Bleaching effectiveness and cytotoxicity of new experimental formulation of niobium-based bleaching gel.

OBJECTIVES: The development of new bleaching agents with minimum concentration of hydrogen peroxide (HP), without adverse effects, and with bleaching effectiveness, has great clinical relevance. The aim of this study was to evaluate the bleaching efficacy and cytotoxicity of a new niobium-based bleaching gel, compared to already available HP-based gels. MATERIALS AND METHODS: For the bleaching efficacy analysis, 40 bovine incisors were randomly divided into 4 groups according to the established bleaching protocol: control, untreated; 35HP, 35% HP bleaching gel; 6HP, 6% HP bleaching gel; NbHP, niobium gel associated with 3% HP gel. The color variation was measured in a spectrophotometer and the values of ΔL, Δa, Δb, and ΔE obtained. For the cell viability assay by MTT, MC3T3 cells were exposed to bleaching gel extracts (1:500, 1:250, 1:125 dilutions; immediately and 24 h). Statistical tests were performed (P < 0.05). RESULTS: The color alteration for all bleaching gels was significant compared to control (P < 0.05), but the NbHP gel showed a significant ΔE than other gels, with expressive color alteration at 14 days (P < 0.05). The 35HP showed high cytotoxicity regarding control and the most groups in all periods and extracts analyzed (P < 0.05), while the NbHP showed greater cell viability than control in the immediate period, dilution of the 1:500 and superior to 6HP in the most extracts at 24 h. CONCLUSION: The new experimental niobium-based gel has bleaching efficacy similar to that of gels with a high concentration of HP, and it has high cytocompatibility. CLINICAL RELEVANCE: The use of this new generation of niobium-based whitening gel associated with a low concentration of hydrogen peroxide represents the possibility of a tooth whitening with lower dentin sensitivity.

Comparison of toxicity of Ti3 C2 and Nb2 C Mxene quantum dots (QDs) to human umbilical vein endothelial cells.

Recently, we developed highly fluorescent Ti3 C2 and Nb2 C Mxene quantum dots (QDs) for labeling of in vitro models. However, the mechanism of the toxicity of the prepared QDs was not explored before. In this study, we addressed the possible mechanism associated with cytotoxicity of the QDs to human umbilical vein endothelial cells (HUVECs). Exposure to up to 100 µg/ml Ti3 C2 but not Nb2 C QDs for 24 h significantly induced cytotoxicity. The exposure also increased intracellular Ti and Nb elements, indicating the internalization of both types of QDs. None of the QDs promoted interleukin 6 (IL-6) and IL-8 releases. Rather, Ti3 C2 QDs significantly reduced IL-6 and IL-8 release, indicating that the toxicity of Ti3 C2 QDs was not due to elevated inflammatory responses. Exposure to Ti3 C2 but not Nb2 C QDs resulted in increased LC3B-II/I ratio and beclin-1 proteins, biomarkers of autophagy, as well as the accumulation of autophagic substance p62. Ti3 C2 QDs also more effectively promoted pro-caspase 3 but not pro-caspase 8 compared with Nb2 C QDs. Furthermore, pre-treatment with autophagic modulators altered the cytotoxicity of Ti3 C2 QDs, which further confirmed the role of autophagic dysfunction in Ti3 C2 QD-induced toxicity to HUVECs. In conclusion, the results from this study suggested that high levels of Ti3 C2 QDs could induce cytotoxicity to HUVECs by inducing the dysfunction of autophagy. Nb2 C QDs appeared to be more biocompatible to HUVECs compared with Ti3 C2 QDs at the same mass concentrations, which suggested a role of composition of Mxene QDs to determine their toxicity to human endothelial cells.

Cytotoxic, hematologic and histologic effects of niobium pentoxide in Swiss mice.

The use of metal devices in medical application is increasing but it remains incompletely understood the physiological effects of component degradation. Niobium (Nb) alloys have already been investigated in the 1980's and recent studies demonstrated the potential of Nb as an implant material. The purpose of this study was to determine cytotoxic, hematologic and histologic effects of niobium in Swiss mice. Animals were treated with a single dose of 3 % niobium oxide (Nb2O5) diluted in PBS, i.p. Cytotoxic assay, hematologic and histologic evaluation were done 3, 7 and 12 days after niobium treatment. Data have shown increased number of cells after niobium treatment, but there was no difference in cell viability. Furthermore, it was not observed hematological modification 3, 7 or 12 days after niobium treatment. Despite the fact that animals treated with niobium for 3 and 7 days showed mild degeneration in hepatocytes, mice kept alive for 12 days showed liver cells regeneration. Our results suggested that niobium cytotoxicity was not progressive because 12 days after treatment there was an evident liver regeneration. Data obtained indicated that niobium may be promising alternatives to biomedical applications.

Quaternary Ti-20Nb-10Zr-5Ta alloy during immersion in simulated physiological solutions: formation of layers, dissolution and biocompatibility.

Samples of the quaternary Ti-20Nb-10Zr-5Ta alloy were immersed in Hanks' simulated physiological solution and in minimum essential medium (MEM) for 25 days. Samples of Ti metal served as controls. During immersion, the concentration of ions dissolved in MEM was measured by inductively coupled plasma mass spectrometry, while at the end of the experiment the composition of the surface layers was analyzed by X-ray photoelectron spectroscopy, and their morphology by scanning electron microscopy equipped for chemical analysis. The surface layer formed during immersion was comprised primarily of TiO2 but contained oxides of alloying elements as well. The degree of oxidation differed for different metal cations; while titanium achieved the highest valency, tantalum remained as the metal or is oxidized to its sub-oxides. Calcium phosphate was formed in both solutions, while formation of organic-related species was observed only in MEM. Dissolution of titanium ions was similar for metal and alloy. Among alloying elements, zirconium dissolved in the largest quantity. The long-term effects of alloy implanted in the recipient's body were investigated in MEM, using two types of human cells-an osteoblast-like cell line and immortalized pulmonary fibroblasts. The in vitro biocompatibility of the quaternary alloy was similar to that of titanium, since no detrimental effects on cell survival, induction of apoptosis, delay of growth, or change in alkaline phosphatase activity were observed on incubation in MEM.

Ecotoxicity and environmental safety assessment of two-dimensional niobium carbides (MXenes).

Two-dimensional (2D) MXenes have gained great interest in water treatment, biomedical, and environmental applications. The antimicrobial activity and cell toxicity of several MXenes including Nb4C3Tx and Nb2CTx have already been explored. However, potential side effects related to Nb-MXene toxicity, especially on aquatic pneuma, have rarely been studied. Using zebrafish embryos, we investigated and compared the potential acute toxicity between two forms of Nb-MXene: the multilayer (ML-Nb4C3Tx, ML-Nb2CTx) and the delaminated (DL-Nb2CTx, and DL-Nb4C3Tx) Nb-MXene. The LC50 of ML-Nb4C3Tx, ML-Nb2CTx, DL-Nb2CTx, and DL-Nb4C3Tx were estimated to be 220, 215, 225, and 128 mg/L, respectively. Although DL-Nb2CTx, and DL-Nb4C3Tx derivatives have similar sizes, DL-Nb4C3Tx not only shows the higher mortality (LC50 = 128 mg/L Vs 225 mg/L), but also the highest teratogenic effect (NOEC = 100 mg/L Vs 200 mg/L). LDH release assay suggested more cell membrane damage and a higher superoxide anion production in DL-Nb4C3Tx than DL-Nb2CTx,. Interestingly, both DL-Nb-MXene nanosheets showed insignificant cardiac, hepatic, or behavioral toxic effects compared to the negative control. Embryos treated with the NOEC of DL-Nb2CTx presented hyperlocomotion, while embryos treated with the NOEC of DL-Nb4C3Tx presented hyperlocomotion, suggesting developmental neurotoxic effect and muscle impairment induced by both DL-Nb-MXene. According to the Fish and Wildlife Service (FSW) Acute Toxicity Rating Scale, all tested Nb-MXene nanosheets were classified as "Practically not toxic". However, DL-Nb4C3Tx should be treated with caution as it might cause a neurotoxic effect on fauna when it ends up in wastewater in high concentrations.

Influence of heat treatment and oxygen doping on the mechanical properties and biocompatibility of titanium-niobium binary alloys.

The most commonly used titanium (Ti)-based alloy for biological applications is Ti-6Al-4V, but some studies associate the vanadium (V) with the cytotoxic effects and adverse reactions in tissues, while aluminum (Al) has been associated with neurological disorders. Ti-Nb alloys belong to a new class of Ti-based alloys with no presence of Al and V and with elasticity modulus values that are very attractive for use as a biomaterial. It is well known that the presence of interstitial elements (such as oxygen, for example) changes the mechanical properties of alloys significantly, particularly the elastic properties, the same way that heat treatments can change the microstructure of these alloys. This article presents the effect of heat treatment and oxygen doping in some mechanical properties and the biocompatibility of three alloys of the Ti-Nb system, characterized by density measurements, X-ray diffraction, optical microscopy, Vickers microhardness, in vitro cytotoxicity, and mechanical spectroscopy.

Preparation, formation mechanism, photocatalytic, cytotoxicity and antioxidant activity of sodium niobate nanocubes.

A hydrothermal method was employed to prepare the sodium niobate (NaNbO3) nanocubes. We executed time dependent experiments to illustrate the formation mechanism of sodium niobate nanocubes. It was observed that the morphology of NaNbO3 nanocubes was dependent on the reaction time and 12hr reaction time was found to be suitable. Morphology, composition, structure and optical properties of sodium niobate nanocubes were evaluated by scanning electron microscope, X-ray energy-dispersive spectrometer, X-ray diffraction and UV-visible diffuse reflectance spectrometer. The photocatalytic activity of sodium niobate was studied for photocatalytic hydrogen production. It was anticipated that the sodium niobate (NaNbO3) cubes exhibited good photocatalytic activity under UV light irradiation using lactic acid as sacrificial agent. The cytotoxicity activity of sodium niobate nanocubes was studied as well at different concentrations (5 mg/mL, 3 mg/mL, 1 mg/mL, and 0.25 mg/mL) against human colon colorectal carcinoma cell line (HCT116) by MTT assay and EC50 was found to be 1.9 mg/mL. Sodium niobate proved to be a good DPPH free radical scavenging material, tested at different concentrations. It was noticed that peak intensity at 517 nm was decreased after 30 minute incubation, further supporting the antioxidant activity. This study will be useful for design and engineering of materials that can be used in biomedical applications and in photocatalysis.

Cytotoxicity analysis of a novel titanium alloy in vitro: adhesion, spreading, and proliferation of human gingival fibroblasts.

A recently developed novel Ti-29Nb-13Ta-4.6Zr alloy (Ti-Ta) was investigated physically and chemically, and the results suggested it to be a possibly suitable dental material. In this study we analyzed the effects of the alloy, in comparison with those of other dental metals, on the adhesion, spreading, and proliferation of human gingival fibroblasts (Gin-1 cells) in vitro. The Gin-1 cells adhered and spread well on the Ti-Ta as well as on commercially pure titanium (Ti) and commercial Ti-6Al-7Nb alloy (Ti-Al), forming long processes showing a typical fibroblastic morphology that was close to that on glass. The proliferation of Gin-1 cells was significantly suppressed on Au-Pd-Ag alloy (Au-Pd) and commercially pure copper (Cu); however, the cells proliferated as well on Ti-Ta as they did on Ti, Ti-Al, and glass. Though most of the Gin-1 cells on Cu and about half of them on Au-Pd died after 1 day and 5 days of culture, respectively, the cells on Ti-Ta, Ti, Ti-Al and glass showed 100% viability even after 5 days of culture. These results suggest that the newly developed Ti-Ta alloy has biocompatibility as good as that of Ti and Ti-Al with respect to morphology and proliferation of Gin-1 cells in vitro.

Investigating the structure and biocompatibility of niobium and titanium oxides as coatings for orthopedic metallic implants.

Applying sol gel based coatings to orthopedic metallic implant materials can significantly improve their properties and lifespan in vivo. For this work, niobium (Nb2O5) and titanium (TiO2) oxides were prepared via solution processing in order to determine the effect of atomic arrangement (amorphous/crystalline) on bioactivity. Thermal evaluation on the synthesized materials identified an endotherm for Nb2O5 at 75 °C with 40% weight loss below 400 °C, and minimal weight loss between 400 and 850 °C. Regarding TiO2 an endotherm was present at 92 °C with 25% weight loss below 400 °C, and 4% between 400 and 850 °C. Phase evolution was determined using High Temperature X-ray Diffraction (HT-XRD) where amorphous-Nb2O5 (450 °C), hexagonal-Nb2O5 (525 °C), orthorhombic-Nb2O5 (650 °C), amorphous-TiO2 (275 °C) and tetragonal TiO2 (500 °C) structures were produced. Simulated body fluid (SBF) testing was conducted over 1, 7 and 30 days and resulted in positive chemical and morphological changes for crystalline Nb2O5 (525 °C) and TiO2 (500 °C) after 30 days of incubation. Rod-like CaP deposits were observed on the surfaces using Scanning Electron Microscopy (FE-SEM) and Grazing Incidence-X-ray Diffraction (GI-XRD) shows that the deposits were X-ray amorphous. Cell viability was higher with the TiO2 (122%) samples when compared to the growing cell population while Nb2O5 samples exhibited a range of viability (64-105%), partially dependent on materials atomic structure.

Porous niobium coatings fabricated with selective laser melting on titanium substrates: Preparation, characterization, and cell behavior.

Nb, an expensive and refractory element with good wear resistance and biocompatibility, is gaining more attention as a new metallic biomaterial. However, the high price of the raw material, as well as the high manufacturing costs because of Nb's strong oxygen affinity and high melting point have limited the widespread use of Nb and its compounds. To overcome these disadvantages, porous Nb coatings of various thicknesses were fabricated on Ti substrate via selective laser melting (SLM), which is a 3D printing technique that uses computer-controlled high-power laser to melt the metal. The morphology and microstructure of the porous Nb coatings, which had pores ranging from 15 to 50 µm in size, were characterized with scanning electron microscopy (SEM). The average hardness of the coating, which was measured with the linear intercept method, was 392±37 HV. In vitro tests of the porous Nb coating which was monitored with SEM, immunofluorescence, and CCK-8 counts of cells, exhibited excellent cell morphology, attachment, and growth. The simulated body fluid test also proved the bioactivity of the Nb coating. Therefore, these new porous Nb coatings could potentially be used for enhanced early biological fixation to bone tissue. In addition, this study has shown that SLM technique could be used to fabricate coatings with individually tailored shapes and/or porosities from group IVB and VB biomedical metals and their alloys on stainless steel, Co-Cr, and other traditional biomedical materials without wasting raw materials.

Fatigue performance and cyto-toxicity of low rigidity titanium alloy, Ti-29Nb-13Ta-4.6Zr.

A beta type titanium alloy, Ti-29Nb-13Ta-4.6Zr, was newly designed and developed for biomedical applications. The new alloy contains non-toxic elements such as Nb, Ta, and Zr. In the present study, phases that appeared in the new alloy through various aging treatments were characterized by hardness tests and microstructural observations in order to identify the phase transformation. Fatigue properties of the new alloy were investigated. Young's modulus and cyto-toxicity of the new alloy were also evaluated. Precipitated phases distribute homogeneously over the whole specimen, and they are alpha phase, a small amount of omega phase, and beta phase when the new alloys are subjected to aging treatment at 673K for 259.2ks after solution treatment at 1063K for 3.6ks. The fatigue strength of the new alloy subjected to aging at 673K for 259.2ks after solution treatment at 1063K for 3.6ks is much better than when subjected to other aging treatments. In this case, the fatigue limit is around 700MPa. Young's modulus of the new alloy is much smaller than that of Ti-6Al-4V ELI. The cyto-toxicity of the new alloy is equivalent to that of pure Ti. Therefore, it is proposed that the new alloy, Ti-29Nb-13Ta-4.6Zr, will be of considerable use in biomedical applications.

Antitumor activity of ionic niobocene and molybdenocene complexes in high oxidation states.

Four air-stable niobocene complexes [(C5H5)2NbCl2]+X- with X = BF4, AsF6, SbF6, SO3CF3 and the molybdenocene derivative [(C5H5)2MoCl2]2+[SbF6]2- were investigated for antitumor properties against Ehrlich ascites tumor in female CF1 mice. All compounds are new, salt-like complexes containing a cationic metallocene moiety, where the early transition metals niobium and molybdenum in the high oxidation states +5 and +6 function as central atoms. The niobocene complexes containing tetrafluoroborate (BF4-) or trifluoromethanesulfonate (CF3SO3-) as anions only induced a maximal cure rate of 50% and led to increases in life span of 182% and 178% following application of optimal doses. The other two niobocene compounds with hexafluoroarsenate (AsF6-) and hexafluoroantimonate (SbF6-) as anions and the molybdenocene derivative [(C5H5)2MoCl2]2+[SbF6]2- effected a maximal cure rate of 100% and increases in life span of 346%, 376%, and 332%, respectively, determined on the key date, i.e., on day 90 after transplantation. On applying the niobocene hexafluoroantimonate complex [(C5H5)2NbCl2] +[SbF6]-, the optimal dose range with a cure rate of 100% was rather broad and extended from 20 mg/kg to 40 mg/kg. Correspondingly, the value of the therapeutic index (TI) was high and amounted to 7.2. In the case of the niobocene hexafluoroarsenate and the molybdenocene hexafluoroantimonate complexes, the TI value decreased to 5.3 and 2.6 respectively. Neither impairments of the general condition nor any conspicuous symptoms could be detected after application of therapeutic doses of the five compounds investigated. Compared to the neutral niobocene dichloro complex [(C5H5)2NbCl2], the therapeutic range of the ionic niobocene derivative [(C5H5)2NbCl2]+[SbF6]- was broadened, the TI value markedly elevated from 2.9 to 7.2, and the toxic symptoms were impressively reduced. The niobocene hexafluoroantimonate complex was the most effective compound investigated in the present study.

Effects of six particulate metals on osteoblast-like MG-63 and HOS cells in vitro.

The effects of six particulate metals (Al, Ti, Zr, Nb, Ta and Cr) on cell viability and alkaline phosphatase (ALP) activity were studied in vitro using two types of osteoblast-like cells, MG-63 and HOS cells. The cell viability in the presence of Al, Ti and Zr was depressed at lower concentrations than in the presence of Nb, Ta and Cr. The average sizes of the Al, Ti, Zr, Nb, Ta and Cr particulates were 6.48 microm, 16.99 microm, 5.07 microm, 14.18 microm, 8.32 microm and 23.27 microm respectively. The interaction of HOS cells with the particulates was more sensitive than that of MG-63 cells. ALP activity increased at higher concentrations only with the Al particulates; other experimental conditions did not exert an influence on ALP activity. These findings suggest that the cell viability of osteoblast-like cells might be influenced by particulate size and metal type, but ALP activity was not influenced by these factors.

[Evaluation on biocompatibility of Ti-Fe-Mo-Mn-Nb-Zr alloy].

In this study, the general toxicity tests including acute toxicity test, haemolysis test, MTT assay of Ti-Fe-Mo-Mn-Nb-Zr alloys were carried out. The morphology of these cells was also observed under phase-contrast microscope. By using X-ray photoelectron spectroscopy(XPS), the kind and mol% of element in surface film were studied. The kind and concentration of element in dipping fluid were investigated by ICP atomic emission spectrometry. The results showed the primary component is TiO2 in surface film. The dipping fluid of Ti-Fe-Mo-Mn-Nb-Zr alloys contains Fe 0.2-1.07 mg/l and Mn 0.16-0.5 mg/l; such dental materials are beneficial to health. No cytotoxic effect was disclosed by in vitro and in vivo tests. The level of cytotoxicity was grade 0 and 1; the haemolysis degree was 0.558%-0.642%, i.e. less than 5%. The cells growing in the extract showed normal morphology. These data indicate that Ti-Fe-Mo-Mn-Nb-Zr alloy, as a dental material, has good biocompatibility.

Radiopacity, pH and antimicrobial activity of Portland cement associated with micro- and nanoparticles of zirconium oxide and niobium oxide.

The aim of this study was to evaluate some properties of the calcium silicate materials Mineral Trioxide Aggregate (MTA) and Portland cement (PC) with microparticulated (micro) and nanoparticulated (nano) zirconium oxide (ZrO2) or niobium oxide (Nb2O5). The experimental materials: White PC (PC), MTA-Angelus(®) (MTA), PC+ZrO2micro, PC+ZrO2nano, PC+Nb2O5micro and PC+Nb2O5nano were submitted to radiopacity and pH evaluations. Furthermore, the antimicrobial activity against different microorganisms was assessed by agar diffusion test. MTA presented higher radiopacity than other materials. However, all materials except PC presented higher radiopacity than recommended by ISO/ADA. MTA promoted higher pH values in all analyzed periods (p≤0.05). At the initial periods, PC and PC+ZrO2micro showed pH similar to MTA. All materials showed antimicrobial activity against the evaluated microorganisms. In conclusion, ZrO2 and Nb2O5 could be alternative radiopacifiers to be added to calcium silicate materials.

MRI-compatible Nb-60Ta-2Zr alloy used for vascular stents: haemocompatibility and its correlation with protein adsorption.

Nb-60Ta-2Zr is a newly developed MRI-compatible alloy used for vascular stents. In this work, its haemocompatibility was investigated, including platelet adhesion (lactate dehydrogenase activity), platelet activation (P-selectin expression), coagulation and haemolysis. For comparison, parallel assessments for these factors were performed for the niobium, tantalum, 316L stainless steel (316L SS) and L605 Co-Cr alloy (L605). In addition, albumin and fibrinogen were selected to examine the correlation of protein adsorption with platelet adhesion and metal surface properties. The propensity for platelet adhesion and activation on the Nb-60Ta-2Zr alloy was at nearly the same level as that for Nb and Ta but was slightly less than those of 316L SS and L605. The mitigated platelet adhesion and activation of the Nb-60Ta-2Zr alloy is associated with its decreased adsorption of fibrinogen. The Nb-60Ta-2Zr alloy has a longer clotting time and exhibits significantly superior thromboresistance than 316L SS and L605. Moreover, the haemolysis rate of the Nb-60Ta-2Zr alloy satisfies the bio-safety requirement of the ISO 10993-4 standard. The favourable haemocompatiblity of the Nb-60Ta-2Zr alloy provides evidence of its good biocompatibility and of its suitability as a candidate stent material.

Radiopacity and cytotoxicity of Portland cement associated with niobium oxide micro and nanoparticles.

OBJECTIVE: Mineral Trioxide Aggregate (MTA) is composed of Portland Cement (PC) and bismuth oxide (BO). Replacing BO for niobium oxide (NbO) microparticles (Nbµ) or nanoparticles (Nbη) may improve radiopacity and bioactivity. The aim of this study was to evaluate the radiopacity and cytotoxicity of the materials: (1) PC; (2) White MTA; (3) PC+30% Nbµ; (4) PC+30% Nbη. MATERIAL AND METHODS: For the radiopacity test, specimens of the different materials were radiographed along an aluminum step-wedge. For cell culture assays, Saos-2 osteoblastic-cells (ATCC HTB-85) were used. Cell viability was evaluated through MTT assay, and bioactivity was assessed by alkaline phosphatase activity assay. RESULTS: The results demonstrated higher radiopacity for MTA, followed by Nbµ and Nbη, which had similar values. Cell culture analysis showed that PC and PC+NbO associations promoted greater cell viability than MTA. CONCLUSIONS: It was concluded that the combination of PC+NbO is a potential alternative for composition of MTA.

Cytocompatibility of pure metals and experimental binary titanium alloys for implant materials.

OBJECTIVE: This study was performed to evaluate the biocompatibility of nine types of pure metal ingots (Ag, Al, Cr, Cu, Mn, Mo, Nb, V, Zr) and 36 experimental titanium (Ti) alloys containing 5, 10, 15, and 20 wt% of each alloying element. METHODS: The cell viabilities for each test group were compared with that of CP-Ti using the WST-1 test and agar overlay test. RESULTS: The ranking of pure metal cytotoxicity from most potent to least potent was as follows: Cu>Al>Ag>V>Mn>Cr>Zr>Nb>Mo>CP-Ti. The mean cell viabilities for pure Cu, Al, Ag, V, and Mn were 21.6%, 25.3%, 31.7%, 31.7%, and 32.7%, respectively, which were significantly lower than that for the control group (p<0.05). The mean cell viabilities for pure Zr and Cr were 74.1% and 60.6%, respectively (p<0.05). Pure Mo and Nb demonstrated good biocompatibility with mean cell viabilities of 93.3% and 93.0%, respectively. The mean cell viabilities for all the Ti-based alloy groups were higher than 80% except for Ti-20 Nb (79.6%) and Ti-10 V (66.9%). The Ti-10 Nb alloy exhibited the highest cell viability (124.8%), which was higher than that of CP-Ti. Based on agar overlay test, pure Ag, Cr, Cu, Mn, and V were ranked as 'moderately cytotoxic', whereas the rest of the tested pure metals and all Ti alloys, except Ti-10 V (mild cytotoxicity), were ranked as 'noncytotoxic'. SIGNIFICANCE: The results obtained in this study can serve as a guide for the development of new Ti-based alloy implant systems.

Harmonic nanocrystals for biolabeling: a survey of optical properties and biocompatibility.

Nonlinear optical nanocrystals have been recently introduced as a promising alternative to fluorescent probes for multiphoton microscopy. We present for the first time a complete survey of the properties of five nanomaterials (KNbO(3), LiNbO(3), BaTiO(3), KTP, and ZnO), describing their preparation and stabilization and providing quantitative estimations of their nonlinear optical response. In the light of their prospective use as biological and clinical markers, we assess their biocompatibility on human healthy and cancerous cell lines. Finally, we demonstrate the great potential for cell imaging of these inherently nonlinear probes in terms of optical contrast, wavelength flexibility, and signal photostability.

In vitro cytotoxicity and hemocompatibility studies of Ti-Nb, Ti-Nb-Zr and Ti-Nb-Hf biomedical shape memory alloys.

The in vitro cytotoxicity and hemocompatibility of the Ti-Nb, Ti-Nb-Zr and Ti-Nb-Hf biomedical shape memory alloys (SMAs) were investigated by cell culture (L-929 fibroblast cell), hemolytic test and platelet adhesion test, with CP Ti as a reference material. The cytotoxicity test indicates that all the Ti-Nb, Ti-Nb-Zr and Ti-Nb-Hf SMAs show over 94% cell viability for different incubation times (2, 4 and 7 days) in comparison with a negative control and CP Ti. The cell morphology observation shows good polygon-like adherent growth and proliferation of L-929 in the extracts of all the test samples and CP Ti. These results suggest excellent cytocompatibility for the Ti-Nb, Ti-Nb-Zr and Ti-Nb-Hf SMAs. The hemolytic test reveals that the hemolysis ratios of the Ti-Nb, Ti-Nb-Zr and Ti-Nb-Hf alloys are far less than 5%, so they cannot give rise to acute hemolysis. The platelet morphology observation shows almost the same adhered platelet morphology and activation ratio for the test samples in comparison with CP Ti, except the Ti-22Nb-6Hf alloy, which shows a lower activation ratio of platelets, indicating excellent blood compatibility. Therefore, it is proposed that the Ti-Nb, Ti-Nb-Zr and Ti-Nb-Hf SMAs will be candidates to replace Ti-Ni for biomedical applications.