Enrica Verne

Chapter 9:Surface Functionalization of Bioactive Glasses: Reactive Groups, Biomolecules and Drugs on Bioactive Surfaces for Smart and Functional Biomaterials

Bioactive glasses are well known for their in vitro and in vivo surface reactivity, able to induce the formation of a mineralized layer on their surface and, in turn, bone tissue integration. This peculiar property can be successfully used to modify their surface with reactive groups, biomolecules and drugs, to induce specific interactions between the bioactive surface and the biological environment, obtaining smart and functional biomaterials. This chapter gives an overview of the most common functionalization strategies.

A novel bioactive and antibacterial composite bone cement containing a single inorganic phase

Introduction: Anterior cruciate ligament (ACL) injuries are very common; in Germany incidence of ACL ruptures is estimated at 32 per 100 000 in the general population and in the sports community this rate more than doubles. Current gold standard for anterior cruciate lig- ament repair is reconstruction using an autograft [1]. However, this approach has shown some limitations. A new method has been her- alded by the Knee Team at the Bern University Hospital (Inselspital) and the Sonnenhof clinic called Dynamic Intraligamentary Stabilization (DIS), which keeps ACL remnants in place in order to promote biologi- cal healing and makes use of a dynamic screw system [2]. The aim of this study was to investigate the cytocompatibility of collagen patches in combination with DIS to support regeneration of the ACL. The spe- cific hypothesis we tested was whether MSCs would differentiate towards TCs in co-culture. nMaterials and methods: Primary Tenocytes (TCs) and human bone marrow derived mesenchymal stem cells (MSCs) were harvested from ACL removed during knee prothesis or from bone marrow aspirations (Ethical Permit 187/10). Cells were seeded on two types of three dimensional carriers currently approved for cartilage repair, Novocart (NC, B. Brown) and Chondro-Gide (CG, Geistlich). These scaffolds comprise collagen structures with interconnecting pores originally developed for seeding of chondrocytes in the case of CG. ~40k cells were seeded on punched zylindrical cores of 8 mm in O and cultured on CG or NC patches for up to 7 days. The cells were either cultured as TC only, MSC only or co-cultured in a 1:1 mix on the scaffolds and on both sides of culture inserts (PET, high density pore O 0.4 mm, BD, Fal- con) with cell-cell contact. We monitored DNA content, GAG and HOP-content, tracked the cells using DIL and DIO fluorescent dyes (Molecular Probes, Life technologies) and confocal laser scanning and SEM microscopy as well as RT-PCR of tenocyte specific markers (i.e. col 1 and 3, TNC, TNMD, SCXA&B, and markers of dedifferentiation ACAN, col2, MMP3, MMP13). Finally, H&E stain was interpreted on cryosections and SEM images of cells on the scaffold were taken. Results: ThecLSMimagesshowedcellproliferationoverthe7dayson both matrices, however, on CG there were much fewer MSCs attached than on NC. SEM images showed a roundish chondrocyte-like pheno- type of cells on CG whereas on NC the phenotype was more teno- cyte-like (Fig. 1). Gene expression of both, MSC and TC seem to confirm a more favorable environment in 3D for both patches rather than monolayer control.Hydroxyapatite (HA), [Ca10(PO4)6(OH)2], products are well-known as implantable ceramics for hard tissue reconstitution. HA is based on calcium phosphate, and its chemical composition and crystal structure are similar to the mineral component of human bones and teeth. The aim of this study was to evaluate the bioactivity of natural HA/hardystonite nanobiocomposites soaked in simulated body fluid (SBF). Novel natural HA/hardystonite nanobiocomposite was fabricated with 0 wt.%, 5 wt.%, 10 wt.%, and 15 wt.% of hardystonite in natural HA using ball mill for 20 minutes. The composite mixture was compacted in cylinder steel mould with 10 mm diameter under 20 MPa pressure. The discs pressed were soaked in cell laboratory, Falcon, containing SBF solution by 21 days. Samples weight loss and solution Ph were measured after 1, 3, 7, 14 and 21 days .Also, SBF solution Ca ion concentration were measured for solutions SBF after 21 day. X-ray diffraction (XRD), scanning electron microscopy (SEM) and EDS were performed to characterize the nanocomposite samples. ICP technique was utilized to evaluate Ca ion concentration released in solution SBF. Maximum bioactivity occurred in the sample containing 10 wt.% of hardystonite, which was probably due to two reasons; first, the maximum amorphous glassy phase amount, and second, the minimum crystallinity of nanobiocomposite.