Effect of Selected Crosslinking and Stabilization Methods on the Properties of Porous Chitosan Composites Dedicated for Medical Applications
Chitosan is one of the most commonly employed natural polymers for biomedical applications. However, in order to obtain stable chitosan biomaterials with appropriate strength properties, it is necessary to subject it to crosslinking or stabilization. Composites based on chitosan and bioglass were prepared using the lyophilization method. In the experimental design, six different methods were used to obtain stable, porous chitosan/bioglass biocomposite materials. This study compared the crosslinking/stabilization of chitosan/bioglass composites with ethanol, thermal dehydration, sodium tripolyphosphate, vanillin, genipin, and sodium β-glycerophosphate. The physicochemical, mechanical, and biological properties of the obtained materials were compared. The results showed that all the selected crosslinking methods allow the production of stable, non-cytotoxic porous composites of chitosan/bioglass. The composite with genipin stood out with the best of the compared properties, taking into account biological and mechanical characteristics. The composite stabilized with ethanol is distinct in terms of its thermal properties and swelling stability, and it also promotes cell proliferation. Regarding the specific surface area, the highest value exposes the composite stabilized by the thermal dehydration method.
The Preliminary Assessment of New Biomaterials Necessitates a Comparison of Direct and Indirect Cytotoxicity Methodological Approaches
Background: Cytotoxicity testing is a primary method to establish the safety of biomaterials, e.g., biocomposites. Biomaterials involve a wide range of medical materials, which are usually solid materials and are used in bone regeneration, cardiology, or dermatology. Current advancements in science and technology provide several standard cytotoxicity testing methods that are sufficiently sensitive to detect various levels of cellular toxicity, i.e., from low to high. The aim was to compare the direct and indirect methodology described in the ISO guidelines UNE-EN ISO 10993-5:2009 Part 5. Methods: Cell proliferation was measured using WST-1 assay, and cytotoxicity was measured using LDH test kit. Results: The results indicate that the molecular surface of biomaterials have impact on the cytotoxicity and proliferation profile. Based on these results, we confirm that the indirect method does not provide a clear picture of the cell condition after the exposure to the surface, and moreover, cannot provide complete results about the effects of the material. Conclusions: Comparison of both methods shows that it is pivotal to investigate biomaterials at the very early stages using both indirect and direct methods to access the influence of the released toxins and surface of the material on the cell condition.
Porous chitosan/ZnO-doped bioglass composites as carriers of
In this study, we aimed to assess whether the composite of chitosan/ZnO-doped bioglass can be applied as a suitable scaffold for the incorporation of bioactive peptides. Material of a porous composite with 1:1 ratio of bioglass:polymer was produced and used as a matrix for delivery of peptide. A peptide with the PEPTIDES sequence (Pro-Glu-Pro-Thr-Ile-Asp-Glu-Ser) was chosen as a model peptide. Microstructure and pore sizes of chitosan/ZnO-doped bioglass were assessed. Open porosity and pore sizes of the composite were suitable for enabling the migration of cells and ensuring the easy delivery of nutrients within the implant. In addition, composite showed bioactivity and bactericidal activity against Staphylococcus aureus and Pseudomonas aeruginosa strains. Peptide alone did not have any cytotoxic activity on human fibroblasts and keratinocytes. Also it did not show any antibacterial properties and did not cause hemolysis of red blood cells. The peptide incorporated in composite showed a rapid release in the kinetics profile. The obtained results indicate that there is the technological possibility to incorporate peptides in chitosan/ ZnO-doped bioglass scaffolds. Such biomaterials have potential application in bone tissue engineering.
Proteins, peptides and peptidomimetics as active agents in implant
The recent impact of implants on improving the human life quality has been enormous. During the past two decades we witnessed major advancements in both material and structural development of implants. They were driven mainly by the increasing patients’ demand and the need to address the major issues that come along with the initially underestimated complexity of the bone-implant interface.While both, the materials and design of implants reached a certain, balanced state, recent years brought a shift in focus towards the bone-implant interface as theweakest link in the increasing implant long-term usability. As a result, several approacheswere developed. They aimed at influencing and enhancing the implant osseointegration and its proper behavior when under load and stress.With this review,we would like to discuss the recent advancements in the field of implant surface modifications, emphasizing the importance of chemical methods, focusing on proteins, peptides and peptidomimetics as promising agents for titanium surface coatings.