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1.
Cancer Radiother ; 26(4): 585-593, 2022 Jun.
Article in English | MEDLINE | ID: mdl-35210179

ABSTRACT

PURPOSE: To explore the potential protective effect of Kanglaite injection against radiotherapy-induced mucositis in patients with head and neck cancer. PATIENTS AND METHODS: This was an open-label, single-arm, and phase II trial. The primary endpoint was the incidence of grade 3-4 radiation-induced mucositis. The secondary endpoints were hematological toxicity, non-hematological toxicity, nutritional status, and quality of life. All patients received 20g Kanglaite daily concurrently with radiotherapy. RESULTS: The data of 46 patients were available for analysis. The incidence rates of grade 3 mucositis, pain, dysphagia, and neutropenia were 10.9%, 2.2%, 10.9%, and 6.5%, respectively, while the incidence of grade 4 acute toxicities was zero. The rate of opioid use was 2.2%. Radiotherapy dose reduction was 2.2% and no irradiation field was modified. The nutritional supports were oro-enteral nutritional supplements (13.0%), TPN (10.9%), and feeding tubes (0%) during radiotherapy. After radiotherapy, 52.2% of patients lost weight, and the weight loss was <10%. The mean pain score in the QLQ-H&N35 and QLQ-C30 was <50. Patients had nearly normal physical, emotional, and cognitive functions. CONCLUSIONS: A low incidence of grade 3-4 radiation-induced mucositis and no severe acute toxic events, with favorable nutritional status and quality of life, were observed in cancer patients after Kanglaite injection. Our findings highlight the need for a prospective, multicenter, and randomized study to investigate the effect of Kanglaite injection on the reduction of radiation-induced mucositis in patients with head and neck cancer.


Subject(s)
Head and Neck Neoplasms , Mucositis , Radiation Injuries , Stomatitis , Drugs, Chinese Herbal , Head and Neck Neoplasms/radiotherapy , Humans , Mucositis/etiology , Mucositis/prevention & control , Pain , Quality of Life , Radiation Injuries/epidemiology , Radiation Injuries/etiology , Radiation Injuries/prevention & control , Stomatitis/etiology , Stomatitis/prevention & control
2.
Mater Sci Eng C Mater Biol Appl ; 66: 297-305, 2016 Sep 01.
Article in English | MEDLINE | ID: mdl-27207066

ABSTRACT

Plasma electrolytic oxidation (PEO) was employed to grow different porous titania structures on Ti6Al4V alloy (TC4) substrate using various parameters. It was found that the PEO voltage and working frequency could affect the morphology, the pore size, the pore density, the thickness and the phase composition of titania structures. Thereafter, three typical porous titania structures with nanosize pores, microsize pores and microsize grooves were respectively selected to estimate their bioactivity using SBF immersion test. After soaking at different durations (3-28d), the surface morphology, the chemical composition as well as the phase structure of deposited apatite layers on porous titania were evaluated using SEM, EDS, and XRD. The formation of various biomimetic apatite layers indicated the different influence due to the characteristics of porous titania structures. The porous titania structure with nanosize pores could induce a fast apatite growth at the early immersion stage (~7d), while the one with microsize pores exhibited the best apatite inducing ability at long term immersion (~28d). Based on the experimental results, the formation mechanism of biomimetic apatite affected by the pore structure of titania was discussed as well.


Subject(s)
Apatites/chemistry , Titanium/chemistry , Alloys , Microscopy, Electron, Scanning , Oxidation-Reduction , Plasma Gases , Porosity , Spectrometry, X-Ray Emission , X-Ray Diffraction
3.
Oncogene ; 35(5): 621-30, 2016 Feb 04.
Article in English | MEDLINE | ID: mdl-25915848

ABSTRACT

Tyrosine kinase inhibitors (TKIs) have been documented to have substantial clinical benefits to non-small cell lung cancer with epidermal growth factor receptor (EGFR) mutation. TKI resistance occurs in nearly all patients who receive TKI-targeting therapy, resulting in a modest overall survival benefit. Therefore, establishing a biomarker for early prediction and exploring the mechanism of primary TKI resistance is essential for improving the therapeutic efficacy in non-small cell lung cancer patients. In this study, we provide evidence indicating that paxillin (PXN) overexpression may confer TKI resistance in EGFR-mutant lung cancer cells. Mechanistically, PXN-mediated extracellular signal-regulated kinases (ERK) activation is responsible for TKI resistance via decreased Bcl2-interacting mediator of cell death (BIM) and increased Mcl-1 expression due to modulating their protein stabilities by phosphorylation of BIM at serine 69 and Mcl-1 at threonine 163. The mechanistic action in the cell model was further confirmed by the observation of xenograft tumors in nude mice, revealing that the PXN-mediated TKI resistance was conquered by ERK inhibitor (AZD6244) and Bcl-2 family inhibitor (obatoclax), but the TKI resistance overcome by AZD6244 is more effective than that of obatoclax. Therefore, we suggest that PXN expression may be useful in predicting primary TKI resistance, and combining TKI with ERK inhibitors may clinically benefit EGFR-mutant non-small cell lung cancer patients whose tumors exhibit high PXN expression.


Subject(s)
Apoptosis Regulatory Proteins/metabolism , ErbB Receptors/genetics , Lung Neoplasms/drug therapy , Lung Neoplasms/metabolism , Membrane Proteins/metabolism , Myeloid Cell Leukemia Sequence 1 Protein/metabolism , Paxillin/genetics , Protein Kinase Inhibitors/pharmacology , Proto-Oncogene Proteins/metabolism , Animals , Apoptosis Regulatory Proteins/genetics , Bcl-2-Like Protein 11 , Cell Line, Tumor , Drug Resistance, Neoplasm , Female , Humans , Lung Neoplasms/genetics , Membrane Proteins/genetics , Mice , Mice, Inbred BALB C , Mice, Nude , Myeloid Cell Leukemia Sequence 1 Protein/genetics , Paxillin/metabolism , Protein Stability , Proto-Oncogene Proteins/genetics , Random Allocation , Xenograft Model Antitumor Assays
4.
Biomaterials ; 49: 135-44, 2015 May.
Article in English | MEDLINE | ID: mdl-25725562

ABSTRACT

Biodegradable poly-lactic acid (PLA)--based composites reinforced unidirectionally with high-strength magnesium alloy wires (MAWs) are fabricated by a heat-compressing process and the mechanical properties and degradation behavior are studied experimentally and theoretically. The composites possess improved strengthening and toughening properties. The bending strength and impact strength of the composites with 40 vol% MAWs are 190 MPa and 150 kJ/m(2), respectively, although PLA has a low viscosity and an average molecular weight of 60,000 g/mol. The mechanical properties of the composites can be further improved by internal structure modification and interface strengthening and a numerical model incorporating the equivalent section method (ESM) is proposed for the bending strength. Micro arc oxidization (MAO) of the MAWs is an effective interfacial strengthening method. The composites exhibit high strength retention during degradation and the PLA in the composite shows a smaller degradation rate than pure PLA. The novel biodegradable composites have large potential in bone fracture fixation under load-bearing conditions.


Subject(s)
Alloys/chemistry , Biocompatible Materials/chemistry , Lactic Acid/chemistry , Magnesium/chemistry , Polymers/chemistry , Finite Element Analysis , Oxidation-Reduction , Polyesters , Temperature , Time Factors , Weight-Bearing
5.
Eur Psychiatry ; 30(2): 193-7, 2015 Feb.
Article in English | MEDLINE | ID: mdl-25447350

ABSTRACT

PURPOSE: This study was performed to investigate the association between the mid-brain serotonin transporter (SERT) availability and intelligence quotient (IQ). METHODS: One hundred and thirteen healthy participants, including 52 male and 61 female subjects, were recruited. We used SPECT with [(123)I]ADAM images to determine the SERT availability in the mid-brain, and measured the subjects' IQ using the WAIS-R. RESULTS: We found a significant positive correlation between the mid-brain SERT availability and the IQ of the participants. Even when controlling for age and sex, the significant association still existed. CONCLUSION: This result implied that the higher the SERT binding in the mid-brain, the better the IQ in healthy participants.


Subject(s)
Brain/metabolism , Intelligence , Serotonin Plasma Membrane Transport Proteins/metabolism , Adult , Female , Healthy Volunteers , Humans , Iodine Radioisotopes , Male , Neuroimaging/methods , Tomography, Emission-Computed, Single-Photon/methods
6.
J Mech Behav Biomed Mater ; 34: 27-36, 2014 Jun.
Article in English | MEDLINE | ID: mdl-24556322

ABSTRACT

Porous Ti-Nb-Zr alloys with different porosities from 6.06 to 62.8% are prepared by a two-step foaming powder metallurgy method using TiH2, Nb, and Zr powders together with 0 to 50wt% of NH4HCO3. The effects of the amounts of Nb and Zr as well as the sintering temperature (1473 to 1673K) on their phase composition, porosity, morphology, and mechanical characteristics are investigated. By controlling the porosity, Nb and Zr concentrations as well as the sintering temperature, porous Ti-Nb-Zr alloys with different mechanical properties can be obtained, for example, the hardness between 290 and 63HV, the compressive strength between 1530.5 and 73.4MPa, and the elastic modulus between 10.8 and 1.2GPa. The mechanical properties of the sintered porous Ti-Nb-Zr alloys can be tailored to match different requirements for the human bones and are thus potentially useful in the hard tissue implants.


Subject(s)
Alloys/chemistry , Materials Testing , Mechanical Phenomena , Metallurgy , Biocompatible Materials/chemistry , Elastic Modulus , Hardness , Humans , Niobium/chemistry , Porosity , Powders , Surface Properties , Titanium/chemistry , Zirconium/chemistry
7.
Int Angiol ; 31(6): 534-43, 2012 Dec.
Article in English | MEDLINE | ID: mdl-23222931

ABSTRACT

AIM: Most applications of gradual pressure-decline compressing stockings (GPDCS) are used in the United States and Western European countries, with over a decade of clinical experiments. Up to know, there is no standard establishment of gradual pressure-decline compressing stockings for Asian patients with venous insufficiency and varicose vein formations. METHODS: We collected data on volunteer candidates of varicose vein for general measurements and assessments and magnetic resonance imaging (MRI) by non-contrast enhanced MRV techniques, and for post processing data analysis. RESULTS: Clinical use of GPCDS provide a mild to moderate improvement in the varicose vein conditions of patients with deep venous insufficiency by improving their deep vein circulation, by general measurements; recording major symptoms and complaint; comfort and stretching/flexibility to the candidates after using GPDCS; and area changes/flow velocity changes/available hemoglobin changes in deep veins monitored by MRI. CONCLUSION: The benefits and data collected in these results may help in developing compression stockings standards in Taiwanese and Asian countries, and to establishing criterias for product sizes, compression levels, and related parameters.


Subject(s)
Asian People , Magnetic Resonance Imaging, Cine , Stockings, Compression , Varicose Veins/therapy , Venous Insufficiency/therapy , Adult , Blood Flow Velocity , Female , Humans , Male , Middle Aged , Patient Satisfaction , Predictive Value of Tests , Regional Blood Flow , Stockings, Compression/adverse effects , Taiwan/epidemiology , Time Factors , Treatment Outcome , Varicose Veins/diagnosis , Varicose Veins/ethnology , Varicose Veins/physiopathology , Venous Insufficiency/diagnosis , Venous Insufficiency/ethnology , Venous Insufficiency/physiopathology
8.
Sci Total Environ ; 409(17): 3098-105, 2011 Aug 01.
Article in English | MEDLINE | ID: mdl-21632090

ABSTRACT

At present, soil quality standards used for agriculture do not consider the influence of pH and CEC on the uptake of pollutants by crops. A database with 750 selected paired samples of cadmium (Cd) in soil and paddy rice was used to calibrate soil to plant transfer models using the soil metal content, pH, and CEC or soil Cd and Zn extracted by 0.01 M CaCl2 as explanatory variables. The models were validated against a set of 2300 data points not used in the calibration. These models were then used inversely to derive soil quality standards for Japonica and Indica rice cultivars based on the food quality standards for rice. To account for model uncertainty, strict soil quality standards were derived considering a maximum probability that rice exceeds the food quality standard equal to 10 or 5%. Model derived soil standards based on Aqua Regia ranged from less than 0.3 mg kg⁻¹ for Indica at pH 4.5 to more than 6 mg kg⁻¹ for Japonica-type cultivars in clay soils at pH 7. Based on the CaCl2 extract, standards ranged from 0.03 mg kg⁻¹ Cd for Indica cultivars to 0.1 mg kg⁻¹ Cd for Japonica cultivars. For both Japonica and Indica-type cultivars, the soil quality standards must be reduced by a factor of 2 to 3 to obtain the strict standards. The strong impact of pH and CEC on soil quality standards implies that it is essential to correct for soil type when deriving national or local standards. Validation on the remaining 2300 samples indicated that both types of models were able to accurately predict (> 92%) whether rice grown on a specific soil will meet the food quality standard used in Taiwan.


Subject(s)
Cadmium/analysis , Oryza/metabolism , Soil Pollutants/analysis , Soil/chemistry , Agriculture , Cadmium/chemistry , Cadmium/metabolism , Environmental Pollution/statistics & numerical data , Models, Chemical , Oryza/growth & development , Risk Assessment , Soil Pollutants/chemistry , Soil Pollutants/metabolism , Uncertainty
9.
Gene Ther ; 18(4): 372-83, 2011 Apr.
Article in English | MEDLINE | ID: mdl-21107437

ABSTRACT

The transcription factor Forkhead box O3 (Foxo3) has a critical role in suppressing the expansion of antigen-specific effector T-cell populations; hence, Foxo3 is a potential target for enhancing the antitumor immunity of cancer vaccines. In this report, we evaluated the potential of RNA interference (RNAi)-mediated silencing of Foxo3 in antigen-presenting cells as an adjuvant for HER2/neu DNA cancer vaccines. Bicistronic plasmids expressing the N-terminal extracellular domain of human HER-2/neu and the Foxo3 short hairpin RNA (hN'-neu-Foxo3 shRNA) or the scrambled control (hN'-neu-scramble shRNA) were subcutaneously injected into mice by gene gun administration to elicit antitumor immunity against p185neu-overexpressing MBT-2 bladder tumor cells. We found that mice treated with hN'-neu-Foxo3 shRNA showed greater reductions in tumor growth and longer survival times than mice treated with hN'-neu-scramble shRNA, indicating that the silencing of Foxo3 enhanced the antitumor efficacy of the HER-2/neu cancer vaccine. Cytotoxicity analyses further revealed that the Foxo3 shRNA-enhanced antitumor effect was associated with significant increases in the number of functional CD8(+) T cells and in the levels of cytotoxic T lymphocytes activity. Interleukin-6 was induced by hN'-neu-Foxo3 shRNA treatment but did not have a critical role in the antitumor effect of the hN'-neu-Foxo3 shRNA vaccine. Moreover, in vivo lymphocyte depletion analyses confirmed that the antitumor efficacy of the hN'-neu-Foxo3 shRNA vaccine depended on functional CD8(+) T cells. Finally, Foxo3 suppression was shown to markedly improve the effect of the HER-2/neu DNA vaccine in limiting the growth and lung metastases of MBT-2 cells. Overall, these results support RNAi-mediated silencing of Foxo3 as an effective strategy to enhance the therapeutic antitumor effect of HER-2/neu DNA vaccines against p185neu-positive tumors.


Subject(s)
Antigen-Presenting Cells/metabolism , Cancer Vaccines/immunology , Forkhead Transcription Factors/genetics , Genes, erbB-2 , RNA Interference , Vaccines, DNA/immunology , Animals , Antigen-Presenting Cells/immunology , Biolistics , Cell Line , Chlorocebus aethiops , Dendritic Cells/immunology , Forkhead Box Protein O3 , Genetic Vectors , Humans , Mice , Mice, Inbred C3H , Mice, Inbred C57BL , RNA, Small Interfering/pharmacology , T-Lymphocytes/immunology , Urinary Bladder Neoplasms/prevention & control
10.
J Nanosci Nanotechnol ; 11(12): 10954-7, 2011 Dec.
Article in English | MEDLINE | ID: mdl-22409033

ABSTRACT

To conduct grain refinement induced by plastic deformation, NiTi shape memory alloy is processed by surface mechanical attrition treatment. The process leads to surface nanocrystallization and consequently surface hardening. The cross sectional microhardness of the treated NiTi is measured and compared to those of annealed NiTi specimens with residual stress relaxation and recrystallization. Our results show that surface nanocrystallization induced by surface mechanical attrition treatment is an effective method to enhance the surface hardness and anti-wear properties of NiTi shape memory alloy for the biomedical application.

11.
J Nanosci Nanotechnol ; 11(12): 11176-80, 2011 Dec.
Article in English | MEDLINE | ID: mdl-22409080

ABSTRACT

Surface nanomechanical behavior under nanoindentation of ZrN and ZrCN film on NiTi substrate was studied. The surface hardness and modulus of the films increase initially with larger nanoindentation depths and then reach their maximum values. Afterwards, they diminish gradually and finally reaching plateau values which are the composite modulus and composite hardness derived from the ZrN/ZrCN film and NiTi substrate. They are higher than those of electropolished NiTi SMA due to the properties of ZrN and ZrCN. In comparison, the surface nanomechanical properties of electropolished NiTi exhibit a different change with depths.

12.
J Periodontal Res ; 45(6): 788-95, 2010 Dec.
Article in English | MEDLINE | ID: mdl-20663021

ABSTRACT

BACKGROUND AND OBJECTIVE: The purpose of this study was to evaluate the effect of quercetin, a flavonol that exhibits anti-inflammatory properties, on experimental periodontal destruction in rats. MATERIAL AND METHODS: Osteoclast formation on maxillary palatal alveolus was induced with daily lipopolysaccharide (LPS) injections (0, 1 or 5 mg/mL) for 3 d. Five days later, the osteoclasts on bony surfaces were counted after histochemical staining for tartrate-resistant acid phosphatase. The effect of intragastric quercetin on the osteoclast formation was evaluated in the following three groups: quercetin (75 mg/kg/d by oral feeding); LPS (5 mg/mL); and quercetin plus LPS. Moreover, the effect of quercetin on the ligature-induced periodontitis around maxillary second and mandibular first molars was further evaluated by microcomputerized tomography (on days 0, 4, 8 and 12) and by histometry (on day 8). RESULTS: A dose-dependent increase in osteoclasts occurred after LPS injections. However, quercetin (75 mg/kg) reduced the 5 mg/mL LPS-induced osteoclasts. Using microcomputerized tomography, the bone crest levels at ligation sites were found to be significantly more apical than at the control sites on days 8 and 12; however, the apically located bone crests rebounded in rats from the quercetin-plus-ligation group. Histometry demonstrated significantly more coronal alveolar crest bone levels, less inflammatory cell-infiltrated connective tissue areas and less connective tissue attachments in the ligation-plus-quercetin group compared with those in the ligation group. CONCLUSION: As the quercetin could reduce the LPS-induced osteoclast formation and the ligature-enhanced periodontal inflammation and bone loss, we suggest that it may have an ameliorative effect on periodontal destruction.


Subject(s)
Alveolar Bone Loss/drug therapy , Antioxidants/therapeutic use , Periodontitis/drug therapy , Quercetin/therapeutic use , Administration, Oral , Alveolar Bone Loss/diagnostic imaging , Animals , Antioxidants/administration & dosage , Dose-Response Relationship, Drug , Ligation , Lipopolysaccharides , Male , Osteoclasts/drug effects , Quercetin/administration & dosage , Random Allocation , Rats , Rats, Sprague-Dawley , X-Ray Microtomography
13.
J Nanosci Nanotechnol ; 9(6): 3449-54, 2009 Jun.
Article in English | MEDLINE | ID: mdl-19504867

ABSTRACT

Plasma immersion ion implantation (PIII) is an effective method to increase the corrosion resistance and inhibit nickel release from orthopedic NiTi shape memory alloy. Nitrogen was plasma-implanted into NiTi using different pulsing frequencies to investigate the effects on the nano-scale surface morphology, structure, wettability, as well as biocompatibility. X-ray photoelectron spectroscopy (XPS) results show that the implantation depth of nitrogen increases with higher pulsing frequencies. Atomic force microscopy (AFM) discloses that the nano-scale surface roughness increases and surface features are changed from islands to spiky cones with higher pulsing frequencies. This variation in the nano surface structures leads to different surface free energy (SFE) monitored by contact angle measurements. The adhesion, spreading, and proliferation of osteoblasts on the implanted NiTi surface are assessed by cell culture tests. Our results indicate that the nano-scale surface morphology that is altered by the implantation frequencies impacts the surface free energy and wettability of the NiTi surfaces, and in turn affects the osteoblast adhesion behavior.

14.
Environ Pollut ; 157(8-9): 2435-44, 2009.
Article in English | MEDLINE | ID: mdl-19345457

ABSTRACT

Cadmium (Cd) levels in paddy fields across Taiwan have increased due to emission from industry. To ensure the production of rice that meets food quality standards, predictive models or suitable soil tests are needed to evaluate the quality of soils to be used for rice cropping. Levels of Cd in soil and rice grains were measured in 19 paddy fields across the western plains in Taiwan. Cadmium levels in soil range from less than 0.1 mg kg(-1) to 30 mg kg(-1). Measured Cd levels in brown rice were predicted very well (R(2) > 0.8) based on Cd and Zinc in a 0.01 M CaCl(2) extract or a soil-plant transfer model using the reactive soil Cd content, pH, and cation exchange capacity. In contrast to current soil quality standards used in Taiwan, such models are effective in identifying soils where Cd in rice will exceed food quality standards.


Subject(s)
Agriculture/methods , Cadmium/metabolism , Oryza/metabolism , Soil Pollutants/metabolism , Cadmium/analysis , Guidelines as Topic , Models, Biological , Models, Chemical , Risk Assessment , Soil/chemistry , Soil Pollutants/analysis
15.
Acta Biomater ; 5(6): 2238-45, 2009 Jul.
Article in English | MEDLINE | ID: mdl-19251496

ABSTRACT

A new surface modification protocol encompassing an electropolishing pretreatment (EP) and subsequent photoelectrocatalytic oxidation (PEO) has been developed to improve the surface properties of biomedical nickel titanium (NiTi) shape memory alloy (SMA). Electropolishing is a good way to improve the resistance to localized breakdown of NiTi SMA whereas PEO offers the synergistic effects of advanced oxidation and electrochemical oxidation. Our results indicate that PEO leads to the formation of a sturdy titania film on the EP NiTi substrate. There is an Ni-free zone near the top surface and a graded interface between the titania layer and NiTi substrate, which bodes well for both biocompatibility and mechanical stability. In addition, Ni ion release from the NiTi substrate is suppressed, as confirmed by the 10-week immersion test. The modulus and hardness of the modified NiTi surface increase with larger indentation depths, finally reaching plateau values of about 69 and 3.1GPa, respectively, which are slightly higher than those of the NiTi substrate but much lower than those of a dense amorphous titania film. In comparison, after undergoing only EP, the mechanical properties of NiTi exhibit an inverse change with depth. The deformation mechanism is proposed and discussed. Our results indicate that surface modification by dual EP and PEO can notably suppress Ni ion release and improve the biocompatibility of NiTi SMA while the surface mechanical properties are not compromised, making the treated materials suitable for hard tissue replacements.


Subject(s)
Biocompatible Materials/chemistry , Electrochemistry/methods , Nickel/chemistry , Photochemistry/methods , Titanium/chemistry , Alloys/chemistry , Catalysis , Compressive Strength , Elastic Modulus , Hardness , Materials Testing , Oxidation-Reduction , Surface Properties
16.
J Mater Sci Mater Med ; 20(1): 223-8, 2009 Jan.
Article in English | MEDLINE | ID: mdl-18758918

ABSTRACT

A dense titania film is fabricated in situ on NiTi shape memory alloy (SMA) by anodic oxidation in a Na(2)SO(4) electrolyte. The microstructure of the titania film and its influence on the biocompatibility of NiTi SMA are investigated by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma mass spectrometry (ICPMS), hemolysis analysis, and platelet adhesion test. The results indicate that the titania film has a Ni-free zone near the surface and can effectively block the release of harmful Ni ions from the NiTi substrate in simulated body fluids. Moreover, the wettability, hemolysis resistance, and thromboresistance of the NiTi sample are improved by this anodic oxidation method.


Subject(s)
Biocompatible Materials/chemistry , Nickel/chemistry , Titanium/chemistry , Animals , Biocompatible Materials/toxicity , Coated Materials, Biocompatible/chemistry , Coated Materials, Biocompatible/toxicity , Hemolysis/drug effects , In Vitro Techniques , Materials Testing , Microscopy, Electron, Scanning , Nickel/toxicity , Platelet Adhesiveness , Rabbits , Spectrum Analysis , Surface Properties , Titanium/toxicity , X-Rays
17.
Nano Lett ; 8(11): 3803-8, 2008 Nov.
Article in English | MEDLINE | ID: mdl-18950232

ABSTRACT

Nanophase materials are promising alternative implant materials in tissue engineering. Here we report for the first time the large-scale direct growth of nanostructured bioactive titanates on three-dimensional (3D) microporous Ti-based metal (NiTi and Ti) scaffolds via a facile low temperature hydrothermal treatment. The nanostructured titanates show characteristics of 1D nanobelts/nanowires on a nanoskeleton layer. Besides resembling cancelous bone structure on the micro/macroscale, the 1D nanostructured titanate on the exposed surface is similar to the lowest level of hierarchical organization of collagen and hydroxyapatite. The resulting surface displays superhydrophilicity and favors deposition of hydroxyapatite and accelerates cell attachment and proliferation. The remarkable simplicity of this process makes it widely accessible as an enabling technique for applications from engineering materials treatment including energy-absorption materials and pollution-treatment materials to biotechnology.


Subject(s)
Biomimetic Materials/chemistry , Nanostructures/chemistry , Nanostructures/ultrastructure , Titanium/chemistry , Microscopy, Electron , Porosity , X-Ray Diffraction
18.
Acta Biomater ; 3(5): 795-806, 2007 Sep.
Article in English | MEDLINE | ID: mdl-17466609

ABSTRACT

Fenton's oxidation is traditionally used to remove inorganic and organic pollutants from water in waster water treatment. It is an advanced oxidation process in which H2O2 is catalytically decomposed by ferrous irons into hydroxyl radicals (*OH) which have a higher oxidation potential (2.8V) than H2O2. In the work reported here, we for the first time use Fenton's oxidation to modify the surface of biomedical NiTi shape memory alloy (SMA). The influences of Fenton's oxidation on the surface microstructure, blood compatibility, leaching of harmful Ni ions and corrosion resistance in simulated body fluids is assessed using scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, inductively coupled plasma mass spectrometry, electrochemical tests, hemolysis analysis and the blood platelet adhesion test. The mechanical stability of the surface titania film produced by Fenton's oxidation as well as their effects on the shape memory behavior of the SMA are studied by bending tests. Our results show that Fenton's oxidation produces a novel nanostructured titania gel film with a graded structure on the NiTi substrate without an intermediate Ni-rich layer that is typical of high-temperature oxidation. Moreover, there is a clear Ni-free zone near the top surface of the titania film. The surface structural changes introduced by Fenton's oxidation improve the electrochemical corrosion resistance and mitigate Ni release. The latter effects are comparable to those observed after oxygen plasma immersion ion implantation reported previously and better than those of high-temperature oxidation. Aging in boiling water improves the crystallinity of the titania film and further reduces Ni leaching. Blood platelet adhesion is remarkably reduced after Fenton's oxidation, suggesting that the treated SMA has improved thrombo resistance. Enhancement of blood compatibility is believed to stem from the improved hemolysis resistance, the surface wettability and the intrinsic electrical characteristics of the titania film. The titania film produced by Fenton's oxidation has good mechanical stability and does not adversely impact the shape memory behavior of NiTi. Our work suggests that Fenton's oxidation is a promising low-temperature, low-cost surface modification method for improving the surface properties of biomedical NiTi SMA.


Subject(s)
Alloys/chemistry , Biocompatible Materials/chemistry , Hydrogen Peroxide/chemistry , Iron/chemistry , Nickel/chemistry , Platelet Adhesiveness/physiology , Titanium/chemistry , Animals , Cells, Cultured , Corrosion , Oxidation-Reduction , Rabbits , Surface Properties
19.
J Biomed Mater Res A ; 82(2): 469-78, 2007 Aug.
Article in English | MEDLINE | ID: mdl-17295249

ABSTRACT

NiTi shape memory alloy is one of the promising orthopedic materials due to the unique shape memory effect and superelasticity. However, the large amount of Ni in the alloy may cause allergic reactions and toxic effects thereby limiting its applications. In this work, the surface of NiTi alloy was modified by nitrogen plasma immersion ion implantation (N-PIII) at various voltages. The materials were characterized by X-ray photoelectron spectroscopy (XPS). The topography and roughness before and after N-PIII were measured by atomic force microscope. The effects of the modified surfaces on nickel release and cytotoxicity were assessed by immersion tests and cell cultures. The XPS results reveal that near-surface Ni concentration is significantly reduced by PIII and the surface TiN layer suppresses nickel release and favors osteoblast proliferation, especially for samples implanted at higher voltages. The surfaces produced at higher voltages of 30 and 40 kV show better adhesion ability to osteoblasts compared to the unimplanted and 20 kV PIII samples. The effects of heating during PIII on the phase transformation behavior and cyclic deformation response of the materials were investigated by differential scanning calorimetry and three-point bending tests. Our results show that N-PIII conducted using the proper conditions improves the biocompatibility and mechanical properties of the NiTi alloy significantly.


Subject(s)
Biocompatible Materials , Nickel , Titanium , Animals , Biomechanical Phenomena , Cells, Cultured , Electrochemistry , Materials Testing , Mice , Microscopy, Electron, Scanning , Nitrogen , Osteoblasts/cytology , Spectrum Analysis , Surface Properties , X-Rays
20.
J Biomed Mater Res A ; 81(4): 948-55, 2007 Jun 15.
Article in English | MEDLINE | ID: mdl-17252548

ABSTRACT

Porous NiTi shape memory alloys are one of the promising biomaterials for surgical implants because of their unique shape memory effects and porous structure with open pores. However, the complex surface morphology and larger area of porous NiTi compared to dense NiTi make it more vulnerable from the viewpoint of release of nickel, which can cause deleterious effects in the human body. It is also more difficult to modify the exposed surfaces of a porous structure using conventional surface modification technologies. In this work, oxidation in conjunction with postreaction heat treatment was used to modify the surfaces of porous single-phase NiTi prepared by capsule-free hot isostatic pressing to mitigate Ni leaching and enhance the surface properties. Differential scanning calorimetry thermal analysis, uniaxial compression tests, inductively-coupled plasma mass spectrometry, and cell cultures reveal that porous NiTi alloys oxidized at 450 degrees C for 1 h have an austenite transition temperature below 37 degrees C, excellent superelasticity, lower nickel release, and no cytotoxicity.


Subject(s)
Copper/metabolism , Nickel/metabolism , Osteoblasts/cytology , Titanium/metabolism , Alloys/metabolism , Animals , Calorimetry, Differential Scanning , Cells, Cultured , Elasticity , Mice , Oxidation-Reduction , Porosity , Spectrum Analysis , Surface Properties , Temperature , X-Ray Diffraction
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