Jasmin Hum

Combining Collagen and Bioactive Glasses for Bone Tissue Engineering: A Review

Collagen (COL), the most abundant protein in mammals, offers a wide range of attractive properties for biomedical applications which are the result of its biocompatibility and high affinity to water. However, due to the relative low mechanical properties of COL its applications are still limited. To tackle this disadvantage of COL, especially in the field of bone tissue engineering, COL can be combined with bioactive inorganic materials in a variety of composite systems. One of such systems is the collagen-bioactive glass (COL-BG) composite family, which is the theme of this Review. BG fillers can increase compressive strength and stiffness of COL-based structures. This article reviews the relevant literature published in the last 15 years discussing the fabrication of a variety of COL-BG composites. In vitro cell studies have demonstrated the osteogenic, odontogenic, and angiogenic potential of these composite systems, which has been confirmed by stimulating specific biochemical indicators of relevant cells. Bony integration and connective tissue vessel formation have also been studied by implantation of the composites in vivo. Areas of future research in the field of COL-BG systems, based on current challenges, and gaps in knowledge are highlighted.

45S5 Bioglass®-derived scaffolds coated with organic–inorganic hybrids containing graphene

Highly porous 45S5 Bioglass®-based scaffolds fabricated by a foam replication technique were coated with electrically conductive organic-inorganic hybrid layers containing graphene by a solution method. α,ω-Triethoxysilane terminated poly (ethylene glycol) and tetraethoxysilane were used as the precursors of the organic-inorganic hybrid coatings, that contained 1.5 wt.% of homogeneously dispersed graphene nanoplatelets. The resulting coated scaffolds retained their original high porosity and interconnected pore structure after coating. The presence of graphene did not impair the bioactivity of the scaffolds in simulated body fluid. Initial tests carried out using MG-63 cells demonstrated that both uncoated scaffolds and scaffolds coated with organic/inorganic hybrids containing graphene offered the cultured cells an adequate surface for cell attachment, spreading and expression of extracellular matrix. The results showed that scaffolds coated with graphene are biocompatible and they can support cellular activity. The electrical conductivity introduced by the coating might have the potential to increase tissue growth when cell culture is carried out under an applied electric field.

Osteogenic differentiation of umbilical cord and adipose derived stem cells onto highly porous 45S5 Bioglass®‐based scaffolds

In the context of bone tissue engineering (BTE), combinations of bioactive scaffolds with living cells are investigated to optimally yield functional bone tissue for implantation purposes. Bioactive glasses are a class of highly bioactive, inorganic materials with broad application potential in BTE strategies. The aim of this study was to evaluate bioactive glass (45S5 Bioglass(®)) samples of composition: 45 SiO2, 24.5 CaO, 24.5 Na2O, and 6 P2O5 (in wt%) as scaffold materials for mesenchymal stem cells (MSC). Pore architecture of the scaffolds as well as cell behavior in the three-dimensional environment was evaluated by several methods. Investigations concerned the osteogenic cell attachment, growth and differentiation of adipose tissue derived MSC (adMSC) compared with MSC from human full term umbilical cord tissues (ucMSC) on porous Bioglass(®)-based scaffolds over a cultivation period of 5 weeks. Differences in lineage-specific osteogenic differentiation of adMSC and ucMSC on Bioglass(®) samples were demonstrated. The investigation led to positive results in terms of cell attachment, proliferation, and differentiation of MSC onto Bioglass(®)-based scaffolds confirming the relevance of these matrices for BTE applications.

Gelatin Coated 45S5 Bioglass®-Derived Scaffolds for Bone Tissue Engineering

Highly porous 45S5 Bioglass® scaffolds were fabricated by the foam replica method and successfully coated with a well attached gelatin layer by dipping and pipetting methods. Depending on macropore size of the scaffold and gelatin concentration, mechanically enhanced scaffolds with improved compressive strength in comparison to uncoated scaffolds could be obtained while preserving the high and interconnected porosity that is required for bone in-growth. Moreover, the scaffolds bioactivity by immersion in simulated body fluid (SBF) was investigated showing that gelatin coating preserves the intrinsic bioactivity of the Bioglass® scaffold. It was also shown that the gelatin layer can be loaded with tetracycline hydrochloride for developing scaffolds with drug delivery capability.

Collagen as Coating Material for 45S5 Bioactive Glass-Based Scaffolds for Bone Tissue Engineering

Highly porous 45S5 bioactive glass-based scaffolds were fabricated by the foam replica technique and coated with collagen by a novel method. After an initial cleaning step of the bioactive glass surface to expose reactive –OH groups, samples were surface functionalized by (3-aminopropyl)triethoxysilane (APTS). Functionalized scaffolds were immersed in a collagen solution, left for gelling at 37 °C, and dried at room temperature. The collagen coating was further stabilized by crosslinking with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysuccinimide (NHS). Applying this coating method, a layer thickness of a few micrometers was obtained without affecting the overall scaffold macroporosity. In addition, values of compressive strength were enhanced by a factor of five, increasing from 0.04 ± 0.02 MPa for uncoated scaffolds to 0.18 ± 0.03 MPa for crosslinked collagen-coated scaffolds. The composite material developed in this study exhibited positive cell (MG-63) viability as well as suitable cell attachment and proliferation on the surface. The combination of bioactivity, mechanical competence, and cellular response makes this novel scaffold system attractive for bone tissue engineering.

Bioactive glass combined with zein as composite material for the application in bone tissue engineering

Abstract The present study has focused on the development of new composite scaffolds based on the combination of zein with bioactive glass for the application in bone tissue engineering. Porous polymeric matrices were produced by the salt leaching technique. By incorporating 45S5 bioactive glass particles the lack of bioactivity can be remedied. However, the addition of bioactive glass is influencing the plasticization behavior of the zein matrix during the salt leaching which negatively affects the compression strength as well as the degradation behavior. This paper describes the process during leaching and explains the different behavior of zein with and without the presence of bioactive glass

Mesoporous Bioactive Glass-Based Controlled Release Systems

Following on from the introduction and discussions centred on porous silica drug delivery systems (DDS) in Chapter 4 , this next chapter introduces and highlights the benefits of a related but compositionally extended family of biomaterials—mesoporous bioactive glasses. Rather than just containing silica, these materials include other ions which may have beneficial effects for the properties of the DDS in question or may even have therapeutic effects in their own right. General synthetic considerations for these inorganic systems will be introduced as will the effects the inclusion of non-silica-based ions into the mesoporous glass network has on both the physical properties and microstructure of the product glasses. The drug releasing properties of these systems will also be discussed as will the availability of different product morphologies to assist in achieving the desired in vitro therapeutic response.