Structural connectivity and bioactivity in sol-gel silicate glass design.

Bioactive glasses (BGs) bond with bone by forming hydroxy carbonate apatite (HCA) upon reaction in physiological fluid, a phenomenon known as bioactivity. BGs structural network connectivity determines their bioactivity. Sol-gel BGs are synthesized through the hydrolysis and condensation of metal alkoxide precursors in the presence of a catalyst, in aqueous environments. Several sol-gel synthesis parameters directly impact BG network connectivity: pH (i.e. acid or basic catalysis), water to alkoxide ratio (Rw), alkoxide type and presence of dopant ions. However, the relationship between bioactivity and these parameters remains surprisingly unexplored. This study highlights the relationship between synthesis pH, Rw, network connectivity and bioactivity in silica-based sol-gel BGs and BGs doped with titanium (Ti) ions (TiBGs), the latter selected for their known ability to enhance network connectivity. BGs and TiBGs are synthesized with various Rw values under acidic and basic conditions, and their bioactivity is assessed in simulated body fluid for 7 days. Increasing Rw decreases network connectivity and increases bioactivity of BGs with high network connectivity, as observed for base-catalyzed BGs and for both acid and base catalyzed TiBGs, but not in BGs with lower connectivity as evidenced in acid-catalyzed BGs. Basic catalysis of TiBGs prevents crystalline TiO2 domain formation, which was instead consistently observed in TiBGs synthesized under acidic catalysis. These findings help the design of BGs for applications where ion release needs to be enhanced even in the presence of dopants that slow down HCA formation, and of BGs with specific properties, e.g. TiO2-containing BGs with potential bactericidal activity. STATEMENT OF SIGNIFICANCE: Bioactive glasses (BGs) bond with bone by dissolving and forming hydroxycarbonate apatite (HCA) on their surface, offering applications in medicine and dentistry. BG's network connectivity influences its dissolution rate, and hence HCA formation. While solution-gelation (sol-gel) is commonly used for BG production, the effect of sol gel synthesis parameters on HCA formation remains unexplored. We studied the relationship between synthesis parameters (water-to-alkoxide ratio (Rw), catalyst, and dopant ions, particularly titanium), BG network connectivity, and HCA formation. We find that increasing Rw with any catalyst enhances HCA formation, particularly in glasses with high network connectivity. This understanding allows tailoring BG synthesis for different applications, e.g. those requiring doping with ions that increase network connectivity and fills a crucial gap in BG literature.

Soil Microbial Communities Altered by Titanium Ions in Different Agroecosystems of Pitaya and Grape.

Titanium (Ti) is an element beneficial to plant growth. Application of titanium to roots or leaves at low concentrations can improve crop yield and performance. However, the effect of titanium ions on the bulk soil microbial community of planted crops remains unclear. This study aimed to explore the effects of titanium on soil bacterial and fungal communities. Field surveys were conducted to determine the effect of titanium ions on bulk soil microbial communities in pitaya and grape plantations of Panzhihua and Xichang areas, respectively. Full-length 16S rRNA and internal transcribed spacer (ITS) amplicon sequencing were performed using PacBio Sequel to further explore the composition and structure of soil microbiota. The application of titanium ions significantly altered the composition and structure of soil microbiota. Root irrigation with titanium ions in pitaya gardens reduced the diversity of soil fungi and bacteria. However, the decline in bacterial diversity was not statistically significant. Meanwhile, foliar spray of titanium ions on grapes greatly reduced the soil microbial diversity. The bulk soil microbiota had a core of conserved taxa, and titanium ions significantly altered their relative abundances. Furthermore, the application of titanium increased the interaction network of soil fungi and bacteria compared with the control group. Thus, titanium ions potentially improve the stability of the soil microbial community. IMPORTANCE Pitaya and grape are important cash crops in the Panzhihua and Xichang areas, respectively, where they are well adapted. Titanium is a plant growth-promoting element, but the interaction between titanium and soil microorganisms is poorly understood. Titanium ions are still not widely used for growing pitaya and grape in the two regions. Thus, we investigated the effects of titanium ions on soil microbial communities of the two fruit crops in these two regions. Microbial diversity decreased, and the community structure changed; however, the addition of titanium ions enhanced cooccurrence relationships and improved the stability of the community. This study provides a basis for the importance of titanium ion application in crop cultivation.

Analysis of serum levels of titanium and aluminium ions in patients with early onset scoliosis operated upon using the magnetic growing rod-a single centre study of 14 patients.

STUDY DESIGN: A cross-sectional retrospective Level 3 study. OBJECTIVE: To study the serum levels of Titanium and Aluminium ions in patients operated using the magnetically controlled growing rod (MCGR) system. 14 consecutive patients of early onset scoliosis with varying etiology managed with MCGR system with a minimum follow-up of 24 months were selected for the study. The group consisted of two boys (14.3%) and 12 girls (85.7%). The average age of the patients at the time of surgery was 10.4 years (5-15 years). The average period of follow-up was 43.7 months (28-79 months). After informed consent of the subjects and their caretakers, serum levels of titanium and aluminium were measured. These levels were then assessed with regards to the number of screws used, number of distractions and complications. METHODS: The concentration of titanium and aluminium ions in the serum was measured using high resolution inductively coupled plasma mass spectrometry. RESULTS: For the sake of ease of assessment, patients were divided into three etiology-based groups-idiopathic (n = 6), neuromuscular (n = 2) and syndromic (n = 6). The mean serum titanium level was 15.9 µg/L (5.1-28.2 µg/L) while that of aluminium was 0.1 µmol/L (0.1-0.2 µmol/L). Of the 14 patients, 2 (14.2%) patients had mechanical failure (actuator pin dysfunction), 3 (21.4%) had rod breakage requiring revision surgery and one patient (7.1%) had surgical site infection managed with appropriate antibiotics. Patients undergoing revision for rod breakage did not show any metallosis of the tissues during surgery. CONCLUSION: Analysis of patients with scoliosis operated using the magnetic growing rod system concludes that it is accompanied by presence of titanium in the blood but whether clinically significant or not needs to be ascertained by comparison of preoperative and postoperative blood concentrations of the titanium ions in individual subjects. The aluminium ion concentration remains within normal limits. Though implant malfunction may raise the titanium levels in the blood, its clinical significance needs to be determined. The aluminium levels are not affected irrespective to the presence or absence of complications. The long-term effects of raised titanium levels in the blood also warrant further prospective studies designed for precise and deeper analyses.

Role of the Hippo-YAP/NF-κB signaling pathway crosstalk in regulating biological behaviors of macrophages under titanium ion exposure.

The presence of metal ions, such as titanium (Ti) ions, is toxic to adjacent tissues of implants. Indeed, Ti ions may induce an inflammatory response through the NF-κB pathway, thus causing damage to soft and hard tissues. The involvement of Yes-associated protein (YAP), a key factor of the Hippo pathway, in an immuno-inflammatory response has been confirmed, whereas its role in Ti ion-mediated inflammation has not been elucidated. Therefore, this study aimed to investigate the role of signal crosstalk between the Hippo/YAP and NF-κB signaling pathways in the pro-inflammatory effect of Ti ions on macrophages. In our work, RAW264.7 cells were cocultured with Ti ions. The migration capacity of macrophages under Ti ion exposure was measured by transwell assay. Western blot analysis was used to detect the expressions of related proteins. Polymerase chain reaction was used to evaluate the expression of pro-inflammatory cytokines. The nucleus translocation of YAP and P65 was visualized and analyzed via immunofluorescence staining. The results showed that the migration of macrophages was promoted under Ti ion exposure. Ten parts per million Ti ions induced nuclear expression of YAP and activated the NF-κB pathway, which finally upregulated the expression of pro-inflammatory cytokines in macrophages. Moreover, the inhibition of the NF-κB pathway rescued the reduction of YAP expression under Ti ion exposure. Most importantly, the overexpression of YAP exacerbated the inflammatory response mediated by Ti ions through the NF-κB pathway. In summary, this study explored the mechanism of Hippo-YAP/NF-κB pathway crosstalk involved in the regulation of macrophage behaviors under Ti ion exposure.

Phosphoric acid functionalized magnetic sorbents for selective enrichment of TiO2 nanoparticles in surface water followed by inductively coupled plasma mass spectrometry detection.

Phosphoric acid functionalized superparamagnetic iron oxide was synthesized, and different adsorption behavior of TiO2 NPs and titanium ions on it was found. By means of dispersion-corrected density functional theory (DFT-D), the adsorption mechanism of TiO2 NPs and titanium ions on the functionalized sorbents was explored, and the difference in the adsorption behavior was attributed to the different deprotonated forms of phosphates and the competitive adsorption of OH- anion with respect to either TiO2 NPs or aqueous titanium ions. Based on the different adsorption performance of phosphoric acid functionalized sorbents for TiO2 NPs and titanium ions under pH 3, a method by combining magnetic solid phase extraction (MSPE) with inductively coupled plasma mass spectrometry (ICP-MS) was established for the selective quantification of trace TiO2 NPs in environmental water. Under the optimal experimental conditions, the detection limit of TiO2 NPs was 17 ng/L with an enrichment factor of 400. The developed MSPE-ICPMS method was applied to the detection of trace TiO2 NPs in the Yangtze River and the East Lake water. Sub µg/L level of TiO2 NPs was found in the tested water samples, and recoveries of 91-110% and 90-110% were obtained for TiO2 NPs at three concentration levels in spiked water samples, respectively. The developed method exhibited high adsorption capacity and low detection limit for target TiO2 NPs, and was demonstrated with great potential for monitoring TiO2 NPs in the environment.

Titanium Ions Inhibit the Bacteria in Vase Solutions of Freshly Cut Gerbera jamesonii and Extend the Flower Longevity.

Titanium ions significantly promote plant growth, but the mechanism is still unclear. Cut flowers are ideal materials for the study of plant growth and senescence. In this study, freshly cut Gerbera jamesonii were used to study the effects of titanium ions (8 mg/L) on the flower longevity. Flowering observation showed that the gerbera vase life was significantly prolonged in the presence of titanium ions. Plate colony counts showed that the amounts of bacteria in the vase solution of the control group were approximately 1700 times more than that of titanium ion treatment group. High-throughput sequencing was used to determine the sequences of 16S rRNA gene V3-V4 variable regions of the vase solutions to analyze bacterial species, their average proportions, and absolute abundance. The results showed that the titanium ions reduced the entire bacterial counts as well as altered the absolute abundance of different bacterial species in the vase solution. The most prevalent bacteria were mainly Enterobacteriaceae, Pseudomonas veronii, Pseudomonas sp., Delftia sp., Agrobacterium sp., Sphingobacterium multivorum, Acinetobacter johnsonii, and Clostridiaceae. In combination with plate colony counts, we demonstrated that all the bacterial growths were significantly inhibited by titanium ions, regardless of their average proportions increased or decreased. These results showed that titanium ions could extend effectively the longevity of gerberas and possess the broad-spectrum antibacterial properties. This study provides a basis for further mechanism exploration of titanium ions action and its applications in cut flower preservation and agricultural production.

Degradation of nitrobenzene wastewater in an acidic environment by Ti(IV)/H2O2/O3 in a rotating packed bed.

The rotating packed bed (RPB) as a continuous flow reactor performs very well in degradation of nitrobenzene wastewater. In this study, acidic nitrobenzene wastewater was degraded using ozone (O3) combined with hydrogen peroxide and titanium ions (Ti(IV)/H2O2/O3) or using only H2O2/O3 in a RPB. The degradation efficiency of nitrobenzene by Ti(IV)/H2O2/O3 is roughly 16.84% higher than that by H2O2/O3, and it reaches as high as 94.64% in 30 min at a H2O2/O3 molar ratio of 0.48. It is also found that the degradation efficiency of nitrobenzene is significantly affected by the high gravity factor, H2O2/O3 molar ratio, and Ti(IV) concentration, and it reaches a maximum at a high gravity factor of 40, a Ti(IV) concentration of 0.50 mmol/L, a pH of 4.0, a H2O2/O3 molar ratio of 0.48, a liquid flow rate of 120 L/h, and an initial nitrobenzene concentration of 1.22 mmol/L. Both direct ozonation and indirect ozonation are involved in the reaction of O3 with organic pollutants. The indirect ozonation due to the addition of different amounts of tert-butanol (·OH scavenger) in the system accounts for 84.31% of the degradation efficiency of nitrobenzene, indicating that the nitrobenzene is dominantly oxidized by ·OH generated in the RPB-Ti(IV)/H2O2/O3 process. Furthermore, the possible oxidative degradation mechanisms are also proposed to better understand the role of RPB in the removal of pollutants. Graphical abstract ᅟ.

Can degradation products released from dental implants affect peri-implant tissues?

This study aimed to assess the literature available on the effects, on peri-implant tissues, of degradation products released from dental implants as a consequence of therapeutic treatment for peri-implantitis and/or of wear-corrosion of titanium. A literature review of the PubMed medline database was performed up to December 31, 2016. The following search terms were used: "titanium wear and dental implant"; "titanium corrosion and dental implant"; "bio-tribocorrosion"; "peri-implantitis"; "treatment of peri-implantitis"; "titanium particles release and dental implant"; and "titanium ion release and dental implant". The keywords were applied to the database in different combinations without limits of time period or type of work. In addition, the reference lists of relevant articles were searched for further studies. Seventy-nine relevant scientific articles on the topic were retrieved. The results showed that pro-inflammatory cytokines, infiltration of inflammatory response cells and activation of the osteoclasts activity are stimulated in peri-implant tissues in the presence of metal particles and ions. Moreover, degenerative changes were reported in macrophages and neutrophils that phagocytosed titanium microparticles, and mutations occurred in human cells cultured in medium containing titanium-based nanoparticles. Debris released from the degradation of dental implants has cytotoxic and genotoxic potential for peri-implant tissues. Thus, the amount and physicochemical properties of the degradation products determine the magnitude of the detrimental effect on peri-implant tissues.

Induction of Chronic Inflammation and Altered Levels of DNA Hydroxymethylation in Somatic and Germinal Tissues of CBA/CaJ Mice Exposed to (48)Ti Ions.

Although the lung is one of the target organs at risk for cancer induction from exposure to heavy ions found in space, information is insufficient on cellular/molecular responses linked to increased cancer risk. Knowledge of such events may aid in the development of new preventive measures. Furthermore, although it is known that germinal cells are sensitive to X- or γ-rays, there is little information on the effects of heavy ions on germinal cells. Our goal was to investigate in vivo effects of 1 GeV/n (48)Ti ions (one of the important heavy ions found in the space environment) on somatic (lung) and germinal (testis) tissues collected at various times after a whole body irradiation of CBA/CaJ mice (0, 0.1, 0.25, or 0.5 Gy, delivered at 1 cGy/min). We hypothesized that (48)Ti-ion-exposure induced damage in both tissues. Lung tissue was collected from each mouse from each treatment group at 1 week, 1 month, and 6 months postirradiation. For the testis, we collected samples at 6 months postirradiation. Hence, only late-occurring effects of (48)Ti ions in the testis were studied. There were five mice per treatment group at each harvest time. We investigated inflammatory responses after exposure to (48)Ti ions by measuring the levels of activated nuclear factor kappa B and selected pro-inflammatory cytokines in both tissues of the same mouse. These measurements were coupled with the quantitation of the levels of global 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC). Our data clearly showed the induction of chronic inflammation in both tissues of exposed mice. A dose-dependent reduction in global 5hmC was found in the lung at all time-points and in testes collected at 6 months postirradiation. In contrast, significant increases in global 5mC were found only in lung and testes collected at 6 months postirradiation from mice exposed to 0.5 Gy of 1 GeV/n (48)Ti ions. Overall, our data showed that (48)Ti ions may create health risks in both lung and testicular tissues.

Efeito de partículas metálicas liberadas dos implantes dentários sobre os tecidos peri-implantares / The effect of metallic particles released from dental implants on peri-implant tissues

Objetivo: realizar uma revisão da literatura sobre os efeitos das partículas metálicas liberadas nos tecidos peri-implantares, como consequência do uso de técnicas terapêuticas empregadas no tratamento de doenças peri-implantares e/ou pela degradação do implante. Material e métodos: foi efetuado um levantamento bibliográfico através de pesquisas em livros, textos e base de dados PubMed entre o período de 1977 a 2015. Os seguintes termos foram explorados: "titanium wear e dental implant", "titanium corrosion e dental implant", "bio-tribocorrosion", "peri-implantitis", "treatment of peri-implantitis", "titanium particles release e dental implant", "titanium ion release e dental implant", e "tratamento da peri-implantite". Foram selecionados 91 artigos científicos, definidos como os mais relevantes sobre o tema. Resultados: há liberação de citocinas pró-inflamatórias, infiltrado de células de resposta inflamatória e ativação dos osteoclastos nos tecidos peri-implantares, em contato com partículas e íons metálicos. Ainda, foram reportadas alterações degenerativas em macrófagos, e neutrófilos que fagocitaram micropartículas de titânio, bem como mutações em células humanas em cultura contendo nanopartículas de TiO2. Conclusão: partículas metálicas liberadas a partir do sistema de implantes têm potencial citotóxico e genotóxico, e são capazes de induzir resposta inflamatória nos tecidos peri-implantares.

Objective: to review the literature regarding the effect of metallic particles released at the peri-implant tissues, as a consequence of therapeutic techniques to treat peri-implant diseases and/or by implant degradation. Material and methods: a search was made at the PubMed from 1977 to 2015. The following terms were combined: titanium wear and dental implant", "titanium corrosion and dental implant", "bio-tribocorrosion", "peri-implantitis", "treatment of peri-implantitis", "titanium particles release and dental implant", "titanium ion release and dental implant", and "peri-implant treatment". 91 scientific articles were selected to define the most relevant topics. Results: there is pro-infl ammatory cytokine release, inflammatory cell infiltrate and osteoclast activation over the peri-implant tissues contacting particles and metallic ions. Also, degenerative changes on macrophages and neutrophils engulfing titanium microparticles were reported, as well as mutations on culture human cells containing TiO2 nanoparticles. Conclusion: metallic particles released from the dental implant system can be cytotoxic and genotoxic in nature and to induce inflammatory response at the peri-implant tissues.