/PTH1R/OCN axis. This 3D-printed bioscaffold provides a multifunctional biomineralization-inspired system that remodels the "barren" diabetic microenvironment and sheds light on the new bone regeneration approaches for TIIDM.

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.

3D Biocomposites Comprising Marine Collagen and Silica-Based Materials Inspired on the Composition of Marine Sponge Skeletons Envisaging Bone Tissue Regeneration

Ocean resources are a priceless repository of unique species and bioactive compounds with denouement properties that can be used in the fabrication of advanced biomaterials as new templates for supporting the cell culture envisaging tissue engineering approaches. The collagen of marine origin can be sustainably isolated from the underrated fish processing industry by-products, while silica and related materials can be found in the spicules of marine sponges and diatoms frustules. Aiming to address the potential of biomaterials composed from marine collagen and silica-based materials in the context of bone regeneration, four different 3D porous structure formulations (COL, COL:BG, COL:D.E, and COL:BS) were fabricated by freeze-drying. The skins of Atlantic cod (Gadus morhua) were used as raw materials for the collagen (COL) isolation, which was successfully characterized by SDS-PAGE, FTIR, CD, and amino acid analyses, and identified as a type I collagen, produced with a 1.5% yield and a preserved characteristic triple helix conformation. Bioactive glass 45S5 bioglass® (BG), diatomaceous earth (D.E.) powder, and biosilica (BS) isolated from the Axinella infundibuliformis sponge were chosen as silica-based materials, which were obtained as microparticles and characterized by distinct morphological features. The biomaterials revealed microporous structures, showing a porosity higher than 85%, a mean pore size range of 138-315 μm depending on their composition, with 70% interconnectivity which can be favorable for cell migration and ensure the needed nutrient supply. In vitro, biological assays were conducted by culturing L929 fibroblast-like cells, which confirmed not only the non-toxic nature of the developed biomaterials but also their capability to support cell adhesion and proliferation, particularly the COL:BS biomaterials, as observed by calcein-AM staining upon seven days of culture. Moreover, phalloidin and DAPI staining revealed well-spread cells, populating the entire construct. This study established marine collagen/silica biocomposites as potential scaffolds for tissue engineering, setting the basis for future studies, particularly envisaging the regeneration of non-load-bearing bone tissues.

Using Copper-Doped Mesoporous Bioactive Glass Nanospheres to Impart Anti-Bacterial Properties to Dental Composites

Experimental dental resin composites containing copper-doped mesoporous bioactive glass nanospheres (Cu-MBGN) were developed to impart anti-bacterial properties. Increasing amounts of Cu-MBGN (0, 1, 5 and 10 wt%) were added to the BisGMA/TEGDMA resin matrix containing micro- and nano-fillers of inert glass, keeping the resin/filler ratio constant. Surface micromorphology and elemental analysis were performed to evaluate the homogeneous distribution of filler particles. The study investigated the effects of Cu-MBGN on the degree of conversion, polymerization shrinkage, porosity, ion release and anti-bacterial activity on S. mutans and A. naeslundii. Experimental materials containing Cu-MBGN showed a dose-dependent Cu release with an initial burst and a further increase after 28 days. The composite containing 10% Cu-MBGN had the best anti-bacterial effect on S. mutans, as evidenced by the lowest adherence of free-floating bacteria and biofilm formation. In contrast, the 45S5-containing materials had the highest S. mutans adherence. Ca release was highest in the bioactive control containing 15% 45S5, which correlated with the highest number of open porosities on the surface. Polymerization shrinkage was similar for all tested materials, ranging from 3.8 to 4.2%, while the degree of conversion was lower for Cu-MBGN materials. Cu-MBGN composites showed better anti-bacterial properties than composites with 45S5 BG.

Bioactive inorganic particles-based biomaterials for skin tissue engineering

The challenge for treatment of severe cutaneous wound poses an urgent clinical need for the development of biomaterials to promote skin regeneration. In the past few decades, introduction of inorganic components into material system has become a promising strategy for improving performances of biomaterials in the process of tissue repair. In this review, we provide a current overview of the development of bioactive inorganic particles-based biomaterials used for skin tissue engineering. We highlight the three stages in the evolution of the bioactive inorganic biomaterials applied to wound management, including single inorganic materials, inorganic/organic composite materials, and inorganic particles-based cell-encapsulated living systems. At every stage, the primary types of bioactive inorganic biomaterials are described, followed by citation of the related representative studies completed in recent years. Then we offer a brief exposition of typical approaches to construct the composite material systems with incorporation of inorganic components for wound healing. Finally, the conclusions and future directions are suggested for the development of novel bioactive inorganic particles-based biomaterials in the field of skin regeneration.

Development of SiC-TiO2-Graphene neem extracted antimicrobial nano membrane for enhancement of multiphysical properties and future prospect in dental implant applications

This paper presents the coating technology on Nano membrane using SiC-TiO2-Graphene with varying percentages of Azadirachta indica (Neem) extract with an objective to develop new coating materials. The nanomembranes have been synthesized by electrospinning machine over aluminum foil paper using the raw materials PVA grain, SiC, TiO2, Graphene, and neem. The nanomembranes have been characterized by SEM, XRD, FTIR, Surface Roughness, antibacterial, and Cytotoxicity test. FTIR analysis established the presence of PVA and neem indicating the formation of different organic compounds. It also confirmed that no chemical reaction occurred during the synthesis process. The membrane's roughness analysis obtained average roughness values from 1.15 to 3.84. The formation of homogeneous and smooth membranes with the formation of micropores was confirmed by SEM analysis. Miller Indices identified different types of crystal structures in XRD analysis. Antibacterial activity increased with the increase of the percentage of neem confirmed by the antibacterial test. No toxic effects were observed from the membrane during the cytotoxicity test. The obtained data confirmed that the synthesized nanomembrane could be used in different biomedical applications.

Mesoporous Nanoparticles for Diagnosis and Treatment of Liver Cancer in the Era of Precise Medicine

Primary liver cancer is the seventh-most-common cancer worldwide and the fourth-leading cause of cancer mortality. In the current era of precision medicine, the diagnosis and management of liver cancer are full of challenges and prospects. Mesoporous nanoparticles are often designed as specific carriers of drugs and imaging agents because of their special morphology and physical and chemical properties. In recent years, the design of the elemental composition and morphology of mesoporous nanoparticles have greatly improved their drug-loading efficiency, biocompatibility and biodegradability. Especially in the field of primary liver cancer, mesoporous nanoparticles have been modified as highly tumor-specific imaging contrast agents and targeting therapeutic medicine. Various generations of complexes and structures have been determined for the complicated clinical management requirements. In this review, we summarize these advanced mesoporous designs in the different diagnostic and therapeutic fields of liver cancer and discuss the relevant advantages and disadvantages of transforming applications. By comparing the material properties, drug-delivery characteristics and application methods of different kinds of mesoporous materials in liver cancer, we try to help determine the most suitable drug carriers and information media for future clinical trials. We hope to improve the fabrication of biomedical mesoporous nanoparticles and provide direct evidence for specific cancer management.

MiR-4458-loaded gelatin nanospheres target COL11A1 for DDR2/SRC signaling pathway inactivation to suppress the progression of estrogen receptor-positive breast cancer

RNA interference is a promising way to treat cancer and the construction of a stable drug delivery system is critically important for its application. Gelatin nanospheres (GNs) comprise a biodegradable drug vehicle with excellent biocompatibility, but there are limited studies on its delivery and role in the stabilization of miRNA and siRNA. Breast cancer is the most diagnosed type of female cancer worldwide. Abnormal miRNA expression is closely related to the occurrence and progression of estrogen receptor-positive (ER+) breast cancer. In this study, miR-4458 was upregulated in ER+ breast cancer and could inhibit MCF-7 cell viability, colony formation, migration, and invasion. Collagen type XI alpha 1 (COL11A1) was identified as a directly interacting protein of miR-4458 and an important component of the extracellular matrix. High COL11A1 expression was positively correlated with poor prognosis, lower overall survival, disease-free survival, and a late tumor-node-metastasis stage. COL11A1 knockdown could inhibit MCF-7 cell migration and invasion. GNs were used to load a miR-4458 mimic or COL11A1 siRNA (si-COL11A1) to achieve sustained and controlled release in xenograft nude mice. Their tumor volume was decreased, tumor cell apoptosis was promoted, and hepatic metastasis was significantly inhibited. Moreover, the DDR2/SRC signaling pathway was inactivated after transfection with the miR-4458 mimic and si-COL11A1. In conclusion, GNs can be potentially used to deliver siRNA or miRNA, and miR-4458 and COL11A1 can be possible targets for ER+ breast cancer treatment.

An Injectable Epigenetic Autophagic Modulatory Hydrogel for Boosting Umbilical Cord Blood NK Cell Therapy Prevents Postsurgical Relapse of Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) exhibits resistance to conventional treatments due to the presence of cancer stem cells (CSCs), causing postsurgical relapse and a dismal prognosis. Umbilical cord blood natural killer (UCB-NK) cell-based immunotherapy represents a promising strategy for cancer treatment. However, its therapeutic efficacy is greatly restrained by downregulation of the NK cell activation ligand MHC class I-related chain A/B (MICA/B) and autophagy-mediated degradation of NK cell-derived granzyme B (GZMB) in CSCs. Herein, it is demonstrated that suberoylanilide hydroxamic acid (SAHA) epigenetically downregulates let-7e-5p and miR-615-3p to increase MICA/B expression and that 3-methyl adenine (3MA) inhibits autophagy-mediated GZMB degradation, thereby sensitizing breast CSCs to UCB-NK cells. Then, an injectable hydrogel is designed to codeliver SAHA and 3MA to enhance UCB-NK cell infusion efficacy in TNBC. The hydrogel precursors can be smoothly injected into the tumor resection bed and form a stable gel in situ, allowing for a pH-sensitive sustained release of SAHA and 3MA. Moreover, UCB-NK cell infusion in combination with the hydrogel efficiently controls postsurgical relapse of TNBC. In addition, the hydrogel exhibits good hemostasis and wound-healing functions. Therefore, the work provides proof of concept that an injectable epigenetic autophagic modulatory hydrogel augments UCB-NK cell therapy to combat postsurgical relapse of TNBC.

Impact of Copper-Doped Mesoporous Bioactive Glass Nanospheres on the Polymerisation Kinetics and Shrinkage Stress of Dental Resin Composites

We embedded copper-doped mesoporous bioactive glass nanospheres (Cu-MBGN) with antibacterial and ion-releasing properties into experimental dental composites and investigated the effect of Cu-MBGN on the polymerisation properties. We prepared seven composites with a BisGMA/TEGDMA (60/40) matrix and 65 wt.% total filler content, added Cu-MBGN or a combination of Cu-MBGN and silanised silica to the silanised barium glass base, and examined nine parameters: light transmittance, degree of conversion (DC), maximum polymerisation rate (R_max), time to reach R_max, linear shrinkage, shrinkage stress (PSS), maximum PSS rate, time to reach maximum PSS rate, and depth of cure. Cu-MBGN without silica accelerated polymerisation, reduced light transmission, and had the highest DC (58.8 ± 0.9%) and R_max (9.8 ± 0.2%/s), but lower shrinkage (3 ± 0.05%) and similar PSS (0.89 ± 0.07 MPa) versus the inert reference (0.83 ± 0.13 MPa). Combined Cu-MBGN and silica slowed the R_max and achieved a similar DC but resulted in higher shrinkage. However, using a combined 5 wt.% Cu-MBGN and silica, the PSS resembled that of the inert reference. The synergistic action of 5 wt.% Cu-MBGN and silanised silica in combination with silanised barium glass resulted in a material with the highest likelihood for dental applications in future.

The interplay of collagen/bioactive glass nanoparticle coatings and electrical stimulation regimes distinctly enhanced osteogenic differentiation of human mesenchymal stem cells

Increasing research has incorporated bioactive glass nanoparticles (BGN) and electric field (EF) stimulation for bone tissue engineering and regeneration applications. However, their interplay and the effects of different EF stimulation regimes on osteogenic differentiation of human mesenchymal stem cells (hMSC) are less investigated. In this study, we introduced EF with negligible magnetic field strength through a well-characterized transformer-like coupling (TLC) system, and applied EF disrupted (4/4) or consecutive (12/12) regime on type I collagen (Col) coatings with/without BGN over 28 days. Additionally, dexamethasone was excluded to enable an accurate interpretation of BGN and EF in supporting osteogenic differentiation. Here, we demonstrated the influences of BGN and EF on collagen topography and maintaining coating stability. Coupled with the release profile of Si ions from the BGN, cell proliferation and calcium deposition were enhanced in the Col-BGN samples after 28 days. Further, osteogenic differentiation was initiated as early as d 7, and each EF regime was shown to activate distinct pathways. The disrupted (4/4) regime was associated with the BMP/Smad4 pathways that up-regulate Runx2/OCN gene expression on d 7, with a lesser effect on ALP activity. In contrast, the canonical Wnt/β-Catenin signaling pathway activated through mechanotransduction cues is associated with the consecutive (12/12) regime, with significantly elevated ALP activity and Sp7 gene expression reported on d 7. In summary, our results illustrated the synergistic effects of BGN and EF in different stimulation regimes on osteogenic differentiation that can be further exploited to enhance current bone tissue engineering and regeneration approaches. STATEMENT OF SIGNIFICANCE: The unique release mechanisms of silica from bioactive glass nanoparticles (BGN) were coupled with pulsatile electric field (EF) stimulation to support hMSC osteogenic differentiation, in the absence of dexamethasone. Furthermore, the interplay with consecutive (12/12) and disrupted (4/4) stimulation regimes was investigated. The reported physical, mechanical and topographical effects of BGN and EF on the collagen coating, hMSC and the distinct progression of osteogenic differentiation (canonical Wnt/β-Catenin and BMP/Smad) triggered by respective stimulation regime were not explicitly reported previously. These results provide the fundamentals for further exploitations on BGN composites with metal ions and rotation of EF regimes to enhance osteogenic differentiation. The goal is sustaining continual osteogenic differentiation and achieving a more physiologically-relevant state and bone constructs in vitro.

Periodic Patchy Spheres Self-Assembled by AmBCAn' Multiblock Terpolymers

We have designed A_mBCA_n^' multiblock terpolymers and studied their self-assembly using self-consistent field theory, aiming to generate the periodically arranged patchy spheres and thus to clarify the regulation mechanism of the number of patches. A number of two-dimensional phase diagrams are constructed for three typical architectures A₂BCA₂^', A₂BCA₃^', and A₃BCA₂^'. Four kinds of stable patchy spheres with the number of patches as 2 (S₂), 4 (S₄), 5 (S₅), and 6 (S₆) are obtained. These phases follow a common transition sequence of S₂ → S₄ → S₅ → S₆ along with the increasing of the volume fraction of C-block (f_C), which forms the core sphere patched with B-domains. Moreover, the S₆ phase exhibits the widest stability window, while S₅ has the narrowest one. The increased arms of A'-blocks in A₂BCA₃^' architecture deflect the phase boundaries toward large f_C and accordingly expand the regions of these patchy spheres due to the amplified effect of spontaneous curvature. In contrast, the increased arms of A-blocks in A₃BCA₂^' remarkably expands the window of S₆ but narrows those of the other patchy spheres, which is mainly caused by increased packing frustration resulting from the reduced extension of the more divided A-blocks. The widest window of the S₆ phase reaches Δf_C ∼ 0.13, which is readily accessed by experiment. Our work not only demonstrates a self-assembly strategy to engineer the patchy spheres, but also sheds light on the regulation mechanism of the patchy number.

A Self-Assembled Matrix System for Cell-Bioengineering Applications in Different Dimensions, Scales, and Geometries

Stem cell bioengineering and therapy require different model systems and materials in different stages of development. If a chemically defined biomatrix system can fulfill most tasks, it can minimize the discrepancy among various setups. By screening biomaterials synthesized through a coacervation-mediated self-assembling mechanism, a biomatrix system optimal for 2D human mesenchymal stromal cell (hMSC) culture and osteogenesis is identified. Its utility for hMSC bioengineering is further demonstrated in coating porous bioactive glass scaffolds and nanoparticle synthesis for esiRNA delivery to knock down the SOX-9 gene with high delivery efficiency. The self-assembled injectable system is further utilized for 3D cell culture, segregated co-culture of hMSC with human umbilical vein endothelial cells (HUVEC) as an angiogenesis model, and 3D bioprinting. Most interestingly, the coating of bioactive glass with the self-assembled biomatrix not only supports the proliferation and osteogenesis of hMSC in the 3D scaffold but also induces the amorphous bioactive glass (BG) scaffold surface to form new apatite crystals resembling bone-shaped plate structures. Thus, the self-assembled biomatrix system can be utilized in various dimensions, scales, and geometries for many different bioengineering applications.

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.

Boswellia sacra Extract-Loaded Mesoporous Bioactive Glass Nano Particles: Synthesis and Biological Effects

Bioactive glasses (BGs) are being increasingly considered for numerous biomedical applications. The loading of natural compounds onto BGs to increase the BG biological activity is receiving increasing attention. However, achieving efficient loading of phytotherapeutic compounds onto the surface of bioactive glass is challenging. The present work aimed to prepare novel amino-functionalized mesoporous bioactive glass nanoparticles (MBGNs) loaded with the phytotherapeutic agent Boswellia sacra extract. The prepared amino-functionalized MBGNs showed suitable loading capacity and releasing time. MBGNs (nominal composition: 58 wt% SiO₂, 37 wt% CaO, 5 wt% P₂O₅) were prepared by sol-gel-modified co-precipitation method and were successfully surface-modified by using 3-aminopropyltriethoxysilane (APTES). In order to evaluate MBGNs loaded with Boswellia sacra, morphological analysis, biological studies, physico-chemical and release studies were performed. The successful functionalization and loading of the natural compound were confirmed with FTIR, zeta-potential measurements and UV-Vis spectroscopy, respectively. Structural and morphological evaluation of MBGNs was done by XRD, SEM and BET analyses, whereas the chemical analysis of the plant extract was done using GC/MS technique. The functionalized MBGNs showed high loading capacity as compared to non-functionalized MBGNs. The release studies revealed that Boswellia sacra molecules were released via controlled diffusion and led to antibacterial effects against S. aureus (Gram-positive) bacteria. Results of cell culture studies using human osteoblastic-like cells (MG-63) indicated better cell viability of the Boswellia sacra-loaded MBGNs as compared to the unloaded MBGNs. Therefore, the strategy of combining the properties of MBGNs with the therapeutic effects of Boswellia sacra represents a novel, convenient step towards the development of phytotherapeutic-loaded antibacterial, inorganic materials to improve tissue healing and regeneration.

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.

Coatings of hydroxyapatite–bioactive glass microparticles are proposed as a way to create adhesion between hydrogels and biological tissues using adsorption of the microparticles across the interface.

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.

Cerium oxide nanoparticles loaded nanofibrous membranes promote bone regeneration for periodontal tissue engineering

Bone regeneration is a crucial part in the treatment of periodontal tissue regeneration, in which new attempts come out along with the development of nanomaterials. Herein, the effect of cerium oxide nanoparticles (CeO2 NPs) on the cell behavior and function of human periodontal ligament stem cells (hPDLSCs) was investigated. Results of CCK-8 and cell cycle tests demonstrated that CeO2 NPs not only had good biocompatibility, but also promoted cell proliferation. Furthermore, the levels of alkaline phosphatase activity, mineralized nodule formation and expressions of osteogenic genes and proteins demonstrated CeO2 NPs could promote osteogenesis differentiation of hPDLSCs. Then we chose electrospinning to fabricate fibrous membranes containing CeO2 NPs. We showed that the composite membranes improved mechanical properties as well as realized release of CeO2 NPs. We then applied the composite membranes to in vivo study in rat cranial defect models. Micro-CT and histopathological evaluations revealed that nanofibrous membranes with CeO2 NPs further accelerated new bone formation. Those exciting results demonstrated that CeO2 NPs and porous membrane contributed to osteogenic ability, and CeO2 NPs contained electrospun membrane may be a promising candidate material for periodontal bone regeneration.

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.

Immunomodulatory bioactive glasses for tissue regeneration

The regulatory functions of the immune response in tissue healing, repair, and regeneration have been evidenced in the last decade. Immune cells play central roles in immune responses toward inducing favorable tissue regenerative processes. Modulating and controlling the immune cell responses (particularly macrophages) is an emerging approach to enhance tissue regeneration. Bioactive glasses (BGs) are multifunctional materials exhibiting osteogenic, angiogenic, and antibacterial properties, being increasingly investigated for various tissue regeneration scenarios, including bone regeneration and wound healing. On the other hand, the immunomodulatory effects of BGs in relation to regenerating tissues have started to be understood, and key knowledge is emerging. This is the first review article summarizing the immunomodulatory effects of BGs for tissue repair and regeneration. The immune response to BGs is firstly introduced, discussing potential mechanisms regarding the immunomodulation effects induced by BGs. Moreover, the interactions between the immune cells involved in the immunomodulation process and BGs (dissolution products) are summarized in detail. Particularly, a well-regulated and timely switch of macrophage phenotype from pro-inflammatory to anti-inflammatory is crucial to constructive tissue regeneration through modulating osteogenesis, osteoclastogenesis, and angiogenesis. The influence of BG characteristics on macrophage responses is discussed. We highlight the strategies employed to harness macrophage responses for enhanced tissue regeneration, including the incorporation of active ions, surface functionalization, and controlled release of immunomodulatory molecules. Finally, we conclude with our perspectives on future research challenges and directions in the emerging field of immunomodulatory BGs for tissue regeneration. STATEMENT OF SIGNIFICANCE: Immunomodulatory effects of bioactive glasses (BGs) in relation to bone regeneration and wound healing have started to be understood. We summarize those studies which have focused on immunomodulatory BGs for tissue regeneration. We first introduce the potential mechanisms of the immunomodulation effects induced by BGs. Interactions between the cells involved in immunomodulation processes and BGs (and their dissolution products, biologically active ions) are elaborated. We highlight the strategies employed to modulate macrophage responses for enhancing tissue regeneration, including incorporation of active ions, surface functionalization, and controlled release of immunomodulatory agents. This is the first review article summarizing and outlining the immunomodulatory effects of BGs for tissue regeneration. We anticipate that increasing research efforts will start to emerge in the area of immunomodulatory BGs.

Nanocomposite coating of albumin/Li-containing bioactive glass nanospheres promotes osteogenic activity of PEEK

Polyetheretherketone (PEEK) is an important material applied in orthopedic applications, as it posses favorable properties for orthopedic implants, e.g., radiolucency and suitable elastic modulus. However, PEEK exhibits insufficient osteogenesis and osteointegration that limits its clinical applications. In this study, we aimed to enhance the osteogenisis of PEEK by using a surface coating approach. Nanocomposite coating composed of albumin/lithium containing bioactive glass nanospheres was fabricated on PEEK through dip-coating method. The presence of nanocomposite coating on PEEK was confirmed by SEM, FTIR, and XRD techniques. Nanocomposite coatings significantly enhanced hydrophilicity and roughness of PEEK. The nanocomposite coatings also enhanced adhesion, proliferation, and osteogenic differentiation of bone mesenchymal stem cells due to the presence of bioactive glass nanospheres and the BSA substrate film. The results indicate the great potential of the nanocomposite coating in enhancing osteogenesis and osteointegration of PEEK implants.

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.

Non-viral nanoparticles for RNA interference: Principles of design and practical guidelines

Ribonucleic acid interference (RNAi) is an innovative treatment strategy for a myriad of indications. Non-viral synthetic nanoparticles (NPs) have drawn extensive attention as vectors for RNAi due to their potential advantages, including improved safety, high delivery efficiency and economic feasibility. However, the complex natural process of RNAi and the susceptible nature of oligonucleotides render the NPs subject to particular design principles and requirements for practical fabrication. Here, we summarize the requirements and obstacles for fabricating non-viral nano-vectors for efficient RNAi. To address the delivery challenges, we discuss practical guidelines for materials selection and NP synthesis in order to maximize RNA encapsulation efficiency and protection against degradation, and to facilitate the cytosolic release of oligonucleotides. The current status of clinical translation of RNAi-based therapies and further perspectives for reducing the potential side effects are also reviewed.

Mesoporous bioactive glasses for regenerative medicine

Stem cells are the central element of regenerative medicine (RM). However, in many clinical applications, the use of scaffolds fabricated with biomaterials is required. In this sense, mesoporous bioactive glasses (MBGs) are going to play an important role in bone regeneration because of their striking textural properties, quick bioactive response, and biocompatibility. As other bioactive glasses, MBGs are mainly formed by silicon, calcium, and phosphorus oxides whose ions play an important role in cell proliferation as well as in homeostasis and bone remodeling process. A common improvement of bioactive glasses for RM is by adding small amounts of oxides of elements that confer them additional biological capacities, including osteogenic, angiogenic, antibacterial, anti-inflammatory, hemostatic, or anticancer properties. Moreover, MBGs are versatile in terms of the different ways in which they can be processed, such as scaffolds, fibers, coatings, or nanoparticles. MBGs are unique because their textural properties are so high that they still exhibit outstanding bioactive responses even after adding extra inorganic ions or being processed as scaffolds or nanoparticles. Moreover, they can be further improved by loading with biomolecules, drugs, and stem cells. This article reviews the state of the art and future perspectives of MBGs in the field of RM of hard tissues.