Karolina Jurczyk

Nanostructured Titanium-10 wt% 45S5 Bioglass-Ag Composite Foams for Medical Applications

The article presents an investigation on the effectiveness of nanostructured titanium-10 wt% 45S5 Bioglass-1 wt% Ag composite foams as a novel class of antibacterial materials for medical applications. The Ti-based composite foams were prepared by the combination of mechanical alloying and a “space-holder” sintering process. In the first step, the Ti-10 wt% 45S5 Bioglass-1 wt% Ag powder synthesized by mechanical alloying and annealing mixed with 1.0 mm diameter of saccharose crystals was finally compacted in the form of pellets. In the next step, the saccharose crystals were dissolved in water, leaving open spaces surrounded by metallic-bioceramic scaffold. The sintering of the scaffold leads to foam formation. It was found that 1:1 Ti-10 wt% 45S5 Bioglass-1 wt% Ag/sugar ratio leads to porosities of about 70% with pore diameter of about 0.3–1.1 mm. The microstructure, corrosion resistance in Ringer’s solution of the produced foams were investigated. The value of the compression strength for the Ti-10 wt% 45S5 Bioglass-1 wt% Ag foam with 70% porosity was 1.5 MPa and the Young’s modulus was 34 MPa. Silver modified Ti-10 wt% 45S5 Bioglass composites possess excellent antibacterial activities against Staphylococcus aureus. Porous Ti-10 wt% 45S5 Bioglass-1 wt% foam could be a possible candidate for medical implants applications.

Mechanical and corrosion properties of titanium ― hydroxyapatite nanocomposites

In the present work Ti-HA (3, 10, 20, 50 vol%) nanocomposites were produced by the combination of mechanical alloying and powder metallurgical process. The experimental results show, that Ti-HA nanocomposites have better mechanical and corrosion properties in comparison with microcrystalline titanium. For example: Vickers microhardness of Ti-10 vol% HA nanocomposite is 1500 HV0.2 (pure Ti metal – 250 HV0.2) and corrosion resistance in Ringer solution is Ic = 1.19 • 10-7 A/cm2, Ec = -0.41 V for Ti-10 vol% HA and Ic = 1.31 • 10-5 A/cm2, Ec = -0.36 V for Ti. In conclusion, titanium – ceramics nanocomposite are suitable for hard tissue replacement from the point of view of both mechanical and corrosion properties.

Antibacterial activity of nanostructured Ti–45S5 bioglass–Ag composite against Streptococcus mutans and Staphylococcus aureus

Mechanical alloying and annealing at 1150 °C for 2 h under an argon atmosphere were used to prepare Ti–45S5 bioglass nanocomposites. Ti–45S5 bioglass material was chemically modified by silver. The antibacterial activity of Ti–10% 45S5 bioglass nanocomposite containing silver against Streptococcus mutans and Staphylococcus aureus was studied. Nanocomposites were characterized by X-ray diffraction, scanning electron microscopy equipped with an electron energy dispersive spectrometer and transmission electron microscopy to evaluate phase composition, crystal structure and grain size. In vitro bacterial adhesion study indicated a significantly reduced number of Streptococcus mutans and Staphylococcus aureus on the bulk nanostructured Ti–45S5 bioglass–Ag plate surface in comparison to that on microcrystalline Ti plate surface. Nanostructured Ti-based biomaterials can be considered to be the future generation of dental implants.

In vitro biocompatibility of titanium after plasma surface alloying with boron.

Recently, the effect of different sizes of precursor powders during surface plasma alloying modification on the properties of titanium surface was studied. In this work we show in vitro test results of the titanium (α-Ti) after plasma surface alloying with boron (B). Ti-B nanopowders with 2 and 10wt% B were deposited onto microcrystalline Ti substrate. The in vitro cytocompatibility of these biomaterials was evaluated and compared with a conventional microcrystalline Ti. During the studies, established cell line of human gingival fibroblasts and osteoblasts were cultured in the presence of tested materials, and its survival rate and proliferation activity were examined. For this purpose, MTT assay, flow cytometric and fluorescent microscopic evaluation were made. Biocompatibility tests carried out indicate that the Ti after plasma surface alloying with B could be a possible candidate for dental implants and other medicinal applications. Plasma alloying is a promising method for improving the properties of titanium, thus increasing the field of its applications.

Development of β Type Ti23Mo-45S5 Bioglass Nanocomposites for Dental Applications

Titanium β-type alloys attract attention as biomaterials for dental applications. The aim of this work was the synthesis of nanostructured β type Ti23Mo-x wt % 45S5 Bioglass (x = 0, 3 and 10) composites by mechanical alloying and powder metallurgy methods and their characterization. The crystallization of the amorphous material upon annealing led to the formation of a nanostructured β type Ti23Mo alloy with a grain size of approximately 40 nm. With the increase of the 45S5 Bioglass contents in Ti23Mo, nanocomposite increase of the α-phase is noticeable. The electrochemical treatment in phosphoric acid electrolyte resulted in a porous surface, followed by bioactive ceramic Ca-P deposition. Corrosion resistance potentiodynamic testing in Ringer solution at 37 °C showed a positive effect of porosity and Ca-P deposition on nanostructured Ti23Mo 3 wt % 45S5 Bioglass nanocomposite. The contact angles of glycerol on the nanostructured Ti23Mo alloy were determined and show visible decrease for bulk Ti23Mo 3 wt % 45S5 Bioglass and etched Ti23Mo 3 wt % 45S5 Bioglass nanocomposites. In vitro tests culture of normal human osteoblast cells showed very good cell proliferation, colonization, and multilayering. The present study demonstrated that porous Ti23Mo 3 wt % 45S5 Bioglass nanocomposite is a promising biomaterial for bone tissue engineering.

Electrochemical Formation and Corrosion Properties of Porous TiOx Biomaterials

Formation of porous TiOx layers on Ti during electrochemical etching in H3PO4, CH3COOH electrolytes modified by HF and NH4F was described. The anodization resulted in porous TiOx formation, useful in tissue growth and bone bonding. The pore dimensions increased due to the increase of HF or NH4F content in H3PO4 electrolyte. During anodization at 10 V for 30 min, when the HF content increased from 0.5 to 10%, the pore diameter increased from 30 nm up to 8 m, respectively. Anodization in CH3COOH electrolyte resulted in non-uniform etching with flat hexagonal islands with nanopores inside surrounded by micropores. Corrosion properties of the etched samples were investigated in Ringer’s solution at 37oC and were compared to the unetched sample. The best corrosion resistance showed the samples etched at 10 V for 30 min in 1M H3PO4 + 2% HF and 1M H3PO4 + 10% NH4F, what can be attributed to thick oxide layer. We find, that porous sample presented good biocompatibility with human osteoblasts.

Nanoscale Nickel-Free Austenitic Stainless Steel

In this work Ni-free austenitic stainless steels with nanostructure were synthesized by mechanical alloying (MA), heat treatment and nitrogenation of elemental Fe, Cr, Mn and Mo microcrystalline powders. The phase transformation from ferritic to austenitic was confirmed by XRD analysis. The mechanical and corrosion properties of the produced biomaterials were investigated. Additionally, the biocompatibility of nickel-free austenitic stainless steels with nanostructure and microcrystalline 316L steel, were analyzed studying the behaviour of Normal Human Osteoblast (NHOst) cells from Cambrex (CC-2538). An enhancement of the properties due to the nanoscale structures in the bulk consolidated materials was observed.

Osteoblast Behaviour on Nanostructured Ti-Bioceramic Composites

Ti and Ti-based alloys are preferred materials in the production of implants in both medical and dental applications. One of the methods that allow the change of biological properties of Ti alloys is the modification of their chemical composition and microstructure. In this study, new biocompatible, nanostructured Ti-x vol% SiO2, Ti-x vol% 45S5 Bioglass, and Ti-x vol% HAp (x=0, 3, 10) materials have been developed, manufactured and studied in terms of their biocompatibility. These materials give the possibility of controlling in detail the grain structure and the composition of the alloy and, consequently, the mechanical and biocompatibility performances. Our results of in vitro studies show that these bionanocomposites have excellent biocompatibility and could integrate with bone. After 1st day of incubation cells show good adhesion to the surface of studied samples in the form of filopodia. After 5 days of incubation, the typical monolayer was observed. With regard to microcrystalline Ti it could help to obtain better dental implants with better mechanical properties and corrosion resistance.

Molecular analysis of biocompatibility of anodized titanium with deposited silver nanodendrites

Titanium (>99.6% purity) and its anodically oxidized modifications, with and without deposited silver nanodendrites regarding its biocompatibility were evaluated. In human gingival fibroblasts and osteoblast cell lines grown on tested samples, the level of expression of genes encoding αV (ITGAV) and β1 (ITGB1) integrin subunits also genes encoding focal adhesion (FAK) and extracellular-signal regulated (ERK) kinases was assessed. For this purpose, the qualitative and quantitative PCR technique was used. The expression of studied genes was dependent on the origin of cell lines and the type of evaluated material. The high expression of PBGD and ITGAV genes in fibroblasts grown on the surface of anodically modified titanium with deposited silver nanodendrites indicates potentially high biocompatibility of these samples for soft tissue cells. The high expression of the ITGB1 and ERK1 genes and the enhanced expression of the FAK gene in osteoblasts cells grown on the tested material was also observed. Summarizing, the nanocrystalline Ti modified with silver deposits showed higher biocompatibility in comparison with the conventional pure Ti samples.