Surface coordination layer passivates oxidation of copper.

Owing to its high thermal and electrical conductivities, its ductility and its overall non-toxicity1-3, copper is widely used in daily applications and in industry, particularly in anti-oxidation technologies. However, many widespread anti-oxidation techniques, such as alloying and electroplating1,2, often degrade some physical properties (for example, thermal and electrical conductivities and colour) and introduce harmful elements such as chromium and nickel. Although efforts have been made to develop surface passivation technologies using organic molecules, inorganic materials or carbon-based materials as oxidation inhibitors4-12, their large-scale application has had limited success. We have previously reported the solvothermal synthesis of highly air-stable copper nanosheets using formate as a reducing agent13. Here we report that a solvothermal treatment of copper in the presence of sodium formate leads to crystallographic reconstruction of the copper surface and formation of an ultrathin surface coordination layer. We reveal that the surface modification does not affect the electrical or thermal conductivities of the bulk copper, but introduces high oxidation resistance in air, salt spray and alkaline conditions. We also develop a rapid room-temperature electrochemical synthesis protocol, with the resulting materials demonstrating similarly strong passivation performance. We further improve the oxidation resistance of the copper surfaces by introducing alkanethiol ligands to coordinate with steps or defect sites that are not protected by the passivation layer. We demonstrate that the mild treatment conditions make this technology applicable to the preparation of air-stable copper materials in different forms, including foils, nanowires, nanoparticles and bulk pastes. We expect that the technology developed in this work will help to expand the industrial applications of copper.

Impact of Pulmonary Vein Anatomy on Long-term Outcome of Cryoballoon Ablation for Atrial Fibrillation.

Variant pulmonary vein anatomy (PVA) has been reported to influence the recurrence of atrial fibrillation (AF) after radiofrequency ablation. However, the effects of PVA on AF in patients undergoing cryoballoon ablation (CBA) remain unknown. The present study aimed to examine the impact of PVA on the long-term outcome of CBA for AF. A total of 78 patients (mean age 60.7±10.9 years, 64.1% males) with symptomatic and drug-refractory paroxysmal AF were enrolled in the study. Left atrium (LA) and PVA acquired at computed tomography angiography (CTA) were reconstructed with CARTO® 3 SYSTEM. Patients were routinely evaluated by 24-hour Holter monitoring following CBA. Cox regression was used to detect the predictors of AF recurrence after CBA. The results showed abnormal PVA in 30 patients (38.5%) and 18 patients (23.1%) had left common PV (LCPV). Electrical pulmonary vein isolation was achieved in all patients. After a mean follow-up of 689.5±103.8 days, it was found that patients with abnormal PVA had similar AF recurrence rate to those with normal PVA (26.7% vs. 25.0%, P=0.54), and there was no significant difference in AF recurrence rate between LCPV patients and non-LCPV patients (33.7% vs. 23.3%, P=0.29). Cox regression analysis showed that AF duration (72.9±9.0 vs. 42.3±43.2 months, HR 1.001; 95%CI 1.003-1.014; P<0.001) and cryo-applications of right-side PVs (3.0±1.6 vs. 4.7±1.7, HR 0.661; 95% CI 0.473-0.925; P=0.016) were independent predictors of freedom from AF, but PVA was not identified as a predictor of long-term success. In conclusion, the variant PVA cannot significantly influence the long-term outcome of AF patients undergoing CBA; longer AF duration and less cryo-applications of right-side PVs are associated with higher AF recurrent rate.

Cryoballoon ablation in Chinese patients with paroxysmal atrial fibrillation: 1-year follow-up.

OBJECTIVES: We assessed the effectiveness and safety of cryoballoon ablation (CBA) in the Chinese population with paroxysmal atrial fibrillation (AF) with a 1-year follow-up and determined the association of early recurrence of atrial tachyarrhythmias (ERAT) with late recurrence (LR). METHODS: A total of 114 patients (age 61 ± 10 years, 78 males) with paroxysmal AF who underwent CBA were consecutively enrolled. After procedures, patients were observed for 3 days with continuous electrocardiogram monitoring in the hospital with routine follow-up visits at 3 months, 6 months, and 1 year. Documented atrial tachyarrhythmia >30 seconds was defined as recurrence. ERAT was defined as any recurrence during the first 3 months, and LR was recurrence between 3 and 12 months. RESULTS: With the first 3 months as blanking period, 76% of patients were free of LR at 12 months. Five patients (4%) experienced complications, including phrenic nerve palsy, stroke, and groin complications. Forty-five percent of patients had ERAT in the first 3 months and 31% of patients had ERAT in the first 3 days. Patients with ERAT had higher LR rate (LRR) than those without ERAT (43% vs 8%, P < 0.001). The LRR of patients with ERAT only in the first 3 days was lower than those with ERAT both in the first 3 days and in 4-90 days (29% vs 64%, P = 0.036). CONCLUSIONS: CBA was an effective and safe treatment option for paroxysmal AF. Patients with ERAT had higher LRR after CBA of AF. The time when ERAT occurred had an impact on LRR.

Controllable degradation of medical magnesium by electrodeposited composite films of mussel adhesive protein (Mefp-1) and chitosan.

To control the degradation rate of medical magnesium in body fluid environment, biocompatible films composed of Mussel Adhesive Protein (Mefp-1) and chitosan were electrodeposited on magnesium surface in cathodic constant current mode. The compositions and structures of the films were characterized by atomic force microscope (AFM), scanning electron microscope (SEM) and infrared reflection absorption spectroscopy (IRAS). And the corrosion protection performance was investigated using electrochemical measurements and immersion tests in simulated body fluid (Hanks' solution). The results revealed that Mefp-1 and chitosan successfully adhered on the magnesium surface and formed a protective film. Compared with either single Mefp-1 or single chitosan film, the composite film of chitosan/Mefp-1/chitosan (CPC (chitosan/Mefp-1/chitosan)) exhibited lower corrosion current density, higher polarization resistance and more homogenous corrosion morphology and thus was able to effectively control the degradation rate of magnesium in simulated body environment. In addition, the active attachment and spreading of MC3T3-E1 cells on the CPC film coated magnesium indicated that the CPC film was significantly able to improve the biocompatibility of the medical magnesium.

Tuning the surface microstructure of titanate coatings on titanium implants for enhancing bioactivity of implants.

Biological performance of artificial implant materials is closely related to their surface characteristics, such as microtopography, and composition. Therefore, convenient fabrication of artificial implant materials with a cell-friendly surface structure and suitable composition was of great significance for current tissue engineering. In this work, titanate materials with a nanotubular structure were successfully fabricated through a simple chemical treatment. Immersion test in a simulated body fluid and in vitro cell culture were used to evaluate the biological performance of the treated samples. The results demonstrate that the titanate layer with a nanotubular structure on Ti substrates can promote the apatite-inducing ability remarkably and greatly enhance cellular responses. This highlights the potential of such titanate biomaterials with the special nanoscale structure and effective surface composition for biomedical applications such as bone implants.

Effectiveness of cysteine proteases on protein/pigment film removal.

OBJECTIVE: Theaflavin (TF) from the black tea can react to human salivary proline-rich proteins (PRPs) to form stains on exposed dental surfaces. Here, we employed a model of protein/pigment film using TF and dephosphorylated bovine ß-casein (Dß-CN), which has an extended conformation, similar to that of salivary PRPs, on a sensor surface to assess the efficacy of cysteine proteases (CPs) including papain, stem bromelain, and ficin, on removing TF bound to Dß-CN and the control TF readsorption on the residual substrate surfaces was also measured. METHODS: The protein/pigment complex film was built by using a quartz crystal microbalance with dissipation (QCM-D). The efficacies of CPs were assessed by Boltzman equation model. The surface details were detected by grazing angle infrared spectroscopy spectra, atomic force microscopy images, and contact angles. RESULTS: The efficacy order of CPs on hydrolyzing protein/pigment complex film is ficin>papain>bromelain. The results from grazing angle infrared spectroscopy spectra, atomic force microscopy images, and contact angles demonstrated that TF bound on the Dß-CN was effectively removed by the CPs, and the amount of TF readsorption on both the residual film of the Dß-CN/TF and the Dß-CN was markedly decreased after hydrolysis. CONCLUSION: This study indicates the potential application of the CPs for tooth stain removal and suggests that these enzymes are worthy of further investigation for use in oral healthcare.

Anodic TiO2 nanotubular arrays with pre-synthesized hydroxyapatite--an effective approach to enhance the biocompatibility of titanium.

Electrochemically anodized TiO2 nanotubular arrays can provide large surface areas for biological species attachment. In order to further enhance the biocompatibility of Ti medical implants, we deposited a pre-synthesized hydroxyapatite inside and on the nanotubular arrays, and examined the biocompatibility of the anodized TiO2 nanotubular arrays with pre-synthesized hydroxyapatite by in vitro assessment in simulated body fluid, and in vitro cell culture. The results showed that the hydroxyapatite coating was able to be induced on TiO2 nanotubular arrays with pre-synthesized hydroxyapatite within 5 days while only a thin film composed of calcium phosphorous chemicals formed on as-formed TiO2 nanotubular arrays. The cell culture evaluation further proved the enhancement of cell attachment and proliferation on TiO2 nanotubular arrays with pre-synthesized hydroxyapatite as opposed to those without pre-synthesized hydroxyapatite. The present study proves that formation of TiO2 nanotubular arrays with pre-synthesized hydroxyapatite a promising method to enhance the biocompatibility of Ti implants.

Fabrication and photoelectrochemical properties of ZnS/Au/TiO2 nanotube array films.

A highly ordered TiO(2) nanotube array film was fabricated by an anodic oxidation method. The film was modified by Au nanoparticles (NPs) formed by a deposition-precipitation technique and was covered with a thin ZnS shell prepared by a successive ionic layer adsorption and reaction (SILAR) method. The photoelectrochemical properties of the prepared ZnS/Au/TiO(2) composite film were evaluated by incident photon-to-current conversion efficiency (IPCE), and photopotential and electrochemical impedance spectroscopy (EIS) measurements under white light illumination. The results indicated that the Au NPs could expand the light sensitivity range of the film and suppress the electron-hole recombination, and the ZnS shell could inhibit the leakage of photogenerated electrons from the surface of Au NPs to the ZnS/electrolyte interface. When the 403 stainless steel in a 0.5 M NaCl solution was coupled to the ZnS/Au/TiO(2) nanotube film photoanode under illumination, its potential decreased by 400 mV, showing that the composite film had a better photocathodic protection effect on the steel than that of a pure TiO(2) nanotube film.

The effect of pinacidil on postshock activation and ventricular defibrillation threshold in canine hearts.

AIM: To determine the postshock activation patterns with both successful and failed shocks in a canine model of ventricular fibrillation, and whether piniacidil, an early after-depolarization (EAD) inhibitor, altered the defibrillation threshold (DFT) and postshock activation patterns. METHODS: In 6 beagles, a basket catheter with 64 unipolar electrodes was placed in the LV for global endocardial mapping, a monophasic action potential catheter was inserted into the LV apex, and a catheter with the negative electrode in the right ventricle and the positive electrode in the superior vena cava was inserted for defibrillation. The DFT, 90% action potential duration (APD(90)) and activation recovery interval (ARI) were evaluated before and after pinacidil administration (loading dosage 0.5 mg/kg and maintenance dosage 0.5 mg·kg(-1)·h(-1), iv). Electrical heterogeneities were defined with the dispersion of ARI. After successful and failed shocks with near-DFT strength, the earliest postshock activation patterns (focal or nonfocal endocardial activation), interval and location were detected. RESULTS: Pinacidil significantly decreased APD(90) (from 178±16 ms to 168±18 ms) and ARI from (152±10 ms to 143±10 ms) at pacing cycle length of 300 ms. The drug significantly increased VF activation rate (from 10.0±1.9 Hz to 10.8±2.0 Hz). The drug did not affect the dispersion of ARI, neither it changed DFT (baseline: 480±110 V; pinacidil: 425±55 V, P>0.05). The earliest postshock activation arose locally on the LV apical endocardium before and after the drug treatment. Pinacidil significantly prolonged the postshock cycle length of cycles 2 to 5 for the successful episodes but not for the failed episodes. CONCLUSION: Pinacidil increases the postshock cycle length suggesting that EAD may play a role in postshock activation, while it fails to alter DFT suggesting that EAD produced by shock does not determine a defibrillation success or failure.

[Studies on the saliva adsorption and the salivary film property on the hydroxyapatite surface].

OBJECTIVE: To evaluate the thickness and viscoelasticity of whole saliva (WS), parotid saliva (PS) and submandibular/sublingual gland saliva (SMSLS) film adsorption on the hydroxyapatite (HA) surface. METHODS: Ultra-thin layer of HA nanocrystals was coated on the dissipation TiO(2) sensor of gold quartz crystal microbalance using electrophoretic deposition technique. The thickness of the HA layer was measured by the ellipsometer, and element analysis was conducted using X-ray photoelectron spectroscopy. Atomic force microscopy and scanning electron microscope were used to observe its morphology. The in-situ adsorption thickness, the shear elastic modulus and the shear viscosity of salivary layers (WS, PS and SMSLS) on HA surfaces were investigated. The statistical data were analysed by an one-way ANOVA analysis followed by a SNK-q test. RESULTS: The results show that the HA layer was a plate-like morphology with 1.53 ± 0.12 in Ca/P molar ratio, (19.1 ± 0.9) nm in the thickness and (6.5 ± 1.6) nm in the roughness. The thickness of salivary film was SMSLS [(21.84 ± 1.25) nm] > WS[(17.91 ± 1.35) nm] > PS [(14.30 ± 1.03 nm) (P < 0.05). The shear elastic modulus of salivary film was PS [(0.61 ± 0.01) MPa] > SMSLS [(0.31 ± 0.09) MPa] and WS [(0.25 ± 0.03) MPa] (P < 0.05). The trend of the shear viscosity was opposite to one of thickness. CONCLUSIONS: The characteristics of saliva adsorption on HA surface suggest that the thicker, softer and more hydrated properties for the SMSLS and WS films are likely to afford a stronger lubrication to protect oral surfaces from wear and dehydration. The viscoelasticity of the PS film is probably related to the retention covering the oral cavity.

Ibutilide decreases defibrillation threshold by the reduction of activation pattern complexity during ventricular fibrillation in canine hearts.

BACKGROUND: Ibutilide has been commonly used for pharmacologic cardioversion of atrial fibrillation and flutter in clinical settings. The objective of this study was to investigate the effects of ibutilide on the defibrillation threshold (DFT), restitution properties, dispersion of refractoriness and activation patterns during ventricular fibrillation (VF). METHODS: Ibutilide was administrated intravenously in six open-chest beagles. Before and after the drug administration, 20-second episodes of VF were electrically induced and recorded with a 10×10 unipolar electrode plaque sutured on the lateral epicardium of the left ventricle. DFT and VF activation patterns, including type of epicardial activation maps, VF cycle length (VF-CL), conduction velocity, wavelength (WL) and reentry incidence, were measured. Restitution properties and dispersion of refractoriness were estimated from activation recovery intervals (ARI) during pacing. RESULTS: Compared to baseline, ibutilide markedly decreased the DFT by 31% ((491 ± 14) V vs. (337 ± 59) V, P < 0.01). The drug significantly reduced the maximal slope of the restitution curve (1.34 ± 0.08 vs. 0.76 ± 0.06, P < 0.01) and its epicardial dispersion (0.36 ± 0.09 vs. 0.21 ± 0.06, coefficient of variation, P = 0.03). The dispersion of refractoriness was enhanced at the pacing cycle length of 300 ms to 160 ms by ibutilide. The drug significantly increased the VF-CL ((96 ± 19) ms vs. (112 ± 20) ms, P < 0.01) and the WL ((41 ± 9) mm vs. (52 ± 14) mm, P = 0.02) during VF, and reduced the reentry incidence by 25% (0.08 ± 0.02 vs. 0.06 ± 0.02, P < 0.01). In the epicardial activation maps, ibutilide significantly reduced the percentage of more complex activation maps during VF. CONCLUSIONS: Intravenous ibutilide significantly decreased the DFT. It might be due to reduction of activation pattern complexity during VF.

[In situ measurement of the permeability of concrete by FTIR-MIR].

Fourier transform infrared spectroscopy with multiple internal reflection mode (FTIR-MIR) has been applied for the first time to measure the permeability of concrete. The effect of water-cement ratio and curing time on the microstructure and permeability of concrete was studied. Also, the penetration process of H2O and SO4(2-) through the concrete specimens was investigated. The results indicated that the movement of H2O through unsaturated concrete was mainly caused by capillary suction and the movement of SO4(2-) through unsaturated concrete should take into account diffusion, advection caused by a capillary suction flow and the reaction between SO4(2-) and the cement hydration products. The permeability of concrete was determined by its microstructure. With the decrease in water-cement ratio and the increase in curing time, the porosity and the connectivity of pores in concrete decreased, which resulted in the decrease of concrete permeability.

Affinity interactions between natural pigments and human whole saliva.

OBJECTIVE: The aim of the present study was to assess the null hypothesis that there are no differences of affinity between pigments and human whole saliva (WS), and the affinity is not influenced by the functional groups of pigments, temperatures, pH values, and salt concentrations. METHODS: The affinity constants of interactions between WS and theaflavin (TF)/curcumin (Cur)/cyanidin (Cy) were determined by surface plasmon resonance (SPR) and fluorescence quenching. Mass-uptake at various temperatures, pH values, and salt concentrations was also carried out. RESULTS: The order of affinity of the pigments binding to WS is TF>Cur>Cy. A large number of complexes and precipitations of pigments/proteins were formed through a quick, strong, and almost irreversible binding process. The mass-uptake of pigments was affected not only by the functional groups, but also by molecular weight of pigments, temperatures, pH values, and salt concentrations. CONCLUSION: The complex of pigments may easily and rapidly deposit onto the WS film, and are difficult to remove from the WS surface. However, the complex of pigments can be reduced by properly regulating the physicochemical conditions, such as temperatures, pH values, and salt concentrations.

Nitrogen-doped TiO2 nanotube array films with enhanced photocatalytic activity under various light sources.

Highly ordered nitrogen-doped titanium dioxide (N-doped TiO(2)) nanotube array films with enhanced photocatalytic activity were fabricated by electrochemical anodization, followed by a wet immersion and annealing post-treatment. The morphology, structure and composition of the N-doped TiO(2) nanotube array films were investigated by FESEM, XPS, UV-vis and XRD. The effect of annealing temperature on the morphology, structures, photoelectrochemical property and photo-absorption of the N-doped TiO(2) nanotube array films was investigated. Liquid chromatography and mass spectrometry were applied to the analysis of the intermediates coming from the photocatalytic degradation of MO. The experimental results showed that there were four primary intermediates existing in the photocatalytic reaction. Compared with the pure TiO(2) nanotube array film, the N-doped TiO(2) nanotubes exhibited higher photocatalytic activity in degradating methyl orange into non-toxic inorganic products under both UV and simulated sunlight irradiation.

The interactions of epigallocatechin-3-gallate with human whole saliva and parotid saliva.

OBJECTIVE: The aim of the present study was to assess the null hypothesis that the astringency and loss of lubrication in the oral cavity are not related to the properties of the epigallocatechin-3-gallate (EGCG) adlayer, the affinity and the entropy-drive of EGCG binding to saliva. METHODS: The mass, thickness, and viscoelasticity of the EGCG adlayer and the temperature dependence of EGCG adsorption onto saliva surfaces were determined by quartz crystal microbalance with dissipation (QCM-D). The affinities of EGCG to human whole saliva (WS) and to parotid saliva (PS) were carried out by QCM-D monitoring and fluorescence quenching. RESULTS: The stiffer and more compact EGCG adlayers were formed on saliva surfaces at various concentrations of EGCG. The affinity for EGCG binding to WS was higher than that to PS. The precipitation of EGCG/saliva was temperature-dependent. The driving force of EGCG binding to saliva is dominated by the hydrogen bond, the hydrophobic reaction, and the entropy-drive, which were confirmed by the FTIR spectra and the measurement of temperature- dependence, respectively. CONCLUSION: The viscoelasticity of the EGCG adlayer, the affinity of EGCG to saliva, and the priority of EGCG binding to hydrophobic proteins on the mucosa may account for the oral astringency and loss of lubrication.

In situ electrochemical monitoring of reactive oxygen and nitrogen species released by single MG63 osteosarcoma cell submitted to a mechanical stress.

The oxidative stress responses of single MG63 osteosarcoma cells submitted to a brief mechanical stress have been investigated by amperometry at platinized carbon fiber electrodes for monitoring and characterizing the nature and the amounts of the various reactive oxygen (ROS) and reactive nitrogen species (RNS) released. It was thus shown that, on average, a single MG63 cell released prominent amounts of reactive nitrogen species (17 fmol NO(*), 6 fmol ONOO(-), and 5 fmol NO(2)(-)) together with a comparatively small quantity of H(2)O(2) (2 fmol). These species resulted from the primary production of 13 fmol for O(2)(*-) and 28 fmol for NO(*) per single cell as reconstructed from the stoichiometries of the ROS and RNS releases. The high NO(*)/H(2)O(2) and NO(*)/O(2)(*-) ratios thus found are perfectly consistent with previous claims that the malignant bone formation ability of the osteosarcoma cells is related to a specific high production of NO* associated to a small one of O(2)(*-).

[Evaluation of three transmission parameters of dental opal porcelains and the correlations among parameters].

OBJECTIVE: To measure the translucency parameter (TP), masking effect (ME), and contrast ratio (CR) of opal porcelain of Ceramco, Shofu, Noritake, and Vita, and to compare the correlations among the three transmission parameters, in order to provide reference for selecting opal porcelain correctly. METHODS: The color of specimens was measured according to CIE L*a*b* under different background and reflectance mode with a Color-Eye 7000A spectrophotometer. The color difference, TP, and ME value were calculated. Within 400-750 nm spectra, the ratio of light reflectance was measured, and CR was also calculated. The data was compared by ANOVA and SNK-q test (alpha=0.05). The correlation and multiple linear regression between TP, CR, and ME were analyzed (alpha=0.05). RESULTS: There were statistical difference with different shade of the same brands (P<0.05). The correlations between ME and TP, TP and CR, ME and CR were existed (P<0.05). TP was correlated not only with ME but also with CR based on multiple regression analysis (P<0.05). The partial correlation coefficients were statistically significant (P<0.05). CR was the main devotion to translucency parameter on multiple regressions. CONCLUSION: It is recommended to select opal porcelains based on transmission parameters. CR value has an inner significance of opaque property of opal porcelain and can express opacity property of opal porcelain more appropriately than ME.

[The influence of accelerated aging on color and microstructure of light-curing composite resin].

OBJECTIVE: The aim of this investigation was to examine the changes of the color stability, surface microstructure and chemical constitution of light-curing composite resin after accelerated aging, and the relations between them. METHODS: Four light-curing composite resin were aged in an accelerated aging instrument. The color was measured by CIE L*a*b* with a spectrophotometer after treatment for 24 h and 96 h. And the color differences were calculated. Environmental scanning electron microscopy (ESEM) and Fourier transform infrared spectroscopy (FTIR) spectrometer were used to examine the microstructure and chemical composition of the specimens before and after accelerated aging. The color differences were analyzed statistically by repeated-measures two-way analysis of variance and t-test after aging for 24 h and 96 h. The level of significance was defined as alpha=0.05. RESULTS: The materials demonstrated statistically significant differences in color after aging between the 24 h and 96 h (P<0.05). There were significant influences on the microstructure and the chemical composition after aging. The matrix appeared some concaves and pores, the filler particles exposed after aging. The energy of chemical bonds were weaken or broken under the aging, and the unsaturated polymer reacted again. CONCLUSION: The color differences of the composite resin increase with the aging time and irradiation dose. The hybrid filled composites have the best color stability.

A novel nano-micro structured octacalcium phosphate/protein composite coating on titanium by using an electrochemically induced deposition.

In this study, a novel nano-micro structured octacalcium phosphate/protein (OCP/protein) composite coating has been successfully constructed on titanium substrate by using an electrochemically induced deposition technique. The structure and composition of the composite coating were investigated by XRD, XPS, SEM and FTIR. It is shown that the composite coating consists of OCP and protein with a highly ordered and hierarchically porous structure in nano-micro scale, similar to the naturalbone structure. The nanoindentation experiment proves a good mechanical property for the OCP/protein composite coating on titanium substrate. In the osteoblast cell culture in vitro, the cell adhesion for the OCP/protein composite coating is observed to be greatly improved.

Some critical structure factors of titanium oxide nanotube array in its photocatalytic activity.

A highly ordered TiO2 nanotube array on Ti substrate was fabricated by using an electrochemical anodic oxidation method. The morphology, crystalline phase, and photoelectrochemical property of the nanotube array were characterized. The photocatalytic activity of the nanotube array was evaluated by the decolorization of methyl orange in aqueous solution using the different light sources. The effects of structure and morphology of the nanotube array on its photocatalytic activity were investigated. It was found that the photoabsorption behavior of the TiO2 nanotube film depended on the structures of the nanotube array. The nanotube array films exhibited a drastically enhanced photocurrent, and a higher photocatalytic activity compared with the TiO2 nanoparticle film prepared by the regular sol-gel method. The experimental results indicated that the film thickness markedly influenced the photocatalytic activity of nanotube array film, and the 2.5 microm-thick TiO2 nanotube array film appeared a maximum photodegradation efficiency to methyl orange. However, for a given nanotube length, the tube diameter was only very slightly affected the photocatalytic efficiency in this work. The explanation for some critical structure factors of TiO2 nanotube array in the photocatalytic activity was discussed as well.