Doxorubicin loaded cerium substituted hydroxyapatite nanoparticles: A promising new therapeutic approach for bone regeneration, doxorubicin delivery, and cancer treatment

The current study used the precipitation method to prepare pure calcium hydroxyapatite (HA) and cerium-substituted hydroxyapatite (Ce-HA) nanoparticles, where cerium ions were exchanged into the HA structure at different concentrations ranging from 3 to 7 wt%. X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM), Fourier transform infrared (FTIR) spectroscopy, Brunauer-Emmett-Teller (BET) surface area measurements, and zeta potential were used to examine the structural characteristics of the nanoparticles. Additionally, the antibacterial and antifungal effects of the produced materials on Gram-positive, Gram-negative, and fungal bacterial species were studied. Nanoparticles with cerium doping showed effective antibacterial and antifungal properties. All samples were tested for bioactivity in simulated body fluid (SBF), and the formation of an apatite layer on their surfaces was highlighted using SEM in conjunction with energy-dispersive X-rays (EDX).Doxorubicin (DOX) release from Ce-HA nanoparticles and pure HA was tested in phosphate-buffered saline (PBS) for up to 28 days. Both nanoparticles were able to release the drug while still being semi-fully loaded. Similarly, the cytotoxic effect of all produced samples on the MG-63 cell line was evaluated, and all samples showed good cytocompatibility. The cytotoxic effect of doxorubicin-loaded nanoparticles showed promising anticancer activity against bone cancer cells, especially samples with high cerium content. The resulting nanoparticles show excellent promising ability for the delivery of doxorubicin to bone cancer with the capacity for bone regeneration.

Nanodevices based on mesoporous glass nanoparticles enhanced with zinc and curcumin to fight infection and regenerate bone

Nanotechnology-based approaches are emerging as promising strategies to treat different bone pathologies such as infection, osteoporosis or cancer. To this end, several types of nanoparticles are being investigated, including those based on mesoporous bioactive glasses (MGN) which exhibit exceptional structural and textural properties and whose biological behaviour can be improved by including therapeutic ions in their composition and loading them with biologically active substances. In this study, the bone regeneration capacity and antibacterial properties of MGNs in the SiO2-CaO-P2O5 system were evaluated before and after being supplemented with 2.5% or 4% ZnO and loaded with curcumin. in vitro studies with preosteoblastic cells and mesenchymal stem cells allowed determining the biocompatible MGNs concentrations range. Moreover, the bactericidal effect of MGNs with zinc and curcumin against S. aureus was demonstrated, as a significant reduction of bacterial growth was detected in both planktonic and sessile states and the degradation of a pre-formed bacterial biofilm in the presence of the nanoparticles also occurred. Finally, MC3T3-E1 preosteoblastic cells and S. aureus were co-cultured to investigate competitive colonisation between bacteria and cells in the presence of the MGNs. Preferential colonisation and survival of osteoblasts and effective inhibition of both bacterial adhesion and biofilm formation of S. aureus in the co-culture system were detected. Our study demonstrated the synergistic antibacterial effect of zinc ions combined with curcumin and the enhancement of the bone regeneration characteristics of MGNs containing zinc and curcumin to obtain systems capable of simultaneously promoting bone regeneration and controlling infection. STATEMENT OF SIGNIFICANCE: In search of a new approach to regenerate bone and fight infections, a nanodevice based on mesoporous SiO2-CaO-P2O5 glass nanoparticles enriched with Zn2+ ions and loaded with curcumin was designed. This study demonstrates the synergistic effect of the simultaneous presence of zinc ions and curcumin in the nanoparticles that significantly reduces the bacterial growth in planktonic state and is capable to degrade pre-formed S. aureus biofilms whereas the nanosystem exhibits a cytocompatible behaviour in the presence of preosteoblasts and mesenchymal stem cells. Based on these results, the designed nanocarrier represents a promising alternative for the treatment of acute and chronic infections in bone tissues, while avoiding the significant current problem of bacterial resistance to antibiotics.

Effect of Thermal Treatments and Ion Substitution on Sintering and Crystallization of Bioactive Glasses: A Review

Bioactive glasses (BGs) are promising materials for bone regeneration due to their ability to bond with living bone tissue. However, thermal stability and mechanical properties of BGs need improvement for better clinical performance. In this paper, we present an overview of the influence of different ions on the sintering and crystallization of BGs. Specifically, this review focuses on the impact of thermal treatments on the crystallization of 45S5 and other significant BG compositions. Potential applications of these thermally treated BGs, such as scaffolds, BG-based composites, and thermally sprayed coatings, are explored. Moreover, the substitution of ions has been investigated as a method to enhance the thermal properties of BGs. Notably, zinc, potassium, and strontium have been studied extensively and have demonstrated promising effects on both the thermal and the mechanical properties of BGs. However, it is important to note that research on ion inclusion in BGs is still in its early stages, and further investigation is necessary to fully comprehend the effects of different ions on sintering and crystallization. Therefore, future studies should focus on optimizing the ion substitution method to improve the thermal, mechanical, and even biological properties of BGs, thereby enhancing their potential for various biomedical applications.

Alginate Beads Containing Cerium-Doped Mesoporous Glass and Curcumin: Delivery and Stabilization of Therapeutics

Cancer is a leading cause of death worldwide, its genesis and progression are caused by homeostatic errors, and reactive oxygen species play a major role in promoting aberrant cancer homeostasis. In this scenario, curcumin could be an interesting candidate due to its versatile antioxidant, anti-inflammatory, anti-tumor, anti-HIV, and anti-infection properties. Nonetheless, the major problem related to its use is its poor oral bioavailability, which can be overcome by encapsulating it into small particles, such as hydrogel beads containing mesoporous silica. In this work, various systems have been synthesized: starting from mesoporous silica glasses (MGs), cerium-containing MGs have been produced; then, these systems have been loaded with 4 to 6% of curcumin. Finally, various MGs at different compositions have been included in alginate beads. In vitro studies showed that these hybrid materials enable the stabilization and effective delivery of curcumin and that a synergic effect can be achieved if Ce³⁺/Ce⁴⁺ and curcumin are both part of the beads. From swelling tests, it is possible to confirm a controlled curcumin release compartmentalized into the gastrointestinal tract. For all beads obtained, a curcumin release sufficient to achieve the antioxidant threshold has been reached, and a synergic effect of cerium and curcumin is observed. Moreover, from catalase mimetic activity tests, we confirm the well-known catalytic activity of the couple Ce³⁺/Ce⁴⁺. In addition, an extremely good radical scavenging effect of curcumin has been demonstrated. In conclusion, these systems, able to promote an enzymatic-like activity, can be used as drug delivery systems for curcumin-targeted dosing.

Gallium containing bioactive materials: A review of anticancer, antibacterial, and osteogenic properties

The incorporation of gallium into bioactive materials has been reported to enhance osteogenesis, to influence blood clotting, and to induce anti-cancer and anti-bacterial activity. Gallium-doped biomaterials prepared by various techniques include melt-derived and sol-gel-derived bioactive glasses, calcium phosphate bioceramics, metals and coatings. In this review, we summarize the recently reported developments in antibacterial, anticancer, osteogenesis, and hemostasis properties of Ga-doped biomaterials and briefly outline the mechanisms leading to Ga biological effects. The key finding is that gallium addition to biomaterials has great potential for treating bone-related diseases since it can be efficiently transferred to the desired region at a controllable rate. Besides, it can be used as a potential substitute for antibiotics for the inhibition of infections during the initial and advanced phases of the wound healing process. Ga is also used as an anticancer agent due to the increased concentration of gallium around excessive cell proliferation (tumor) sites. Moreover, we highlight the possibility to design different therapeutic approaches aimed at increasing the efficiency of the use of gallium containing bioactive materials for multifunctional applications.

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

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

Effect of Ce-doped bioactive glass/collagen/chitosan nanocomposite scaffolds on the cell morphology and proliferation of rabbit’s bone marrow mesenchymal stem cells-derived osteogenic cells

Background

Cerium-containing materials have wide applications in the biomedical field, because of the mimetic catalytic activities of cerium. The study aims to deeply estimate the biocompatibility of different scaffolds based on Ce-doped nanobioactive glass, collagen, and chitosan using the first passage of rabbit bone marrow mesenchymal stem cells (BM-MSCs) directed to osteogenic lineage by direct and indirect approach. One percentage of glass filler was used (30 wt. %) in the scaffold, while the percentage of CeO₂ in the glass was ranged from 0 to 10 mol. %. Cytotoxicity was evaluated by monitoring of cell morphological changes and reduction in cell proliferation activity of BMMSCs maintained under osteogenic condition using proliferation assays, MTT assay for the direct contact of cells/scaffolds twice in a week, trypan blue and hemocytometer cell counting for indirect contact of cells/scaffolds extracts at day 7. Cell behaviors growth, morphology characteristics were monitored daily under a microscope and cell counting were conducted after 1 week of the incubation of the cells with the extracts of the four composite scaffolds in the osteogenic medium at the end of the week.

Results

Showed that at 24 h after direct contact with composite scaffold, all scaffolds showed proliferation of cells > 50% and increased in cell density on day 7. The scaffold of the highest percentage of CeO₂ in bioactive glass nanoparticles (sample CL/CH/C10) showed the lowest inhibition of cell proliferation (< 25%) at day 7. Moreover, the indirect cell viability test showed that all extracts from the four composite scaffolds did not demonstrate a toxic effect on the cells (inhibition value < 25%).

Conclusion

The addition of CeO₂ to the glass composition improved the biocompatibility of the composite scaffold for the proliferation of rabbit bone marrow mesenchymal stem cells directed to osteogenic lineage.

Supplementary Information

The online version contains supplementary material available at 10.1186/s43141-022-00302-x.

Ion-doped mesoporous bioactive glass: preparation, characterization, and applications using the spray pyrolysis method

Biotechnology is used extensively in medical procedures, dentistry, statures, biosensors, bio electrodes, skin substitutes, and medicine delivery systems. Glass is biocompatible and can be used in permanent implantation applications without risk. The porosity of BG matrixes, combined with their huge specific surface area, greatly aids the formation of hydroxyl carbonate apatite. Zn-Doped bioglass can be made in the lab in a variety of ways, depending on how it will be used in medical treatment. The melt-quenching technique, spray pyrolysis method, sol-gel process for BG fabrication, spray drying method, and modified Stöber method are examples of such strategies. Spray pyrolysis is a comprehensive approach that is an undeniably versatile and effective material synthesis technology. It is a low-cost, non-vacuum method for producing materials in the form of powders and films that may be deposited on a variety of substrates, and is a straightforward method to adapt for large-area deposition and industrial production processes. For better utility in medical care, MBG fabricated in the laboratory should be characterized using various characterization methods such as SEM, TEM, BET, and XRD.

Rapid hemostasis and high bioactivity cerium-containing mesoporous bioglass for hemostatic materials

A two-step-acid-catalyzed-self-assembly method was used to prepare cerium-containing mesoporous bioactive glass with P123 as a template. The results showed that MBG without cerium and MBG with cerium slightly affected its surface area, and its water absorption rate was significantly higher. In vitro coagulation experiments showed that Ce-MBG significantly reduces prothrombin time (PT) and activated partial thromboplastin time (APTT), indicating that MBG containing Ce could promote coagulation and platelet adhesion compared with MBG. These suggested that Ce-MBG may be a good dressing with hemostatic properties, which could shorten the bleeding time of the wound and control the bleeding.

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

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

Cerium Containing Bioactive Glasses: A Review

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

Cerium and gallium containing mesoporous bioactive glass nanoparticles for bone regeneration: Bioactivity, biocompatibility and antibacterial activity

In recent years, mesoporous bioactive glass nanoparticles (MBGNPs) have generated great attention in biomedical applications. In this study, cerium and gallium doped MBGNPs were prepared by microemulsion assisted sol-gel method in the binary SiO₂-CaO system. MBGNPs with spheroidal and pineal shaped morphology were obtained. Nitrogen sorption analysis elucidated the mesoporous structure of synthesized nanoparticles with high specific surface area. X-ray diffraction analysis confirmed the amorphous nature of the nanoparticles. The chemical compositions of all samples were determined by inductively coupled plasma-optical emission spectrometry (ICP-OES), which revealed that the contents of cerium and gallium could be tailored by adjusting the concentrations of the precursors used for the synthesis. All MBGNPs exhibited in vitro bioactivity when immersed in simulated body fluid, except the particles doped with higher amounts than 1 mol% of cerium. MBGNPs showed antibacterial activity against S. aureus and E. coli without exhibiting cytotoxicity towards MG-63 osteoblast-like cells. Mentioned features of the obtained Ce and Ga-doped MBGNPs make them useful for multifunctional applications such as drug delivery carriers or bioactive fillers for bone tissue engineering applications.

Nanotechnology for angiogenesis: opportunities and challenges

Angiogenesis plays a critical role within the human body, from the early stages of life (i.e., embryonic development) to life-threatening diseases (e.g., cancer, heart attack, stroke, wound healing). Many pharmaceutical companies have expended huge efforts on both stimulation and inhibition of angiogenesis. During the last decade, the nanotechnology revolution has made a great impact in medicine, and regulatory approvals are starting to be achieved for nanomedicines to treat a wide range of diseases. Angiogenesis therapies involve the inhibition of angiogenesis in oncology and ophthalmology, and stimulation of angiogenesis in wound healing and tissue engineering. This review aims to summarize nanotechnology-based strategies that have been explored in the broad area of angiogenesis. Lipid-based, carbon-based and polymeric nanoparticles, and a wide range of inorganic and metallic nanoparticles are covered in detail. Theranostic and imaging approaches can be facilitated by nanoparticles. Many preparations have been reported to have a bimodal effect where they stimulate angiogenesis at low dose and inhibit it at higher doses.

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

Mesoporous bioactive glass nanoparticles (MBGNs) are emerging biomaterials for bone repair/regeneration, considering their favorable pro-osteogenic and proangiogenic activities. To further improve their therapeutic effects, the endowment of MBGNs with additional antioxidant properties is of particular interest to target oxidative stress related to bone remodeling and diseases. To this end, we developed antioxidant cerium-containing MBGNs (Ce-MBGNs) (particle size of 100-300 ​nm) by using a postimpregnation strategy to incorporate Ce, through which the shape, pore structure, and dispersity of the nanoparticles were preserved. The incorporated amount of Ce could be tailored by adjusting the concentration of the Ce precursor solution. When impregnated at a relatively low temperature (20 ​°C), Ce-MBGNs containing either 1.8 or 2.8 ​mol% of Ce were produced, while the formation of by-product cerium oxide nanoparticles (nanoceria) could be avoided. In both developed Ce-MBGNs, the concentration of Ce4+ was higher than that of Ce3+, while the relative molar percentage of Ce4+ was similar (∼74%) in both Ce-MBGNs. The obtained Ce-MBGNs were evidenced to be non-cytotoxic against fibroblasts at the concentration of 1 ​mg/mL. Moreover, the incorporation of Ce into MBGNs significantly reduced the expression of oxidative stress-related genes in macrophages (J774a.1). Particularly in the presence of pro-oxidation agents, Ce-MBGNs could downregulate the expression of oxidative stress-related genes in comparsion with the polystyrene plates (control). When cultured with Ce-MBGNs, the expression of proinflammatory-related genes in macrophages could also be downregulated in comparsion with MBGNs and the control. Ce-MBGNs also exhibited pro-osteogenic activities through suppressing pro-osteoclastogenic responses. The obtained results highlight the great potential of the developed Ce-MBGNs in a variety of biomedical applications, particularly in treating bone defects under inflammatory conditions, considering their antioxidant, anti-inflammatory, and pro-osteogenesis activities.

In Vitro Effect of Gallium-Doped Bioactive Glass on Enamel Anti-Demineralization and Bond Strength of Orthodontic Resins

White spot lesions (WSL) that occur on teeth after orthodontic appliances have been attached are caused by bacterial demineralization of the enamel surface. This study investigated the anti-demineralization effect of orthodontic resins containing mesoporous bioactive glass nanoparticles (MBN) doped with gallium, which has antibacterial activity, as well as MBN with increased calcium and phosphate contents as these ions can remineralize enamel. Resins (CF, CharmFill Flow, Dentkist, Seoul, South Korea) containing 1%, 3%, and 5% Ga-doped MBN (GaMBN) were characterized using scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and isothermal tests, and their physical properties were measured in terms of Vickers microhardness, bracket retention force, and adhesive remnant index (ARI). Cell viability in the resins was confirmed by testing human dental pulp stem cells (hDPSCs), and ion release tests were performed after 1, 7, and 14 days to determine whether the resins released Ga3+, Ca2+, and PO43–. After 14 days, antibacterial activity was determined using Streptococcus mutans (S. mutans)—the bacteria that causes tooth decay—and the chemical remineralization effect was investigated using a cycle of acid–base solutions. The microhardness of the resins increased with GaMBN concentration whereas their bracket retention force, ARI, and cell viability remained unchanged. The bacterial activity of the 5%-GaMBN resin decreased after 24 and 48 h; however, the change in activity was not statistically significant. Anti-demineralization testing demonstrated that the degree of enamel demineralization decreased as the GaMBN concentration increased, which indicates that resins containing 5%-GaMBN may be viable orthodontic adhesives for preventing WSLs.

Incorporation of cerium oxide in hollow mesoporous bioglass scaffolds for enhanced bone regeneration by activating the ERK signaling pathway

Hierarchically porous structures and bioactive compositions of artificial biomaterials play a positive role in bone defect healing and new bone regeneration. Herein, cerium oxide nanoparticles-modified bioglass (Ce-BG) scaffolds were firstly constructed by the incorporation of hollow mesoporous Ce-BG microspheres in CTS via a freeze-drying technology. The interconnected macropores in Ce-BG scaffolds facilitated the in-growth of bone cells/tissues from material surfaces into the interiors, while the hollow cores and mesopore shells in Ce-BG microspheres provides more active sites for bone mineralization. The cerium oxide nanoparticles in the scaffolds rapidly promoted the proliferation and osteogenic differentiation of human bone marrow-derived mesenchymal stem cells (hBMSCs), as confirmed by the up-regulation of osteogenesis-related markers such as OCN, ALP and COL-1. The enhanced osteoinductivity of Ce-BG scaffolds was mainly related to the activated ERK pathway, and it was blocked by adding a selective ERK1/2 inhibitor (SCH772984). In vivo rat cranial defect models revealed that Ce-BG scaffolds accelerated collagen deposition, osteoblast formation and bone regeneration as compared to BG scaffolds. The exciting results demonstrated that the synergistic effects between hierarchically porous structures and cerium oxide nanoparticles contributed to osteogenic ability, and hollow mesoporous Ce-BG scaffolds would be a novel platform for bone regeneration.

In vitro drug release behavior of Ce-doped nano-bioactive glass carriers under oxidative stress

Ce-containing bioactive glasses are known to decrease reactive oxygen activities inside the body. That is because of their excellent catalytic activities which come from the fast interchange of Ce³⁺/Ce⁴⁺ oxidation states. This research was mainly aimed at preparing new Ce-doped nano-bioactive glasses based on 60SiO₂-(10-x)B₂O₃-25CaO-5P₂O₅-xCeO₂, in mole% (x = 0 and 5 mol%) as multifunctional bone fillings. Moreover, the glasses were used as a delivery system for ciprofloxacin to intensely solve the bone infection complications. Nevertheless, there were no previous works studied of the nature immersing solution effect on the drug release behavior from Ce-doped nano-bioactive glass carriers. Therefore, phosphate-free and phosphate-containing buffer solutions with/without superoxide species (H₂O₂) were used to investigate the efficacy of this drug delivery system in different environment. The results showed that Ce addition enhanced the formation of apatite layer and cell viability. Moreover, the percentage of released drug was apparently affected by the glass composition and nature of soaking fluid, specifically, in the media containing superoxide species (H₂O₂). In conclusion, the prepared Ce-doped glass nanoparticles illustrated multifunctional bone filling material, but when it intended to be utilized as a drug delivery system, the nature of surrounding medium have to be taken into consideration.

Enhanced cellular osteogenic differentiation on Zn-containing bioglass incorporated TiO2 nanorod films

Surface nanotopography and bioactive ions have been considered to play critical roles on the interactions of biomaterials with cells. In this study, a TiO₂ nanorod film incorporated with Zn-containing bioactive glass (TiO₂/Zn-BG) was prepared on tantalum substrate, trying to evaluate the synergistic effects of nanotopograpgy and bioactive ions to promote cellular osteogenic differentiation activity. The expression of osteogenic-related genes, ALP as well as the ECM mineralization on TiO₂/Zn-BG film were significantly upregulated compared to that of the film without TiO₂ nanorod nanostructure (Zn-BG) or without Zn (TiO₂/BG). Moreover, a much low Zn²⁺ release level on TiO₂/Zn-BG film was beneficial to promote the osteogenesis, which could be ascribed to that a semi-closed space established by TiO₂ nanorods with adhered cells provided an appropriate micro-environment that facilitated Zn²⁺ adsorption.

Osteogenic Effect of ZnO-Mesoporous Glasses Loaded with Osteostatin

Mesoporous Bioactive Glasses (MBGs) are a family of bioceramics widely investigated for their putative clinical use as scaffolds for bone regeneration. Their outstanding textural properties allow for high bioactivity when compared with other bioactive materials. Moreover, their great pore volumes allow these glasses to be loaded with a wide range of biomolecules to stimulate new bone formation. In this study, an MBG with a composition, in mol%, of 80% SiO₂⁻15% CaO⁻5% P₂O₅ (Blank, BL) was compared with two analogous glasses containing 4% and 5% of ZnO (4ZN and 5ZN) before and after impregnation with osteostatin, a C-terminal peptide from a parathyroid hormone-related protein (PTHrP107-111). Zn2+ ions were included in the glass for their bone growth stimulator properties, whereas osteostatin was added for its osteogenic properties. Glasses were characterized, and their cytocompatibility investigated, in pre-osteoblastic MC3T3-E1 cell cultures. The simultaneous additions of osteostatin and Zn2+ ions provoked enhanced MC3T3-E1 cell viability and a higher differentiation capacity, compared with either raw BL or MBGs supplemented only with osteostatin or Zn2+. These in vitro results show that osteostatin enhances the osteogenic effect of Zn2+-enriched glasses, suggesting the potential of this combined approach in bone tissue engineering applications.

Highly-Bioreactive Silica-Based Mesoporous Bioactive Glasses Enriched with Gallium(III)

Beneficial effects in bone cell growth and antibacterial action are currently attributed to Ga3+ ions. Thus, they can be used to upgrade mesoporous bioactive glasses (MBGs), investigated for tissue engineering, whenever they released therapeutic amounts of gallium ions to the surrounding medium. Three gallium-enriched MBGs with composition (in mol %) xSiO₂-yCaO-zP₂O₅-5Ga₂O₃, being x = 70, y = 15, z = 10 for Ga_1; x = 80, y = 12, z = 3 for Ga_2; and x = 80, y = 15, z = 0 for Ga_3, were investigated and compared with the gallium-free 80SiO₂-15CaO-5P₂O₅ MBG (B). 29Si and 31P MAS NMR analyses indicated that Ga3+ acts as network modifier in the glass regions with higher polymerization degree and as network former in the zones with high concentration of classical modifiers (Ca2+ ions). Ga_1 and Ga_2 exhibited a quick in vitro bioactive response because they were coated by an apatite-like layer after 1 and 3 days in simulated body fluid. Although we have not conducted biological tests in this paper (cells or bacteria), Ga_1 released high but non-cytotoxic amounts of Ga3+ ions in Todd Hewitt Broth culture medium that were 140 times higher than the IC90 of Pseudomonas aeruginosa bacteria, demonstrating its potential for tissue engineering applications.

In-situ preparation of scholzite conversion coatings on titanium and Ti-6Al-4V for biomedical applications

A scholzite (CaZn₂(PO₄)₂·2H₂O) coating was prepared in situ on commercially pure titanium (cpTi) and Ti-6Al-4V (Ti64) substrates using the chemical conversion technology, and its phase composition and microstructure, as well as mechanical, chemical and biological properties were investigated to explore potential applications as a bioactive coating on bone implants. It is indicated that the coating consists mainly of monoclinic scholzite crystals with nano-thick laminar morphology. The crystals on cpTi aggregate to flower-like particles with the diameter of 5-10μm, while form a network structure homogeneously on Ti64. The scratch test shows that the interfacial bonding strength between the coatings and substrates is higher than 40N. Electrochemical measurements indicate that the corrosion behavior of the coatings is not inferior compared with that of oxide film on substrates. MG63 osteoblast-like cells show good adherence and significantly proliferation and differentiation characteristics on the scholzite coated cpTi and Ti64 (p<0.05) in in-vitro cell tests, demonstrating the cytocompatibility of Ti is significantly improved by the scholzite coating. It is suggested that the scholzite coating might be a promising option in hard tissue replacements for early osteogenesis.

SiO₂-CaO-P₂O₅ Bioactive Glasses: A Promising Curcuminoids Delivery System

In this paper, we report the study of the loading and the release of curcuminoids by bioactive glasses (BG) and mesoporous bioactive glasses (MBG). Through a detailed spectroscopic study, it was possible to determine the amount and the type of molecules released in water and in simulated body fluid (SBF). In particular, curcumin and K2T21 show a good ability to be released in di-keto and keto-enolic form, depending from the pH. However, after 24 h, the amount of pristine curcumin release is very low with a consequent increment of degradation products derived by curcuminoids. The presence of –OH groups on curcuminoids is a fundamental pre-requisite in order to obtain a high loading and release in polar solution such as water and SBF. The substrate on which we loaded the drugs does not seem to affect significantly the loading and the release of the drugs. The environment, instead, affects the release: for all the drugs, the release in SBF, buffered at pH of 7.4, is slightly worse than the release in water (basic pH values).

Formation initiation and structural changes of phosphate conversion coating on titanium induced by galvanic coupling and Fe2+ ions

A scholzite coating was precipitated on Ti by a galvanically coupled approach and addition of iron ions in the bath.

Synthesis and characterization of cerium- and gallium-containing borate bioactive glass scaffolds for bone tissue engineering

Bioactive glasses are widely used in biomedical applications due to their ability to bond to bone and even to soft tissues. In this study, borate based (13-93B3) bioactive glass powders containing up to 5 wt% Ce2O3 and Ga2O3 were prepared by the melt quench technique. Cerium (Ce+3) and gallium (Ga+3) were chosen because of their low toxicity associated with bacteriostatic properties. Bioactive glass scaffolds were fabricated using the polymer foam replication method. In vitro degradation and bioactivity of the scaffolds were evaluated in SBF under static conditions. Results revealed that the cerium- and gallium-containing borate glasses have much lower degradation rates compared to the bare borate glass 13-93B3. In spite of the increased chemical durability, substituted glasses exhibited a good in vitro bioactive response except when the Ce2O3 content was 5 wt%. Taking into account the high in vitro hydroxyapatite forming ability, borate glass scaffolds containing Ce+3 and Ga+3 therapeutic ions are promising candidates for bone tissue engineering applications.

In vitro antibacterial capacity and cytocompatibility of SiO2-CaO-P2O5 meso-macroporous glass scaffolds enriched with ZnO

Zn²⁺ ions exhibit osteogenic, angiogenic and antimicrobial properties. For this reason, they are often added in small amounts to bioceramics being investigated for bone tissue engineering. In this paper, the cytocompatibility and antibacterial properties of 80% SiO₂-15% CaO-5% P₂O₅ (mol%) mesoporous bioactive glass (MBG) scaffolds substituted with 4.0% and 7.0% of ZnO were studied and compared with the Zn-free scaffold. Cell proliferation, morphology, differentiation and cytotoxic effects of Zn²⁺ ions released from the samples were examined by culturing human osteoblast-like cells (HOS) osteoblasts both in the presence of sample extracts and on the scaffold surface. The bacterial inhibition capacity of the scaffolds was explored by using Gram-positive Stapylococcus aureus bacteria, responsible for numerous infections in orthopedic surgery, to simulate a severe infection. Our results show that the Zn-MBG scaffolds possess a hierarchical meso-macropore structure suitable for osteoblast growth. Furthermore, the amount of Zn²⁺ released from the scaffold with 4.0% ZnO was found to be more favorable for HOS cell development than that released from the scaffold including 7.0% ZnO. Zn²⁺ released to the medium from both scaffolds exhibited antibacterial properties against S. aureus. Thus, the cytocompatibility and the antibacterial ability exhibited by the MBG scaffold containing 4.0% ZnO make it a suitable candidate for bone regeneration applications.

Mesoporous bioactive scaffolds prepared with cerium-, gallium- and zinc-containing glasses

Mesoporous bioactive glass scaffolds (MBG_Scs), based on 80% SiO(2)-15% CaO-5% P(2)O(5) (in mol.%) mesoporous sol-gel glasses substituted with Ce(2)O(3), Ga(2)O(3) (both 0.2% or 1.0%) and ZnO (0.4% or 2.0%), were synthesized by combination of evaporation-induced self-assembly and rapid prototyping techniques. Cerium, gallium and zinc trace elements were selected because of their inherent beneficial biological properties. Fabricated scaffolds were characterized and compared with unsubstituted scaffold (B_Sc). All of them contained well interconnected ultralarge pores (pores >400 μm) ideal for vascular ingrowth and proliferation of cells. Macropores of size 100-400 μm were present inside the scaffolds. In addition, low-angle X-ray diffraction showed that B_Sc and scaffolds with substituent contents up to 0.4% exhibited ordered mesoporosity useful for hosting molecules with biological activity. The textural properties of B_Sc were a surface area of 398 m(2) g(-1), a pore diameter of 4.3 nm and a pore volume of 0.43 cm(3) g(-1). A slight decrease in surface area and pore volume was observed upon substitution with no distinct effect on pore diameter. In addition, all the MBG_Scs except 2.0% ZnO_Sc showed quite quick in vitro bioactive response. Hence, the present study is a positive addition to ongoing research into preparing bone tissue engineering scaffolds from bioceramics containing elements of therapeutic significance.