骨修复介孔生物活性玻璃的研究进展

介绍了生物活性玻璃、介孔生物玻璃的组成、性质,着重综述了介孔生物玻璃的研究现状、制备方法,以及在药物输送和骨组织再生方面的应用,指出介孔生物玻璃是骨组织工程较好的候选材料.     

Characterization,in vitro bioactivity and biological studies of sol-gel-derived TiO2 substituted 58S bioactive glass

Bioactive glasses (BGs) have been used for bone formation and bone repair processes in recent years. This study investigated the titanium substitution effect on 58S BGs (Ti-BGs) 60SiO₂-(36 − X)CaO-4P₂O₅-XTiO₂ (X = 0, 3, and 5 mol.%) prepared by the sol-gel technique, and the main goal was to find the optimum amount of titanium in Ti-BGs. Synthesized BGs, which were investigated after immersion in simulated body fluid (SBF), were tested by X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy. Moreover alkaline phosphate (ALP) activity, 3-(4,5dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and antibacterial studies were employed to investigate the biological properties of Ti-BGs. According to the FTIR and XRD test results, hydroxyapatite (HA) formation on Ti-BGs surfaces was confirmed. Meanwhile, the presence of 5 mol.% compared to 3 mol.% increased the HA grain distribution and their size on the Ti-BGs surface. Additionally, MTT and ALP results confirmed that the optimal amount of titanium substitution in BG was 5 mol.%. Since 5 mol.% Ti incorporated BG (BG-5) had the highest biocompatibility level, antibacterial properties, maximum cell proliferation, and ALP activity among the synthesized Ti-BGs, it is presented as the best candidate for further in vivo investigations.     

Physico-chemical and biological studies on three-dimensional porous silk/spray-dried mesoporous bioactive glass scaffolds

The incorporation of a bioactive inorganic phase in polymeric scaffolds is a good strategy for the improvement of the bioactivity and the mechanical properties, which represent crucial features in the field of bone tissue engineering. In this study, spray-dried mesoporous bioactive glass particles (SD-MBG), belonging to the binary system of SiO₂-CaO (80:20 mol%), were used to prepare composite scaffolds by freeze-drying technique, using a silk fibroin matrix. The physico-chemical and biological properties of the scaffolds were extensively studied. The scaffolds showed a highly interconnected porosity with a mean pore size in the range of 150 µm for both pure silk and silk/SD-MBG scaffolds. The elastic moduli of the silk and silk/SD-MBG scaffolds were 1.1±0.2 MPa and 6.9±1.0 MPa and compressive strength were 0.5±0.05 MPa and 0.9±0.2 MPa, respectively, showing a noticeable increase of the mechanical properties of the composite scaffolds compared to the silk ones. The contact angle value decreased from 105.3° to 71.2° with the incorporation of SD-MBG particles. Moreover, the SD-MBG incorporation countered the lack of bioactivity of the silk scaffolds inducing the precipitation of hydroxyapatite layer on their surface already after 1 day of incubation in simulated body fluid. The composite scaffolds showed good biocompatibility and a good alkaline phosphatase activity toward human mesenchymal stromal cells, showing the ability for their use as three-dimensional constructs for bone tissue engineering.     

Facile fabrication of hollow mesoporous bioactive glass spheres: From structural behaviour to in vitro biology evaluation

Bone defects accompanied by infection or inflammation can significantly delay the healing process. To simultaneously achieve controlled release of local antibiotics for infection control and bone healing, bone-implantable delivery systems have been considered as a promising strategy. This study aims to improve drug loading capacity of bone-implantable delivery systems by introducing hollow structure mesoporous bioactive glass nanospheres (HMBGs) through a sol–gel process. Particularly, such core–shell bimodal-porous structured nanoparticles were prepared through a sacrificing template using cetyltrimethylammonium bromide (CTAB) as surfactant. It was found that varying the amount of CTAB during the synthesis process is a simple and effective approach for tuning the particle size, morphology, and structure of HMBGs. For in vitro drug release, HMBGs could sustain storage and release of vancomycin hydrochloride (VAN) via diffusion-controlled mechanism, thereby inhibiting the bacteria growth in the subsequent bacterial study. Moreover, HMBGs incorporated with VAN provided a biomimetic microenvironment favored by cell adhesion and proliferation. These findings support the compatibility of HMBG nanoparticles with antibiotics and their potential application in the treatment of infectious bone defects.     

Effect of boron oxide on mechanical and thermal properties of bioactive glass coatings for biomedical applications

Bioactive glass coatings can improve the osteo integration of metallic implants with the host tissue, thereby increasing their lifespan and overall success rate. However, complex composition-structure-property relations in phosphosilicate-based bioactive glasses make experimental determination of these relations and related composition design of bioactive coatings challenging. By applying molecular dynamics (MD)-based atomistic simulations with recently developed effective potentials, this work addresses the challenge by using a material genome approach to obtain the composition and structure effects on various key properties for bioactive coating applications. A series of potential bioactive glass compositions were studied and the composition effects on the mechanical and thermal properties that are critical to these bioactive glasses as a coating to metallic implants were calculated. Particularly, by varying the level of B₂O₃ to SiO₂ substitutions, the effect of composition on various key properties was elucidated. It was found that by using cation in a 1 to 1 ratio (BO_3/2 to SiO₂) instead of the commonly used substitutions (B₂O₃ to SiO₂), the composition effect can be more clearly expressed and, hence, recommended in future composition designs. Together with careful structural analysis, the origin of property changes can be elucidated. The atomistic computer simulation-based approach is, thus, an effective way to guide future bioactive glass designs for bioactive coatings and other applications.     

Structural behavior and in vitro bioactivity evaluation of hydroxyapatite-like bioactive glass based on the SiO2-CaO-P2O5 system

Silicate bioglass is of great importance in bone engineering because of its excellent bioactivity and osteogenic effects. In this study, hydroxyapatite-like bioactive glass based on the xSiO₂-CaO-P₂O₅ (x = 30, 45, 60 and 90 mol.%, Ca/P = 1.67) system was synthesized by the sol-gel method, and the corresponding structural evolution, apatite-forming ability and cytotoxicity were systematically investigated. The results suggest that both a higher heat treatment temperature and a lower SiO₂ content increase the crystallinity tendency of the bioglass, and the samples become obviously compact as the SiO₂ amount increases from 30 to 90 mol.%. Compared with the samples with higher SiO₂ content, the 30Si sample shows more remarkable internal connected mesoporous structures, with a higher specific surface area up to 129.12 m²/g, exhibiting excellent hydroxyapatite formation in simulated body fluid. Moreover, no obvious inhibitory effect was presented on human periodontal ligament cells (hPDLCs) for any of the silicate glass samples.     

Effect of S53P4 bioactive glass content on structural and in-vitro behavior of hydroxyapatite/bioactive glass mixtures prepared by mechanical milling

This work presents silicon-substituted hydroxyapatite preparation through planetary ball milling using biogenic hydroxyapatite and different wt% of S53P4 bioactive glass (5, 10, 15, and 20 wt%) sources for the first time. The prepared mixtures showed a BHAp lattice contraction with SiO₄^4? incorporation; rich- and poor-Si phases were subsequently identified. Furthermore, two types of interaction among the functional groups in the S53P4 and BHAp mixtures are proposed. First, the 95-5 (wt.%) sample displayed a BHAp lattice with SiO₄^4?, CO₃^2?, and OH^? ions substitution. In samples with S53P4 BG content higher than 95-5, the lattice substitution was related to SiO₄^4?, PO₄^3?, and CO₃^2? ions, and a dehydroxylation process occurred in the BHAp. Finally, the bioactive behavior of the samples was studied by immersion in Hank's solution for 7, 14, and 28 days. The results showed that the mixtures formed a bone-like apatite layer with a dune-like morphology that increased in size and quantity with increasing S53P4 content in the mixtures.     

Effect of chloride ions in Tris buffer solution on bioactive glass apatite mineralization

Degradation and apatite precipitation of Bioglass 45S5 were characterized in two different tris(hydroxymethyl)aminomethane (Tris) buffer solutions. In the conventional one, pH was adjusted to 7.4 using hydrochloric acid (Tris-HCl buffer). In the other one, acetic acid was used instead, thereby obtaining a Tris buffer solution, which was virtually free of chloride ions (Tris-HAc). EDX results showed that chloride ions present in Tris-HCl buffer solution were incorporated into the apatite formed during immersion experiments, forming a (partially) substituted chlorapatite. No chloride ions were detected in apatite precipitated in Tris-HAc. Although no significant differences in the rate of apatite formation were observed during the time points studied here (6 hours to 7 days), the presence of chloride ions may affect very early stages of apatite formation. It may therefore be advantageous to use modified Tris buffer solutions, which do not contain high concentrations of ions involved in apatite formation, when studying early time point release kinetics or apatite precipitation of bioactive glasses.     

蠕虫孔状介孔Cr_2O_3的制备与表征

以硝酸铬为金属源,活性炭为硬模板,用真空辅助浸渍法制备了蠕虫孔状介孔Cr_2O_3,采用XRD、BET、TEM、TPR和UV-Vis对样品的物化性能进行了表征。结果表明,制备的介孔Cr_2O_3是具有六方晶型和比表面积高达112m^2·g^(-1)的晶体,平均孔径约6.5nm,与体相材料相比,介孔Cr_2O_3表现出良好的低温还原性能和吸光性能,这与其表面形貌和晶体结构有关。     

Preparation,characterization and in vitro biological response of simultaneous co-substitution of Zr+4/Sr+2 58S bioactive glass powder

In the present study, structure of zirconium-containing bioactive glass (58S-BG (Zr-BG)) with optimal fixed Zr content (5 mol.%) was modified by incorporation of strontium (Sr). These Zr and Sr-containing BGs (ZS-BGs) were synthesized by sol-gel method and substitution of Ca with modifier ions (Sr content = 0, 3, 6, 9, and 12 mol.%). The results obtained from characterization by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR), and energy-dispersive X-ray spectroscopy (EDS) techniques from surface of all the ZS-BGs revealed formation of hydroxyapatite (HA) after 7 days of immersion in the simulated body fluid (SBF) solution. Evaluation of changes in the SBF solution, by monitoring pH variations and ions? concentration, was in agreement with the results of morphological and structural investigations. The in-vitro biological function of synthesized BGs was studied through (MTT) assay and alkaline phosphatase (ALP) activity analysis. The results showed that all the specimens significantly stimulated proliferation and viability of MC3T3 osteoblast-like cells. Furthermore, antibacterial studies confirmed less resistance of methicillin-resistant Staphylococcus aureus (MRSA) bacteria against ZS-BGs. Eventually, the results of in-vitro bio-analysis were clarified and confirmed by two cell staining techniques of Live/Dead and Dapi/Actin. This confirmation was achieved by observing the increased quantity of live cells and their nuclei as well as the decreased number of dead cells after co-culturing with all ZS-BGs.     

Self-reduction of Eu3+ to Eu2+ in europium-doped Li2B4O7 glass prepared in air

Motivated by the detection of neutrons, europium-doped Li₂B₄O₇ glasses enriched with both lithium and boron elements with high cross-section capture were developed. A highly effective method of realizing the self-reduction of Eu³⁺ to Eu²⁺ ions in europium-doped Li₂B₄O₇ glasses prepared by high temperature melt-quenching technology in air was revealed. The self-reduction of Eu³⁺ to Eu²⁺ ions can be easily achieved by the partial replacement of B₂O₃ with BN within 2 mol% concentration. And the effect of partially replacing B₂O₃ with BN on the optical properties of europium-doped Li₂B₄O₇ glass are systematically studied by transmittance, photoluminescence, and radioluminescence spectra, together with the luminescence decay curves.     

溶胶-凝胶原位合成钒钨钛催化剂及NH3-SCR性能

利用溶胶-凝胶技术原位合成V₂O₅-WO₃/TiO₂介孔结构脱硝催化剂。通过XRD、BET、SEM和XPS等手段对催化剂结构与组成进行表征,发现结构导向剂CTAB促进催化剂的比表面积和孔容的增加,促进催化剂活性组分的分散与裸露的V活性组分数量增加;且随CTAB含量的增加,V⁴⁺/V⁵⁺的比值降低,即降低了催化剂表面钒物种的氧化能力,有利于提高催化剂的低温脱硝活性与高温选择性。催化活性评价结果表明,CTAB对催化剂的脱硝活性有显著促进作用,当CTAB的添加量为0.01（质量）时,催化剂的脱硝活性大于90%的温度窗口最宽为212~393℃,200℃时脱硝效率达85.6%。     

Preparation and properties of ferromagnetic glass ceramics and glass fibers based on the composition of SiO2-B2O3-Fe2O3-SrO

The ferromagnetic glass ceramics in the system SiO₂-B₂O₃-Fe₂O₃-SrO were prepared via four different fabrication methods, i.e., fiber-drawing, melt-quenching, natural-cooling, and annealing, without performing any nucleation and crystallization heat treatments. The influences of chemical composition and fabrication method on the spontaneous crystallization of magnetite were investigated by X-ray diffraction, scanning and transmission electron microscopy. The X-ray diffraction patterns show the presence of nanometric magnetite crystals in the glass matrix, and the increasing boron oxide can promote the spontaneous crystallization of magnetite. The estimated size of crystallized magnetite varies between 12 and 50 nm. The magnetic properties of the glass ceramics derived from the four fabrication methods were analyzed using a Vibrating sample magnetometer (VSM), Agilent HP8722ES vector network analyzer and Mössbauer spectra. We find that both the saturation magnetization (M_S) and coercivity (H_jc) depend on the chemical composition and fabrication method. The calorimetric measurements were carried out using Orton Standard Dilatometers.     

Ab initio molecular dynamics simulation of the structural and electronic properties of aluminoborosilicate glass

In this study, the structural and electronic properties of aluminoborosilicate glass, which has a wide range of applications in fields such as microelectronics and displays, were examined using ab initio molecular dynamic simulations. Computing models containing 220 atoms correctly described the local structure of the glass. The reliability of the computing models was verified by the consistency between the experimental results, obtained using high-energy X-ray diffraction and solid-state nuclear magnetic resonance, and the simulation results pertaining to structural factors, pair distribution functions, Qⁿ distribution, and elastic properties. The presence of B and Al increased the flexibility and asymmetry of the system, as shown by the bond angle and ring size distributions. Based on the electronic properties, we observed that the introduction of Al and B atoms into the network could also cause covalent interactions with the O atoms, similar to that with Si atoms. However, the Na and Mg atoms still interacted with all kinds of atoms in the network via charge transfer and exhibited highly non-localized effects on the charge of the network formers. These results extend our understanding of the structure of aluminoborosilicate glass and have guiding significance for improving and designing new types of this glass.     

B_2O_3／Al_2O_3催化剂结构和性能的研究

采用溶胶凝胶法和浸渍法,在500℃下焙烧2 h,制备不同组成的B2O3／Al2O3催化剂。通过X射线衍射、热失重、傅立叶红外光谱等测试方法对所制备的催化剂的结构进行表征。通过催化剂与二苯甲酰基甲烷(DBM)配位情况对催化剂的性能表征。研究表明:焙烧获得的主催化剂晶型为γ-Al2O3,添加第二组分B2O3,可以提高与DBM的配位能力,以改善Al2O3的催化活性。     

B2O3对LTPS用基板玻璃结构和黏温性能的影响

以LTPS用无碱基板玻璃配比料方,探讨B₂O₃对无碱硼铝硅酸盐玻璃结构和黏温性能的影响。通过红外光谱和X射线光电子能谱对玻璃试样进行网络结构分析,并测试了玻璃试样的高温黏度、软化点温度、退火点温度和应变点温度。结果表明:B₂O₃含量较低(0.13%)时,B³⁺以四配位的[BO₄]存在;随着B₂O₃含量升高,满足[BO₄]形成之外的B;逐渐以[BO₃]的形式存在;[BO₃]含量增多,玻璃黏度逐渐下降。     

The synergistic effect of combining the bioactive glasses with polymer blends on biological and material properties

The possibility of combining the advantages of bioresorbable polymers blending and the modification of blend matrix with bioactive ceramic fillers was presented for the first time in order to obtain composite materials for biomedical applications. Two kinds of sol-gel-derived bioactive glasses: S2-high silica and A2-high lime content were combined with PCL/PLGA blend at different volume ratio, that is, 25/75, 50/50, and 75/25. Materials were fabricated in the form of thin films using a solvent casting method. The influence of these variables on surface properties (morphology, roughness, wettability), their mechanical performance, in vitro bioactivity and Saos-2 osteoblast-like cell response (cell viability, alkaline phosphatase activity), were successfully investigated. Due to the specificity of fabrication route, studies were conducted to examine the opposite surfaces of the films, that is, Petri dish glass- or air-exposed during casting. It was demonstrated that the PCL/PLGA ratio of blend matrix, as well as chemical composition of gel-derived bioactive glass particles, are two-key factors that allow altering the surface and mechanical properties of the materials in a wide range. This, in turn, modulates significantly the bioactivity of materials and the response of osteoblast-like cells. Our findings indicate the new possibilities of designing biodegradable and highly bioactive composite materials with potential osteogenic properties.     

The influence of 3-glycidyloxypropyl trimethoxysilane on the rheological and in-vitro behavior of injectable composites containing 64S bioactive glass,chitosan, and gelatin

The effect of cross-linker 3-glycidyloxypropyl trimethoxysilane (GPTMS) on the injectability, bioactivity, rheology, washout resistance, and cellular behavior of bio-nano composite pastes containing a sol–gel derived bioactive glass (BG), chitosan (Cn), and gelatin (Gel), were studied. The results indicated that the structural integrity of the samples in the stimulated body fluid (SBF) was improved from 80% to 90% with the increase in the GPTMS content. In addition, the viscosity and injectability of the paste were affected, so that the later changed from 96% to 73% and the former changed from 132 × 10³ to 210 × 10³ Pa.s, with addition of 20 wt% GPTMS. Furthermore, the bioactivity of the pastes was improved with the use of GPTMS. No toxicity was observed in the cellular studies of the GPTMS containing paste after 7 days, and the cells kept their shape and were attached firmly to the paste surface. The results of the present work showed that the use of GPTMS was beneficial in enhancing the properties of injectable paste.     

制备条件对B2O3/TiO2-ZrO2催化剂结构的影响

采用XRD和低温氮吸附等测试方法，研究了制备条件对TiO2-ZrO2催化剂的结构性质和催化性能的影响。结果表明，选择合适的焙烧温度，并用适量的B2O3改性后，能大大改善催化剂的孔结构参数；孔分布向更大的中孔方向移动，使反应物分子可到达的孔体积增大，提高了催化剂的内表面利用率，有利于环己酮肟气相Beckmann重排反应的进行。     

Na2O-Li2O-Al2O3-SiO2-P2O5玻璃的结构与性能的分子动力学模拟

磷硅酸盐玻璃因有着良好的生物活性和光学性能,已广泛用于生物材料、光纤等领域。运用分子动力学模拟方法研究Li₂O含量对Na₂O–Al₂O₃–SiO₂–P₂O₅玻璃的微观结构以及扩散性能影响,着重讨论了其微观结构与维氏硬度,扩散系数之间的关系。结果表明:玻璃的磷网络聚合度（Q^p）随着Li₂O逐渐替代Na₂O而增加,硬度随着Q^p的增加而增大。体系中Li⁺的自扩散系数比Na⁺大,即Li⁺比Na⁺更易扩散。Li⁺的势垒随着Li₂O增加而逐渐变小,Li₂O对Na₂O取代有益于Li⁺扩散。