Post-processing of titanium 3D printouts with radio frequency plasma

Additive manufacturing is a technology of great interest for biomedical engineering and medicine since it enables to mimic natural structures. The 3D printouts require post-processing to ensure desired surface properties and interaction with living matter. The presented research focuses on novel approaches involving plasma treatment of Ti6Al4V scaffolds obtained by Direct Metal Printing. Solid samples and scaffolds of two various geometries were treated in atmospheres of pure argon, argon and oxygen or pure oxygen. The effect of post-processing was evaluated with scanning electron microscopy, measurements of mass, and surface roughness. In all the examined cases the proposed post-processing method reduces the amount of loosely bonded powder particles remaining after printing. The changes of mass before and after the treatment are much lower than in the case of popular wet chemical methods. The character of undergoing post-processing depends on the process atmosphere resulting in physical etching or the combination of physical etching and chemical oxidation. The action of argon or argon/ oxygen plasma reduces mass to the level of only 1% while by use of pure oxygen atmosphere even the slight increase of the overall sample mass is observed. The plasma etching was successfully introduced for the treatment of titanium 3D printouts to minimize the detachment of powder particles. That method not only is much softer than chemical etching but it can also lead to specific surface structurization that may be beneficial regarding medical applications of such printouts

Assessment of the properties of HAp micropowders after ion exchange process in silver nitrate solution

Bioceramic materials, such as hydroxyapatite (HAp), are characterized by high biocompatibility in the presence of tissues and body fluids without causing toxic or allergic reactions. Hydroxyapatite, due to its similarity to structures found in bones, is used both in the form of powders, e.g. as additives to bone cements, and implants coatings. However, this material is not characterized by antimicrobial properties, therefore attempts are made to improve its properties by introducing additional elements into the hydroxyapatite structure. Thanks to HAp’s high ion-exchange ability, silver can be introduced into its structure. The calcium ions present in the HAp structure can be easily replaced by silver ions to create a material endowed with high biocompatibility and antibacterial properties. The presented study is based on the analysis of the morphology of the modified powders via scanning electron microscopy (SEM), their chemical composition via X-ray energy dispersive spectroscopy (EDS) and chemical structure via X-ray diffraction (XRD) and Raman spectroscopy. The powders obtained through the ion exchange were mixtures of silver phosphates Ag3PO4 and HAp. The highest silver content was found in the sample modified with a 1M concentration of AgNO3 in the aqueous solution. It was also determined that the annealing of the obtained powders under vacuum at 800°C resulted in the formation of metallic silver and a change in the structure of HAp to β-TCP

Changes of structure and properties of PMMA-based bone cements with hydroxyapatite after degradation process

PMMA-based bone cements are commonly used for implant fixation or as bone void fillers. Hydroxyapatite added as a filler to bone cement may positively affect the final properties of the material, in particular its biological properties. In this study, the preparation of poly(methyl methacrylate)-based bone cements with incorporated hydroxyapatite (HAp) is reported. The purpose of this article is to examine the proper-ties of bone cements enriched with HAp filler (the concentration of 3wt% and 6wt%) and reveal the changes in the composites properties (chemical structure, surface morphology and distribution of HAp in the composite matrix, moisture absorption, hardness in Shore D scale) during the long-term incubation in the PBS (phosphate-buffered saline) solution at 37°C. The incubation lasted up to 21 days, but only the period when the changes actually occurred was analysed. The studies have shown that the samples containing HAp absorb more moisture and have a lower hardness. These characteristics vary depending on the concentration of HAp. There is no elution of HAp and ZrO2 from the composite during the incubation. The surface morphology and chemical structure do not change during long-term studies. The obtained bone cements are characterized by high stability in the PBS solution