In vivo evaluation of cerium,gallium and vanadium-doped borate-based bioactive glass scaffolds using rat subcutaneous implantation model

The main objective of this study was to evaluate the cerium, gallium and vanadium-containing bioactive borate glass scaffolds for soft tissue applications and determine the potential toxicity of these scaffolds on the adjacent tissues. The effects of the cerium, gallium and vanadium substitution on the soft tissue ingrowth and angiogenesis in porous borate based bioactive glass scaffolds were investigated using rat subcutaneous implantation model. For this purpose, bioactive borate glass powders containing therapeutic ions were prepared by melt-cast method and subsequently scaffolds were fabricated using polymer foam replication technique. The scaffolds were implanted subcutaneously for 4 weeks in Sprague Dawley rats. Bare borate glass scaffolds with the same microstructure were used as the control. Histology was used to evaluate tissue ingrowth and blood vessel formation in the implants. Additionally, the antibacterial activities of cerium, gallium and vanadium containing porous bioactive glass scaffolds were investigated in vitro by a zone inhibition method. Results revealed that addition of cerium ions to the borate glass network caused an increase in blood vessel formation. On the other hand, a decrease was obtained in angiogenesis in gallium and vanadium-containing glasses. All of the scaffolds prepared in the study did not show any antibacterial activity towards Escherichia coli and Staphylococcus aureus.     

Research of antibacterial activity on silver containing yttria-stabilized–zirconia bioceramic

An antibacterial bioceramic, silver containing yttria-stabilized zirconia (YSZ), was fabricated by sintering for dental prosthesis applications. The biocompatibility, hemocompatibility and antibacterial ability of the silver containing YSZ were evaluated. The addition of silver did not cause tetragonal phase to transform into monoclinic phase and the silver containing YSZ maintained an excellent mechanical property. Furthermore, the sintered silver containing YSZ showed no toxicity and possessed a good antibacterial ability against both Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) cell.     

The impact of Nb2O5 on in-vitro bioactivity and antibacterial activity of CaF2–CaO–B2O3–P2O5–SrO glass system

This work consists of in vitro bioactivity (in SBF) and antibacterial studies (against S. aureus and E. coli bacteria) of Nb₂O₅ doped bioactive glasses. X-ray diffraction and scanning electron microscopy investigations indicated deposition of Nb-HAp (hydroxyapatite) crystalline layer on the samples after exposing to SBF. The spectroscopy investigations also indicated the deposition of HAp layer on these samples. The magnitude of HAp deposited on the glasses found to be relying on concentration of Nb₂O₅ dopant; this conclusion was drawn by determining weight loss of the glasses due to exposure to SBF and also by assessing the variation of pH of the remnant fluid as functions of Nb₂O₅content. The studies further indicated the maximal content of hydroxyapatite was deposited on the surface the glasses doped with 4.0 mol% of Nb₂O₅. The antibacterial studies (against E. coli and S. aureus bacteria) of these glasses indicated the maximal killing effect of bacteria of the samples admixed with 4.0 mol% of Nb₂O₅. This result is attributed to the occupancy of maximal fraction of Nb ions in NbO₆ structural units (confirmed by IR and Raman spectroscopic results) in this sample that paved the way for easy disintegration of the glass and to act on the bacteria. Overall, the results of bioactivity studies of Nb₂O₅ doped bioglasses indicated that the Nb₂O₅ not only enhanced bioactivity potential but also exhibited antimicrobial activity.     

Fabrication and in vitro characterization of antibacterial magneto-luminescent core-shell bioactive glass nanoparticles

When nanomaterials with antibacterial properties were sent to the infected area, it was predicted that infection and related complications could be prevented. The nanoparticles can be designed to possess magnetic and luminescence (magneto-luminescent) properties to be effectively targeted and localized at the infection foci without dispersing into the body. Simultaneously, the magneto-luminescent characteristic of particles allows visualization and confirmation of localized particles at the desired area. In this regard, there are no studies on the use of antibacterial magneto-luminescent bioactive glass for orthopedic applications and the treatment of orthopedic device-related infections. In this study, antibacterial magneto-luminescent 58S bioactive glasses were synthesized by the modified Stöber using coupled with a layer-by-layer assembly approach to possess core/shell particle morphology. SPION/Bioactive glass nanoparticles had an average size of 50 nm and displayed superparamagnetic behavior. While the saturation magnetization value (σ_s) of the undoped 58S sample was 25.32 emu/g, that of the co-doped sample (2% Eu, 2% Zn) was 21.74 emu/g; this showed that the doping slightly reduced the magnetization value. Europium (Eu) doping of SPION/Bioactive glass nanoparticles induced characteristic red emission originating from Eu emissions belonging to ⁵D₀–⁷F_J (J = 1–4) transitions and the strongest peak was at 612 nm (electric-dipole transition, ⁵D₀–⁷F₂). Color chromaticity coordinates confirmed emission in the red region. XPS spectrum revealed the existence of Eu and Zn dopant elements in 58S bioactive glass. After soaking characteristic peaks at 31.74° and 45.43° belonging to the hexagonal hydroxyapatite phase were detected in the XRD data, confirming the SEM images. 2% Eu doped SPION/Bioactive glass nanoparticles had the highest osteoblast viability up to 7 days in vitro, while doping the samples with 2% zinc did not yield bone cell viability as high as the Eu doped ones. Importantly, Eu doped SPION/Bioactive glass nanoparticles inhibited gram-positive Staphylococcus aureus (S. aureus) and gram-negative Escherichia coli (E. coli) growth up to 48 h in vitro. The results showed that Eu doping of SPION/Bioactive glass nanoparticles increased osteoblast viability and inhibited bacterial growth, while possessing superparamagnetic properties and exhibiting red luminescence.     

Structural characterization and evaluation of antibacterial and angiogenic potential of gallium-containing melt-derived and gel-derived glasses from CaO-SiO2 system

Gallium-containing glasses were synthesized by the sol-gel and traditional melting techniques to obtain bioactive amorphous materials with antibacterial and angiogenic properties. The influence of gallium ion addition on glass structure was described using two spectroscopic methods (FTIR and ²⁹Si MAS NMR). DSC (Differential Scanning Calorimetry) analysis revealed differences in thermal properties, which were explained by varying ionicity of the chemical bonds. The study shows that gallium ions addition causes a significant difference in glass structure and, as a consequence, in thermal properties, microstructure, and biological response. Dissolution products of the researched glasses incubated in SBF and distillated water were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). To perform the indirect in vitro biocompatibility studies, human osteoblast-like cells (MG-63) were cultivated in the supernatants, which were obtained by incubation of the glass powders in the cell culture medium. The evaluation of the potential angiogenic properties of gallium-doped glasses was performed by measuring the release of human vascular endothelial growth factor (VEGF) from MG-63 cells. Dissolution products of the all samples were tested for antibacterial activity against gram-negative (E. coli) and gram-positive bacteria (S. aureus).     

Investigation of antibacterial activity and related mechanism of a ruthenium(II) polypyridyl complex

Metal based drug represents a novel group of antimicrobial agents with potential application for the control of bacterial and fungal infections. In this study, we fabricate ruthenium(II) complex containing the polypyridyl ligands, namely [Ru(phen)₂(tip)] (ClO₄)₂ (RuTh) and carefully investigate its antibacterial activities against both the Gram-negative (G −) bacteria Escherichia coli (E. coli) and the Gram-positive (G +) bacteria Staphylococcus aureus (S. aureus). The RuTh is more toxic to S. aureus than that to E. coli. The antibacterial effects of RuTh are further investigated, revealing specific mechanisms. The results demonstrate that RuTh functions as a bactericide against the E. coli and S. aureus through disrupting bacterial cell wall integrity and its cellular components.     

Luminescence and structural evolution in ultra-low melting quaternary tin fluorophosphate glasses (NaF-SnF2-SnO-P2O5)

For transparent low melting inorganic glass, which is relevant for sealing and additional applications, Pb-containing glasses have reached the lowest melting point and best comprehensive performance. Considering potential toxicity and regulatory limitations, there is urgent need to develop Pb-free ultra-low melting point glass. Herein, we systemically investigated the structure and luminescence evolution of the Pb-free ultra-low melting quaternary tin fluorophosphate glasses (NaF-SnF₂-SnO-P₂O₅), in which varied NaF content was tuned to affect the properties of glass. With NaF content increases, the Sn-O and P-O bonds have been gradually transformed to Sn-F and P-F bonds, and the phosphrous tetrahedron PO₄ has been converted to PO₃F. The weaken bonding results in the decrease of the ultra-low melting point to 329°C when NaF increased to 15 a.t.%, 29^oC lower than the ternary glass. The blue shifts of both absorption and photoluminescence spectra were observed due to the higher ionic character of glass structure with NaF increases. As reported previously in the ternary tin fluorophosphate glass, the quaternary glass system also shows a phosphorescence behavior (∼1 s) due to the existence of oxygen vacancies. Additionally, the changes in oxygen vacancy defects correlate with the NaF content, thus affecting the decay time as well. The ultra-low melting point luminescent quaternary tin fluorophosphate glasses (NaF-SnF₂-SnO-P₂O₅) may be relevant for opto-electronic applications such as the packaging in displays or light-emitting diodes.     

Facile preparation and good performance of nano-Ag/metallocene polyethylene antibacterial coatings

Metallocene polyethylene/nano-silver coatings were prepared by a facile air-spray method on polymer films. Different from the prevailing strategy to endow polyethylene with antibacterial performance, we used metallocene polyethylene sol and nano-silver as a precursor to deposit coatings on polymers at a relatively low operating temperature. Antibacterial coatings with excellent mechanical properties, water resistance, and low silver release were achieved. The composite coatings were examined in terms of surface characteristics, mechanical properties, and antibacterial activity against two representative bacterial strains including Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The composite coatings exhibited favorable microstructure, good mechanical properties, and suitable crystallinity. The antimicrobial tests indicated that the fabricated composite coatings showed promising antibacterial activity against E. coli and S. aureus. Furthermore, Ag ions released by the composite coating after 30 days were under 1.2 ppb. These results indicated a promising prospect of the composite coating for wide antibacterial applications.     

The preparation and properties of zirconia-doped Y–Si–Al–O–N oxynitride glasses and glass-ceramics

Two series (N-9 and N-18 series) of zirconia-doped Y–Si–Al–O–N oxynitride glasses and glass-ceramics were designed. Nominal compositions of the glass samples in equivalent percent (eq%) are xZr: (24–0.25x)Y: (15–0.25x)Al: (61–0.5x)Si: 91O: 9 N and xZr: (24–0.25x)Y: (15–0.25x)Al: (61–0.5x)Si: 82O: 18 N (x=0, 2, 4, 6), respectively. The obtained samples were characterized by differential thermal analysis (DTA), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Densities, Vickers hardness, fracture toughness, glass transition temperature, and thermal expansion coefficient data were established for each sample. Effect of Zr and N content on glass network structure, thermal and mechanical properties was investigated. It was found that the addition of zirconia is effective in preparing Y–Si–Al–O–N oxynitride glasses with lower glass transition temperature and higher hardness.     

Rb+-doped CsPbBr3 quantum dots with multi-color stabilized in borosilicate glass via crystallization

All-inorganic lead halide quantum dots (QDs) have attracted immense interest because of their excellent photoelectric properties. By virtue of a similar ionic radius and the same valence state, Rb⁺/Cs⁺ mixed-cation have become a novel mechanism to adjust multi-color emission. However, their poor stability remains a serious problem that has not been solved satisfactorily. Interestingly, QDs glass shows good thermostability and moisture susceptibility. Herein, CsPbBr₃: xRb (x = 0, 0.4, 0.6, 0.8) QD glasses which yield tunable emission spectra (475–523 nm) were synthesized successfully via glass crystallization. Most importantly, the as-prepared QDs glasses exhibited ultrastability under various atmospheric, water and heat conditions. Thus, synthesis of a mixed-cation perovskite QDs glass is a new method to achieve stable multi-color emission. They are also expected to become a new generation of photoelectric materials and can be prospectively applied to light-emitting devices.     

Radiophotoluminescence phenomenon in copper-doped aluminoborosilicate glass

Radiophotoluminescence phenomena have been widely investigated on various types of materials for dosimetry applications. We report that an aluminoborosilicate glass containing 0.005 mol% copper exhibits intense photoluminescence in the visible region induced by X-ray and γ-ray irradiation. The luminescence is assigned to the 3d⁹4s¹ → 3d¹⁰ transition of Cu⁺. The proportionality of the intensity of the induced photoluminescence to the irradiation dose was confirmed up to 0.5 kGy using ⁶⁰Co γ-ray irradiation. Based on the spectroscopic results, a potential mechanism was proposed for the enhancement of the photoluminescence. The exposure to the ionizing radiation generates electron-hole pairs in the glass, and the electrons are subsequently captured by the Cu²⁺ ions, which are converted to Cu⁺ and emit the luminescence. For the glass containing 0.01 mol% copper, the pronounced enhancement of the photoluminescence was not observed because the reverse reaction, ie, the capture of the holes by the Cu⁺ ions, becomes prominent. The photoluminescence induced by the irradiation was stably observed for the glasses kept at room temperature and even for the glasses heat-treated at 150°C. However, the induced photoluminescence could be eliminated by the heat treatment at a temperature at 500°C, and the glass returned to the initial pre-irradiation state. The Cu-doped aluminoborosilicate glass is a potential candidate for use in dosimetry applications.     

Allylimidazolium salt based antibacterial polymer coatings produced by thiol–ene photocuring

Photocurable formulations containing trifunctional thiol, trifunctional ene, and antibacterial allylimidazolium salts have been employed for transparent antibacterial coatings. The antibacterial component 1-allyl-3-dodecylimidazolium salt (ADIm) is prepared and chemically attached to polymer networks using a one-step thiol–ene photocuring reaction. Ultra-small (USANS) and small angle neutron scattering (SANS) measurements show that the photocured polymers are loosely networked three-dimensional structures with a mass fractal of approximately 2.7 ± 0.2. The minimum inhibitory concentration (MIC) for the ADIm was determined to be 500 μg/ml and 15.63 μg/ml for Escherichia coli (Gram negative) and Staphylococcus aureus (Gram positive) bacteria, respectively. Coating formulations containing 10 mol% of the antibacterial ADIm photocured on glass substrates showed strong antibacterial activity against environmental bacteria such as E. coli and/or S. aureus.     

Quaternary and pentanary mesoporous bioactive glass nanoparticles as novel nanocarriers for gallic acid: Characterisation,drug release and antibacterial activity

Mesoporous bioactive glass nanoparticles (MBGNs) have gained considerable attention as multifunctional platforms for simultaneously releasing ions and phytotherapeutic compounds. Thus, in the first part of this study, MBGNs based on the 53SiO₂–4P₂O₅–20CaO–23Na₂O (wt %) (S53P4) composition were synthesized by a microemulsion assisted sol-gel method. More precisely, P₂O₅ was substituted with B₂O₃ and Na₂O with MgO and/or ZnO. For B containing MBGNs all ions were successfully incorporated into the borosilicate structure without inducing crystallisation. In contrast, for S53P4 a poorly crystalline hydroxyapatite phase was identified. All MBGNs had a typical spherical shape with an internal radial network of mesopores. Additionally, for S53P4 a second fraction of particles with a smaller size and compact core was observed. Secondly, the feasibility of MBGNs as nanocarriers for gallic acid (GA) was evaluated. All drug-loaded samples showed a similar in vitro release profile which can be divided into three main phases: burst release, slow release and sustained release. Among the different compositions, S53P4 exhibited the highest cumulative release, whereas B and Mg containing particles exhibited the opposite. The presence of Zn in the MBGN compositions improved their antibacterial effect against both E. coli and S. aureus. Moreover, it was shown that depending on the MBGNs’ composition, the antibacterial activity of GA loaded MBGNs can be enhanced. Thus, the results proved that MBGNs can be used as controlled drug delivery system and, by tailoring the composition, a synergistic antibacterial effect can be achieved, considering that GA and biologically active ions are simultaneously released.     

Photoluminescence and decay characteristics of cerium,gallium and vanadium - containing borate-based bioactive glass powders for bioimaging applications

Biomaterials having photoluminescent properties play a crucial role in real-time bioimaging after in vivo implantation. In this study, photoluminescence properties and decay characteristics of the borate-based 13–93B3 glasses containing different concentrations of cerium, gallium, and vanadium oxides were investigated for biomedical applications. The borate-based bioactive glass powders were prepared using melt-quench technique and size reduction was performed through planetary ball milling. Bioactivity of the prepared powders was investigated in simulated body fluid at 37 °C under static conditions. The photoluminescent properties and decay kinetics of the as-prepared and the SBF-treated bioactive glass powders were analyzed by steady-state and time-resolved photoluminescence measurements. Results revealed that the cerium activated glasses exhibited an intense luminescence centered at 538 nm. Broad-band emission of the gallium and vanadium doped samples was centered at 440 and 572 nm, respectively. All of the SBF-treated glasses exhibited enhanced lifetimes and bi-exponential decays both in nanosecond and microsecond regime measurements. It was concluded that depending on the dopant concentration, bioactive glass particles prepared in the study showed remarkable photoluminescence and have potential to be used in bioimaging applications.     

The study of antimicrobial activity and preservative effects of nanosilver ingredient

In this study, we investigated the antimicrobial activity of silver nanoparticles (Ag-NPs) and platinum nanoparticles (Pt-NPs) aqueous solution, which were prepared using different stabilizer, such as sodium dodecylsulfate (SDS) and poly-(N-vinyl-2-pyrrolidone) (PVP), for Staphylococcus aureus (S. aureus) and Escherichia coli (E.coli) by measuring the minimum inhibitory concentration (MIC). Antimicrobial effect of Ag-NPs for S. aureus and E. coli was investigated using cup diffusion method. The growth of Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria were inhibited by Ag-NPs. The MIC of Ag-NPs for S. aureus and E. coli were 5 and 10 ppm, respectively. But the Au-NPs stabilized with SDS did not show antimicrobial activity. Also, the Pt-NPs stabilized with PVP (or SDS) did not show antimicrobial activity for the test organisms.     

Ancient Roman nano-technology: Insight into the manufacture of mosaic tesserae opacified by calcium antimonate

Opaque mosaic glass tesserae containing calcium antimonates from Ancient Messene, Greece (1st–4th century CE) were investigated by scanning electron microscopy, Raman spectroscopy and X-ray diffraction. Both trigonal CaSb₂O₆ and cubic Ca₂Sb₂O₇, with crystallite diameters below 1?μm, were identified as opacifying agents. To better understand ancient technologies, we prepared model glasses that were opacified by crystallisation via a secondary heat treatment, by direct crystallisation during the melting process, or by the addition of pre-reacted calcium antimonate to a base glass. We found that direct crystallisation replicated the antique glass artefacts most accurately.We demonstrated that 0.2?wt% of nucleating agents like TiO₂ and SnO₂ already exert significant influence on the crystallisation behaviour of calcium antimonates. Secondary scattering centres such as silica and carbonates contribute to the optical appearance. Concurrently, we reproduced opaque white glass ceramics in a reconstructed, wood-fired, Roman-type glass furnace built by Wiesenberg (2014).     

Antibacterial properties of plasma-modified and triclosan or bronopol coated polyethylene

The antibacterial properties of medical polyethylene (PE) were enhanced by coating with triclosan or bronopol and plasma immersion ion implantation (PIII). O₂ plasma was first employed to produce a more hydrophilic surface on the PE, followed by argon or hydrogen plasma treatment to enhance the coating of triclosan or bronopol onto the surface. The modified surfaces were characterized by XPS, FTIR, SEM, and contact angle measurements. The antibacterial properties were evaluated utilizing the method of plate-counting of Staphylococcus aureus (Gram positive) and Escherichia coli (Gram negative). Our experimental results show that the plasma-modified PE with triclosan exhibits excellent antibacterial properties. Even after 6 weeks, the antibacterial effects against E. coli and S. aureus remain at high levels of 99.9 and 68.4%. The plasma-modified PE with bronopol has better antibacterial performances against E. coli and S. aureus in the beginning. Afterwards, the antibacterial effects degrade relatively rapidly. Our results reveal that non-reactive argon plasma was better than reactive hydrogen plasma in improving the antibacterial properties of PE. Bacterial adhesion on the modified samples was also investigated and the number of active adhered bacteria was observed to be always low.     

Effect of BaO substitution for CaO on the structural and thermal properties of SiO2–B2O3–Al2O3–CaO–Na2O–P2O5 bioactive glass system used for implant coating applications

The present study replaced 3.30 and 9.00 mol.% BaO for CaO in a SiO₂–B₂O₃–Al₂O₃–CaO–Na₂O–P₂O₅ bioactive glass system used for implant coating applications. Variations of the glass structure, thermal properties, cytotoxicity, and radiopacity of glasses were studied. As demonstrated by the results, upon adding barium oxide to the glass structure, the weight density increased significantly, while a slight decrease in oxygen density was determined. Introducing barium oxide into glass composition did not cause any considerable change in the spectra of FTIR and Raman. It was demonstrated that the amount of bridging oxygen in the glass structure remained quite unaffected. The hot stage microscopy evaluations revealed further shrinkage of barium-containing frits due to lower viscosity and hence, higher viscous flow of these glasses. By substituting barium oxide for calcium oxide and increasing its concentration, the glass transition temperature (T_g) and the dilatometric softening temperature (T_d) decreased, while the thermal expansion coefficient increased. Moreover, upon substituting 9 mol.% barium oxide for calcium oxide, a 30 °C reduction in maximum sintering temperature (T_ms) of the glass was obtained, whereas the shrinkage rate was increased 1.7 times. It was indicated that the sintering process of barium-incorporated glasses would easily proceed without any phase crystallization. The barium-incorporated glasses exhibited more radiopacity. Additionally, no cytotoxic effect was caused by the substitution, and the Ba-containing glasses could be used for biomedical applications and implant coating as well.