SrO-Containing Bioactive Glasses in the SiO2-CaO-P2O5 System: A Comprehensive Review.

Tricalcium Phosphate ( TCP ) was doped with 0.5, 2.0, and 5.0 mol% Strontium Oxide ( SrO ) through the wet precipitation process to investigate the influence of SrO on the biological and mechanical properties of TCP . XRD results showed that SrO doping did not change the phase stability of the β‐phase of TCP during sintering at 1120°C. The apparent density of TCP increased from 95.1 ± 2.5% to 99.4 ± 0.5% with the addition of 5.0 mol% SrO doping. SrO doping also increased the compressive strength of pure β‐ TCP from 121.1 ± 21.4 MPa to 185.9 ± 16.7 MPa with 5 mol% SrO addition. Initially, the addition of 0.5 and 2.0 mol% SrO had a statistically insignificant impact on the as‐processed samples' compressive strength. When the samples were immersed in a simulated body fluid for 12 weeks, the addition of SrO improved the compressive strength from 109.4 ± 22.9 MPa for pure TCP to 208.8 ± 34.6 MPa with 5.0 mol% SrO addition. An improvement in h FOB cell attachment and proliferation was observed for all dopant concentrations using field emission scanning electron microscope (FE‐SEM) imaging and MTT assay studies, indicating excellent biocompatibility of all the samples. 2.0 mol% SrO doping showed the best cell differentiation and proliferation results. It was shown that SrO simultaneously improved mechanical properties of TCP such as compressive strength as well as biological properties via enhanced cell attachment and proliferation.

Structural origin of high bioactivity in zirconia containing bioactive glasses.

Chapter 4 - Bioactive glasses and ceramics for tissue engineering

In this work blends based on calcium aluminate cement (CAC) containing bioactive glass (BG) (5, 7.5 and 10 wt%) and strontium oxide (1 wt%) were produced aiming improve their bioactivity and the capacity to stimulate the bone regeneration. In the first part, the blends containing only BG were characterized as theoretical density, microhardness, uniaxial cold crush strength after SBF and apparent porosity and pore size distribution before and after SBF treatment. In the second part, bioactivity and cell culture tests were also conducted in the blends containing BG and strontium oxide. The addition of 7.5 wt% of BG in homogeneous calcium aluminate cement (CH) improved its mechanical properties as microhardness and uniaxial cold crushing strength. The blends were more bioactive due to the presence of a highly soluble amorphous phase as confirmed by means of SEM/EDX mainly for 7.5 wt% BG without and with Sr from 1 day in SBF. FTIR analyses indicated the formation the apatite-like phase by means of increase of intensity of the PO43- peaks after SBF treatment. All blends allowed the development of the osteoblastic phenotype and the formation of mineralized matrix increased due to the inclusion of BG and Sr promoting the osteogenesis process.

The effect of mesoporous bioactive glass on the physiochemical, biological and drug-release properties of poly( dl-lactide-co-glycolide) films

Critical-sized bone defects have, in many cases, posed challenges to the current gold standard treatments. Bioactive glasses are reported to be able to stimulate more bone regeneration than other bioactive ceramics; however, the difficulty in producing porous scaffolds made of bioactive glasses has limited their extensive use in bone regeneration. On the other hand, calcium phosphate ceramics such as synthetic hydroxyapatite and tricalcium phosphate are widely used in the clinic, but they stimulate less bone regeneration. This paper gives an overview of the recent developments in the field of bioactive nanoparticles, with a focus on nanohydroxyapatite and bioactive glasses for bone repair and regeneration. First, a brief overview of the chemical structure and common methods used to produce synthetic nanohydroxyapatite and bioactive glasses has been presented. The main body of the paper covers the physical and biological properties of these biomaterials, as well as their composites with biodegradable polymers used in bone regeneration. A summary of existing challenges and some recommendations for future directions have been brought in the concluding section of this paper.

Strontium oxide-functionalized 3D-printed polycaprolactone/β-tricalcium phosphate nanocomposite scaffolds with osteogenic microenvironment remodeling for accelerated bone regeneration.

Hydroxyapatite forming ability, ion release and antibacterial activity of the melt-derived SiO2–P2O5–Na2O–CaO–F glasses modified by replacing CaO with SrO and ZnO

Bioactive glasses are known to stimulate bone healing, and the incorporation of strontium has the potential to increase their potency. In this study, calcium oxide in the 45S5 bioactive glass composition was partially (50%, Sr50) or fully (100%, Sr100) substituted with strontium oxide on a molar basis. The effects of the substitution on bioactive glass properties were studied, including density, solubility, and in vitro cytotoxicity. Stimulation of osteogenic differentiation was investigated using mesenchymal stromal cells obtained from rat bone marrow. Strontium substitution resulted in altered physical properties including increased solubility. Statistically significant reductions in cell viability were observed with the addition of bioactive glass powders to culture medium. Specifically, addition of ≥ 13.3 mg/ml of 45S5 bioactive glass or Sr50, or ≥ 6.7 mg/ml of Sr100, resulted in significant inhibition. Real‐time PCR analyses detected the upregulation of genes associated with osteoblastic differentiation in the presence of all bioactive glass compositions. Some genes, including Alpl and Bglap, were further stimulated in the presence of Sr50 and Sr100. It was concluded that strontium‐substituted bioactive glasses promoted osteogenesis in a differentiating bone cell culture model and, therefore, have considerable potential for use as improved bioactive glasses for bone tissue regeneration. © 2015 The Authors. Journal of Tissue Engineering and Regenerative Medicine Published by John Wiley & Sons Ltd.

Bioceramics play an important role in repairing and regenerating bone defects. Annually, more than 500,000 bone graft procedures are performed in the United states and approximately 2.2 million are conducted worldwide. The estimated cost of these procedures approaches $2.5billion per year. Around 60% of the bone graft substitutes available on the market involve bioceramics. It is reported that bioceramics in the world market increase by 9% per year. For this reason, the research of bioceramics has been one of the most active areas during, the past several years. Considering the significant importance of bioceramics, our goal was to compile this book to review the latest research advances in the field of bioceramics. The text also summarizes our work during the past 10 years in an effort to share innovative concepts, design of bioceramisc, and methods for material synthesis and drug delivery. We anticipate that this text will provide some useful information and guidance in the bioceramics field for biomedical engineering researchers and material scientists. Information on novel mesoporous bioactive glasses and silicate-based ceramics for bone regeneration and drug delivery are presented. Mesoporous bioactive glasses have shown multifunctional characteristics of bone regeneration and drug delivery due to their special mesopore structures,whereas silicated-based bioceramics, as typical third-generation biomaterials,possess significant osteostimulation properties. Silica nanospheres with a core-shell structure and specific properties for controllable drug delivery have been carefully reviewed-a variety of advanced synthetic strategies have been developed to construct functional mesoporous silica nanoparticles with a core-shell structure, including hollow, magnetic, or luminescent, and other multifunctional core-shell mesoporous silica nanoparticles. In addition, multifunctional drug delivery systems based on these nanoparticles have been designed and optimized to deliver the drugs into the targeted organs or cells,with a controllable release fashioned by virtue of various internal and external triggers. The novel 3D-printing technique to prepare advanced bioceramic scaffolds for bone tissue engineering applications has been highlighted, including the preparation, mechanical strength, and biological properties of 3D-printed porous scaffolds of calcium phosphate cement and silicate bioceramics. Three-dimensional printing techniques offer improved large-pore structure and mechanical strength. In addition , biomimetic preparation and controllable crystal growth as well as biomineralization of bioceramics are summarized, showing the latest research progress in this area. Finally, inorganic and organic composite materials are reviewed for bone regeneration and gene delivery. Bioactive inorganic and organic composite materials offer unique biological, electrical, and mechanical properties for designing excellent bone regeneration or gene delivery systems. It is our sincere hope that this book will updated the reader as to the research progress of bioceramics and their applications in bone repair and regeneration. It will be the best reward to all the contributors of this book if their efforts herein in some way help reader in any part of their study, research, and career development.

Bioactive glasses (BGs) are a kind of biomaterials with osteoconductive and osteoinductive properties and are able to create a strong bond with host bone and promote osteogenesis after implantation. According to their compositions, bioactive glasses can be classified as silicate BGs, phosphate BGs, and borate BGs. Nowadays, silicate BGs are still the most common, while phosphate BGs and borate BGs have higher dissolution and degradation rates. Melt-quenching and sol-gel process are two basic methods to produce melt-derived BGs and sol-gel BGs, respectively. The latter requires lower heat treatment temperature with higher specific surface area and biological activity. Bioactive glass-ceramics can be obtained by heat treatment, which improves the mechanical strength but slightly reduces the bioactivity. Nano-bioactive glasses with the higher specific surface area can be obtained by changing the structure size of the materials by other treatment methods. On this basis, 3D BGs scaffolds can be made, and hybrid BGs scaffolds as well by combining with other biomaterials to obtain the 3D interconnected pores with the hierarchical or bionic structures, to enhance the mechanical strength, osteogenic activity and provide mechanical support suitable for the host bone. However, the bioactivity of BGs depends on the degradation rate, to some extent, which is contradictory to the mechanical strength. An appropriate porosity or controllable degradation rate can be selected to meet the common needs of early support and osteogenesis. In basic studies, it was found that BGs could act on cells by releasing ions or through the macropinocytosis pathway, up-regulating the expression of related genes or promoting osteogenesis. The degradation rates of BGs are related to their structures and compositions, which enables the quantitative prediction of the change of mechanical strength during degradation. Progress has also been made in structural mechanics and testing methods.

Designing a biomaterial with excellent bioactivity, biocompatibility, mechanical strength, porosity, and osteogenic properties is essential to incorporate therapeutic agents in order to promote efficient bone regeneration. The work intended to prepare bioactive glass with tailor-made equal Ca/P (CP) ratio to obtain clinophosinaite (Cpt) as dominant phase. Clinophosinaite (Na3 CaPSiO7 ) is one of the rarest phases of bioactive glass (BG), which is supposed to play key role in bioactivity. The novelty of this work is to track the required sintering temperature to attain equimolar calcium phosphate-containing clinophosinaite phase and its behavior. Further, its consequent physicochemical and biological properties were analyzed. Phase transition from Rhenanite to Cpt, and later the Cpt emerged as dominant phase with increase of calcination temperature from 700 to 1000°C was studied. The quantifying evolution of Cpt with Rhenanite over increasing annealing temperature also results with the major morphological modifications. BET analysis confirmed the surface area and porosity (Type-IV mesoporous) were gradually elevated upto 900°C, which had contrary effect on mechanical strength. Formation of hydroxyl carbonate apatite (HCA) layer confirmed the bioactivity of the prepared samples at varying time intervals. The CP samples demonstrated better hemocompatibility in post-immersion (i.e., less than 1% of lysis) when compared with pre-immersion. Enhanced protein adsorption and cumulative release (85%) of Simvastatin (SIM) drug was attained at 900°C treatment.

Drug loaded bioglass nanoparticles and their coating for efficient tissue and bone regeneration

Osteogenic-angiogenic coupled response of cobalt-containing mesoporous bioactive glasses in vivo

In the arena of orthopaedic surgery, autograft is considered to be the gold standard for correction of fracture repair or other bone pathologies. But, it has some limitations such as donor site morbidity and shortage of supply, which evolved the use of allograft that also has some disadvantages such as immunogenic response to the host, low osteogenicity as well as possibilities of disease transmission. Despite the benefits of autografts and allografts, the limitations of each have necessitated the pursuit of alternatives biomaterials that has the ability to initiate osteogenesis, and the graft should closely mimic the natural bone along with regeneration of fibroblasts. A variety of artificial materials such as demineralised bone matrix, coralline hydroxyapatite and calcium phosphate-based ceramics such as hydroxyapatite (HA), β-tricalcium phosphate (β-TCP) and bioactive glass have been used over the decades to fill bone defects almost without associated soft tissue development. Most of them were having only the properties of osteointegration and osteoconduction. Only bioactive glass possesses osteogenic property that stimulates proliferation and differentiation of osteoprogenitor cells and in some cases influencing the fibroblastic properties. But, this material has also some disadvantages such as short-term and low mechanical strength along with decreased fracture resistance; but, this was further minimised by ion doping that positively enhanced new bone formation. There are many metal ions such as magnesium (Mg), strontium (Sr), manganese (Mn), iron (Fe), zinc (Zn), silver (Ag) and some rare earths that have been doped successfully into bioactive glass to enhance their mechanical and biological properties. In some of the cases, mesoporous bioactive glass materials with or without such doping have also been employed (with homogeneous distribution of pores in the size ranging between 2 and 50 nm). These biomaterials can be served as scaffold for bone regeneration with adequate mechanical properties to restore bone defects and facilitate healing process by regeneration of soft tissues as well. This chapter encompasses the use of bioactive glass in bulk and mesoporous form with doped therapeutic ions, their role in bone tissue regeneration, use as delivery of growth factors as well as coating material for orthopaedic implants.