Daniela Ionita

Changing bioperformance of TiO2 amorphous nanotubes as an effect of inducing crystallinity

Controlled-diameter TiO(2) nanotubes were obtained by electrochemical anodizing of two different substrates (Ti and Ti6Al7Nb) in an aqueous electrolyte. As-formed TiO(2) nanotubes are amorphous and by subjecting to thermal treatments, the structure becomes crystalline. An optimal thermal treatment with a specific anatase/rutile ratio was chosen, determined from X-ray diffraction (XRD). The electrochemical behaviour of annealed and as-formed samples was followed with Tafel plots and Electrochemical impedance spectroscopy (EIS), while surface analysis involved scanning electron microscopy (SEM) and contact angle measurements (CA). Annealed samples have a more hydrophilic character than as-formed as well as a better stability in bioliquids. Such behaviour of annealed samples is connected with a better biocompatibility expressed in terms of cell morphology and gene expression of bone specific markers obtained from Reverse Transcription Polymerase Chain Reaction (RT-PCR).

Antimicrobial activity of the surface coatings on TiAlZr implant biomaterial

This study is devoted to antimicrobial activity of new surface coatings on TiAlZr. Ti alloys such as TiAlZr are used as implant biomaterials, but, despite the good behavior of such alloys in simulated conditions, bacterial infections appear after the introduction of an implant into the body. The infections are typically caused by the adherence and colonization of bacteria on the surfaces of the implants. The study presents preparation and surface morphology characterization of coatings obtained via anodizing, as well as biomimetic coatings with hydroxyapatite and silver ions with and without antibiotic. The percentage inhibition of Escherichia coli bacteria growth was evaluated for each of the studied coating, and a Trojan-horse model of silver nanoparticles (nAg) antibacterial activity at interface was proposed. Such coatings could be more important taking into account that antibacterial treatments with antibiotics are becoming less effective due to their intensive use.

Present and Future Trends in TiO2 Nanotubes Elaboration, Characterization and Potential Applications

The paper is focused on TiO2 nanotubes elaboration, characterization and potential applications, starting from the idea that monitoring anodizing conditions is a way to obtain nanotubes with various dimensions and various potential applications related to the change of hydrophilic – hydrophobic balance, biocompatibility, nano-porosity, stability, etc. Such properties are important for the use of Ti as biomaterial, as self–cleaning, solar energy conversion, controllable wettability, photocatalysis, etc. The electrochemical behaviour of the nanotubes was monitoring by Tafel plots and open circuit potential determinations, and was discussed in connection with surface features evaluated from scanning electron microscopy, atomic force microscopy and contact angle measurements.

In vitro hemocompatibility and corrosion behavior of new Zr-binary alloys in whole human blood

AbstractThe aim of this study is to evaluate the accuracy of three binary alloys’ composition, and their biocompatibility. Depending on the intended use of the medical devices made from these materials, dynamic or static tests should be performed. We have chosen static tests as we thought they may be used as knee or hip replacement, and not as cardiac valves.Three binary alloys ( Zr10Nb, Zr2.5Nb and Zr12Ta) were obtained from high purity powders (>99.9%), using an induction furnace first, and an electric arc furnace for a perfect homogenization. Their final composition was verified with a XRF analyzer-INNOV-X.Hemolysis tests can determine the degree of red blood cells lysis and the release of hemoglobin. The released hemoglobin quantity was extremely small, under 2%, in all cases, and the coagulation tests showed no risk for thrombosis. The electrochemical behavior was also studied in biological fluid, human female serum, and showed a low corrosion rate.The obtained alloys do not cause hemolysis, so they are hemocompatible with all blood types.

Activity of vancomycin release from bioinspired coatings of hydroxyapatite or TiO2 nanotubes

Herein we investigate the efficiency of various biomimetic coatings for localized drug delivery, using vancomycin as key therapeutic drug, which is a widely used antibiotic for the treatment of strong infections caused by positive Gram bacteria. We evaluate classical hydroxyapatite and biomimetic hydroxyapatite-collagen coatings obtained by electrochemical deposition as well as TiO2 nanotubes arrays obtained by electrochemical anodization. Surface morphology, compositional and structural data confirm the incorporation of vancomycin into the layers and drug release profiles for vancomycin evaluate their release ability. Namely, hydroxyapatite coatings lead to a ≈92% vancomycin release after 30h and hydroxyapatite-collagen to 85%, while the TiO2 nanotubes layers lead to 78% release. The antibacterial effect of such drug loaded coatings is evaluated against S. aureus (Gram-positive bacteria). Our study shows that the vancomycin incorporated hydroxyapatite coatings lead to a faster release, while the nanotubular coatings may lead to longer time release and additionally both types of coatings ensure a good antibacterial inhibition.

Influence of Doping Ions on the Antibacterial Activity of Biomimetic Coating on CoCrMo Alloy

In this study biomimetic fluoridated phosphate doped hydrophilic coatings with various ions on CoCrMo alloy were prepared by electrodeposition. Cu and Zn ions were chosen for doping because of their well known antibacterial activity. The structures of the coatings were identified using Fourier-transform Infrared (FTIR) analysis. X-ray Diffraction (XRD) analysis was performed to evaluate crystallite dimensions of the specimen surface. The contact angle was measured in order to establish the hydrophilic/hydrophobic balance and to compute surface energy. All studied samples have a hydrophilic character which is weaken after doping. The time evolution of ions releasing from the coatings was evaluated with an inductively plasma mass spectrometer after immersion in saline phosphate. The hemolytic experiments indicate that except the fluoridated coatings doped with Zn which is slightly hemolytic, all other samples are non hemolytic. The test for antibacterial activity for Staphylococcus aureus and Pseudomonas aeruginosa indicated that the fluoridated biomimetic coating doped with various positive ions increases bacterial growth inhibition level significantly. Fluoridated phosphate coating doped with Cu has best antibacterial activity.

Microstructure, surface characterization and long-term stability of new quaternary Ti-Zr-Ta-Ag alloy for implant use

The novel Ti-20Zr-5Ta-2Ag alloy was characterised concerning its microstructure, morphology, mechanical properties, its passive film composition and thickness, its long-term electrochemical stability, corrosion resistance, ion release rate in Ringer solution of acid, neutral and alkaline pH values and antibacterial activity. The new alloy has a crystalline α microstructure (by XRD). Long-term XPS and SEM analyses show the thickening of the passive film and the deposition of hydroxyapatite in neutral and alkaline Ringer solution. The values of the electrochemical parameters confirm the over time stability of the new alloy passive film. All corrosion parameters have very favourable values in time which attest a high resistance to corrosion. Impedance spectra evinced a bi-layered passive film formed by the barrier, insulating layer and the porous layer. The monitoring of the open circuit potentials indicated the stability of the protective layers and their thickening in time. The new alloy releases (by ICP-MS measurements) very low quantities of Ti, Zr, Ag ions and no Ta ions. The new alloy exhibits a low antibacterial activity.

Periodontal materials and cell biology for guided tissue and bone regeneration

The present review is intended to find links between periodontal materials of the dentomaxillary apparatus and cell biology at the beginning of a century fraught with various forms of periodontal diseases and needing new treatment strategies. The manuscript has two different parts. The first describes the anatomy of tooth supporting structures, as well as related pathologies. The second part is related to cell and molecular biology in the context of periodontal regeneration.

Biomimetic Hybrid Inorganic/Organic Coatings in the Increasing of the Integration Capacity of TiAlVZr Bioalloy

This paper will address key issues related to the synthesis, characterization and utilization of inorganic/organic hybrid coatings on TiAlVZr bioalloy to control adsorption at interface and the integration capacity of the implant. To enhance the integration capacity function of the biomaterial is necessary to control the composition and structure via the use of hybrid materials consisting of organic and inorganic biomimetic phases [1,2]. Such composite coatings mimic the structure of natural materials of tissues, in our case hydroxyapatite (HA) by association of bovine serum albumin (BSA) with calcium phosphates matrices. Calcium phosphate coating have been deposited on metal substrates by electrochemical method.

BSA/HA Coating on Titanium Alloy for Direct Bond Formation

A biomimetic bovine serum albumin protein/hydroxyapatite coating was prepared by electrochemically co-precipitation on TiAlZr surface. Coating prepared in the presence and in absence of BSA were characterized by Scanning electron microscopy (SEM), Fourier Transformat Infrared microscopy (FTIR), and contact angle measurements. The calcium ion release content was determined using the inductively coupled plasma spectrophotometer (ICP-MS). The advantages of this chip and convenient electrochemical procedure of bioactivation is discussed over the commonly used procedures which prepared phosphate coatings modulate their properties without imitation of the mode in which hydroxyapatite bone crystals are formed in the body.