Fabrication of porous bioactive glass particles by one step sintering

In this study, we reported a facile method to prepare porous bioactive glass microparticles. Porous particles were synthesized by sintering hollow bioactive glass microspheres obtained using a sol-gel co-template technology. The results showed that porous bioactive glass particles possessed a narrow particle size distribution, a relatively porous surface morphology and a hollow structure. It is worth to say that the resulting microparticles present an amorphous structure although the sintering temperature was improved compared to hollow microspheres. The presence of macropore on the shell may provide an efficient method to carry drugs in the hollow cores. Considering the high deposit rate of nanoscale apatite for bioactive glass materials, the porous microparticles should have potential applications in drug and bioactive molecules delivery, in addition to bone tissue regeneration.     

Synthesis and characterization of hollow glass microspheres coated by SnO2 nanoparticles

The composite of hollow glass microspheres coated by SnO₂ nanoparticles has been successfully fabricated via sol-gel method. The phase structures, morphologies, particle size, shell thickness, chemical compositions of the composite have been characterized by XRD, FESEM, and EDX. The results show that SnO₂ coating on hollow glass microspheres can be achieved, and the coating layers are constituted by SnO₂ nanoparticles of mean size ca. 15 nm. The SnO₂ coating layers grow thicker with the increased concentration of SnCl₄. The effects of parameters (reaction temperature, concentration of NaOH and SnCl₄, and time) were investigated to yield SnO₂ coating on hollow glass microspheres, and the UV-vis absorption spectra of the composites were studied.     

Preparation,characterization, in vitro bioactivity and protein loading/release property of mesoporous bioactive glass microspheres with different compositions

Mesoporous bioactive glass microspheres (MBGMs) with large mesopores have attracted considerable attention in the field of bone tissue regeneration and drug delivery systems due to their excellent bioactivity, biocompatibility and high specific area. In this study, a loose structure of MBGMs with adjustable chemical compositions was synthesized by the combination of sol-gel and water-in-oil (W/O) microemulsion. All the prepared MBGMs possessed a large mesopore diameter that increased with CaO content, a high surface area and good apatite-inducing formation ability. In vitro protein absorption and release assays demonstrated that the MBGMs exhibited decreased loading efficiency and burst release behavior as the CaO content increased. Additionally, an enhanced BSA-loading amount and prolonged release curve were obtained after the surfaces of MBGMs were modified by amine groups. Furthermore, the preliminary in vitro cell experiments showed that MBGMs exhibited good biocompatibility. The results indicated that MBGMs could be a promising candidate as a drug/protein carrier for bone tissue regeneration.     

Facile synthesis and in vitro bioactivity of radial mesoporous bioactive glass with high phosphorus and calcium content

A novel uniform monodispersed radial mesoporous bioactive glass nanosphere (MBG) with high phosphorus and calcium content has been successfully synthesized. The synthesis was first taken place in a cyclohexane-water biphasic stratification reaction system, which fabricated the radial mesoporous SiO₂-P₂O₅ nanosphere (SPN) using hexadecyltrimethyl ammonium bromide (CTAB) as a template agent and triethanolamine (TEA) as a hydrolysis catalyst. Solid reactions were then carried out to synthesize SiO₂-CaO-P₂O₅ MBG using SPN as both the silicon source and phosphorus source, and Ca(NO₃)₂ as the calcium source. The prepared MBG not only displayed the radial structure and high specific surface area (~321 m²/g), but also had high phosphorus and calcium content. The results of energy dispersive spectrometer (EDS) demonstrated that P₂O₅ content was enhanced by properly increasing the reaction temperature. The in vitro bioactivity test showed that MBG had an excellent ability of inducing apatite formation. Furthermore, the MBG showed excellent biocompatibility at a low concentration of 50–100 μg/mL in vitro, and it would have a promising prospect as drug delivery system for bone tissue regeneration.     

Synthesis of high surface area mesoporous bioactive glass nanospheres

Mesoporous bioactive glass (MBG) nanospheres having the composition of SiO₂-CaO-P₂O₅ with both a large specific surface area (∼ 1040 m² g^− 1) and pore volume (1.54 cm³ g^− 1) were prepared using the ionic surfactant, cetyltrimethyl-ammonium bromide (CTAB), as a template. The size of the nanospheres depends on the amount of CaO that is incorporated and can be controlled over the range of diameters from 20 to 200 nm under dilute aqueous condition. In vitro bioactivity studies were carried out in simulated body fluid (SBF). Cytotoxicity tests of the MBG nanospheres were also performed by observing their influence on J774 macrophages at various concentrations.     

Bioactive glass nanotube scaffold with well-ordered mesoporous structure for improved bioactivity and controlled drug delivery

In this study, a novel mesoporous bioactive glass nanotube (MBGN) scaffold has been fabricated via template-assisted sol-gel method using bacterial cellulose (BC) as template and nonionic block copolymer (P123) as pore-directing agent. The scaffold was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared (FTIR) spectroscopy, and N₂ adsorption-desorption analysis. Furthermore, simvastatin was used to evaluate the loading efficiency and release kinetics of the scaffold. The obtained scaffold displays nanofiber-like morphology, ordered mesopores on the tube walls, and interconnected three-dimensional (3D) network structure that completely replicates the BC template. In addition, it shows dual pore sizes (16.2 and 3.3 nm), large specific surface area (537.2 m² g⁻¹) and pore volume (1.429 cm³ g⁻¹). More importantly, the scaffold possesses excellent apatite-forming ability and sustainable drug release as compared to the counterpart scaffold without mesopores. This unique scaffold can be considered a promising candidate for drug delivery and bone tissue regeneration.     

An inexpensive route to prepare mesoporous hollow silica microspheres using W/O ethanol/edible soybean oil macroemulsion as the template

Mesoporous hollow silica microspheres were prepared by using W/O emulsion consisting of ethanol droplets as a template in edible soybean oil. Ethanol droplets containing ammonia solution were generated by employing ultrasonication in pure soybean oil. The droplets were colloidally stabilized by means of a cationic surfactant, cetyltrimethylammonium bromide (CTAB). Later on, another proportion of soybean oil dissolving tetraethyl orthosilicate (TEOS) was added to the W/O emulsion. The sol-gel reaction of TEOS was achieved only at the interface of the emulsion droplets, resulting in hollow silica microspheres. After washing the resultant with acetone, mesoporous hollow silica microspheres were simply obtained. Throughout this liquid template-based process, mesoporous hollow silica microspheres can be inexpensively synthesized without employing solid templates.     

Synthesis and in vitro bioactivity of mesoporous bioactive glass scaffolds

The main objective of the present study was to determine the effect of thermal treatment procedures (calcination temperature, heating rate and duration time) on the synthesis of SiO₂–CaO–P₂O₅ mesoporous bioactive glass scaffolds. This is accomplished by thermogravimetric analyses, Fourier transform infrared (FTIR) absorption spectra, X-ray diffraction (XRD) and by analysis of nitrogen adsorption/desorption isotherms. In vitro bioactivity can also be assessed by the cytotoxic effect of the glasses on the NIH-3T3 cell line, and by characterization of MC-3T3-E1 cell attachment.     

Synthesis and characterization of SiO2-CaO-P2O5 hollow nanospheres for biomedical applications

A ternary system of SiO₂-CaO-P₂O₅ hollow nanospheres has been successfully prepared by sol-gel method using polystyrene (PS) nanospheres as template. The inorganic shell was produced using tetraorthosilicate (TEOS) as the silica source and tri-calciumphospate as calcium and phosphorus sources, respectively. The positive surface charge of the template and the [template]/[TEOS] ratio were the key parameters for the creation of a stable primary inorganic network and the further growth of the shell. The removal of the polymeric core through a thermal treatment procedure created an inner void space with mean diameter 250 nm while the outer mean diameter was 330 nm.     

Synthesis and characterisation of nanobioactive glass for biomedical applications

In recent years, bioactive materials have become important in applications such as implantation, bone regeneration, scaffold, oral implantation and antioxidant materials because of their excellent bioactivity, biocompatibility, osteoconductivity and osteoinductive properties. When exposed to simulated body fluid, bioactive glasses have the ability to bond with both hard and soft tissues through the formation of a hydroxyapatite layer. Nowadays, nanotechnology is emerging as a nascent technology in all disciplines because of its high surface-to-volume ratio and unique properties at nanoscale length. The impact of nanotechnology in biomaterials is of interest because of the enhancement in their biocompatibility and bioactivity. In this investigation, the preparation of nanobioactive glasses by using different methods (such as sol-gel, hydrothermal and sonochemical) is discussed in detail. The structural and morphological characterisation of the prepared samples was made.     

A controlled formation of cage-like nanoporous hollow silica microspheres

Cage-like hollow silica microspheres composed of mesoporous silica nanoparticles and macroporous interparticle voids were fabricated via the latex-surfactant dual templates route, simply by controlling the surfactant additions below its critical micelle concentration. The surface area, pore volume increase, and both the mesopore and macropore sizes decrease with the increase in surfactant amount. The surfactant cations preferentially assemble with negatively charged silica species generated by the hydrolysis and condensation of tetraethyl orthosilicate to form composite silica-surfactant nanoparticles. The electrostatic repulsion between the silica-surfactant composite nanoparticles and negatively charged polystyrene (PS) beads is smaller than that between surfactant-free silica and PS, favoring the deposition of composite nanoparticles on the surface of PS template. In the meantime, the deposited nanoparticles also have reduced repulsion from their neighbors, favoring their bridging to form silica shells. The more the surfactant is used, the less the repulsion exists among the composite particles and the smaller the interparticle macroporous voids are.     

空心玻璃微珠表面化学镀Ni-P合金磁性涂层的研究

采用化学镀工艺在空心玻璃微珠表面包覆了一层磁性的Ni-P合金涂层,对其进行了表面金属化改性.分别用X射线衍射仪(XRD)、傅立叶变换红外光谱仪(FT-IR)、扫描电子显微镜(SEM)以及振动样品磁强计(VSM)对化学镀前后空心玻璃微珠的形貌、组成、结构以及磁性能进行了表征.结果表明:通过化学镀工艺制备的Ni-P合金涂层由原子团簇组成;涂层为非晶结构并具有较好的磁性能;化学镀后空心玻璃微珠的X射线衍射强度和红外透射强度均降低.     

Effective surface pretreatment of hollow glass microspheres via a combined KF roughening and alkali washing strategy for the following metallization

Surface roughening of hollow glass microspheres (HGMs) is a necessary step determining their adhesion ability with the following electroless plated metallization coating. In this paper, a new KF roughening and alkali washing strategy was proposed to replace HF roughening as a surface pretreatment for the following electroless plating metallization. In order to remove the byproduct of K₂SiF₆ from the roughening reaction of KF with HGMs, NaOH washing and KOH washing were conducted, the former of which was found to dissolve K₂SiF₆ effectively. The effects of KF roughening temperature, alkali concentration and HGMs loading on the recovery ratio, phase composition, surface morphology and performance of HGMs were investigated, through which such a pretreating strategy was found to not only decrease the damage ratio of HGMs compared to that by HF roughening, but also render the metallized HGMs a competitive absorbing ability for the electromagnetic wave in X-band and Ku-band. Finally, the related surface treatment and electroless plating mechanism were discussed. This paper illustrates successfully a new pretreatment strategy for development of lightweight HGMs-supported functional materials.     

空心玻璃微球表面接枝聚苯乙烯及其性能研究

空心玻璃微球表面改性有利于改善其与基体间的相容性,提高复合泡沫性能.通过接枝聚苯乙烯对空心玻璃微球进行表面处理,采用SEM、IR、热失重等方法分析了反应条件对接枝的影响.结果表明,接枝反应过程中提高反应温度、延长反应时间有利于接枝率的提高,但温度过高会加速单体自聚,降低接枝率.接枝处理后,随着聚合物层的增厚,空心玻璃微球表面缺陷减小,破损率降低,抗压强度得到一定程度提高.     

空心玻璃微珠表面包覆Ni-P／Co-Fe-P复合镀层的研究

通过化学镀在空心玻璃微珠（HGM）表面沉积了镍磷合金颗粒镀层，利用偶联取代传统的粗化处理，结合适当的镀覆工艺实现了镀层与微珠的紧密结合并达到了均匀完整包覆；在此基础上，进行了镍磷镀层表面湿化学还原法包覆钴铁合金的研究。利用扫描电子显微镜、X射线能谱仪、X射线衍射仪及振动样品磁强计对包覆层的形貌、组成、晶体结构和改性后微珠的静磁性能进行了分析测试。结果表明，复合镀层由非晶态合金组成，其中镍磷镀层为单层颗粒膜，而后续沉积的钴铁合金镀层呈条带状生长于镍磷镀层表面；沉积钴铁合金后微珠的磁性有了明显改善。     

炭微球的结构演变:从实心到中空(英文)

采用简单的空气氧化法由实心炭微球制备中空结构的炭微球。通过场发射扫描电子显微镜、高分辨透射电子显微镜、X-射线衍射仪、拉曼光谱和热重分析仪对产物的形貌和结构进行表征。结果表明:中空炭微球的石墨化程度较低。在炭微球的空气热氧化过程中,反应温度对炭微球从实心到中空的结构演变起着关键性的作用,温度越高,中空炭微球的内径越大、壁越薄。其形成机理可认为是炭微球的曲率和结晶度协同作用的结果。亦即,实心炭微球进行热氧化时,其内部的大曲率和低结晶度更易氧化,以致形成中空炭微球。     

In vitro evaluation of borate-based bioactive glass scaffolds prepared by a polymer foam replication method

Borate-based bioactive glass scaffolds with a microstructure similar to that of human trabecular bone were prepared using a polymer foam replication method, and evaluated in vitro for potential bone repair applications. The scaffolds (porosity = 72 ± 3%; pore size = 250–500 μm) had a compressive strength of 6.4 ± 1.0 MPa. The bioactivity of the scaffolds was confirmed by the formation of a hydroxyapatite (HA) layer on the surface of the glass within 7 days in 0.02 M K₂HPO₄ solution at 37 °C. The biocompatibility of the scaffolds was assessed from the response of cells to extracts of the dissolution products of the scaffolds, using assays of MTT hydrolysis, cell viability, and alkaline phosphatase activity. For boron concentrations below a threshold value (0.65 mM), extracts of the glass dissolution products supported the proliferation of bone marrow stromal cells, as well as the proliferation and function of murine MLO-A5 cells, an osteogenic cell line. Scanning electron microscopy showed attachment and continuous increase in the density of MLO-A5 cells cultured on the surface of the glass scaffolds. The results indicate that borate-based bioactive glass could be a potential scaffold material for bone tissue engineering provided that the boron released from the glass could be controlled below a threshold value.     

Effect of magnesia on structure, degradability and in vitro bioactivity of CaO-MgO-P2O5-SiO2 system ceramics

CaO-MgO-P₂O₅-SiO₂ system ceramics with various magnesia contents (0, 5, 10 and 20 mol%) were successfully prepared by sintering the sol-gel-derived powder compacts. The ceramic degradation was evaluated through the weight loss in the tris-(hydroxymethyl)-aminomethane and hydrochloric acid (Tris-HCl) buffer solution, and their ability to form apatite was determined by soaking in simulated body fluid (SBF). Results indicated that the ceramics structure was greatly influenced by magnesia contents. New crystal phases of Ca₂MgSi₂O₇ and SiO₂ were formed when magnesia was added and with an increase of magnesia concentration the phase of Ca₂MgSi₂O₇ increased with a simultaneous decline of β-CaSiO₃. In addition, studies showed that magnesia played an important role in affecting the degradability and apatite forming ability of CaO-MgO-P₂O₅-SiO₂ system ceramics. It is observed that with increasing magnesia concentration, the ceramic degradability gradually decreased and the formation of apatite on samples was delayed.     

Preparation and evaluation of a novel bioactive glass/lysozyme/PLGA composite microsphere

Objective: The objective of this study was to fabricate a novel nano-bioceramics incorporated lysozyme poly (d, l-lactide-co-glycolide) (PLGA) microsphere.

Methods: The nano-bioceramics was used as a biodegradable and sustained-release antacid to stabilize the lysozyme in the drug release process. First, the nano-bioceramics were prepared by sol-gel method, and then were characterized by energy dispersive X-ray analysis, dynamic light scattering and in vitro degradation test. Second, the lysozyme PLGA microsphere incorporated with nano-bioceramic was fabricated by the S/W/O/W emulsion solvent evaporation method. The microsphere was characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and UV circular dichroism (UV CD). Finally the in vitro drug release and bioactivity test was carried out.

Results: The composition of the nano-bioceramics was 58% SiO₂, 36% CaO, 6% P₂O₅, and the average particle size was 295?nm. The nano-bioceramics incorporated lysozyme PLGA microspheres were prepared by the multi-emulsion method. The SEM results showed that the bioceramics was uniformly distributed in the PLGA microsphere. Results from in vitro lysozyme release test exhibited a prolonged release time for 1month. The FTIR and UVCD results suggested that the lysozyme in the drug release process had a similar secondary structure conformation to the native one. The Micrococcus lysodeikticus test showed that the microspheres incorporated with bioceramics provided long-term protein stability against the acidic environment resulted from PLGA’s degradates and more than 90% of the lysozyme released over the 1 month period was preserved in a bioactive form.

Conclusion: A novel bioceramics incorporated lysozyme PLGA microsphere was prepared with potentials for sustained protein release formulation.     

Composite nanofiber of bioactive glass nanofiller incorporated poly(lactic acid) for bone regeneration

A novel composite nanofiber of poly(lactic acid) (PLA) incorporated with the nanocomponent of bioactive glass was exploited using an electrospinning method. Small concentrations of the bioactive glass phase added up to 10% facilitated the generation of a nanofibrous matrix with hundreds of nanometers in diameter without a formation of beads. The addition of the bioactive glass phase greatly enhanced the in vitro apatite formation on the nanofiber surface under a body simulating medium. Osteoblastic cells were demonstrated to adhere well on the composite nanofiber and grow actively with culturing time, suggesting its usefulness as a supporting matrix for the hard tissue regeneration.