Reinforcement of resin based cement with titania nanotubes

Sarcoma cell-specific radiation sensitization by titanate scrolled nanosheets: insights from physicochemical analysis and transcriptomic profiling

This study aimed to explore the potential of metal oxides such as Titanate Scrolled Nanosheets (TNs) in improving the radiosensitivity of sarcoma cell lines. Enhancing the response of cancer cells to radiation therapy is crucial, and one promising approach involves utilizing metal oxide nanoparticles. We focused on the impact of exposing two human sarcoma cell lines to both TNs and ionizing radiation (IR). Our research was prompted by previous in vitro toxicity assessments, revealing a correlation between TNs' toxicity and alterations in intracellular calcium homeostasis. A hydrothermal process using titanium dioxide powder in an alkaline solution produced the TNs. Our study quantified the intracellular content of TNs and analyzed their impact on radiation-induced responses. This assessment encompassed PIXE analysis, cell proliferation, and transcriptomic analysis. We observed that sarcoma cells internalized TNs, causing alterations in intracellular calcium homeostasis. We also found that irradiation influence intracellular calcium levels. Transcriptomic analysis revealed marked disparities in the gene expression patterns between the two sarcoma cell lines, suggesting a potential cell-line-dependent nano-sensitization to IR. These results significantly advance our comprehension of the interplay between TNs, IR, and cancer cells, promising potential enhancement of radiation therapy efficiency.

Micromechanical interlocking structure at the filler/resin interface for dental composites: a review

Dental resin composites (DRCs) are popular materials for repairing caries or dental defect, requiring excellent properties to cope with the complex oral environment. Filler/resin interface interaction has a significant impact on the physicochemical/biological properties and service life of DRCs. Various chemical and physical modification methods on filler/resin interface have been introduced and studied, and the physical micromechanical interlocking caused by the modification of fillers morphology and structure is a promising method. This paper firstly introduces the composition and development of DRCs, then reviews the chemical and physical modification methods of the filler/resin interface, mainly discusses the interface micromechanical interlocking structures and their enhancement mechanism for DRCs, finally give a summary on the existing problems and development potential.

Effect of shape of titanium dioxide nanofillers on the properties of dental composites

The main objective of the present study was to evaluate the effect of the morphology of titanium dioxide nanofillers on the flexural strength and shear bond strength of the dental composite. Spherical and rhombic-shaped nano titanium dioxide fillers were synthesized via solvothermal method and were characterized. Subsequently, these fillers were incorporated into a flowable composite (Filtek^™ Z350 XT Flowable Restorative) at 0.5 wt.% and 1.5 wt.% and the prepared specimens were stored in water for 24 h. The specimens were then evaluated for flexural strength using a universal testing machine. Similarly, the shear bond strength of modified composites to the tooth was evaluated and bond failures were analyzed using stereomicroscope magnification. Incorporation of nanofillers significantly enhanced the flexural strength of flowable composite (p = 0.009) with a significant increase at 0.5wt.% of spherical (p = 0.015) and rhomboidal-shaped fillers (p = 0.010). However, no statistically significant difference in flexural strength was observed among the different shapes of nanofillers. The results of our study did not show a significant effect on the shear bond strength of the composites. Thus the reinforcing ability of titanium dioxide nanofillers on dental composite was confirmed in this study, although the effect of using nanofillers with different morphology was not significant.

The effect of functionalized titanium dioxide nanotube reinforcement on the water sorption and water solubility properties of flowable bulk-fill composite resins

The aim of this study was to investigate the effects of titanium dioxide nanotube addition on the water sorption and water solubility values of different composite resins. Titanium dioxide nanotubes were synthesized from titanium dioxide powder in anatase form and in 13 nm diameter by hydrothermal process and then functionalized with methacrylic acid. Characterization of the nanotubes was performed by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction and Fourier transform infrared spectroscopy. A flowable composite resin (Filtek Ultimate Flowable) and four flowable bulk-fill composite resins (Filtek Bulk Fill Flowable, SDR Bulk Fill Flowable, Venus Bulk Fill, X-tra Base) were tested. Two groups of each composite resin were prepared: groups of the resins without nanotubes; groups of the resins reinforced with 1.0 wt% functionalized titanium dioxide nanotube. Sorption and solubility in water were assessed according to ISO 4049 standards after 1, 7, 14, 21 days immersion periods. Data were analyzed using Mann-Whitney U and Kruskal-Wallis H tests (p  <  0.05). Long cylindrical tubular structures with a diameter of 41.09-72.49 nm were observed in electron microscopy analysis. The band at 1636 cm^- 1 showed the existence of the vinyl (C=C) bond of methacrylic acid coordinated to the nanotubes in Fourier transform infrared spectroscopy analysis. None of the materials tested in this study exceeded the maximum sorption and solubility values established by ISO. Regarding the water solubility, negative values were obtained. TiO₂ nanotube reinforcement decreased the water sorption and solubility values significantly at different evaluation periods in all composite resins except for Venus (p < 0.05).

Development of Newly Formulated Nanoalumina-/Alkasite-Based Restorative Material

Purpose

Nanotechnology offers considerable scope in dentistry to improve dental treatment, care, and prevention of oral diseases through the use of nanosized biomaterials. This study assessed the effect of incorporating alumina nanoparticles (Al₂O₃ NPa) to the recently introduced alkasite-based restorative material (Cention N) on its mechanical properties and surface topographical features.

Materials and Methods

Alumina nanopowder was incorporated into the powder component of Cention N at 5 and 10% (w/w). The unblended powder was used as a control. Compressive strength was assessed using a universal testing machine. Surface microhardness and roughness were evaluated using the Vickers microhardness test and surface profilometer, respectively. Surface topography was inspected using a scanning electron microscope (SEM). Data were analyzed by ANOVA and Tukey's test (P < 0.05).

Results

Incorporation of either 5 or 10% (w/w) Al₂O₃ NPa into alkasite-based restorative materials (Cention N) increased both its compressive strength and surface microhardness. This increase was significant with the use of lower concentration Al₂O₃ NPa (5% w/w). Meanwhile, there was an increase in surface roughness values of Cention N modified with either 5 or 10% (w/w) Al₂O₃ NPa. This increase was only significant in the case of 10% (w/w) Al₂O₃ NPa.

Conclusion

Incorporation of 5% (w/w) Al₂O₃ NPa into the newly introduced alkasite-based restorative material (Cention N) seems to produce a promising restorative material with high compressive strength and surface hardness without adversely affecting its surface roughness properties. Thus, nanotechnology implementation into Cention N restorative material may be strongly helpful for a diversity of clinical applications.

Titanium dioxide nanotubes with triazine-methacrylate monomer to improve physicochemical and biological properties of adhesives

OBJECTIVE

Formulate experimental adhesives containing titanium dioxide nanotubes (nt-TiO₂) or titanium dioxide nanotubes with a triazine-methacrylate monomer (nt-TiO₂:TAT) and evaluate the effect of these fillers on the physical, chemical, and biological properties of the adhesives.

METHODS

First, nt-TiO₂ were synthesized via a hydrothermal method. The nt-TiO₂ were mixed with a triazine-methacrylate monomer (TAT) to formulate nt-TiO₂:TAT, which were characterized by transmission electron microscopy (TEM). The nt-TiO₂, TAT, and nt-TiO₂:TAT were evaluated via Fourier Transform Infrared, Ultraviolet-visible, and micro-Raman spectroscopies. An experimental adhesive resin was formulated with bisphenol A glycerolate dimethacrylates, 2-hydroxyethyl methacrylate, and photoinitiator/co-initiator system. nt-TiO₂ or nt-TiO₂:TAT were incorporated at 2.5 wt.% and 5 wt.% in the adhesive. The base resin without nt-TiO₂ or nt-TiO₂:TAT was used as a control group. The adhesives were evaluated for antibacterial activity, cytotoxicity, polymerization kinetics, degree of conversion (DC), Knoop hardness, softening in solvent (ΔKHN%), ultimate tensile strength (UTS), 24 h- and 1 year- microtensile bond strength (μ-TBS).

RESULTS

TEM confirmed the nanotubular morphology of TiO₂. FTIR, UV-vis, and micro-Raman analyses showed the characteristic peaks of each material, indicating the impregnation of TAT in the nt-TiO₂. Adhesives with nt-TiO₂:TAT showed antimicrobial activity against biofilm formation compared to control (p < 0.05), without differences in the viability of planktonic bacteria (p > 0.05). All groups showed high percentages of pulp cell viability. The polymerization kinetics varied among groups, but all presented DC above 50%. The addition of 5 wt.% of nt-TiO₂ and both groups containing nt-TiO₂:TAT showed higher values ​​of Knoop hardness compared to the control (p < 0.05). The groups with nt-TiO₂:TAT presented lower ΔKHN% (p < 0.05) and higher UTS (p < 0.05) than the control group. After one year, the group with 5 wt.% of nt-TiO₂, as well as both groups containing nt-TiO₂:TAT, showed higher μ-TBS than the control (p < 0.05).

SIGNIFICANCE

The mixing of a triazine-methacrylate monomer with the nt-TiO₂ generated a filler that improved the physicochemical properties of the adhesive resins and provided antibacterial activity, which could assist in preventing carious lesions around tooth-resin interfaces. The set of physical, chemical, and biological properties of the formulated polymer, together with the greater stability of the bond strength over time, make nt-TiO₂:TAT a promising filler for dental adhesive resins.

Synthesizing 1D and 2D metal oxide nanostructures: using metal acetate complexes as building blocks

1D and 2D metal oxide nanostructures are important for potential applications in alternative energy, batteries, supercapacitors, catalysts, biomaterials, and electronic nanodevices. Many current approaches for making the desired nanomaterials require multiple steps, which are often exotic and complex for production on a commercial scale. In contrast, the sol-gel reactions between metal alkoxides and organic acids have emerged as a simple protocol for producing metal oxides and inorganic/organic hybrid materials with a controllable 1D or 2D architecture. Our knowledge of this process continues to evolve through the fundamental goal of designing a desired nanostructure from the corresponding molecular building blocks. Our research was driven by the discovery of various morphologies by fine-tuning the synthesis parameters, such as the reaction temperature and molar ratio of the reactants, as well as switching solvents. These discoveries lead to several quesions: What are the building blocks of the 1D and 2D nanostructures and how does the self-assembly occur? What are the reaction kinetics and the mechanisms of nanostructure formation? What role does the solvent play in the assembly process? What are the effects of reaction temperature and pressure? How can we manipulate the nanostructure-for example, the parallel growth of 1D semiconductors-from a substrate surface? And lastly, what are the industrial applications of macroporous aerogels and xerogels? This minireview will highlight documented research accounts to answer these questions.

Nanomaterials in Dentistry: State of the Art and Future Challenges

Nanomaterials are commonly considered as those materials in which the shape and molecular composition at a nanometer scale can be controlled. Subsequently, they present extraordinary properties that are being useful for the development of new and improved applications in many fields, including medicine. In dentistry, several research efforts are being conducted, especially during the last decade, for the improvement of the properties of materials used in dentistry. The objective of the present article is to offer the audience a complete and comprehensive review of the main applications that have been developed in dentistry, by the use of these materials, during the last two decades. It was shown how these materials are improving the treatments in mainly all the important areas of dentistry, such as endodontics, periodontics, implants, tissue engineering and restorative dentistry. The scope of the present review is, subsequently, to revise the main applications regarding nano-shaped materials in dentistry, including nanorods, nanofibers, nanotubes, nanospheres/nanoparticles, and zeolites and other orders porous materials. The results of the bibliographic analysis show that the most explored nanomaterials in dentistry are graphene and carbon nanotubes, and their derivatives. A detailed analysis and a comparative study of their applications show that, although they are quite similar, graphene-based materials seem to be more promising for most of the applications of interest in dentistry. The bibliographic study also demonstrated the potential of zeolite-based materials, although the low number of studies on their applications shows that they have not been totally explored, as well as other porous nanomaterials that have found important applications in medicine, such as metal organic frameworks, have not been explored. Subsequently, it is expected that the research effort will concentrate on graphene and zeolite-based materials in the coming years. Thus, the present review paper presents a detailed bibliographic study, with more than 200 references, in order to briefly describe the main achievements that have been described in dentistry using nanomaterials, compare and analyze them in a critical way, with the aim of predicting the future challenges.

Yttria-stabilized tetragonal zirconia polycrystal/resin luting agent bond strength: Influence of Titanium dioxide nanotubes addition in both materials

PURPOSE

To evaluate the shear bond strength (SBS) between Y-TZP and a resin luting agent, after 1 of 2 enhancing strategies with TiO_2--nts was applied, either to the resin luting agent or the Y-TZP mass, in different concentrations.

METHODS

In the Strategy TiO₂-nts on ceramic, the resin luting agent Panavia F2.0™ (Kuraray) and an experimental Y-TZP with added concentrations of TiO_2--nts (0%, 1%, 2%, and 5% vol/vol) and a commercial Y-TZP, comprised 5 different groups (n = 10). In the Strategy TiO₂-nts on cement, the resin luting agent RelyX U200™ (3 M ESPE) was added with different concentrations of TiO_2--nts (0%, 0.3%, 0.6%, 0.9% wt/wt) luted to a commercial Y-TZP, comprising 4 different groups (n = 10). The Y-TZP discs were included in acrylic bases, and a cylinder (3 × 3 mm) of the correspondent luting agent for each respective group was applied over them. After 24 h, specimens were subjected to SBS assessments in a universal testing machine. Field emission scanning electron microscopy and energy dispersive X-ray spectroscopy analyses were also performed on Y-TZP surfaces. Data were analyzed via analysis of variance and Tukey tests (α = 0.05).

RESULTS

TiO₂-nts on ceramic influenced the bond strength significantly, but not linearly; TiO₂-nts on cement did not influence bond strength when analyzed separately, nor in comparison with the first.

CONCLUSION

Y-TZP enhancements with TiO₂-nts led to a higher SBS with Panavia F2.0, a 5% TiO_2--nt concentration presented the highest bond strength. Modified Rely X U200 did not improve SBS.

Assessment of the Impact of the Addition of Nanoparticles on the Properties of Glass-Ionomer Cements

The aim of the study was to evaluate the effects of incorporation of Al2O3, ZrO2 and TiO2 nanoparticles into glass-ionomer cements (GICs). Two different GICs were used in the study. Four groups were prepared for each material: the control group (without nanoparticles) and three groups modified by the incorporation of nanoparticles at 2, 5 or 10 wt %, respectively. Cements were mixed and placed in moulds (4 mm × 6 mm); after setting, the samples were stored in saline (one day and one week). Compressive strengths were measured and the morphology of the fractured surfaces was analyzed by scanning electron microscopy. The elements released into the storage solutions were determined by Inductively coupled plasma-optical emission spectrometry (ICP-OES). Addition of nanoparticles was found to alter the appearance of cements as examined by scanning electron microscopy. Compressive strength increased with the addition of ZrO2 and especially TiO2 nanoparticles, whereas the addition of Al2O3 nanoparticles generally weakened the cements. The ion release profile of the modified cements was the same in all cases. The addition of Al2O3, ZrO2 and TiO2 nanoparticles into GICs is beneficial, since it leads to reduction of the microscopic voids in the set cement. Of these, the use of ZrO2 and TiO2 nanoparticles also led to increased compressive strength. Nanoparticles did not release detectable levels of ions (Al, Zr or Ti), which makes them suitable for clinical use.

Effect of zinc oxide nanoparticles on the flexural strength of polymethylmethacrylate denture base resin

Purpose:

This study evaluated the flexural strength of polymethyl methacrylate (PMMA) reinforced with various concentrations of zinc oxide (Zn O) nanoparticles.

Materials and methods:

Nano ZnO was added in 0, 0.4, 0.6, 0.8, 1.2 and 1.4 percentage to PMMA denture base material. 60 specimens of heat cure polymerizing acrylic resin of dimensions 10mm x 4mm x 80mm were fabricated in accordance to ISO 20795-1-2013. The specimens were divided into 6 groups. Acrylic specimens were processed according to manufacturer’s instruction. Three-point bending test was performed to evaluate the flexural strength. Surface analysis was performed with scanning electron microscopy (SEM) to observe the fracture surfaces of specimens. ANOVA and Tukey tests were used for the statistical analysis (p < 0.05).

Results:

Statistical analysis revealed significant differences in strength between groups. The flexural strength improved with the addition ZnO nanoparticles. Highest mean value was observed in Group nZn -14 (91.31 MPa) and lowest in control Group nZn-0 (61.36 MPa). ANOVA and Tukey’s honestly significance test found statistical significant differences among the groups ( p<0.001).

Conclusion:

The addition of ZnO nanoparticles in all concentrations increased the flexural strength of acrylic resin when compared to the control group.

Characterization of Titanium Nanotube Reinforced Cementitious Composites: Mechanical Properties, Microstructure, and Hydration

In recent years, nano-reinforcing technologies for cementitious materials have attracted considerable interest as a viable solution for compensating the poor cracking resistance of these materials. In this study, for the first time, titanium nanotubes (TNTs) were incorporated in cement pastes and their effect on the mechanical properties, microstructure, and early-age hydration kinetics was investigated. Experimental results showed that both compressive (~12%) and flexural strength (~23%) were enhanced with the addition of 0.5 wt.% of TNTs relative to plain cement paste at 28 days of curing. Moreover, it was found that, while TNTs accelerated the hydration kinetics of the pure cement clinker phase (C₃S) in the early age of the reaction (within 24 h), there was no significant effect from adding TNTs on the hydration of ordinary Portland cement. TNTs appeared to compress the microstructure by filling the cement paste pore of sizes ranging from 10 to 100 nm. Furthermore, it could be clearly observed that the TNTs bridged the microcracks of cement paste. These results suggested that TNTs could be a great potential candidate since nano-reinforcing agents complement the shortcomings of cementitious materials.

Effects of incorporation of 2.5 and 5 wt% TiO2 nanotubes on fracture toughness, flexural strength, and microhardness of denture base poly methyl methacrylate (PMMA)

PURPOSE

The aim of this preliminary study was to investigate, for the first time, the effects of addition of titania nanotubes (n-TiO2) to poly methyl methacrylate (PMMA) on mechanical properties of PMMA denture base.

MATERIALS AND METHODS

TiO2 nanotubes were prepared using alkaline hydrothermal process. Obtained nanotubes were assessed using FESEM-EDX, XRD, and FT-IR. For 3 experiments of this study (fracture toughness, three-point bending flexural strength, and Vickers microhardness), 135 specimens were prepared according to ISO 20795-1:2013 (n of each experiment=45). For each experiment, PMMA was mixed with 0% (control), 2.5 wt%, and 5 wt% nanotubes. From each TiO2:PMMA ratio, 15 specimens were fabricated for each experiment. Effects of n-TiO2 addition on 3 mechanical properties were assessed using Pearson, ANOVA, and Tukey tests.

RESULTS

SEM images of n-TiO2 exhibited the presence of elongated tubular structures. The XRD pattern of synthesized n-TiO2 represented the anatase crystal phase of TiO2. Moderate to very strong significant positive correlations were observed between the concentration of n-TiO2 and each of the 3 physicomechanical properties of PMMA (Pearson's P value ≤.001, correlation coefficient ranging between 0.5 and 0.9). Flexural strength and hardness values of specimens modified with both 2.5 and 5 wt% n-TiO2 were significantly higher than those of control (P≤.001). Fracture toughness of samples reinforced with 5 wt% n-TiO2 (but not those of 2.5% n-TiO2) was higher than control (P=.002).

CONCLUSION

Titania nanotubes were successfully introduced for the first time as a means of enhancing the hardness, flexural strength, and fracture toughness of denture base PMMA.

Evaluation of surface roughness of different restorative composites after polishing using atomic force microscopy

INTRODUCTION

Resin based composites are widely used aesthetic restorative materials in clinical restorative dentistry. The filler size and the percentage of fillers affects smooth surface, clinical durability, aesthetics, better optical properties, compatibility with natural enamel tissue, surface gloss, and preventing the discoloration of the restoration. The finishing and polishing of tooth-coloured restorations are necessary clinical steps for better aesthetics and longevity of restored teeth.

AIM

In this study nano composites were chosen, because these contain nano particles which provide better overall composites features, including the quality of polished surface. The aim of this study was to evaluate the surface roughness of different newer posterior composites.

MATERIAL AND METHOD

Five commercially available posterior restorative composite were tested in this study. All the specimens were polished with shofu multi step polishing system. After polishing the samples were all analyzed by atomic force microscopy which is used to study surface topography and surface morphology of materials.

RESULTS

The values of surface roughness of each specimen were statistically analyzed using Kruskal Wallis ANOVA, and Pair wise comparisons by Mann-Whitney U test setting the statistical significance at p ≤ 0.05.

CONCLUSION

Tetric Evo Ceram, Z350 exhibited less surface roughness compared to Ever X, Clearfil Majesty and Sure fil SDR. There was no statistical difference between groups regarding surface rough ness between groups.

The incorporation of nanoparticles into conventional glass-ionomer dental restorative cements

Conventional glass-ionomer cements (GICs) are popular restorative materials, but their use is limited by their relatively low mechanical strength. This paper reports an attempt to improve these materials by incorporation of 10 wt% of three different types of nanoparticles, aluminum oxide, zirconium oxide, and titanium dioxide, into two commercial GICs (ChemFil® Rock and EQUIA™ Fil). The results indicate that the nanoparticles readily dispersed into the cement matrix by hand mixing and reduced the porosity of set cements by filling the empty spaces between the glass particles. Both cements showed no significant difference in compressive strength with added alumina, and ChemFil® Rock also showed no significant difference with zirconia. By contrast, ChemFil® Rock showed significantly higher compressive strength with added titania, and EQUIA™ Fil showed significantly higher compressive strength with both zirconia and titania. Fewer air voids were observed in all nanoparticle-containing cements and this, in turn, reduced the development of cracks within the matrix of the cements. These changes in microstructure provide a likely reason for the observed increases in compressive strength, and overall the addition of nanoparticles appears to be a promising strategy for improving the physical properties of GICs.

Resin composites reinforced by nanoscaled fibers or tubes for dental regeneration

It has been stated clearly that nanofillers could make an enhancement on the mechanical performances of dental composites. In order to address current shortage of traditional dental composites, fillers in forms of nanofibers or nanotubes are broadly regarded as ideal candidates to greatly increase mechanical performances of dental composites with low content of fillers. In this review, the efforts using nanofibers and nanotubes to reinforce mechanical performances of dental composites, including polymeric nanofibers, metallic nanofibers or nanotubes, and inorganic nanofibers or nanotubes, as well as their researches related, are demonstrated in sequence. The first purpose of current paper was to confirm the enhancement of nanofibers or nanotubes' reinforcement on the mechanical performances of dental restorative composite. The second purpose was to make a general description about the reinforcement mechanism of nanofibers and nanotubes, especially, the impact of formation of interphase boundary interaction and nanofibers themselves on the advanced mechanical behaviors of the dental composites. By means of the formation of interface interaction and poststretching nanofibers, reinforced effect of dental composites by sorts of nanofibers/nanotubes has been successfully obtained.

Synthesis and characterization of novel TiO2-poly(propylene fumarate) nanocomposites for bone cementation

A novel composite material made from poly(propylene fumarate) (PPF) and titania nanofibers has been synthesized for potential use as an orthopaedic biomaterial with TiO₂ nanofibers chemically linked to the PPF matrix as a reinforcing phase to enhance its mechanical properties.

Determination of surface roughness and topography of dental resin-based nanocomposites using AFM analysis

The aim of this study was to determine surface roughness and topography of polished dental resin-based nanocomposites. Four representative dental resin-based nanocomposites were tested in the study: two nanohybrids (Filtek Z550 and Tetric EvoCeram) and two nanofilled (Filtek Ultimate Body and Filtek Ultimate Translucent); and two reference materials: one microfilled (Gradia Direct) and one microhybrid (Filtek Z250). Polymerized cylindrical specimens (4 mm x 2 mm) were polished with multi-step polishing system- Super Snap. Immediately after the polishing, topography of each specimen was examined by Veeco di CP-II Atomic Force Microscope. Specimen's surface has been scanned in 6 points in contact mode with CONT20A-CP tips. 1 Hz scan rate and 256 × 256 resolution were used to obtain topography on a 90 µm × 90 µm scanning area. Measured topography data were processed by Image Processing and Data Analysis v2.1.15 software. Following parameters were compared among specimens: average roughness and maximum peak-to-valley distance. All of the tested materials had similar average surface roughness after finishing and polishing procedure. The lowest values occurred in the material Filtek Ultimate Body, and the highest in the Filtek Z550. When interpreting maximum peak-to-valley distance the larger differences in values (up to 100%) occurred in Filtek Z550, Filtek Z250 and Filtek Ultimate Body, which is a result of the deep polishing channels and tracks. Type, size, distribution of fillers and filler loading in tested materials, didn't influence average roughness values, but had an impact on maximum peak-to-valley distance values.

The radiosensitization effect of titanate nanotubes as a new tool in radiation therapy for glioblastoma: a proof-of-concept

BACKGROUND AND PURPOSE

One of the new challenges to improve radiotherapy is to increase the ionizing effect by using nanoparticles. The interest of titanate nanotubes (TiONts) associated with radiotherapy was evaluated in two human glioblastoma cell lines (SNB-19 and U87MG).

MATERIALS AND METHODS

Titanate nanotubes were synthetized by the hydrothermal treatment of titanium dioxide powder in a strongly basic NaOH solution. The cytotoxicity of TiONts was evaluated on SNB-19 and U87MG cell lines by cell proliferation assay. The internalization of TiONts was studied using Transmission Electron Microscopy (TEM). Finally, the effect of TiONts on cell radiosensitivity was evaluated using clonogenic assay. Cell cycle distribution was evaluated by flow cytometry after DNA labeling. DNA double-stranded breaks were evaluated using γH2AX labeling.

RESULTS

Cells internalized TiONts through the possible combination of endocytosis and diffusion with no cytotoxicity. Clonogenic assays showed that cell lines incubated with TiONts were radiosensitized with a decrease in the SF2 parameter for both SNB-19 and U87MG cells. TiONts decreased DNA repair efficiency after irradiation and amplified G2/M cell-cycle arrest.

CONCLUSION

Our results indicated that further development of TiONts might provide a new useful tool for research and clinical therapy in the field of oncology.

Synthesis and characterization of poly(methyl methacrylate)-based experimental bone cements reinforced with TiO2-SrO nanotubes

In an attempt to overcome existing limitations of experimental bone cements we here demonstrate a simple approach to synthesizing strontium-modified titania nanotubes (n-SrO-TiO(2) tubes) and functionalize them using the bifunctional monomer methacrylic acid. Then, using 'grafting from' polymerization with methyl methacrylate, experimental bone cements were produced with excellent mechanical properties, radiopacity and biocompatibility. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive spectroscopy mapping and backscattered SEM micrographs revealed a uniform distribution of SrO throughout the titanium matrix, with retention of the nanotubular morphology. Nanocomposites were then reinforced with 1, 2, 4 and 6 wt.% of the functionalized metal oxide nanotubes. Under the mixing and dispersion regime employed in this study, 2 wt.% appeared optimal, exhibiting a more uniform dispersion and stronger adhesion of the nanotubes in the poly(methyl methacrylate) matrix, as shown by TEM and SEM. Moreover, this optimum loading provided a significant increase in the fracture toughness (K(IC)) (20%) and flexural strength (40%) in comparison with the control matrix (unfilled) at P<0.05. Examination of the fracture surfaces by SEM showed that toughening was provided by the nanotubes interlocking with the acrylic matrix and crack bridging during fracture. On modifying the n-TiO(2) tubes with strontium oxide the nanocomposites exhibited a similar radiopacity to a commercial bone cement (CMW 1), while exhibiting a significant enhancement of osteoblast cell proliferation (242%) in vitro compared with the control at P<0.05.