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One major challenge when developing new biomaterials is translating in vitro testing to in vivo models. We have recently shown that a single formulation of a bone tissue adhesive, phosphoserine modified cement (PMC), is safe and resorbable in vivo. Herein, we screened many new adhesive formulations, for cytocompatibility and bioactive ion release, with three cell lines: MDPC23 odontoblasts, MC3T3 preosteoblasts, and L929 fibroblasts. Most formulations were cytocompatible by indirect contact testing (ISO 10993-12). Formulations with larger amounts of phosphoserine (>50%) had delayed setting times, greater ion release, and cytotoxicity in vitro. The trends in ion release from the adhesive that were cured for 24 h (standard for in vitro) were similar to release from the adhesives cured only for 5–10 min (standard for in vivo), suggesting that we may be able to predict the material behavior in vivo, using in vitro methods. Adhesives containing calcium phosphate and silicate were both cytocompatible for seven days in direct contact with cell monolayers, and ion release increased the alkaline phosphatase (ALP) activity in odontoblasts, but not pre-osteoblasts. This is the first study evaluating how PMC formulation affects osteogenic cell differentiation (ALP), cytocompatibility, and ion release, using in situ curing conditions similar to conditions in vivo.

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Recent medical applications have specific requirements on materials and Nitinol can fulfil them due to its exceptional characteristics, which can be further improved by modifications of the material surface. Various surface nanostructuring methods are utilized to enhance characteristics of oxide layer, which naturally develops on the Nitinol surface, leading to improved biocompatibility and corrosion resistance. This review is focused on studies investigating the behavior of various cell types on surface nanotubes and ordered nanopores prepared by anodic oxidation, a technique allowing fabrication of nanostructures with defined parameters. Results showed that certain dimensions of nanotubes positively affect adhesion and viability of osteoblasts and endothelial cells on the surface, contrary to negative effect on smooth muscle cells, both required by the medical applications. Furthermore, increased antibacterial effect correlated with the nanostructure topography and release rates of Ni ions.

As the consumption of implants increases, so do the requirements for individual types of implants, for example, improved biocompatibility or longevity. Therefore, the nano-modification of the titanium surface is often chosen. The aim was to characterize the modified surface with a focus on medical applications. The titanium surface was modified by the anodic oxidation method to form nanotubes. Subsequently, the material was characterized and analyzed for medical applications-surface morphology, surface wettability, chemical composition, and release of ions into biological fluids. A human gingival fibroblasts (HGFb) cell line was used in the viability study. A homogeneous layer of nanotubes of defined dimensions was formed on the titanium surface, ensuring the material's biocompatibility-the preparation conditions influence the resulting properties of the nanostructured surface. Nanostructured titanium exhibited more suitable characteristics (e.g., wettability, roughness, ion release) for biological applications than compared to pure titanium. It was possible to understand the behavior of the modified layer on the titanium surface and its effect on cell behavior. Another contribution of this work is the combination of material characterization (ion release) with the study of cytocompatibility (direct contact of cells with metals).