Anodization
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Nowadays, titanium and its alloys are the most commonly used implantable materials. The surface topography and chemistry of titanium-based implants are responsible for osseointegration. One of the methods to improve biocompatibility of Ti implants is a modification with sodium hydroxide (NaOH) or 3-aminopropyltriethoxysilane (APTES). In the present study, anodic titanium dioxide (ATO) layers were electrochemically fabricated, and then immersed in a NaOH solution or in NaOH and APTES solutions. The functionalized samples were characterized by using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). All samples were examined as drug delivery systems and scaffolds for cell culturing. Based on the parameters of the fitted desorption-desorption-diffusion (DDD) model parameters, it was concluded that the modification with NaOH increased the amount of released ibuprofen and inhibited the release process. Osteoblast-like cell line (SAOS-2) was used to investigate the cell response on the non-modified and modified ATO samples. The MTS test and immunofluorescent staining were carried out to examine cell adhesion and proliferation. The data showed that the modification of nanoporous TiO2 layers with small molecules such as APTES enhanced metabolic activity of adhered cells compared with the non-modified and NaOH-modified TiO2 layers. In addition, the cells had a polygonal-like morphology with distinct projecting actin filaments and were well dispersed over the whole analyzed surface.
- MeSH
- buněčná adheze účinky léků MeSH
- buněčné linie MeSH
- elektrochemické techniky MeSH
- elektrody MeSH
- hydroxid sodný chemie MeSH
- lékové transportní systémy * MeSH
- lidé MeSH
- osteoblasty cytologie účinky léků MeSH
- poréznost MeSH
- povrchové vlastnosti MeSH
- proliferace buněk účinky léků MeSH
- propylaminy chemie MeSH
- silany chemie MeSH
- titan chemie MeSH
- velikost částic MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Stripping voltammetric determination of purine bases in the presence of copper ions at mercury, amalgam, or carbon-based electrodes has recently been utilized in analysis of DNA or synthetic oligodeoxynucleotides (ODNs). Here we report on copper-enhanced label-free anodic stripping detection of guanine and adenine bases in acid-hydrolyzed DNA at anodically oxidized boron-doped diamond electrode (AO-BDDE). The AO-BDDE was successfully applied in a three-electrode microcell in which an approximately 50 microL drop of the analyte solution can be efficiently stirred during the accumulation step by streaming of an inert gas. Accelerated mass transport due to the solution motion in the presence of copper resulted in enhancement of the guanine oxidation signal by about 2 orders of magnitude (compared to accumulation of the analyte from still solution not containing copper), allowing an easy detection of approximately 25 fmol of the ODNs. The proposed technique is shown to be suitable for a determination of purine (particularly guanine) content in DNA samples. Applications of the technique in magnetic bead-based DNA assays (such as hybridization with DNA sequences exhibiting asymmetrical distribution of purine/pyrimidine nucleotides between the complementary strands or monitoring of amplification of specific DNA fragments in a duplex polymerase chain reaction) are demonstrated.
- MeSH
- bor chemie MeSH
- diamant chemie MeSH
- DNA-dependentní DNA-polymerasy metabolismus MeSH
- DNA MeSH
- elektrochemie MeSH
- elektrody MeSH
- financování organizované MeSH
- hydrolýza MeSH
- kationty chemie MeSH
- kyseliny chemie MeSH
- měď chemie MeSH
- oligonukleotidy chemie MeSH
- oxidace-redukce MeSH
- puriny chemie MeSH
- sekvence nukleotidů MeSH
The present study reports on a comprehensive investigation of mechanisms of in vitro cytotoxicity of high aspect ratio (HAR) bundles formed from anodic TiO2 nanotube (TNT) layers. Comparative cytotoxicity studies were performed using two types of HAR TNTs (diameter of ∼110 nm), differing in initial thickness of the nanotubular layer (∼35 μm for TNTs-1 vs. ∼10 μm for TNTs-2). Using two types of epithelial cell lines (MDA-MB-231, HEK-293), it was found that nanotoxicity is highly cell-type dependent and plausibly associates with higher membrane fluidity and decreased rigidity of cancer cells enabling penetration of TNTs to the cell membrane towards disruption of membrane integrity and reorganization of cytoskeletal network. Upon penetration, TNTs dysregulated redox homeostasis followed by DNA fragmentation and apoptotic/necrotic cell death. Both TNTs exhibited haemolytic activity and rapidly activated polarization of RAW 264.7 macrophages. Throughout the whole study, TNTs-2 possessing a lower aspect ratio manifested significantly higher cytotoxic effects. Taken together, this is the first report comprehensively investigating the mechanisms underlying the nanotoxicity of bundles formed from self-organised 1-D anodic TNT layers. Except for description of nanotoxicity of industrially-interesting nanomaterials, the delineation of the nanotoxicity paradigm in cancer cells could serve as solid basis for future efforts in rational engineering of TNTs towards selective anticancer nanomedicine.
- MeSH
- apoptóza účinky léků MeSH
- buněčné linie MeSH
- elektrody MeSH
- fragmentace DNA MeSH
- lidé MeSH
- myši MeSH
- nanotrubičky toxicita MeSH
- nekróza chemicky indukované MeSH
- peroxidace lipidů MeSH
- reaktivní formy kyslíku metabolismus MeSH
- titan toxicita MeSH
- viabilita buněk účinky léků MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
This work describes the preparation of transparent TiO₂ nanotube (TNT) arrays on fluorine-doped tin oxide (FTO) substrates. An optimized electrolyte composition (0.2 mol dm-3NH₄F and 4 mol dm-3H₂O in ethylene glycol) was used for the anodization of Ti films with different thicknesses (from 100 to 1300 nm) sputtered on the FTO glass substrates. For Ti thicknesses 600 nm and higher, anodization resulted in the formation of TNT arrays with an outer nanotube diameter around 180 nm and a wall thickness around 45 nm, while for anodized Ti thicknesses of 100 nm, the produced nanotubes were not well defined. The transmittance in the visible region (λ = 500 nm) varied from 90% for the thinnest TNT array to 65% for the thickest TNT array. For the fabrication of transparent TNT arrays by anodization, the optimal Ti thickness on FTO was around 1000 nm. Such fabricated TNT arrays with a length of 2500 nm exhibit stable photocurrent densities in aqueous electrolytes (~300 µA cm-2at potential 0.5 V vs. Ag/AgCl). The stability of the photocurrent response and a sufficient transparency (≥65%) enables the use of transparent TNT arrays in photoelectrochemical applications when the illumination from the support/semiconductor interface is a necessary condition and the transmitted light can be used for another purpose (photocathode or photochemical reaction in the electrolyte).
- MeSH
- elektrody MeSH
- ethylenglykol chemie MeSH
- fluor chemie MeSH
- fluoridy chemie MeSH
- fotochemické procesy MeSH
- kvartérní amoniové sloučeniny chemie MeSH
- nanotechnologie metody MeSH
- nanotrubičky chemie ultrastruktura MeSH
- sloučeniny cínu chemie MeSH
- sluneční energie MeSH
- titan chemie MeSH
- Publikační typ
- časopisecké články MeSH
Hafnium dioxide (HfO2) is attracting attention for bio-related applications due to its good cytocompatibility, high density, and resistance to corrosion and mechanical damage. Here we synthesize two types of hafnium-oxide thin films on substrates via self-organized electrochemical anodization: (1) an array of hierarchically structured nanorods anchored to a thin oxide layer and (2) a microscopically flat oxide film. The nanostructured film is composed of a unique mixture of HfO2, suboxide Hf2O3, and oxide-hydroxide compound HfO2·nH2O whereas the flat film is mainly HfO2. In vitro interaction of the two films with MG-63 osteoblast-like cells and Gram-negative E. coli bacteria is studied for the first time to assess the potential of the films for biomedical application. Both films reveal good cytocompatibility and affinity for proteins, represented by fibronectin and especially albumin, which is absorbed in a nine times larger amount. The morphology and specific surface chemistry of the nanostructured film cause a two-fold enhanced antibacterial effect, better cell attachment, significantly improved proliferation of cells, five-fold rise in the cellular Young's modulus, slightly stronger production of reactive oxygen species, and formation of cell clusters. Compared with the flat film, the nanostructured one features the weakening of AFM-measured adhesion force at the cell/surface interface, probably caused by partially lifting the nanorods from the substrate due to the strong contact with cells. The present findings deepen the understanding of biological processes at the living cell/metal-oxide interface, underlying the role of surface chemistry and the impact of nanostructuring at the nanoscale.
- MeSH
- biokompatibilní materiály farmakologie MeSH
- buněčné linie MeSH
- Escherichia coli účinky léků MeSH
- hafnium * chemie farmakologie MeSH
- lidé MeSH
- nanostruktury chemie terapeutické užití MeSH
- osteoblasty cytologie účinky léků MeSH
- oxidy * chemie farmakologie MeSH
- povrchové vlastnosti MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Úvod a cíl: Oxidické vrstvy na povrchu titanové slitiny mají vliv na odolnost proti korozi a biokompatibilitu. Vynikající kompatibilita mezi tkání, kostí a slitinou titanu je převážně řízena vlastnostmi jeho stabilní povrchové vrstvy složené z oxidu titaničitého. Oxidové vrstvy mohou být připraveny mnoha různými metodami; oxidační proces a jeho podmínky vedou k různým vrstvám: rozdíly jsou v chemickém složení, mechanických vlastnostech, struktuře atd. Odchylka ve struktuře vrstvy může ovlivnit stabilitu, přilnavost nebo biokompatibilitu vrstvy. Anodická oxidace titanových slitin ve vhodném médiu (a za určitého napětí a proudové hustoty) může vytvořit nejen oxidickou vrstvu, ale také strukturu na povrchu oxidické vrstvy. Tato struktura je obvykle charakterizována póry o velikosti od desítek do stovek nanometrů. Strukturovaný povrch radikálně mění interakci mezi povrchem titanu a buňkami, a tím i chování tohoto materiálu uvnitř těla. Chování buněk na strukturovaném povrchu různých slitin titanu není dosud řádně popsáno. Tato experimentální práce povede k lepšímu pochopení těchto strukturovaných oxidových vrstev. Metody: Anodická oxidace byla provedena na vyleštěných vzorcích z Ti6Al4V ELI. Oxidační proces probíhal v elektrolytu 1M H2SO4 s napětím kolem 100 V a proudovou hustotou 50 mA/cm2. Výsledná oxidická vrstva byla hodnocena a dokumentována pomocí řádkovací elektronové mikroskopie (SEM), kterou byla kontrolována tloušťka oxidické vrstvy a povrchová morfologie. Pozorována byla také změna zbarvení a drsnosti povrchové vrstvy po oxidaci související s růstem oxidů. Cytokompatibilita povrchu materiálu je vyjádřena stanovením plochy povrchu, kterou obsadí buňky po třídenní kultivaci. Jedná se o metodu, která je běžně užívána a akreditována Českým institutem pro akreditaci. K pokusu byly užity buňky MG63 a bylo stanoveno procento buňkami kolonizované plochy povrchu. Hodnocení bylo provedeno na leštěných a anodizovaných površích vzorků z Ti6Al4V ELI. Výsledky byly navzájem porovnány. Výsledky: Byly připraveny vzorky s povrchem nanostrukturovaným pomocí anodické oxidace, přičemž struktura povrchu byla tvořena póry o velikostech v řádech desítek až stovek nanometrů. Výsledky pokusů ukázaly větší vůli buněk kolonizovat anodizovaný povrch. Neanodizovaný povrch byl kolonizován v 56,9 %, kdežto anodizovaný byl při stejných podmínkách kolonizován v 63,5 %. Všechny výběrové soubory byly gaussovsky distribuovány. Závěr: Anodickou oxidací byla připravena nanostrukturovaná oxidická vrstva na vzorcích z Ti6Al4V ELI. Cytokompatibilita vytvořené vrstvy byla porovnávána vůči neoxidovaným vzorkům. Bylo ukázáno, že buňky kolonizují větší plochu povrchu vzorku v případě oxidovaných vzorků.
Introduction, aim: The oxide layers on surface of titanium alloy are infl uencing corrosion resistance and biocompatibility. The compatibility between the bony tissue and titanium alloy is prevalently dependent on properties of a stable titanium dioxide layer. These layers can be prepared by various methods. The oxidation process (and its conditions) is resulting in diff erent types of oxide layer: diff erence in chemical composition, mechanical properties, inner structure etc. The deviation inside of the layers structure may infl uence the stability of the layer, its adhesion or biocompatibility. The anodic oxidation of titanium alloys in appropriate electrolyte (under certain conditions) can lead not only to creation of the oxide layer, but to creation of an oxide layer with structured surface. This kind of structure is usually characterized by pores in nanometer scale. The structured surface radically changes the interaction between the titanium alloys surface and cells; and thus influencing its behavior inside a body. The cell interaction with the structured surfaces is not properly described yet. This work aims for better understanding of such structured layers. Methods: The anodic oxidation was carried out on Ti6Al4V ELI polished samples. The oxidation process was realized in 1M H2SO4 electrolyte with the voltage 100 V and current density 50 mA/cm2. The thickness and surface morphology of the resulting oxide layer were evaluated and documented using a scanning electron microscope (SEM). The changes of color and roughness of the surface after the oxidation were observed as well. The cytocompatibility of the materials surface is expressed by a surface area colonized by cells after the three days of cultivation. This method is standardly used and accredited by ČIA. The MG63 cells were used for the experiment and the percentage of colonized surface area was evaluated. The evaluation was done on polished and oxidized Ti6Al4V ELI samples and the results were compared. Result: The structure of samples prepared using the anodic oxidation consisted of pores with size ranging from tens to hundreds of nanometers. The cytocompatibility testings showed that the cells colonized larger area on the oxidized samples. The cells covered 56.9% of the surface area of the polished samples, while 63.5% of the surface area of the anodized samples. Results of all samples exhibited Gaussian distribution. Conclusion: The anodic oxidation lead to a creation of nanostructured oxide layer on Ti6Al4V ELI samples. The cytocompatibility of this layer was compared to polished samples. It was shown that cells are colonizing the larger surface area on the oxidized samples.
- Klíčová slova
- oxidická vrstva, cytokompatibilita, MG63, anodická oxidace,
- MeSH
- biokompatibilní materiály * MeSH
- buňky MeSH
- lidé MeSH
- titan MeSH
- výzkum MeSH
- Check Tag
- lidé MeSH
This work aims to describe the effect of the surface modification of TiO2 nanotube (TNT) layers on Ti-6Al-4V (TiAlV) alloy by ultrathin TiO2 coatings prepared via Atomic Layer Deposition (ALD) on the growth of MG-63 osteoblastic cells. The TNT layers with two distinctly different inner diameters, namely ∼15 nm and ∼50 nm, were prepared via anodic oxidation of the TiAlV alloy. Flat, i.e., non-anodized, TiAlV alloy foils were used as reference substrates. Additionally, a part of the TNT layers and alloy foils was coated with ultrathin coatings of TiO2 by ALD. The number of TiO2 ALD cycles used was 1 and 5 leading to a nominal TiO2 thickness of ∼0.055 and ∼0.3 nm, respectively. The ultrathin TiO2 coating by ALD enabled to optimize the surface hydrophilicity for optimal cell growth. In addition, coatings shaded impurities of V- and F-based species (stemming from the alloy and the anodization electrolyte) that affect the biocompatibility of the tested materials while preserving the original structure and morphology. The evaluation of the biocompatibility before and after TiO2 ALD coating on TiAlV flat surfaces and TNT layers was carried out using MG-63 osteoblastic cells and compared after incubation for up to 96 h. The cell growth, adhesion, and proliferation of the MG-63 on TiAlV foils and TNT layers showed significant enhancement after the surface modification by TiO2 ALD.
- Publikační typ
- časopisecké články MeSH
In this work, we report for the first time on the use of melt spun glass-forming alloys - Ti75Zr10Si15 (TZS) and Ti60Zr10Si15Nb15 (TZSN) - as substrates for the growth of anodic oxide nanotube layers. Upon their anodization in ethylene glycol based electrolytes, highly ordered nanotube layers were achieved. In comparison to TiO2 nanotube layers grown on Ti foils, under the same conditions for reference, smaller diameter nanotubes (~116nm for TZS and ~90nm for TZSN) and shorter nanotubes (~11.5μm and ~6.5μm for TZS and TZSN, respectively) were obtained for both amorphous alloys. Furthermore, TEM and STEM studies, coupled with EDX analysis, revealed a double-wall structure of the as-grown amorphous oxide nanotubes with Ti species being enriched in the inner wall, and Si species in the outer wall, whereby Zr and Nb species were homogeneously distributed.
