Mesoporous bioactive glass nanoparticles doped with magnesium: drug delivery and acellular in vitro bioactivity

Microstructure, wear, and corrosion properties of PEEK-based composite coating incorporating titania- and copper-doped mesoporous bioactive glass nanoparticles

Poor wear- and corrosion-resistance of 316L SS implants are critical problems in orthopedic implants. This study aims to improve the wear- and corrosion-resistance of 316L SS through surface coating. In this study, a bilayer composite coating consisting of polyether ether ketone (PEEK) as the first layer, and titania (TiO2)- and Cu-doped mesoporous bioactive glass nanoparticles (Cu-MBGNs) were deposited as the second layer on a 316L SS via electrophoretic deposition (EPD). Scanning electron microscopy (SEM) images of the bilayer composite coating showed the distribution of TiO2 and Cu-MBGNs within the PEEK matrix. Energy dispersive spectroscopy (EDS) analysis confirmed the presence of TiO2 and Cu-MBGNs in the bilayer composite coating. Fourier transform infrared spectroscopy (FTIR) identified the functional groups attributed to the PEEK, TiO2 and Cu-MBGNs. X-ray diffraction (XRD) analysis confirmed the presence of TiO2 (anatase) and Cu-MBGNs in the bilayer composite coating. The coating exhibited a strong antibacterial effect against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Incorporating TiO2/Cu-MBGNs into the bilayer composite coating significantly modified the surface of 316L SS by improving the wear- and corrosion-resistance. Pin on disc test revealed that the specific wear rate of ∼(0.4570 ± 0.009) × 10-6 mm3 Nm-1 of the PEEK coating decreased to (0.0482 ± 0.007) × 10-6 mm3 Nm-1 on incorporating TiO2/Cu-MBGNs in PEEK coating under a normal load of 10 N in Dulbecco's Modified Eagle Medium (DMEM). Furthermore, electrochemical impedance spectroscopy (EIS) results revealed that the impedance value of the bilayer composite coating remained ∼4.56 × 105 Ω cm2 compared to 8.81 × 103 Ω cm2 of 316L SS after 24 h immersion in phosphate-buffered saline (PBS). Thus, this study demonstrated that the wear- and corrosion-resistance of 316L SS can be improved by incorporating TiO2/Cu-MBGNs in PEEK-based composite coatings for orthopedic applications.

Stimulus-responsive smart bioactive glass composites for repair of complex tissue defects

Smart biomaterials with active environmental responsiveness have attracted widespread attention in recent years. Previous studies on bioactive glass (BG) have mainly focused on the property of bioactivity, while little attention has been paid to the property of smart response of BG. Herein, we propose the concept of Smart Bioactive Glass Composites (SBGC) which are capable of actively responding to the endogenous disease microenvironment or exogenous physical stimuli, thereby enabling active treatment of tissue defect sites and ultimately promoting tissue regeneration. In this review, the response characteristics of SBGC to different internal and external environments are described. Subsequently, the applications of SBGC in complex tissue defect repair of tumors, infections, and diabetes are reviewed. By deeply analyzing the recent progress of SBGC in different fields, this review will point out the direction for the research of next-generation BG.

Innovative cancer therapy: Unleashing the potential of macromolecule-loaded mesoporous bioactive glasses for precision diagnosis and treatment

Cancer continues to pose a formidable threat, claiming millions of lives annually. A beacon of hope in this battle lies in the realm of bioactive glasses, which have undergone a remarkable evolution over the past five decades. Among these, mesoporous bioactive glasses (MBGs) emerge as a dynamic subset endowed with customizable attributes such as high surface area and porosity. While holding immense promise for cancer care, the full clinical potential of MBGs remains largely unexplored. This review delves into the cutting-edge advancements in MBG technology, illuminating their pivotal role in cancer management - spanning from early detection to targeted therapeutic interventions like photothermal and photodynamic treatments. Furthermore, the molecular mechanisms underpinning MBGs' anticancer properties are elucidated, alongside an exploration of existing limitations in their application. Through this comprehensive synthesis, the significance of MBGs in revolutionizing cancer therapy is underscored, underscoring the urgent need for continued research to unlock their full potential in reshaping the landscape of cancer care.

Biomolecule and Ion Releasing Mesoporous Nanoparticles: Nonconvergent Osteogenic and Osteo-immunogenic Performance

Immune-involved cell communications have recently been introduced as key role players in the fate of mesenchymal stem cells in making bone tissue. In this study, a drug delivery system for bone (re)generation based on copper-doped mesoporous bioactive glass nanoparticles (BGNPs) was developed to codeliver copper as a biologically active ion and icariin as an anti-inflammatory agent. This design was based on temporal inflammation fluctuations from proinflammatory to anti-inflammatory during bone generation. Three in vitro models were performed with human mesenchymal stem cells (hMSCs) to verify the osteo-immunomodulatory effects of released copper ions and icariin: nonstimulated, co-conditioned with macrophage medium and co-cultured with macrophages. Both icariin and copper showed increased levels of alkaline phosphatase activation, indicating a direct osteogenic effect. Copper-doped BGNPs showed the highest increase of osteo-immunogenic properties in a mineralization assay and also induced short-term inflammation. However, the mineralization dropped in copper doped BGNPs after loading with icariin due to copper-icariin chelate formation and inhibition of the early inflammatory phase in the immune-stimulated in vitro models. In the absence of copper, the direct osteogenic properties of icariin overtook its osteo-immunogenic inhibition and increased calcification. Overall, BGNPs doped with 5 mol % copper and no icariin showed the highest bone-forming capacity.

Combining Mesoporous Bioactive Glass Nanoparticles (MBGNs) with Essential Oils to Tackle Bacterial Infection and Oxidative Stress for Bone Regeneration Applications

Bacterial infectious diseases remain one of the significant challenges in the field of bone regeneration applications. Despite the development of new antibiotics, their improper administration has led to the development of multiresistant bacterial strains. In this study, we proposed a novel approach to tackle this problem by loading clove oil (CLV), a natural antibacterial compound, into amino-functionalized mesoporous bioactive glass nanoparticles (MBGNs). The scanning electron microscopy images (SEM) revealed that amino-functionalization and CLV loading did not affect the shape and size of the MBGNs. The successful grafting of the amino groups on the MBGNs' surface and the presence of CLV in the material were confirmed by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy and zeta potential measurements. The increased CLV concentration led to a higher loading capacity, encapsulation efficiency, and antioxidant activity. The in vitro CLV release profile exhibited an initial burst release, followed by a controlled release over 14 days. The loading of CLV into MBGNs led to a stronger antibacterial effect against E. coli and S. aureus, while MG-63 osteoblast-like cell viability was enhanced with no morphological changes compared to the control group. In conclusion, the CLV-MBGNs nanocarriers showed promising properties in vitro as novel drug delivery systems, exploiting essential oils for treating bone infections and oxidative stress.

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

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

The Effect of Iron Oxide Insertion on the In Vitro Bioactivity, and Antibacterial Properties of the 45S5 Bioactive Glass

The aging population and increasing incidence of trauma among younger age groups have heightened the increasing demand for reliable implant materials. Effective implant materials must demonstrate rapid osseointegration and strong antibacterial properties to ensure optimal patient outcomes and decrease the chance of implant rejection. This study aims to enhance the bone-implant interface by utilizing 45S5 bioglass modified with various concentrations of Fe3O4 as a coating material. The effect of the insertion of Fe3O4 into the bioglass structure was studied using Raman spectroscopy which shows that with the increase in Fe3O4 concentration, new vibration bands associated with Fe-related structural units appeared within the sample. The bioactivity of the prepared glasses was evaluated using immersion tests in simulated body fluid, revealing the formation of a calcium phosphate-rich layer within 24 h on the samples, indicating their potential for enhanced tissue integration. However, the sample modified with 8 mol% of Fe3O4 showed low reactivity, developing a calcium phosphate-rich layer within 96 h. All the bioglasses showed antibacterial activity against the Gram-positive and Gram-negative bacteria. The modified bioglass did not present significant antibacterial properties compared to the bioglass base.

Exploring the Impact of Copper Oxide Substitution on Structure, Morphology, Bioactivity, and Electrical Properties of 45S5 Bioglass®

In recent decades, the requirements for implantable medical devices have increased, but the risks of implant rejection still exist. These issues are primarily associated with poor osseointegration, leading to biofilm formation on the implant surface. This study focuses on addressing these issues by developing a biomaterial for implant coatings. 45S5 bioglass® has been widely used in tissue engineering due to its ability to form a hydroxyapatite layer, ensuring a strong bond between the hard tissue and the bioglass. In this context, 45S5 bioglasses®, modified by the incorporation of different amounts of copper oxide, from 0 to 8 mol%, were synthesized by the melt-quenching technique. The incorporation of Cu ions did not show a significant change in the glass structure. Since the bioglass exhibited the capacity for being polarized, thereby promoting the osseointegration effectiveness, the electrical properties of the prepared samples were studied using the impedance spectroscopy method, in the frequency range of 102-106 Hz and temperature range of 200-400 K. The effects of CuO on charge transport mobility were investigated. Additionally, the bioactivity of the modified bioglasses was evaluated through immersion tests in simulated body fluid. The results revealed the initiation of a Ca-P-rich layer formation on the surface within 24 h, indicating the potential of the bioglasses to enhance the bone regeneration process.

ON/OFF based synergetic plasmonic photothermal drug release approach through core-satellite like mussel-inspired polydopamine nanoparticles

One of the studies on new drug delivery and release systems that has increased in recent years is the study using plasmonic nanoparticles. In this study, polydopamine nanoparticles (PDOP NPs), which contribute to photothermal drug release by near infrared radiation (NIR), were decorated with gold nanoparticles (AuNPs) to utilize their plasmonic properties, and a core-satellite-like system was formed. With this approach, epirubicin (EPI)-loaded PDOP NPs were prepared by utilizing the plasmonic properties of AuNPs. Scanning Electron Microscope (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and X-ray Diffraction (XRD) methods were used to evaluate the structural properties of these particles. The release behavior of the prepared structures in acidic (pH 5.0) and neutral (pH 7.4) environments based on the ON/OFF approach was also examined. The biocompatibility properties of the particles were evaluated on mouse fibroblast (L929) and anticancer activities on neuroblastoma (SH-SY5Y) cells. The effects of prepared EPI-loaded particles and laser-controlled drug release on ROS production, genotoxicity, and apoptosis were also investigated in SH-SY5Y cells. With the calculated combination index (CI) value, it was shown that the activity of EPI-loaded AuNP@PDOP NPs increased synergistically with the ON/OFF-based approach. The developed combination approach is considered to be remarkable and promising for further evaluation before clinical use.

Strontium and Zinc Co-Doped Mesoporous Bioactive Glass Nanoparticles for Potential Use in Bone Tissue Engineering Applications

Mesoporous bioactive glass nanoparticles (MBGNs) have attracted significant attention as multifunctional nanocarriers for various applications in both hard and soft tissue engineering. In this study, multifunctional strontium (Sr)- and zinc (Zn)-containing MBGNs were successfully synthesized via the microemulsion-assisted sol-gel method combined with a cationic surfactant (cetyltrimethylammonium bromide, CTAB). Sr-MBGNs, Zn-MBGNs, and Sr-Zn-MBGNs exhibited spherical shapes in the nanoscale range of 100 ± 20 nm with a mesoporous structure. Sr and Zn were co-substituted in MBGNs (60SiO2-40CaO) to induce osteogenic potential and antibacterial properties without altering their size, morphology, negative surface charge, amorphous nature, mesoporous structure, and pore size. The synthesized MBGNs facilitated bioactivity by promoting the formation of an apatite-like layer on the surface of the particles after immersion in Simulated Body Fluid (SBF). The effect of the particles on the metabolic activity of human mesenchymal stem cells was concentration-dependent. The hMSCs exposed to Sr-MBGNs, Zn-MBGNs, and Sr-Zn-MBGNs at 200 μg/mL enhanced calcium deposition and osteogenic differentiation without osteogenic supplements. Moreover, the cellular uptake and internalization of Sr-MBGNs, Zn-MBGNs, and Sr-Zn-MBGNs in hMSCs were observed. These novel particles, which exhibited multiple functionalities, including promoting bone regeneration, delivering therapeutic ions intracellularly, and inhibiting the growth of Staphylococcus aureus and Escherichia coli, are potential nanocarriers for bone regeneration applications.

Eco-friendly synthesis of mesoporous bioactive glass ceramics and functionalization for drug delivery and hard tissue engineering applications

Hard tissue regenerative mesoporous bioactive glass (MBG) has traditionally been synthesized using costly and toxic alkoxysilane agents and harsh conditions. In this study, MBG was synthesized using the cheaper reagent SiO2by using a co-precipitation approach. The surface properties of MBG ceramic were tailored by functionalizing with amino and carboxylic groups, aiming to develop an efficient drug delivery system for treating bone infections occurring during or after reconstruction surgeries. The amino groups were introduced through a salinization reaction, while the carboxylate groups were added via a chain elongation reaction. The MBG, MBG-NH2, and MBG-NH-COOH were analyzed by using various techniques: x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET), scanning electron microscopy and energy-dispersive x-ray spectroscopy. The XRD results confirmed the successful preparation of MBG, and the FTIR results indicated successful functionalization. BET analysis revealed that the prepared samples were mesoporous, and functionalization tuned their surface area and surface properties. Cefixime, an antibiotic, was loaded onto MBG, MBG-NH2, and MBG-NH-COOH to test their drug-carrying capacity. Comparatively, MBG-NH-COOH showed good drug loading and sustained release behavior. The release of the drug followed the Fickian diffusion mechanism. All prepared samples displayed favorable biocompatibility at higher concentration in the Alamar blue assay with MC3T3 cells and exhibited the good potential for hard tissue regeneration, as carbonated hydroxyapatite formed on their surfaces in simulated body fluid.

Devitrite (Na2Ca3Si6O16) phase dominated nanostructured 45S5 bioactive glass: exploring its structural and biological properties

This research study is primarily centred around calcination temperature and time influence on phase formation in bioactive glasses (BGs). In the present study, BG with a nominal composition of 45S5 was synthesized through the sol-gel process. The developed BGs then underwent heat treatment for various sintering durations and temperatures. X-ray diffraction (XRD) patterns of the BGs reveals that the sintering process led to the crystallization of both devitrite (Na2Ca3Si6O16) and combeite (Na2Ca2Si3O9) phases. The field emission scanning electron microscopy study divulges morphological alterations, from sheet-like to rod-like structures to eventually transforming into spherical and sheet-like structures. The surface area and Type-IV mesoporous porosity were validated through Brunauer Emmett Teller analysis, highlighting a notable increase in pore volume and mechanical strength at a lower sintering temperature.In vitroapatite formation was carried out in Hank's balance salt in order to evaluate the bioactivity of the glass. After 7 d of immersion in simulated body fluid (SBF), XRD patterns and scanning electron microscopy micrographs results showed that formation of hydroxyapatite layer on the surface of the BGs. The BG compatibility with erythrocytes (red blood cells) was also studied, and the results revealed that there was only a low 2% lysis, showing good hemocompatibility. The drug loading and release behaviour of the BGs was studied in thein vitroanalysis. The findings showed a high drug encapsulation effectiveness of up to 90% and continuous drug release from the BGs for 24 h. The materials biocompatibility was unambiguously confirmed by cytocompatibility and proliferation studies. This study provides compelling evidence for the exceptional efficacy and promise of the distinct 45S5 BGs in advancing the field of regenerative medicine.

Bio-response of copper-magnesium co-substituted mesoporous bioactive glass for bone tissue regeneration

Mesoporous bioactive glass (MBG) is widely acknowledged in bone tissue engineering due to its mesoporous structure, large surface area, and bioactivity. Recent research indicates that introduction of metallic ions has beneficial impacts on bone metabolism and angiogenesis. Thus, the features of MBG can be modified by incorporating combinations of ions, such as magnesium (Mg) and copper (Cu), which can play a considerable role in bone formation, influencing angiogenesis, osteogenesis, as well as antibacterial properties. In this study, Mg and Cu were co-doped for the first time (in a ratio of 1 : 1) in 80SiO2-5P2O5-(15 - 2x)CaO-xMgO-xCuO glass composition with x = 0, 0.5, 1, and 2 mol%, synthesized using the sol-gel and evaporation-induced self-assembly method. X-ray diffraction analysis confirmed the amorphous nature of the powders, while inductively coupled plasma-optical emission spectrometry verified the existence of dopant ions in the respective amounts. The nitrogen sorption method indicated the formation of uniform cylindrical mesopores which are open at both ends and a high surface area of the powders. TEM images show fringes, indicating an ordered mesoporous structure in all MgCu co-doped systems. In vitro bioactivity was observed in all MBG powders, confirmed by the formation of an apatite phase when placed in simulated body fluid (SBF). Flake-like microstructure characteristics of HAp crystals found on the surface of MBG powders were visualized using FESEM. Cytotoxicity tests at lower concentrations (0.1 and 1 wt/vol%) of co-doped 2MC MBG (co-doping up to 2 mol%) showed cell proliferation and viability of osteoblast-like MG-63 cells and normal human dermal fibroblast (NHDF) cells similar to the basic glass 80S. Antibacterial study of MBG pellets showed an increment in the zone of inhibition with the sequential addition of doping ions. The turbidity measurement of bacterial cultures revealed that the optimal concentration for effectively inhibiting bacterial growth was 1 wt/vol% (i.e., 10 mg mL-1) concentration of MBG extracts. The result suggested that the incorporation of Mg and Cu ions in MBG in lower concentrations of up to 2 mol% can be useful in bone regeneration owing to bioactivity, cell proliferation, and antibacterial characteristics.

Drug kinetics and antimicrobial properties of quaternary bioactive glasses 81S(81SiO2-(16-x)CaO-2P2O5-1Na2O-xMgO); an in-vitro study

Bioactive glasses have recently been attracted to meet the challenge in bone tissue regeneration, repair, healing, dental implants, etc. Among the conventional bio-glasses, a novel quaternary mesoporous nano bio-glass with composition 81S(81SiO2-(16-x)CaO-2P2O5-1Na2O-xMgO) (x = 0, 1.6, 2.4, 4 and 8 mol%) employing Stober's method has been explored for examining the above potential application through in-vitro SBF assay, MTT assay, antimicrobial activity and drug loading and release ability. With increasing the MgO concentration up to 4 mol%, from in-vitro SBF assay, we observe that HAp layer develops on the surface of the nBGs confirmed from XRD, FTIR and FESEM. MTT assay using MG-63 cells confirms the biocompatibility of the nBGs having cell viability >225 % for MGO_4 after 72 h which is more than the clinically used 45S5 bio-glass. We have observed cell viability of >125 % even after 168 h. Moreover, MGO_4 is found to restrict the growth of E. coli by 65 % while S. aureus by 75 %, confirming the antimicrobial activity. Despite an increase in the concentration of magnesium, nBGs are found to be non-toxic towards the RBCs up to 4 mol% of MgO while for 8 %, the hemolysis percentage is >6 % which is toxic. Being confirmed MGO_4 nBG as a bioactive material, various concentrations of drug (Dexamethasone (DEX)) loading and release kinetics are examined. We show that 80 % of loading in case of 10 mg-ml-1 and 70 % of cumulative release in 100 h. The mesoporous structure of MGO_4 having an average pore diameter of 5 nm and surface area of 216 m2 g-1 confirmed from BET supports the loading and release kinetics. We conclude that the quaternary MGO_4 nBG may be employed effectively for bone tissue regeneration due to its high biocompatibility, excellent in-vitro cell viability, antimicrobial response and protracted drug release.

Influence of the Addition of Zinc, Strontium, or Magnesium Oxides to the Bioglass 45S5 Network on Electrical Behavior

45S5 Bioglass has been widely used in regenerative medicine due to its ability to dissolve when inserted into the body. Its typically amorphous structure allows for an ideal dissolution rate for the formation of the hydroxyapatite layer, which is important for the development of new bone. This bioactive capacity can also be controlled by adding other oxides (e.g., SrO, ZnO, and MgO) to the 45S5 Bioglass network or by storing electrical charge. Ions such as zinc, magnesium, and strontium allow for specific biological responses to be added, such as antibacterial action and the ability to increase the rate of osteoblast proliferation. The charge storage capacity allows for a higher rate of bioactivity to be achieved, allowing for faster attachment to the host bone, decreasing the patient's recovery time. Therefore, it is necessary to understand the variation in the structure of the bioglass with regard to the amount of non-bridging oxygens (NBOs), which is important for the bioactivity rate not to be compromised, and also its influence on the electrical behavior relevant to its potential as electrical charge storage. Thus, several bioactive glass compositions were synthesized based on the 45S5 Bioglass formulation with the addition of various concentrations (0.25, 0.5, 1, and 2, mol%) of zinc, strontium, or magnesium oxides. The influence of the insertion of these oxides on the network was evaluated by studying the amount of NBOs using Raman spectroscopy and their implication on the electrical behavior. Electrical characterization was performed in ac (alternating current) and dc (direct current) regimes.

Novel cytotoxicity study of strontium (Sr) doped iron oxide (Fe3O4) nanoparticles aided with ibuprofen for drug delivery applications

This work is aimed at studying the drug delivery applications of iron oxide (Fe3O4) nanoparticles with strontium (Sr) doping with varying molar ratios prepared by the co-precipitation route. The impact of increased strontium content on the particle size and magnetic properties was investigated. The impending of these nanoparticles for drug loading, drug release, and their respective cytotoxicity was also inspected.First, iron oxide nanoparticles were doped with various amounts of strontium, from 0.25, 0.50, and 0.75, to 1 mol using co-precipitation method. These synthesized nanoparticles were characterized by XRD, SEM, EDX, VSM, and FTIR for evaluating crystal structure, phase purity, morphology, composition, magnetic properties, and functional groups, respectively. Drug loading and drug release properties were determined using UV-vis spectroscopy, whereas MTT assay evaluated cytotoxicity. Colloidal stability was assessed using zeta potential in PBS solution.The findings confirmed the successful doping of iron oxide with strontium via XRD and EDX. SEM results confirmed spherical morphology for all and needle-like structure for 1 mol strontium doped sample. For VSM results, a single domain structure was established. It was also observed that the drug encapsulation efficiency increases with increased strontium content. Cytotoxicity results by MTT assay revealed increased cytotoxicity with increasing nanoparticle concentration, and ibuprofen-loaded nanoparticles showed higher cytotoxicity than un-loaded nanoparticles at the same concentration. Zeta potential results showed colloidal stability of iron oxide nanoparticles increased by the addition of strontium.This study provided predominantly comparison of the cytotoxicity of ibuprofen-loaded and non-loaded nanoparticles on Hep-2 cancer cells at similar concentrations for the first time for both Fe3O4 particles and Sr-doped Fe3O4 nanoparticles and enclosed the impact of increasing Sr doping content on Fe3O4 nanoparticles.

Bioactive Glasses Containing Strontium or Magnesium Ions to Enhance the Biological Response in Bone Regeneration

The non-surgical treatments are being required to reconstruct damaged tissue, prioritizing our body's natural healing process. Thus, the use of bioactive materials such as bioactive glass has been studied to support the repair and restoration of hard and soft tissue. Thus, in this work Bioglass 45S5 was developed, adding 1 and 2%mol of SrO or MgO and the physical and biological properties were evaluated. The addition of MgO and SrO at the studied concentrations promoted the slight increase in non-bridging oxygens number, observed through the temperature shift in phase transitions to lower values compared to Bioglass 45S5. The insertion of the ions also showed a positive effect on Saos-2 cell viability, decreasing the cytotoxic of Bioglass 45S5. Besides the Ca/P ratio on the pellets surface demonstrating no evidence of higher reactivity between Bioglass 45S5 and Bioglass with Sr and Mg, micrographs show that at 24 h the Ca/P rich layer is denser than in Bioglass 45S5 after the contact with simulated body fluid. The samples with Sr and Mg show a higher antibacterial effect compared to Bioglass 45S5. The addition of the studied ions may benefit the biological response of Bioglass 45S5 in dental applications as scaffolds or coatings.

Magnesium-Rich Calcium Phosphate Derived from Tilapia Bone Has Superior Osteogenic Potential

We extracted magnesium-rich calcium phosphate bioceramics from tilapia bone using a gradient thermal treatment approach and investigated their chemical and physicochemical properties. X-ray diffraction showed that tilapia fish bone-derived hydroxyapatite (FHA) was generated through the first stage of thermal processing at 600-800 °C. Using FHA as a precursor, fish bone biphasic calcium phosphate (FBCP) was produced after the second stage of thermal processing at 900-1200 °C. The beta-tricalcium phosphate content in the FBCP increased with an increasing calcination temperature. The fact that the lattice spacing of the FHA and FBCP was smaller than that of commercial hydroxyapatite (CHA) suggests that Mg-substituted calcium phosphate was produced via the gradient thermal treatment. Both the FHA and FBCP contained considerable quantities of magnesium, with the FHA having a higher concentration. In addition, the FHA and FBCP, particularly the FBCP, degraded faster than the CHA. After one day of degradation, both the FHA and FBCP released Mg²⁺, with cumulative amounts of 4.38 mg/L and 0.58 mg/L, respectively. Furthermore, the FHA and FBCP demonstrated superior bone-like apatite formation; they are non-toxic and exhibit better osteoconductive activity than the CHA. In light of our findings, bioceramics originating from tilapia bone appear to be promising in biomedical applications such as fabricating tissue engineering scaffolds.

High Boron Content Enhances Bioactive Glass Biodegradation

Derived Hench bioactive glass (BaG) containing boron (B) is explored in this work as it plays an important role in bone development and regeneration. B was also found to enhance BaG dissociation. However, it is only possible to incorporate a limited amount of B. To increase the amount of B in BaG, bioactive borosilicate glasses (BaG-B_x) were fabricated based on the use of the solution-gelation process (sol-gel). In this work, a high B content (20 wt.%) in BaG, respecting the conditions of bioactivity and biodegradability required by Hench, was achieved for the first time. The capability of BaG-B_x to form an apatite phase was assessed in vitro by immersion in simulated body fluid (SBF). Then, the chemical structure and the morphological changes in the fabricated BaG-B_x (x = 0, 5, 10 and 20) were studied. The formation of hydroxyapatite (HAp) layer was observed with X-ray diffraction (XRD) and infrared (IR) spectroscopy. The presence of HAp layer was confirmed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Enhanced bioactivity and chemical stability of BaG-B_x were evaluated with an ion exchange study based on Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) and energy dispersive spectroscopy (EDS). Results indicate that by increasing the concentration of B in BaG-Bx, the crystallization rate and the quality of the newly formed HAp layer on BaG-B_x surfaces can be improved. The presence of B also leads to enhanced degradation of BaGs in SBF. Accordingly, BAG-B_x can be used for bone regeneration, especially in children, because of its faster degradation as compared to B-free glass.

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

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

Bioactive nanoglass regulating the myogenic differentiation and skeletal muscle regeneration

Bioactive glass nanoparticles (BGNs) are widely used in the field of biomedicine, including drug delivery, gene therapy, tumor therapy, bioimaging, molecular markers and tissue engineering. Researchers are interested in using BGNs in bone, heart and skin regeneration. However, there is inadequate information on skeletal muscle tissue engineering, limited information on the biological effects of BGNs on myoblasts, and the role of bioactive glass composite materials on myogenic differentiation is unknown. Herein, we report the effects of BGNs with different compositions (60Si-BGN, 80Si-BGN, 100Si-BGN) on the myogenic differentiation in C2C12 cells and in vivo skeletal tissue regeneration. The results showed that 80Si-BGN could efficiently promote the myogenic differentiation of C1C12 cells, including the myotube formation and myogenic gene expression. The in vivo experiment in a rat skeletal muscle defect model also confirmed that 80Si-BGN could significantly improve the complete regeneration of skeletal muscle tissue during 4 weeks implantation. This work firstly demonstrated evidence that BGN could be the bioactive material in enhancing skeletal muscle regeneration.

A novel bioactive glass/graphene oxide composite coating for a polyether ether ketone-based dental implant

Polyether ether ketone (PEEK) is a biocompatible material that lacks antimicrobial activity and bioactivity; therefore, is not appropriate for use as a dental implant. To overcome these deficiencies, a novel composite coating of bioactive glass and graphene oxide was prepared. PEEK discs were polished, cleaned, and the surface treated with sulfuric acid for 15 min. The composite coating consisted of bioactive glass produced by the sol-gel route and doped with 0.75 wt% graphene oxide. X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy-energy dispersive spectroscopy analyses were employed to characterize the composite coating, and the coating adhesion strength quantified using a pull-off test. Cytotoxicity was assessed using osteoblast-like cells and gingival fibroblasts. The wettability of the coated and non-coated samples was determined by optical contact angle assessment, and bioactivity was assessed by immersion in simulated body fluid. The results revealed that the bioactive glass/graphene oxide composite coating, approximately 7 μm thick, was transparent, homogenous with few microcracks and microporosities, but adhered strongly and was not cytotoxic to either osteoblast-like cells or gingival fibroblasts. The wettability of the PEEK sample was increased to <20° after coating with the composite, and apatite formation was detectable after 14 days of immersion in simulated body fluid.

Bioglass obtained via one-pot synthesis as osseointegrative drug delivery system

Osseointegration is a fundamental process during which implantable biomaterial integrates with host bone tissue. The surgical procedure of biomaterial implantation is highly associated with the risk of bacterial infection. Thus, the research continues for biodegradable bone void fillers which are able to stimulate the bone tissue regeneration and locally deliver the antibacterial agent. Herein, we obtained bifunctional bioglass (BG) using novel, preoptimized, rapid one-pot synthesis. Following the ISO Standards, the influence of the obtained BG on osteoblast-mediated phenomena, such as osteoconduction and osteoinduction was assessed and compared to two commercial materials: bioactive glass powder 45S and bioactive glass powder 85S. Direct-contact tests revealed osteoblast adhesion to BG particles; whereas, tests on extracts confirmed high viability of cells incubated with BG extract. Analyses of gene expression, alkaline phosphatase activity, and calcium phosphates deposition confirmed the stimulation of early and late stages of osteoblast differentiation and mineralization. Additionally, an extended evaluation of intracellular calcium fluctuations revealed a possible correlation between osteoblast calcium uptake and extracellular matrix mineralization. Moreover, proposed bioglass exhibited satisfactory doxycycline adsorption capacity and release profile. The obtained results confirmed the bifunctionality of the proposed BG and indicated its potential as osseointegrative bone drug delivery system.

Mesoporous Bioactive Nanoparticles for Bone Tissue Applications

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

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.

Facile post modification synthesis of copper-doped mesoporous bioactive glass with high antibacterial performance to fight bone infection

Successful treatment of infected bone defects caused by multi-drug resistant bacteria (MDR) has become a major clinical challenge, stressing the urgent need for effective antibacterial bone graft substitutes. Mesoporous bioactive glass nanoparticles (MBGNs), a rapidly emerging class of nanoscale biomaterials, offer specific advantages for the development of biomaterials to treat bone infection due to endowed antibacterial features. Herein, we propose a facile post-modification sol-gel strategy to synthesize effective antibacterial MBGNs doped with copper ions (Cu-PMMBGNs). In this strategy, amine functional groups as chelating agents were introduced to premade mesoporous silica nanoparticles (MSNs) which further facilitate the incorporation of high content of calcium (∼17 mol%) and copper ions (∼8 mol%) without compromising nanoparticle shape, mesoporosity, and homogeneity. The resulting nanoparticles were degradable and showed rapidly induce abundant deposition of apatite crystals on their surface upon soaking in simulated body fluids (SBF) after 3 days. Cu-PMMBGNs exhibited a dose-dependent inhibitory effect on Methicillin-resistant Staphylococcus aureus (MRSA) bacteria, which are common pathogens causing severe bone infections. Most importantly, the nanoparticles containing 5 mol% copper ions at concentrations of 500 and 1000 μg.mL^-1 showed highly effective antibacterial performance as reflected by a 99.9 % reduction of bacterial viability. Nanoparticles at a concentration of 500 μg.mL^-1 showed no significant cytotoxicity toward preosteoblast cells (∼85-89 % cell viability) compared to the control group. In addition, the nanoscale properties of synthesized Cu-PMMBGNs (∼100 nm in size) facilitated their internalization into preosteoblast cells, which highlights their potential as intracellular carriers in combating intracellular bacteria. Therefore, these copper-doped nanoparticles hold strong promise for use as an antibacterial component in antibacterial bone substitutes such as hydrogels, nanocomposites, and coatings.

Development and Characterization of Zein/Ag-Sr Doped Mesoporous Bioactive Glass Nanoparticles Coatings for Biomedical Applications

Implants are used to replace damaged biological structures in human body. Although stainless steel (SS) is a well-known implant material, corrosion of SS implants leads to the release of toxic metallic ions, which produce harmful effects in human body. To prevent material degradation and its harmful repercussions, these implanted materials are subjected to biocompatible coatings. Polymeric coatings play a vital role in enhancing the mechanical and biological integrity of the implanted devices. Zein is a natural protein extracted from corn and is known to have good biocompatibility and biodegradability. In this study, zein/Ag-Sr doped mesoporous bioactive glass nanoparticles (Ag-Sr MBGNs) were deposited on SS substrates via electrophoretic deposition (EPD) at different parameters. Ag and Sr ions were added to impart antibacterial and osteogenic properties to the coatings, respectively. In order to examine the surface morphology of coatings, optical microscopy and scanning electron microscopy (SEM) were performed. To analyze mechanical strength, a pencil scratch test, bend test, and corrosion and wear tests were conducted on zein/Ag-Sr doped MBGN coatings. The results show good adhesion strength, wettability, corrosion, and wear resistance for zein/Ag-Sr doped MBGN coatings as compared to bare SS substrate. Thus, good mechanical and biological properties were observed for zein/Ag-Sr doped MBGN coatings. Results suggested these zein/Ag-Sr MBGNs coatings have great potential in bone regeneration applications.

Barium Oxide Doped Magnesium Silicate Nanopowders for Bone Fracture Healing: Preparation, Characterization, Antibacterial and In Vivo Animal Studies

Magnesium silicate (MgS) nanopowders doped with barium oxide (BaO) were prepared by sol-gel technique, which were then implanted into a fracture of a tibia bone in rats for studying enhanced in vivo bone regeneration. The produced nanopowders were characterized using X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), scanning electron microscope with energy-dispersive X-ray spectrometry (SEM-EDX) and transmission electron microscope (TEM). Mechanical and bactericidal properties of the nanopowders were also determined. Increased crystallinity, particle diameter and surface area were found to decrease after the BaO doping without any notable alterations on their chemical integrities. Moreover, elevated mechanical and antibacterial characteristics were recognized for higher BaO doping concentrations. Our animal studies demonstrated that impressive new bone tissues were formed in the fractures while the prepared samples degraded, indicating that the osteogenesis and degradability of the BaO containing MgS samples were better than the control MgS. The results of the animal study indicated that the simultaneous bone formation on magnesium biomaterial silicate and barium MgS with completed bone healing after five weeks of implantations. The findings also demonstrated that the prepared samples with good biocompatibility and degradability could enhance vascularization and osteogenesis, and they have therapeutic potential to heal bone fractures.

The Effect of Ca2+ and Mg2+ Ions Loaded at Degradable PLA Membranes on the Proliferation and Osteoinduction of MSCs

Biodegradable membranes, including Polylactic acid (PLA)-based membranes, are commonly used in bone-tissue-related clinical procedures as biointerface to promote bone tissue regeneration. Calcium (Ca²⁺) and Magnesium (Mg²⁺) ions have been related to the promotion of osteogenesis, where the PLA membranes could be used as carrier and delivery substrate for them to provide osteogenic properties to this material. For this aim, a new ion delivery system based on biodegradable PLA membranes loaded with Mg and hydroxyapatite (HA) particles has been processed by the combination of tape casting and colloidal route. Materials characterization shows that the incorporation of Mg and HA particles changes the surface and hydrophobicity of the PLA membrane, and the in vitro degradation test shows Mg²⁺ and Ca²⁺ ion release and occasionally the precipitation of different ion species onto the membrane surface. Mouse and human Mesenchymal Stem Cells (MSC) were used to define the biocompatibility and bioactivity of these PLA membrane composites, and data indicated Mg²⁺ promotes cell proliferation and potentiates osteoinductive signals, while Ca²⁺ induces the expression of ALP osteogenic marker in human MSCs. Biodegradable PLA membranes loaded with Mg and HA particles is a promising new ion delivery system of Mg²⁺ and Ca²⁺ ions that provides osteogenic signals and works as functional biointerface interfaces with bone tissues.

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.

Cu-Doped Hollow Bioactive Glass Nanoparticles for Bone Infection Treatment

In search of new approaches to treat bone infection and prevent drug resistance development, a nanosystem based on hollow bioactive glass nanoparticles (HBGN) of composition 79.5SiO₂-(18-x)CaO-2.5P₂O₅-xCuO (x = 0, 2.5 or 5 mol-% CuO) was developed. The objective of the study was to evaluate the capacity of the HBGN to be used as a nanocarrier of the broad-spectrum antibiotic danofloxacin and source of bactericidal Cu²⁺ ions. Core-shell nanoparticles with specific surface areas close to 800 m²/g and pore volumes around 1 cm³/g were obtained by using hexadecyltrimethylammonium bromide (CTAB) and poly(styrene)-block-poly(acrylic acid) (PS-b-PAA) as structure-directing agents. Flow cytometry studies showed the cytocompatibility of the nanoparticles in MC3T3-E1 pre-osteoblastic cell cultures. Ion release studies confirmed the release of non-cytotoxic concentrations of Cu²⁺ ions within the therapeutic range. Moreover, it was shown that the inclusion of copper in the system resulted in a more gradual release of danofloxacin that was extended over one week. The bactericidal activity of the nanosystem was evaluated with E. coli and S. aureus strains. Nanoparticles with copper were not able to reduce bacterial viability by themselves and Cu-free HBGN failed to reduce bacterial growth, despite releasing higher antibiotic concentrations. However, HBGN enriched with copper and danofloxacin drastically reduced bacterial growth in sessile, planktonic and biofilm states, which was attributed to a synergistic effect between the action of Cu²⁺ ions and danofloxacin. Therefore, the nanosystem here investigated is a promising candidate as an alternative for the local treatment of bone infections.

Composite Bioinks With Mesoporous Bioactive Glasses-A Critical Evaluation of Results Obtained by In Vitro Experiments

Besides osteoconductivity and a high degradation rate, mesoporous bioactive glasses (MBGs) are specific for their highly ordered channel structure and high specific surface area, making them suitable as drug and/or growth factor delivery systems. On the other hand, the mesoporous channel structure and MBG composition can have an effect on common cell evaluation assays, leading to inconclusive results. This effect is especially important when MBG is mixed in composite bioinks, together with cells. Additionally, the hydrogel component of the ink can influence the degradation of MBG, leading to different ion releases, which can additionally affect the analyses. Hence, our aim here was to show how the MBG structure and composition influence common cell viability and differentiation assays when calcium (Ca)- or magnesium (Mg)-containing glass is part of an alginate-based composite bioink. We suggested pre-labeling of cells with DiI prior to bioprinting and staining with calcein-AM to allow identification of metabolically active cells expressing signals in both green and red channels, allowing the use of fluorescence imaging for cell viability evaluations in the presence of high amounts (7 wt %) of MBGs. The release and uptake of ions during degradation of CaMBG and MgMBG were significantly changed by alginate in the composite bioinks, as confirmed by higher release and uptake from bulk glasses. Additionally, we detected a burst release of Mg2+ from composites only after 24 h of incubation. Furthermore, we demonstrated that released ions and the mesoporous channel structure affect the measurement of lactate dehydrogenase (LDH) and alkaline phosphatase activity (ALP) in bioprinted composite scaffolds. Measured LDH activity was significantly decreased in the presence of CaMBG. On the other hand, the presence of MgMBG induced increased signal measured for the ALP. Taken together, our findings show how composite bioinks containing MBGs can interfere with common analyses, obtaining misleading results.

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.

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

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

Pharmacokinetic and pharmacodynamic evaluation of gemifloxacin chitosan nanoparticles as an antibacterial ocular dosage form

Ocular infections are classified into superficial keratitis, conjunctivitis or deep infections such as corneal abscesses and blepharitis. Herein, we focused on the development of formulation approaches that could prolong the residence time of gemifloxacin (GM) and enhance its corneal penetration to facilitate GM effects both superficially and at the deep tissues. Ionic gelation method was used to prepare eight forms of GM nanoparticles (NPs) formulated from chitosan polymer using sodium tripolyphosphate (TPP)-induced precipitation method. Differential scanning colorimetry (DSC) and X-ray diffraction (XRD) demonstrated the interaction between the chitosan and GM. Particle size, entrapment efficiency and cumulative in vitro release were used to select the optimal formula using Design Expert® software. The mean diameter of the selected NPs was 158. 4 nm. The average entrapment efficiency and cumulative release exhibited by the formulated NPs were 46.6% and 74.9%, respectively. Pharmacokinetics studies carried out on rabbits revealed that the ocularly-administered NPs significantly increased the loaded GM concentration in the tear and aqueous humour samples that suggested enhancement of precorneal retention and transcorneal permeation, respectively. Furthermore, ocular pharmacodynamic studies conducted on rabbits following ocular infection with Staphylococcus aureus or Pseudomonas aeruginosa showed that the administered NPs augmented the antibacterial activity of the delivered GM. This was demonstrated via the histopathological examination of the dissected corneas that showed preserved histological features and reduced bacterial keratitis on using the GM NPs rather than GM solution. Moreover, the GM NPs-treated corneas showed lower viable bacterial counts than the GM solution-treated corneas. Accordingly, our study illustrated the capability of the chitosan NPs to promote the antibacterial activity of GM against eye infections via ocular administration.

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.

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.

An Investigation on Spray-Granulated, Macroporous, Bioactive Glass Microspheres for a Controlled Drug Delivery System

Bioactive glass (BG) has been regarded as an excellent candidate for biomedical applications due to its superior properties of bioactivity, biocompatibility, osteoconductivity and biodegradability. Thus, in this study, we aimed to fabricate drug carriers that were capable of loading therapeutic antibiotics while promoting bone regeneration using macroporous BG microspheres, prepared by a spray drying method. Characterizations of particle morphology and specific surface area were carried out via scanning electron microscopy and nitrogen adsorption/desorption isotherm. Evaluations of in vitro bioactivity were performed based on Kokubo's simulated body fluid to confirm the formation of the hydroxyapatite (HA) layer after immersion. In addition, the in vitro drug release behaviors were examined, using tetracycline as the therapeutic antibiotic in pH 7.4 and 5.0 environments. Finally, the results showed that BG microspheres of up to 33 μm could be mass-produced, targeting various therapeutic situations and their resulting bioactivities and drug release behaviors, and related properties were discussed.

Mesoporous bioactive glasses for regenerative medicine

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

Radiopacity endowed magnetic nanocomposite with hyperthermia andin vitromineralization potential: a combinatorial therapeutic system for osteosarcoma

The development of clinically advanced multifaceted therapeutic materials for osteosarcoma is at the forefront of cancer research. Accordingly, this work presents the design of a multifunctional magnetic nanocomposite composed of maghemite, strontium doped hydroxyapatite and silica nanoparticles prospectively holding indispensable therapeutic features such as magnetic hyperthermia,in vitrobiomineralization, sustained drug release and intrinsic radiopacity for the treatment of osteosarcoma. The optimal composition has been identified by sequentially modulating the ratio of precursors of the magnetic nanocomposite synthesized by sol-gel technique. Structural and morphological characterization by x-ray diffraction, fourier transform infrared spectrum, Brunauer-Emmet-Teller and transmission electron microscopy analyses followed by VSM, hyperthermia and micro-CT analyses essentially assisted in the selective configuration of biofunctional properties. Results exemplify that MSHSr1 has a saturation magnetization of 47.4 emu g^-1and attained hyperthermia temperature (42 °C) at a very low exposure time of 4 min. MSHSr1 is further unique with respect to its exceptional x-ray attenuation ability (contrast enhancement 154.5% in digital radiography; CT number 3100 HU), early biomimetic mineralization (in vitro) evident by the formation of spheroidal apatite layer (Ca/P ratio 1.33) harvested from FESEM-EDX analysis and controlled release of Doxorubicin, the clinically used chemotherapeutic drug: 87.7% at 120 h in tumour analogous pH (6.5) when compared to physiological pH (71.3% at 7.4). MTT assay complemented with cytoskeleton (F-actin) staining of human osteosarcoma (HOS) cells affirm biocompatibility of MSHSr1.In vitrobiomineralization authenticated by Alizarin red S and von Kossa staining has been further corroborated by semi-quantitative calcium estimation of HOS cells cultured with MSHSr1 for two weeks. The results therefore validate the multifunctionality of MSHSr1, and hence could be proposed as a combinatorial therapeutic nanocomposite for osteosarcoma treatment.

Synthesis and Characterization of Mesoporous Mg- and Sr-Doped Nanoparticles for Moxifloxacin Drug Delivery in Promising Tissue Engineering Applications

Mesoporous silica-based nanoparticles (MSNs) are considered promising drug carriers because of their ordered pore structure, which permits high drug loading and release capacity. The dissolution of Si and Ca from MSNs can trigger osteogenic differentiation of stem cells towards extracellular matrix calcification, while Mg and Sr constitute key elements of bone biology and metabolism. The aim of this study was the synthesis and characterization of sol-gel-derived MSNs co-doped with Ca, Mg and Sr. Their physico-chemical properties were investigated by X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray analysis (SEM/EDX), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray fluorescence spectroscopy (XRF), Brunauer Emmett Teller and Brunauer Joyner Halenda (BET/BJH), dynamic light scattering (DLS) and ζ-potential measurements. Moxifloxacin loading and release profiles were assessed with high performance liquid chromatography (HPLC) cell viability on human periodontal ligament fibroblasts and their hemolytic activity in contact with human red blood cells (RBCs) at various concentrations were also investigated. Doped MSNs generally retained their textural characteristics, while different compositions affected particle size, hemolytic activity and moxifloxacin loading/release profiles. All co-doped MSNs revealed the formation of hydroxycarbonate apatite on their surface after immersion in simulated body fluid (SBF) and promoted mitochondrial activity and cell proliferation.

Nanotherapeutics for regeneration of degenerated tissue infected by bacteria through the multiple delivery of bioactive ions and growth factor with antibacterial/angiogenic and osteogenic/odontogenic capacity

Therapeutic options are quite limited in clinics for the successful repair of infected/degenerated tissues. Although the prevalent treatment is the complete removal of the whole infected tissue, this leads to a loss of tissue function and serious complications. Herein the dental pulp infection, as one of the most common dental problems, was selected as a clinically relevant case to regenerate using a multifunctional nanotherapeutic approach. For this, a mesoporous bioactive glass nano-delivery system incorporating silicate, calcium, and copper as well as loading epidermal growth factor (EGF) was designed to provide antibacterial/pro-angiogenic and osteo/odontogenic multiple therapeutic effects. Amine-functionalized Cu-doped bioactive glass nanospheres (Cu-BGn) were prepared to be 50-60 nm in size, mesoporous, positive-charged and bone-bioactive. The Cu-BGn could release bioactive ions (copper, calcium and silicate ions) with therapeutically-effective doses. The Cu-BGn treatment to human umbilical vein endothelial cells (HUVEC) led to significant enhancement of the migration, tubule formation and expression of angiogenic gene (e.g. vascular endothelial growth factor, VEGF). Furthermore, the EGF-loaded Cu-BGn (EGF@Cu-BGn) showed pro-angiogenic effects with antibacterial activity against E. faecalis, a pathogen commonly involved in the pulp infection. Of note, under the co-culture condition of HUVEC with E. faecalis, the secretion of VEGF was up-regulated. In addition, the osteo/odontogenic stimulation of the EGF@Cu-BGn was evidenced with human dental pulp stem cells. The local administration of the EGF@Cu-BGn in a rat molar tooth defect infected with E. faecalis revealed significant in vivo regenerative capacity, highlighting the nanotherapeutic uses of the multifunctional nanoparticles for regenerating infected/damaged hard tissues.

Bioactivity in SBF versus trace element effects: The isolated role of Mg2+ and Zn2+ in osteoblast behavior

The bioactivity assay originally proposed by Kokubo is one of the most commonly used tests to indirectly evaluate the biocompatibility of bioactive glasses. However, extensive evidence has shown that trace elements present in biomaterials may stimulate cellular behavior in different ways even when no apatite formation is observed, i.e., in biomaterials with low or no bioactivity. To further elucidate this topic, we designed three different SiO₂-rich bioglass compositions in which CaO was partially replaced by ZnO and MgO, two oxides known to affect bioactivity as well as osteoblastic behavior. The physicochemical changes induced by the presence of oxides and their effects on biological behavior, as well as the adhesion, proliferation and differentiation of human osteoblast-like osteosarcoma cells (MG-63), were followed by a bioactivity assay in simulated body fluid (SBF). The insertion of ZnO or MgO decreased the glass transition (T_g) and crystallization (T_c) temperatures as a function of the increase in nonbonding oxygens, which was directly reflected in the higher solubility. The release of Mg²⁺ ions from the MgO-containing samples inhibited the bioactivity in SBF, inducing high cell adhesion and proliferation and moderate ALP activity. The release of Zn²⁺ also inhibited the bioactivity in SBF but, in contrast to the release of Mg²⁺, induced low cell adhesion and proliferation and high ALP activity compared to the control.

Nanotechnology Assisted Targeted Drug Delivery for Bone Disorders: Potentials and Clinical Perspectives

Nanotechnology and its allied modalities have brought revolution in tissue engineering and bone healing. The research on translating the findings of the basic and preclinical research into clinical practice is ongoing. Advances in the synthesis and design of nanomaterials along with advances in genomics and proteomics, and tissue engineering have opened a bright future for bone healing and orthopedic technology. Studies have shown promising outcomes in the design and fabrication of porous implant substrates that can be exploited as bone defect augmentation and drug-carrier devices. However, there are dozens of applications in orthopedic traumatology and bone healing for nanometer-sized entities, structures, surfaces, and devices with characteristic lengths ranging from tens 10s of nanometers to a few micrometers. Nanotechnology has made promising advances in the synthesis of scaffolds, delivery mechanisms, controlled modification of surface topography and composition, and biomicroelectromechanical systems. This study reviews the basic and translational sciences and clinical implications of the nanotechnology in tissue engineering and bone diseases. Recent advances in NPs assisted osteogenic agents, nanocomposites, and scaffolds for bone disorders are discussed.

Bioactive Glasses: A Promising Therapeutic Ion Release Strategy for Enhancing Wound Healing

The morbidity, mortality, and burden of burn victims and patients with severe diabetic wounds are still high, which leads to an extensively growing demand for novel treatments with high clinical efficacy. Biomaterial-based wound treatment approaches have progressed over time from simple cotton wool dressings to advanced skin substitutes containing cells and growth factors; however, no wound care approach is yet completely satisfying. Bioactive glasses are materials with potential in many areas that exhibit unique features in biomedical applications. Today, bioactive glasses are not only amorphous solid structures that can be used as a substitute in hard tissue but also are promising materials for soft tissue regeneration and wound healing applications. Biologically active elements such as Ag, B, Ca, Ce, Co, Cu, Ga, Mg, Se, Sr, and Zn can be incorporated in glass networks; hence, the superiority of these multifunctional materials over current materials results from their ability to release multiple therapeutic ions in the wound environment, which target different stages of the wound healing process. Bioactive glasses and their dissolution products have high potency for inducing angiogenesis and exerting several biological impacts on cell functions, which are involved in wound healing and some other features that are valuable in wound healing applications, namely hemostatic and antibacterial properties. In this review, we focus on skin structure, the dynamic process of wound healing in injured skin, and existing wound care approaches. The basic concepts of bioactive glasses are reviewed to better understand the relationship between glass structure and its properties. We illustrate the active role of bioactive glasses in wound repair and regeneration. Finally, research studies that have used bioactive glasses in wound healing applications are summarized and the future trends in this field are elaborated.

In vitro effects of the co-release of icariin and strontium from bioactive glass submicron spheres on the reduced osteogenic potential of rat osteoporotic bone marrow mesenchymal stem cells

Osteoporosis is a metabolic disease that affects bone tissue and is highly associated with bone fractures. Typical osteoporosis fracture treatments, such as bisphosphonates and hormone replacement, present important challenges because of their low bioavailability on the site of action. Options to overcome this issue are systems for the local release of therapeutic agents such as bioactive glasses containing therapeutic molecules and ions. These agents are released during the dissolution process, combining the drugs and ion therapeutic effects for osteoporosis treatment. Among the therapeutic agents that can be applied for bone repair are strontium (Sr) ion and phytopharmaceutical icariin, which have shown potential to promote healthy bone marrow stem cells osteogenic differentiation, increase bone formation and prevent bone loss. Submicron Sr-containing bioactive glass mesoporous spheres with sustained ion release capacity were obtained. Icariin was successfully incorporated into the particles, and the glass composition influenced the icariin incorporation efficiency and release rates. In this work, for the first time, Sr and icariin were incorporated into bioactive glass submicron mesoporous spheres and the in vitro effects of the therapeutic agents release were evaluated on the reduced osteogenic potential of rat osteoporotic bone marrow mesenchymal stem cells, and results showed an improvement on the reduced differentiation potential.