Multifunctional mesoporous bioactive glasses for effective delivery of therapeutic ions and drug/growth factors

Chitosan and hyaluronic acid based injectable dual network hydrogels - Mediating antimicrobial and inflammatory modulation to promote healing of infected bone defects

In bone defects, infections lead to excessive inflammation, increased bacterial, and bone lysis, resulting in irregular wounds that hinder new bone regeneration. Injectable bioactive materials with adequate antimicrobial activity and strong osteogenic potential are urgently required to remedy irregular defects, eradicate bacteria, and facilitate the generation of new bone tissue. In this research, injectable dual-network composite hydrogels consisting of sulfated chitosan, oxidized hyaluronic acid, β-sodium glycerophosphate, and CuSr doped mesoporous bioactive glass loaded with bone morphogenetic protein (CuSrMBGBMP-2) were utilized for the first time to treat infectious bone defects. Initially, the hydrogel was injected into the wound at 37 °C with minimal invasion to establish a stable state and prevent hydrogel loss. Subsequently, sulfated chitosan eliminated bacteria at the wound site and facilitated cell proliferation with oxidized hyaluronic acid. Additionally, CuSrMBGBMP-2 strengthened antibacterial properties, regulated inflammatory reactions, promoted angiogenesis and osteogenic differentiation, addressing the deficiency in late-stage osteogenesis. Specifically, the injectable dual-network hydrogel based on chitosan and hyaluronic acid is minimally invasive, offering antibacterial, anti-inflammatory, pro-angiogenic, and bone regeneration properties. Therefore, this hydrogel with injectable dual network properties holds great promise for the treatment of bone infections in the future.

Gold Nanoparticles Confined in Mesoporous Bioactive Glass for Periodontitis Therapy

Periodontitis is a chronic disease caused by bacterial infection and is characterized with alveolar bone resorption. Bone regeneration in periodontitis remains a critical challenge because bacterial infection induced an unfavorable microenvironment for osteogenesis. Therefore, it is necessary to design proper therapeutic platforms to control bacterial infection and promote bone regeneration. Herein, mesoporous bioactive glass (MBG) with different pore sizes (3.0, 4.3, and 12.3 nm) was used as an in situ reactor to confine the growth of gold nanoparticles (Au NPs), forming MBG@Au hybrids which combine the osteoconductivity of MBG and antibacterial properties of Au NPs. Upon near-infrared (NIR) irradiation, the MBG@Au NPs showed efficient antibacterial properties both in vitro and in vivo. Besides, the osteogenesis properties of MBG@Au also improved under NIR irradiation. Furthermore, the in vivo results demonstrated that MBG@Au can effectively promote alveolar bone regeneration and realize the healing of serious periodontitis.

Smart responsive in situ hydrogel systems applied in bone tissue engineering

The repair of irregular bone tissue suffers severe clinical problems due to the scarcity of an appropriate therapeutic carrier that can match dynamic and complex bone damage. Fortunately, stimuli-responsive in situ hydrogel systems that are triggered by a special microenvironment could be an ideal method of regenerating bone tissue because of the injectability, in situ gelatin, and spatiotemporally tunable drug release. Herein, we introduce the two main stimulus-response approaches, exogenous and endogenous, to forming in situ hydrogels in bone tissue engineering. First, we summarize specific and distinct responses to an extensive range of external stimuli (e.g., ultraviolet, near-infrared, ultrasound, etc.) to form in situ hydrogels created from biocompatible materials modified by various functional groups or hybrid functional nanoparticles. Furthermore, "smart" hydrogels, which respond to endogenous physiological or environmental stimuli (e.g., temperature, pH, enzyme, etc.), can achieve in situ gelation by one injection in vivo without additional intervention. Moreover, the mild chemistry response-mediated in situ hydrogel systems also offer fascinating prospects in bone tissue engineering, such as a Diels-Alder, Michael addition, thiol-Michael addition, and Schiff reactions, etc. The recent developments and challenges of various smart in situ hydrogels and their application to drug administration and bone tissue engineering are discussed in this review. It is anticipated that advanced strategies and innovative ideas of in situ hydrogels will be exploited in the clinical field and increase the quality of life for patients with bone damage.

The unexplored role of alkali and alkaline earth elements (ALAEs) on the structure, processing, and biological effects of bioactive glasses

Bioactive glass has been employed in several medical applications since its inception in 1969. The compositions of these materials have been investigated extensively with emphasis on glass network formers, therapeutic transition metals, and glass network modifiers. Through these experiments, several commercial and experimental compositions have been developed with varying chemical durability, induced physiological responses, and hydroxyapatite forming abilities. In many of these studies, the concentrations of each alkali and alkaline earth element have been altered to monitor changes in structure and biological response. This review aims to discuss the impact of each alkali and alkaline earth element on the structure, processing, and biological effects of bioactive glass. We explore critical questions regarding these elements from both a glass science and biological perspective. Should elements with little biological impact be included? Are alkali free bioactive glasses more promising for greater biological responses? Does this mixed alkali effect show increased degradation rates and should it be employed for optimized dissolution? Each of these questions along with others are evaluated comprehensively and discussed in the final section where guidance for compositional design is provided.

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.

A novel injectable hydrogel prepared from phenylboronic acid modified gelatin and oxidized-dextran for bone tissue engineering

Complicated fractures have always been challenging in orthopaedics. Designing a multifunctional biomaterial that can contribute to the treatment of fractures using a simple operation remains challenging. Here, we developed a trinity hydrogel system consisting of hydrogel prepared from phenylboronic acid modified gelatin and oxidized-dextran, lithium and cobalt co-doped mesoporous bioactive glass nanoparticles (MBGNs), and irisin. This hydrogel material exhibits considerable injectability, fat-to-shape, and self-healing characteristics. In addition, compared to hydrogel prepared from gelatin and oxidized-dextran, the hydrogel material presented a noticeable enhancement in compression stress and adhesion strength towards porcine bone fragments, which enables it more effectively splice bone fragments during surgery. Based on the various interactions between irisin and the hydrogel network, the system exhibited a clear sustained release of irisin. Based on the results of in vitro cell tests, the hydrogel material showed good cytocompatibility. And it also considerably enhanced the in vitro pro-osteogenic and pro-angiogenic capacities of bone marrow mesenchymal stromal cells (BMSCs) and human umbilical vein endothelial cells (HUVECs). In vivo experimental results indicated that this hydrogel considerably improved the repair of cranial defects in rats. The current study provides a feasible strategy for the treatment of bone fractures and stimulation of fracture healing.

Silicon-containing nanomedicine and biomaterials: materials chemistry, multi-dimensional design, and biomedical application

The invention of silica-based bioactive glass in the late 1960s has sparked significant interest in exploring a wide range of silicon-containing biomaterials from the macroscale to the nanoscale. Over the past few decades, these biomaterials have been extensively explored for their potential in diverse biomedical applications, considering their remarkable bioactivity, excellent biocompatibility, facile surface functionalization, controllable synthesis, etc. However, to expedite the clinical translation and the unexpected utilization of silicon-composed nanomedicine and biomaterials, it is highly desirable to achieve a thorough comprehension of their characteristics and biological effects from an overall perspective. In this review, we provide a comprehensive discussion on the state-of-the-art progress of silicon-composed biomaterials, including their classification, characteristics, fabrication methods, and versatile biomedical applications. Additionally, we highlight the multi-dimensional design of both pure and hybrid silicon-composed nanomedicine and biomaterials and their intrinsic biological effects and interactions with biological systems. Their extensive biomedical applications span from drug delivery and bioimaging to therapeutic interventions and regenerative medicine, showcasing the significance of their rational design and fabrication to meet specific requirements and optimize their theranostic performance. Additionally, we offer insights into the future prospects and potential challenges regarding silicon-composed nanomedicine and biomaterials. By shedding light on these exciting research advances, we aspire to foster further progress in the biomedical field and drive the development of innovative silicon-composed nanomedicine and biomaterials with transformative applications in biomedicine.

Repair of Infected Bone Defects with Hydrogel Materials

Infected bone defects represent a common clinical condition involving bone tissue, often necessitating surgical intervention and antibiotic therapy. However, conventional treatment methods face obstacles such as antibiotic resistance and susceptibility to postoperative infections. Hydrogels show great potential for application in the field of tissue engineering due to their advantageous biocompatibility, unique mechanical properties, exceptional processability, and degradability. Recent interest has surged in employing hydrogels as a novel therapeutic intervention for infected bone repair. This article aims to comprehensively review the existing literature on the anti-microbial and osteogenic approaches utilized by hydrogels in repairing infected bones, encompassing their fabrication techniques, biocompatibility, antimicrobial efficacy, and biological activities. Additionally, the potential opportunities and obstacles in their practical implementation will be explored. Lastly, the limitations presently encountered and the prospective avenues for further investigation in the realm of hydrogel materials for the management of infected bone defects will be deliberated. This review provides a theoretical foundation and advanced design strategies for the application of hydrogel materials in the treatment of infected bone defects.

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.

Morphology, Cytotoxicity, and Antimicrobial Activity of Electrospun Polycaprolactone Biomembranes with Gentamicin and Nano-Hydroxyapatite

The aim of this research is to develop new nanocomposite membranes (NMs) for guided bone regeneration from polycaprolactone (PCL), with different concentrations of gentamicin sulfate (GEN) and nano-hydroxyapatite (nHAP) through electrospinning. The obtained NMs were characterized for structure through SEM and AFM, which revealed the influence of GEN and nHAP on the fiber diameter. The addition of GEN lowered the fiber diameter, and the addition of nHAP increased the diameter of the fibers. The NMs demonstrated antibacterial properties against P. aeruginosa, S. aureus, B. cereus, and E. coli depending on the drug concentration, while being negligibly affected by the nHAP content. NM cytotoxicity assessment, performed once using the MTT assay, revealed no cytotoxicity. The developed NMs could be a promising alternative for guided bone regeneration.

Herbalism and glass-based materials in dentistry: review of the current state of the art

Half a million different plant species are occurring worldwide, of which only 1% has been phytochemically considered. Thus, there is great potential for discovering novel bioactive compounds. In dentistry, herbal extracts have been used as antimicrobial agents, analgesics, and intracanal medicaments. Glass-ionomer cement (GIC) and bioactive glass (BAG) are attractive materials in dentistry due to their bioactivity, adhesion, and remineralisation capabilities. Thus, this review summarizes the evidence around the use of phytotherapeutics in dental glass-based materials. This review article covers the structure, properties, and clinical uses of GIC and BAG materials within dentistry, with an emphasis on all the attempts that have been made in the last 20 years to enhance their properties naturally using the wisdom of traditional medicines. An extensive electronic search was performed across four databases to include published articles in the last 20 years and the search was concerned only with the English language publications. Publications that involved the use of plant extracts, and their active compounds for the green synthesis of nanoparticles and the modification of GIC and BAG were included up to May 2023. Plant extracts are a potential and effective candidate for modification of different properties of GIC and BAG, particularly their antimicrobial activities. Moreover, natural plant extracts have shown to be very effective in the green synthesis of metal ion nanoparticles in an ecological, and easy way with the additional advantage of a synergistic effect between metal ions and the phytotherapeutic agents. Medicinal plants are considered an abundant, cheap source of biologically active compounds and many of these phytotherapeutics have been the base for the development of new lead pharmaceuticals. Further research is required to assess the safety and the importance of regulation of phytotherapeutics to expand their use in medicine.

Advanced drug delivery and therapeutic strategies for tuberculosis treatment

Tuberculosis (TB) remains a significant global health challenge, necessitating innovative approaches for effective treatment. Conventional TB therapy encounters several limitations, including extended treatment duration, drug resistance, patient noncompliance, poor bioavailability, and suboptimal targeting. Advanced drug delivery strategies have emerged as a promising approach to address these challenges. They have the potential to enhance therapeutic outcomes and improve TB patient compliance by providing benefits such as multiple drug encapsulation, sustained release, targeted delivery, reduced dosing frequency, and minimal side effects. This review examines the current landscape of drug delivery strategies for effective TB management, specifically highlighting lipid nanoparticles, polymer nanoparticles, inorganic nanoparticles, emulsion-based systems, carbon nanotubes, graphene, and hydrogels as promising approaches. Furthermore, emerging therapeutic strategies like targeted therapy, long-acting therapeutics, extrapulmonary therapy, phototherapy, and immunotherapy are emphasized. The review also discusses the future trajectory and challenges of developing drug delivery systems for TB. In conclusion, nanomedicine has made substantial progress in addressing the challenges posed by conventional TB drugs. Moreover, by harnessing the unique targeting abilities, extended duration of action, and specificity of advanced therapeutics, innovative solutions are offered that have the potential to revolutionize TB therapy, thereby enhancing treatment outcomes and patient compliance.

A better roadmap for designing novel bioactive glasses: effective approaches for the development of innovative revolutionary bioglasses for future biomedical applications

The introduction of bioactive glasses (BGs) precipitated a paradigm shift in the medical industry and opened the path for the development of contemporary regenerative medicine driven by biomaterials. This composition can bond to live bone and can induce osteogenesis by the release of physiologically active ions. 45S5 BG products have been transplanted effectively into millions of patients around the world, primarily to repair bone and dental defects. Over the years, many other BG compositions have been introduced as innovative biomaterials for repairing soft tissue and delivering drugs. When research first started, many of the accomplishments that have been made today were unimaginable. It appears that the true capacity of BGs has not yet been realized. Because of this, research involving BGs is extremely fascinating. However, to be successful, it requires interdisciplinary cooperation between physicians, glass chemists, and bioengineers. The present paper gives a picture of the existing clinical uses of BGs and illustrates key difficulties deserving to be faced in the future. The challenges range from the potential for BGs to be used in a wide variety of applications. We have high hopes that this paper will be of use to both novice researchers, who are just beginning their journey into the world of BGs, as well as seasoned scientists, in that it will promote conversation regarding potential additional investigation and lead to the discovery of innovative medical applications for BGs.

Fabrication of 3D printed Ca3Mg3(PO4)4-based bioceramic scaffolds with tailorable high mechanical strength and osteostimulation effect

Calcium, magnesium and phosphate are predominant constituents in the human bone. In this study, magnesium-calcium phosphate composite bioceramic scaffolds were fabricated utilizing Mg3(PO4)2 and β-Ca3(PO4)2 as starting materials, and their pore structure was constructed by 3D printing. The porosity and compressive strength of the composite bioceramic scaffolds could be adjusted by altering the sintering temperature and the formula of starting materials. The composite bioceramic scaffolds prepared from 60 wt% Mg3(PO4)2 and 40 wt% β-Ca3(PO4)2 were dominated by the Ca3Mg3(PO4)4 phase, and this Ca3Mg3(PO4)4-based bioceramic scaffolds possessed the highest compressive strength (12.7 - 92.4 MPa). Moreover, the Ca3Mg3(PO4)4-based bioceramic scaffolds stimulated cellular growth and osteoblastic differentiation of bone marrow stromal cells. The Ca3Mg3(PO4)4-based bioceramic scaffolds as bone regenerative biomaterials are flexible to the requirement of bone defects at various sites.

In Situ Synthesis of a Tumor-Microenvironment-Responsive Chemotherapy Drug

Current chemotherapy still suffers from unsatisfactory therapeutic efficacy, multi-drug resistance, and severe adverse effects, thus necessitating the development of techniques to confine chemotherapy drugs in the tumor microenvironment. Herein, we fabricated nanospheres of mesoporous silica (MS) doped with Cu (MS-Cu) and polyethylene glycol (PEG)-coated MS-Cu (PEG-MS-Cu) as exogenous copper supply systems to tumors. The synthesized MS-Cu nanospheres showed diameters of 30-150 nm with Cu/Si molar ratios of 0.041-0.069. Only disulfiram (DSF) and only MS-Cu nanospheres showed little cytotoxicity in vitro, whereas the combination of DSF and MS-Cu nanospheres showed significant cytotoxicity against MOC1 and MOC2 cells at concentrations of 0.2-1 μg/mL. Oral DSF administration in combination with MS-Cu nanospheres intratumoral or PEG-MS-Cu nanospheres intravenous administration showed significant antitumor efficacy against MOC2 cells in vivo. In contrast to traditional drug delivery systems, we herein propose a system for the in situ synthesis of chemotherapy drugs by converting nontoxic substances into antitumor chemotherapy drugs in a specific tumor microenvironment.

Trends and perspectives on the commercialization of bioactive glasses

At least 25 bioactive glass (BG) medical devices have been approved for clinical use by global regulatory agencies. Diverse applications include monolithic implants, bone void fillers, dentin hypersensitivity agents, wound dressing, and cancer therapeutics. The morphology and delivery systems of bioactive glasses have evolved dramatically since the first devices based on 45S5 Bioglass®. The particle size of these devices has generally decreased with the evolution of bioactive glass technology but primarily lies in the micron size range. Morphologies have progressed from glass monoliths to granules, putties, and cements, allowing medical professionals greater flexibility and control. Compositions of these commercial materials have primarily relied on silicate-based systems with varying concentrations of sodium, calcium, and phosphorus. Furthermore, therapeutic ions have been investigated and show promise for greater control of biological stimulation of genetic processes and increased bioactivity. Some commercial products have exploited the borate and phosphate-based compositions for soft tissue repair/regeneration. Mesoporous BGs also promise anticancer therapies due to their ability to deliver drugs in combination with radiotherapy, photothermal therapy, and magnetic hyperthermia. The objective of this article is to critically discuss all clinically approved bioactive glass products. Understanding essential regulatory standards and rules for production is presented through a review of the commercialization process. The future of bioactive glasses, their promising applications, and the challenges are outlined. STATEMENT OF SIGNIFICANCE: Bioactive glasses have evolved into a wide range of products used to treat various medical conditions. They are non-equilibrium, non-crystalline materials that have been designed to induce specific biological activity. They can bond to bone and soft tissues and contribute to their regeneration. They are promising in combating pathogens and malignancies by delivering drugs, inorganic therapeutic ions, and heat for magnetic-induced hyperthermia or laser-induced phototherapy. This review addresses each bioactive glass product approved by regulatory agencies for clinical use. A review of the commercialization process is also provided with insight into critical regulatory standards and guidelines for manufacturing. Finally, a critical evaluation of the future of bioactive glass development, applications, and challenges are discussed.

Copper-deposited diatom-biosilica enhanced osteogenic potential in periodontal ligament stem cells and rat cranium

This study aimed to establish that copper-deposited Diatom-biosilica have the potential and possibility for clinical applications in repairing bone defects in a state of inflammation, such as periodontitis. Treatment of alveolar bone defects caused by periodontitis is a major challenge for clinicians. To achieve better repair results, the material should not only be bone conductive but also have the ability to stimulate osteogenesis and angiogenesis at the lesion site. Copper (II) and silicon (IV) ions could react to form basic copper silicate, which promoted both osteogenesis and angiogenesis. The mineralized diatom (Cu-DBs) loaded with copper (II) ions were synthesized by processing diatom shells using a hydrothermal method. Periodontal ligament stem cells (PDLSCs) are used to detect the osteogenic properties of Cu-DBs at the gene and protein levels. Using a rat cranial defect model and a full-thickness skin incision model to test the osteogenic properties of Cu-DBs in vivo. Compared with untreated diatoms (DBs), Cu-DBs extract significantly promoted the expression of osteogenesis-related factors like ALP, RUNX2, BSP, OCN, and OPN in PDLSCs. In vivo experiments further confirmed that Cu-DBs could effectively stimulate the osteogenesis of a rat skull defect and promote angiogenesis, significantly inhibit the inflammatory responses to bone damages, and reduce the infiltration of inflammatory immune cells to the lesion site. Due to the unique chemical characteristics of Si⁴⁺ and Cu²⁺ ions, the Cu-DBs composite biomaterial could enhance the osteogenic differentiation of PDLSCS in vitro, as well as stimulate the osteogenesis of the rat in vivo.

A biomaterial-based therapy using a sodium hyaluronate/bioglass composite hydrogel for the treatment of oral submucous fibrosis

Oral submucous fibrosis (OSF) is a chronic, inflammatory and potentially malignant oral disorder. Its pathophysiology is extremely complex, including excessive collagen deposition, massive inflammatory infiltration, and capillary atrophy. However, the existing clinical treatment methods do not fully take into account all the pathophysiological processes of OSF, so they are generally low effective and have many side effects. In the present study, we developed an injectable sodium hyaluronate/45S5 bioglass composite hydrogel (BG/HA), which significantly relieved mucosal pallor and restricted mouth opening in OSF rats without any obvious side effects. The core mechanism of BG/HA in the treatment of OSF is the release of biologically active silicate ions, which inhibit collagen deposition and inflammation, and promote angiogenesis and epithelial regeneration. Most interestingly, silicate ions can overall regulate the physiological environment of OSF by down-regulating α-smooth muscle actin (α-SMA) and CD68 and up-regulating CD31 expression, as well as regulating the expression of pro-fibrotic factors [transforming growth factor-β1 (TGF-β1), interleukin-10 (IL-10), tumor necrosis factor-α (TNF-α) and tissue inhibitors of metalloproteinase-1 (TIMP-1)] and anti-fibrotic factors [interleukin-1β (IL-1β)] in macrophage. In conclusion, our study shows that BG/HA has great potential in the clinical treatment of OSF, which provides an important theoretical basis for the subsequent development of new anti-fibrotic clinical preparations. STATEMENT OF SIGNIFICANCE: : Oral submucous fibrosis (OSF) is a chronic, inflammatory and potentially malignant mucosal disease with significant impact on the quality of patients' life. However, the existing clinical treatments have limited efficacy and many side effects. There is an urgent need for development of specific drugs for OSF treatment. In the present study, bioglass (BG) composited with sodium hyaluronate solution (HA) was used to treat OSF in an arecoline-induced rat model. BG/HA can significantly inhibit collagen deposition, regulate inflammatory response, promote angiogenesis and repair damaged mucosal epithelial cells, and thereby mitigate the development of fibrosis in vivo.

Mesoporous bioglass capsule composite injectable hydrogels with antibacterial and vascularization promotion properties for chronic wound repair

Building an angiogenesis microenvironment and inhibiting wound infection are of great significance for chronic wound repair. In this paper, polydopamine-encapsulated mesoporous bioglass (MBG@PDA) capsules were constructed to realize the integration of angiogenesis and infection inhibition through the formation of a composite hydrogel with modified hyaluronic acid (HAMA) to promote wound healing. The experiments showed that the composite hydrogel had good adhesion and toughness and promoted the migration of fibroblasts to accelerate the epithelialization process. In addition, in the composite hydrogel, MBG@PDA could release Mg²⁺ to promote the proliferation and migration of vascular endothelial cells for angiogenesis. At the same time, MBG@PDA in the composite hydrogel could facilitate the long-term release of drugs to inhibit the growth of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) for reducing the possibility of wound infection. Finally, the results of in vivo experiments showed that a multifunctional dressing could repair wounds more quickly by promoting angiogenesis and reducing the pathological areas. In summary, the construction of these composite hydrogels can provide a repair method in the wound-repair field.

Halide-containing bioactive glasses enhance osteogenesis in vitro and in vivo

The application of bone substitutes to reconstruct bone defects is a strategy for repairing alveolar bone loss caused by periodontal disease. Bioactive glasses (BGs) are attractive synthetic bone substitutes owing to their abilities to degrade, form bone-like mineral and stimulate bone regeneration. Our previous studies showed that the incorporation of fluoride into alkali-free bioactive silicate glass promoted osteogenesis to some extent in vitro, while the incorporation of chloride facilitated glass degradation and accelerated the formation of hydroxyapatite. However, whether there is a synergistic effect of incorporating fluoride and chloride on further enhancement of osteogenesis and angiogenesis in vitro and in vivo was not known. Therefore, we synthesized three halide-containing BGs with fluoride only, or chloride only, or mixed fluoride and chloride, investigated their physicochemical properties and osteogenic and angiogenic effects both in vitro and in vivo. The results showed that the addition of both fluoride and chloride in a bioactive silicate glass could combine the structural roles of both, leading to a faster apatite formation than the glass with the presence of fluoride only and a more stable fluorapatite formation than the glass with the presence of chloride only, which formed hydroxyapatite upon immersion. The studied BGs were cytocompatible, as suggested by the cytotoxicity evaluation of hPDLSCs cultivated in the extracted BGs-conditioned culture media. More importantly, these BGs stimulated osteogenic differentiation of hPDLSCs without adding growth factors as indicated by the fact that BGs-conditioned media up-regulated the expression of BMP-2, OPN and VEGF of hPDLSCs and promoted the formation of bone nodules and collagen in vitro. By comparison, the incorporation of fluoride facilitated the expression of osteogenic-related biomarkers and bone nodule formation preferentially, while the incorporation of chloride induced the expression of angiogenic-related biomarkers and collagen formation. The in vivo investigation results demonstrated that the developed halide-containing BGs accelerated the process of bone regeneration, while the glass with mixed fluoride and chloride showed the most significant promotion effect among the three BGs. Therefore, our findings revealed a synergistic effect of incorporating fluoride and chloride into a BG on osteogenesis and angiogenesis in vitro and in vivo and highlighted the potential of fluoride and chloride containing bioactive glasses being bone substitutes for clinical use.

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.

Effective treatment of intractable diseases using nanoparticles to interfere with vascular supply and angiogenic process

Angiogenesis is a vital biological process involving blood vessels forming from pre-existing vascular systems. This process contributes to various physiological activities, including embryonic development, hair growth, ovulation, menstruation, and the repair and regeneration of damaged tissue. On the other hand, it is essential in treating a wide range of pathological diseases, such as cardiovascular and ischemic diseases, rheumatoid arthritis, malignancies, ophthalmic and retinal diseases, and other chronic conditions. These diseases and disorders are frequently treated by regulating angiogenesis by utilizing a variety of pro-angiogenic or anti-angiogenic agents or molecules by stimulating or suppressing this complicated process, respectively. Nevertheless, many traditional angiogenic therapy techniques suffer from a lack of ability to achieve the intended therapeutic impact because of various constraints. These disadvantages include limited bioavailability, drug resistance, fast elimination, increased price, nonspecificity, and adverse effects. As a result, it is an excellent time for developing various pro- and anti-angiogenic substances that might circumvent the abovementioned restrictions, followed by their efficient use in treating disorders associated with angiogenesis. In recent years, significant progress has been made in different fields of medicine and biology, including therapeutic angiogenesis. Around the world, a multitude of research groups investigated several inorganic or organic nanoparticles (NPs) that had the potential to effectively modify the angiogenesis processes by either enhancing or suppressing the process. Many studies into the processes behind NP-mediated angiogenesis are well described. In this article, we also cover the application of NPs to encourage tissue vascularization as well as their angiogenic and anti-angiogenic effects in the treatment of several disorders, including bone regeneration, peripheral vascular disease, diabetic retinopathy, ischemic stroke, rheumatoid arthritis, post-ischemic cardiovascular injury, age-related macular degeneration, diabetic retinopathy, gene delivery-based angiogenic therapy, protein delivery-based angiogenic therapy, stem cell angiogenic therapy, and diabetic retinopathy, cancer that may benefit from the behavior of the nanostructures in the vascular system throughout the body. In addition, the accompanying difficulties and potential future applications of NPs in treating angiogenesis-related diseases and antiangiogenic therapies are discussed.

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.

Gamma Radiation Induced Synthesis of Novel Chitosan/Gold/Bioactive Glass Nanocomposite for Promising Antimicrobial, and Antibiofilm Activities

In the present study we reported, for the first time, the gamma irradiation induced synthesis of chitosan/Au/bioactive glass (CS/Au/BG) nanocomposite. The bioactive glass (BG), with the composition 45% SiO2, 32.5% CaO, 15% Na2O, and 7.5% P2O5 wt% was synthesized through the sol–gel technique. XRD, SEM, EDX, and elemental mapping images were utilized to evaluate the structure of pure BG and CS/Au/BG nanocomposite. The antimicrobial efficacy was evaluated by zone of inhibition (ZOI), minimum inhibitory concentration (MIC), growth curve assay, and Ultraviolet irradiation effect. Investigation was carried on the antibiofilm effectiveness. Membrane leakage as well as SEM imaging were used to evaluate the antibacterial reaction mechanism. The crystallite size of CS/Au/BG nanocomposite was determined via Scherer equation as 22.83 nm. CS/Au/BG possessed the most ZOI activity against the tested microbes. The highest inhibition % of BG, and CS/Au/BG nanocomposite was investigated for S. aureus (15.65%, and 77.24%), followed by C. albicans (13.32%, and 64.75%). The quantity of protein leakage was directly-proportional after increasing the concentration of BG, and CS/Au/BG and counted to be 70.58, and 198.25 µg/mL, respectively (after applied 10 mg/mL). The promising results suggested the use of novel CS/Au/BG nanocomposite as an encourage candidate for wastewater treatment application against pathogenic microbes.

Antibiofilm Activity of Biocide Metal Ions Containing Bioactive Glasses (BGs): A Mini Review

One of the major clinical issues during the implantation procedure is the bacterial infections linked to biofilms. Due to their tissue localization and the type of bacteria involved, bacterial infections at implant sites are usually difficult to treat, which increases patient morbidity and even mortality. The difficulty of treating biofilm-associated infections and the emergence of multidrug-resistant bacteria are further challenges for the scientific community to develop novel biomaterials with excellent biocompatibility and antibacterial properties. Given their ability to stimulate bone formation and have antibacterial properties, metal ion-doped bioactive glasses (BGs) have received considerable research. This mini review aims to be successful in presenting the developments made about the role of biocide metal ions incorporated into BGs against the development of bacterial biofilms and the spread of nosocomial diseases.

Zn-Loaded and Calcium Phosphate-Coated Degradable Silica Nanoparticles Can Effectively Promote Osteogenesis in Human Mesenchymal Stem Cells

Nanoparticles such as mesoporous bioactive glasses (MBGs) and mesoporous silica nanoparticles (MSN) are promising for use in bone regeneration applications due to their inherent bioactivity. Doping silica nanoparticles with bioinorganic ions could further enhance their biological performance. For example, zinc (Zn) is often used as an additive because it plays an important role in bone formation and development. Local delivery and dose control are important aspects of its therapeutic application. In this work, we investigated how Zn incorporation in MSN and MBG nanoparticles impacts their ability to promote human mesenchymal stem cell (hMSC) osteogenesis and mineralization in vitro. Zn ions were incorporated in three different ways; within the matrix, on the surface or in the mesopores. The nanoparticles were further coated with a calcium phosphate (CaP) layer to allow pH-responsive delivery of the ions. We demonstrate that the Zn incorporation amount and ion release profile affect the nanoparticle's ability to stimulate osteogenesis in hMSCs. Specifically, we show that the nanoparticles that contain rapid Zn release profiles and a degradable silica matrix were most effective in inducing hMSC differentiation. Moreover, cells cultured in the presence of nanoparticle-containing media resulted in the highest induction of alkaline phosphate (ALP) activity, followed by culturing hMSC on nanoparticles immobilized on the surface as films. Exposure to nanoparticle-conditioned media did not increase ALP activity in hMSCs. In summary, Zn incorporation mode and nanoparticle application play an important role in determining the bioactivity of ion-doped silica nanoparticles.

Strontium-incorporated bioceramic scaffolds for enhanced osteoporosis bone regeneration

The restoration of bone defects caused by osteoporosis remains a challenge for surgeons. Strontium ranelate has been applied in preventative treatment approaches due to the biological functions of the trace element strontium (Sr). In this study, we aimed to fabricate bioactive scaffolds through Sr incorporation based on our previously developed modified amino-functional mesoporous bioactive glass (MBG) and to systematically investigate the bioactivity of the resulting scaffold in vitro and in vivo in an osteoporotic rat model. The results suggested that Sr-incorporated amino-functional MBG scaffolds possessed favorable biocompatibility. Moreover, with the incorporation of Sr, osteogenic and angiogenic capacities were upregulated in vitro. The in vivo results showed that the Sr-incorporated amino-functional MBG scaffolds achieved better bone regeneration and vessel formation. Furthermore, bioinformatics analysis indicated that the Sr-incorporated amino-functional MBG scaffolds could reduce reactive oxygen species levels in bone marrow mesenchymal stem cells in the osteoporotic model by activating the cAMP/PKA signaling pathway, thus playing an anti-osteoporosis role while promoting osteogenesis. This study demonstrated the feasibility of incorporating trace elements into scaffolds and provided new insights into biomaterial design for facilitating bone regeneration in the treatment of osteoporosis.

Sr and Mg Doped Bi-Phasic Calcium Phosphate Macroporous Bone Graft Substitutes Fabricated by Robocasting: A Structural and Cytocompatibility Assessment

Bi-phasic calcium phosphates (BCPs) are considered prominent candidate materials for the fabrication of bone graft substitutes. Currently, supplemental cation-doping is suggested as a powerful path to boost biofunctionality, however, there is still a lack of knowledge on the structural role of such substituents in BCPs, which in turn, could influence the intensity and extent of the biological effects. In this work, pure and Mg- and Sr-doped BCP scaffolds were fabricated by robocasting from hydrothermally synthesized powders, and then preliminarily tested in vitro and thoroughly investigated physically and chemically. Collectively, the osteoblast cell culture assays indicated that all types of BCP scaffolds (pure, Sr- or Sr–Mg-doped) delivered in vitro performances similar to the biological control, with emphasis on the Sr–Mg-doped ones. An important result was that double Mg–Sr doping obtained the ceramic with the highest β-tricalcium phosphate (β-TCP)/hydroxyapatite mass concentration ratio of ~1.8. Remarkably, Mg and Sr were found to be predominantly incorporated in the β-TCP lattice. These findings could be important for the future development of BCP-based bone graft substitutes since the higher dissolution rate of β-TCP enables an easier release of the therapeutic ions. This may pave the road toward medical devices with more predictable in vivo performance.

Acellular bioactivity and drug delivery of new strontium doped bioactive glasses prepared through a hydrothermal process

This work aims to study the kinetics of apatite layer formation on the surface of strontium doped binary bioactive glasses (BG: 63S37C) prepared for the first time by a hydrothermal process and evaluate their potential for drug loading and release using ibuprofen (IBU) as an anti-inflammatory drug vector. First, the binary glass 63S37C was doped with various amounts of strontium, from 0.2 to 1 mol%. Subsequently, the amorphous state of the samples and the microstructure were assessed by TGA, XRD, FTIR, ICP-AES, and SEM-EDS. Next, the in vitro bioactivity was evaluated by following the surface morphology and composition changes of soaked samples for up to 14 days at 37 °C in simulated bodily fluid (SBF). Finally, SEM-EDS spectroscopy showed clearly the appearance of needle-shaped apatite on amorphous glass substrates at the earlier stages of immersion for bioglasses doped with strontium. These findings are also confirmed with XRD and FTIR analysis. Furthermore, 63S37C BG proved that the drug release increased with increasing strontium content. Altogether, this novel class of bioactive glasses may be considered to have a promising future for biomedical applications.

A 3D-printed biphasic calcium phosphate scaffold loaded with platelet lysate/gelatin methacrylate to promote vascularization

3D-printed biphasic calcium phosphate (BCP) scaffolds show great clinical application potential in bone tissue engineering; however, vascularization of the scaffold is a crucial step for bone regeneration and is still difficult to be controlled. To enhance scaffold vascularization, a novel bioactive scaffold loaded with platelet lysate/gelatin methacrylate (PL/GelMA) in a BCP scaffold was proposed for promoting vascularization. The PL/GelMA/BCP scaffold was successfully prepared via digital light processing (DLP) printing and filled with PL/GelMA to promote the vascularization effect. In vitro evaluation indicated that human umbilical vein endothelial cells (HUVECs) adhered well on the PL/GelMA/BCP scaffold, and cell proliferation was significantly promoted by coculture with the scaffold. Moreover, a variety of growth factors (GFs) in the PL were detected which were slowly released from the scaffold to modulate the cell behaviour and promote the formation of blood vessel-like structures. Co-culturing with the PL/GelMA/BCP scaffold upregulated the expression of angiogenesis-related genes in cells. In vitro results showed that a higher capillary formation was also observed in PL/GelMA/BCP scaffolds implanted subcutaneously on the back of the rats. These results indicated that the vascularization ability of BCP was enhanced by filling it with PL/GelMA. The PL/GelMA/BCP scaffold has the potential to promote vascularization in tissue engineering.

PCL nanofibrous incorporating unique matrix fusion protein adsorbed mesoporous bioactive glass for bone tissue engineering

Mesoporous bioactive glass (MBG) is a potential biomedical material in bone defect repairment because of its bioactivity, biocompatibility, and osteoinduction properties. Here we report that Mg-doped MBG scaffold with 3:1 Ca/Mg ratio (MBG-Ca/Mg-3) is good for MC3T3-E1 osteoblast differentiation and mineralization. Mimicking bone extracellular matrix structure by electrospinning, we used MBG-Ca/Mg-3 adsorbed with Osteocalcin-Osteopontin-Biglycan (OOB), a new unique matrix fusion protein, to form OOB@MBG-Ca/Mg-3 scaffold, which has multifunctional ability in calvarial bone defect repairment in vivo. Intriguingly, we found that OOB@MBG-Ca/Mg-3 scaffold increases the expression of osteoblastic marker genes, including bone morphogenetic protein (Bmp2), osteopontin (Opn), Osterix, Runx2 through activation of ERK1/2. We concluded that OOB@MBG-Ca/Mg-3 scaffold promotes osteoblast differentiation and mineralization through ERK1/2 pathway and it can also enhance bone formation in vivo, which provides a new biomaterial in bone tissue engineering.

Using scaffolds as drug delivery systems to treat bone tumor

Surgery is the principal strategy to treat osteosarcoma and other types of bone tumors, but it causes bone defects that cannot be healed spontaneously. After surgery, patients still need to receive radiotherapy and/or chemotherapy to prevent tumor recurrence and metastasis, which leads to systemic side effects. Bone scaffolds exhibit the potentials to load cargos (drugs or growth factors) and act as drug delivery systems (DDSs) in the osteosarcoma postoperative treatment. This review introduces current types of bone scaffolds and highlights representative works using scaffolds as DDSs to treat osteosarcomas. Challenges and perspectives in the scaffold-based DDSs are also discussed. This review may provide references to develop effective and safe strategies for osteosarcoma postoperative treatment.

Mesoporous Bioglasses Enriched with Bioactive Agents for Bone Repair, with a Special Highlight of María Vallet-Regí’s Contribution

Throughout her impressive scientific career, Prof. María Vallet-Regí opened various research lines aimed at designing new bioceramics, including mesoporous bioactive glasses for bone tissue engineering applications. These bioactive glasses can be considered a spin-off of silica mesoporous materials because they are designed with a similar technical approach. Mesoporous glasses in addition to SiO₂ contain significant amounts of other oxides, particularly CaO and P₂O₅ and therefore, they exhibit quite different properties and clinical applications than mesoporous silica compounds. Both materials exhibit ordered mesoporous structures with a very narrow pore size distribution that are achieved by using surfactants during their synthesis. The characteristics of mesoporous glasses made them suitable to be enriched with various osteogenic agents, namely inorganic ions and biopeptides as well as mesenchymal cells. In the present review, we summarize the evolution of mesoporous bioactive glasses research for bone repair, with a special highlight on the impact of Prof. María Vallet-Regí´s contribution to the field.

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.

The Role of Transmission Electron Microscopy in the Early Development of Mesoporous Materials for Tissue Regeneration and Drug Delivery Applications

For the last 20 years, silica-based mesoporous materials have provided a sound platform for the development of biomedical technology applied to tissue engineering and drug delivery. Their unique structural and textural characteristics, chiefly, the ordered distribution of homogeneous and tunable pores with high surface areas and large pore volume, and their excellent biocompatibility provide an excellent starting point for bone tissue regeneration on the mesoporous surface, and also to load species of interest inside the pores. Adequate control of the synthesis conditions and functionalization of the mesoporous surface are critical factors in the design of new systems that are suitable for use in specific medical applications. Simultaneously, the use of appropriate characterization techniques in the several stages of design and manufacture of mesoporous particles allows us to ascertain the textural, structural and compositional modifications induced during the synthesis, functionalization and post-in vitro assays processes. In this scenario, the present paper shows, through several examples, the role of transmission electron microscopy and associated spectroscopic techniques in the search for useful information in the early design stages of mesoporous systems, with application in the fields of tissue regeneration and drug delivery systems.

An In Vitro Evaluation of the Biological and Osteogenic Properties of Magnesium-Doped Bioactive Glasses for Application in Bone Tissue Engineering

Magnesium (Mg2+) is known to play a crucial role in mineral and matrix metabolism of bone tissue and is thus increasingly considered in the field of bone tissue engineering. Bioactive glasses (BGs) offer the promising possibility of the incorporation and local delivery of therapeutically active ions as Mg2+. In this study, two Mg2+-doped derivatives of the ICIE16-BG composition (49.46 SiO2, 36.27 CaO, 6.6 Na2O, 1.07 P2O5, 6.6 K2O (mol%)), namely 6Mg-BG (49.46 SiO2, 30.27 CaO, 6.6 Na2O, 1.07 P2O5, 6.6 K2O, 6.0 MgO (mol%) and 3Mg-BG (49.46 SiO2, 33.27 CaO, 6.6 Na2O, 1.07 P2O5, 6.6 K2O, 3.0 MgO (mol%)) were examined. Their influence on viability, proliferation and osteogenic differentiation of human mesenchymal stromal cells (MSCs) was explored in comparison to the original ICIE16-BG. All BGs showed good biocompatibility. The Mg2+-doped BGs had a positive influence on MSC viability alongside with inhibiting effects on MSC proliferation. A strong induction of osteogenic differentiation markers was observed, with the Mg2+-doped BGs significantly outperforming the ICIE16-BG regarding the expression of genes encoding for protein members of the osseous extracellular matrix (ECM) at certain observation time points. However, an overall Mg2+-induced enhancement of the expression of genes encoding for ECM proteins could not be observed, possibly due to a too moderate Mg2+ release. By adaption of the Mg2+ release from BGs, an even stronger impact on the expression of genes encoding for ECM proteins might be achieved. Furthermore, other BG-types such as mesoporous BGs might provide a higher local presence of the therapeutically active ions and should therefore be considered for upcoming studies.

Ion release behavior of vanadium-doped mesoporous bioactive glass particles and the effect of the released ions on osteogenic differentiation of BMSCs via the FAK/MAPK signaling pathway

Vanadium is an important trace element in bone and is involved in bone metabolism, bone formation, and bone growth, but the roles of various vanadium ions, especially of pentavalent vanadium, in bone tissue regenerative repair have been underestimated and even misinterpreted for a long time. The main purposes of this study are to investigate the release profile of Si, Ca, P, and V ions from vanadium doped mesoporous bioactive glass (V-MBG) particles and to explore the effect of pentavalent vanadium ions on proliferation and osteogenic differentiation of BMSCs as well as the corresponding osteogenic signaling pathway. On the basis of preparations of V-MBG particles with different pentavalent vanadium contents, the ion release behavior from V-MBG in distilled water and simulated body fluid was systemically investigated. Furthermore, the cytocompatibility and osteogenic effect of V-MBG extracts were studied in rBMSCs, and the related molecular mechanisms were preliminarily discussed. The results of dissolution experiments showed that the V ionic concentration exhibited a burst increase and then a sustained slow increase in the two media. The resultant V ions from 1.0V-MBG, 4.0V-MBG and 10.0V-MBG at 21 days were about 1.1, 5.8, and 12.5 mg L^-1 in water, respectively, and 1.6, 4.8 and 12.8 mg L^-1 in SBF, respectively. The release behaviors of Si, Ca, P, and V ions were evidently affected by high contents of incorporated vanadium. The cellular results indicated that compared to the control and MBG groups, the V(V) ions in V-MBG extracts at about 19.4 μM markedly promoted the proliferation, the gene and protein expression of BMP-2 and COL-I, and the ALP activity of rBMSCs in non-osteoinductive media, but insignificantly stimulated the OCN protein synthesis. More deeply, V(V) ions at about 19.4 μM significantly upregulated the gene and protein expressions of Itga 2b, FAK, and pERK1/2, demonstrating that V(V) ions could regulate osteogenic differentiation of rBMSCs through the activation of the Itga 2b-FAK-MAPK (pERK1/2) signaling pathway. The in vivo results further confirmed that V-MBG induced and promoted new bone formation in the defect area compared to the PGC and PGC/V-M0 groups. These results would contribute to modify the perception about the biocompatibility and osteogenic promotion of pentavalent vanadium at an appropriate concentration.

Strontium-Loaded Nanotubes of Ti-24Nb-4Zr-8Sn Alloys for Biomedical Implantation

Ti-24Nb-4Zr-8Sn (Ti2448) alloys, with a relatively low elastic modulus and unique mechanical properties, are desirable materials for oral implantation. In the current study, a multifaceted strontium-incorporating nanotube coating was fabricated on a Ti2448 alloy (Ti2-NTSr) through anodization and hydrothermal procedures. In vitro, the Ti2-NTSr specimens demonstrated better osteogenic properties and more favorable osteoimmunomodulatory abilities. Moreover, macrophages on Ti2-NTSr specimens could improve the recruitment and osteogenic differentiation of osteoblasts. In vivo, dense clots with highly branched, thin fibrins and small pores existed on the Ti2-NTSr implant in the early stage after surgery. Analysis of the deposition of Ca and P elements, hard tissue slices and the bone-implant contact rate (BIC%) of the Ti2-NTSr implants also showed superior osseointegration. Taken together, these results demonstrate that the Ti2-NTSr coating may maximize the clinical outcomes of Ti2448 alloys for implantation applications.

Dissolution of Amorphous S53P4 Glass Scaffolds in Dynamic In Vitro Conditions

The silicate-based bioactive glass S53P4 is clinically used in bone regenerative applications in granule form. However, utilization of the glass in scaffold form has been limited by the high tendency of the glass to crystallize during sintering. Here, careful optimization of sintering parameters enabled the manufacture of porous amorphous S53P4 scaffolds with a strength high enough for surgical procedures in bone applications (5 MPa). Sintering was conducted in a laboratory furnace for times ranging from 25 to 300 min at 630 °C, i.e., narrowly below the commencement of the crystallization. The phase composition of the scaffolds was verified with XRD, and the ion release was tested in vitro and compared with granules in continuous flow of Tris buffer and simulated body fluid (SBF). The amorphous, porous S53P4 scaffolds present the possibility of using the glass composition in a wider range of applications.

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.

Effective Actions of Ion Release from Mesoporous Bioactive Glass and Macrophage Mediators on the Differentiation of Osteoprogenitor and Endothelial Progenitor Cells

Due to their specific mesoporous structure and large surface area, mesoporous bioactive glasses (MBGs) possess both drug-delivery ability and effective ionic release to promote bone regeneration by stimulating osteogenesis and angiogenesis. Macrophages secrete mediators that can affect both processes, depending on their phenotype. In this work, the action of ion release from MBG-75S, with a molar composition of 75SiO₂-20CaO-5P₂O₅, on osteogenesis and angiogenesis and the modulatory role of macrophages have been assessed in vitro with MC3T3-E1 pre-osteoblasts and endothelial progenitor cells (EPCs) in monoculture and in coculture with RAW 264.7 macrophages. Ca²⁺, phosphorous, and silicon ions released from MBG-75S were measured in the culture medium during both differentiation processes. Alkaline phosphatase activity and matrix mineralization were quantified as the key markers of osteogenic differentiation in MC3T3-E1 cells. The expression of CD31, CD34, VEGFR2, eNOS, and vWF was evaluated to characterize the EPC differentiation into mature endothelial cells. Other cellular parameters analyzed included the cell size and complexity, intracellular calcium, and intracellular content of the reactive oxygen species. The results obtained indicate that the ions released by MBG-75S promote osteogenesis and angiogenesis in vitro, evidencing a macrophage inhibitory role in these processes and demonstrating the high potential of MBG-75S for the preparation of implants for bone regeneration.

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.

Mesoporous Silica Nanoparticles and Mesoporous Bioactive Glasses for Wound Management: From Skin Regeneration to Cancer Therapy

Exploring new therapies for managing skin wounds is under progress and, in this regard, mesoporous silica nanoparticles (MSNs) and mesoporous bioactive glasses (MBGs) offer great opportunities in treating acute, chronic, and malignant wounds. In general, therapeutic effectiveness of both MSNs and MBGs in different formulations (fine powder, fibers, composites etc.) has been proved over all the four stages of normal wound healing including hemostasis, inflammation, proliferation, and remodeling. The main merits of these porous substances can be summarized as their excellent biocompatibility and the ability of loading and delivering a wide range of both hydrophobic and hydrophilic bioactive molecules and chemicals. In addition, doping with inorganic elements (e.g., Cu, Ga, and Ta) into MSNs and MBGs structure is a feasible and practical approach to prepare customized materials for improved skin regeneration. Nowadays, MSNs and MBGs could be utilized in the concept of targeted therapy of skin malignancies (e.g., melanoma) by grafting of specific ligands. Since potential effects of various parameters including the chemical composition, particle size/morphology, textural properties, and surface chemistry should be comprehensively determined via cellular in vitro and in vivo assays, it seems still too early to draw a conclusion on ultimate efficacy of MSNs and MBGs in skin regeneration. In this regard, there are some concerns over the final fate of MSNs and MBGs in the wound site plus optimal dosages for achieving the best outcomes that deserve careful investigation in the future.