Siliplant1 B-domain precipitates silica spheres, aggregates, or gel, depending on Si-precursor to peptide ratios.

Silica is extensively deposited by plants, however, only little is known about the molecular control over this process. Siliplant1 is the only known plant protein to precipitate biosilica. The protein contains seven repeats made of three domains. One of the domains exhibits a conserved sequence, which catalyzes silica precipitation in vitro. Here, silica was synthesized by the activity of a peptide carrying this conserved sequence. Infrared spectroscopy and thermal gravimetric analyses showed that the peptide was bound to the mineral. Scanning electron microscopy showed that silica-peptide particles of 22 ± 4 nm aggregated to spherical structures of 200-300 nm when the ratio of silicic acid to the peptide was below 183:1 molecules. When the ratio was about 183:1, similar particles aggregated into irregular structures, and silica gel formed at higher ratios. Solid-state NMR spectra indicated that the irregular aggregates were richer in Si-O-Si bonds as well as disordered peptide. Our results suggest that the peptide catalyzed the condensation of silicic acid and the formation of ∼20 nm particles, which aggregated into spheres. Excess of the peptide stabilized surface Si-OH groups that prevented spontaneous Si-O-Si bonding between aggregates. Under Si concentrations relevant to plant sap, the peptide and possibly Siliplant1, could catalyze nucleation of silica particles that aggregate into spherical aggregates.

Ortho-silicic Acid Plays a Protective Role in Glucocorticoid-Induced Osteoporosis via the Akt/Bad Signal Pathway In Vitro and In Vivo.

Glucocorticoid-induced osteoporosis (GIOP) has been the most common form of secondary osteoporosis. Glucocorticoids (GCs) can induce osteocyte and osteoblast apoptosis. Plenty of research has verified that silicon intake would positively affect bone. However, the effects of silicon on GIOP are not investigated. In this study, we assessed the impact of ortho-silicic acid (OSA) on Dex-induced apoptosis of osteocytes by cell apoptosis assays. The apoptosis-related genes, cleaved-caspase-3, Bcl-2, and Bax, were detected by western blotting. Then, we evaluated the possible role of OSA on osteogenesis and osteoclastogenesis with Dex using Alizarin red staining and tartrate-resistant acid phosphatase (TRAP) staining. We also detected the related genes by quantitative reverse-transcription polymerase chain reaction (qRT-PCR) and western blotting. We then established the GIOP mouse model to evaluate the potential role of OSA in vivo. We found that OSA showed no cytotoxic on osteocytes below 50 µM and prevented MLO-Y4 from Dex-induced apoptosis. We also found that OSA promoted osteogenesis and inhibited osteoclastogenesis with Dex. OSA had a protective effect on GIOP mice via the Akt signal pathway in vivo. In the end, we verified the Akt/Bad signal pathway in vitro, which showed the same results. Our finding demonstrated that OSA could protect osteocytes from apoptosis induced by GCs both in vitro and in vivo. Also, it promoted osteogenesis and inhibited osteoclastogenesis with the exitance of Dex. In conclusion, OSA has the potential value as a therapeutic agent for GIOP.

Alleviating Drought Stress in Brassica juncea (L.) Czern & Coss. by Foliar Application of Biostimulants-Orthosilicic Acid and Seaweed Extract.

Agricultural productivity is negatively impacted by drought stress. Brassica is an important oilseed crop, and its productivity is often limited by drought. Biostimulants are known for their role in plant growth promotion, increased yields, and tolerance to environmental stresses. Silicon in its soluble form of orthosilicic acid (OSA) has been established to alleviate deteriorative effects of drought. Seaweed extract (SWE) also positively influence plant survival and provide dehydration tolerance under stressed environments. The present study was conducted to evaluate the efficacy of OSA and SWE on mitigating adverse effects of drought stress on Brassica genotype RH-725. Foliar application of OSA (2 ml/L and 4 ml/L) and SWE of Ascophyllum nodosum (3 ml/L and 4 ml/L) in vegetative stages in Brassica variety RH 725 under irrigated and rainfed condition revealed an increase in photosynthetic rate, stomatal conductance, transpirational rate, relative water content, water potential, osmotic potential, chlorophyll fluorescence, chlorophyll stability index, total soluble sugars, total protein content, and antioxidant enzyme activity; and a decrease in canopy temperature depression, proline, glycine-betaine, H2O2, and MDA content. Application of 2 ml/L OSA and 3 ml/L SWE at vegetative stage presented superior morpho-physiological and biochemical characteristics and higher yields. The findings of the present study will contribute to developing a sustainable cropping system by harnessing the benefits of OSA and seaweed extract as stress mitigators.

Fluorosilicic acid and cotinine, separately and in combination, induce genotoxicity and telomeric reduction in human osteoblast cell line MG63.

Skeletal fluorosis is a severe case in which bone deformations and bone tissue weakening occur due to excessive fluorine deposition. Recently, data on smoking have been published that smoke constituents can indirectly influence bone mass and interfere in the metabolism of fluorides in humans. Thus, the present in vitro study aimed to assess the genetic instability in human osteoblast MG63 cells exposed to fluorosilicic acid (FA) and cotinine (COT), separately and in combination, in concentrations found in human plasma. For this, cell cytotoxicity was performed by MTT assay; DNA damage was performed by alkaline comet assay (CA), modified by repair endonucleases (+FPG); micronuclei test (MN) using CBMN-Cyt assay; and telomere length (TL) by qPCR in MG63 cells. No cytotoxicity was observed for all concentrations tested in this study. Alkaline CA results showed a significant increase in DNA damage at all FA concentrations (0.03125-0.300 mg/L), in the two highest concentrations of COT (125 and 250 ng/mL), and the highest concentration of FA+COT (0.300 mg/L+250 ng/mL). Alkaline CA+FPG test was used to detect oxidized nucleobases, which occurred at the two highest concentrations of FA, COT, and FA+COT. Micronuclei test showed an increase in the frequency of MN at all concentrations of FA (0.075-0.300 mg/L) except in the lowest concentration (0.03125 mg/L), in the two highest concentrations of COT (125 and 250 ng/mL), and all concentrations of FA+COT. There was no significant difference in nuclear division index, binucleated cells, nucleoplasmic bridge, and nuclear bud. A TL reduction was observed in cells treated with the highest concentrations of FA alone (0.300 mg/L) and FA+COT (0.300 mg/L+250 ng/mL). Finally, our study showed that FA and COT (mainly alone) at concentrations found in human plasma induced oxidative damage and genetic instability in human osteoblast cells.

Multi-component removal of Pb(II), Cd(II), and As(V) over core-shell structured nanoscale zero-valent iron@mesoporous hydrated silica.

The application of nanomaterials for the removal of heavy metals has received a great deal of attention because of their high efficiencies in the environment. But it is difficult to remove multiple heavy metals simultaneously with high efficiency and stability. Herein, the core-shell structured nanoscale zero-valent iron (nZVI) encapsulated with mesoporous hydrated silica (nZVI@mSiO2) were prepared for efficient removal of heavy metals including Pb(II), Cd(II), and metalloid As(V). The material prepared uniformly with a high surface area (147.7 m2 g-1) has a nZVI core with the particle size of 20-60 nm and a modified dendritic mesoporous shell of 19 nm. 0.15 g L-1 of the optimal material exhibited an extraordinary performance on removing Cd(II) and the maximum adsorption capacity for Pb(II), Cd(II), and As(V) reached 372.2 mg g-1, 105.2 mg g-1, and 115.2 mg g-1 with a pH value at 5.0, respectively. The dissolved iron during the reaction showed that the mesoporous silica (mSiO2) played an important role in enhancing the stability of nZVI. In addition, the competitive relationship between the coexistence of two heavy metals was discussed and it was found that the removal efficiency of the material for both was improved when Cd(II) and As(V) were removed synergistically.

Abatement of hydrated silica, arsenic, and coexisting ions from groundwater by electrocoagulation using iron electrodes.

The paper deals with the removal of arsenic (As), hydrated silica (HS), and coexisting ions from groundwater by electrocoagulation (EC) using a laboratory-scale up-flow reactor with sacrificial iron anodes (1018 steel, >99% wt. Fe). Natural groundwater, taken in the northern region of Mexico, contained 25.7 µg L-1 As, 237.8 mg L-1 HS, 1.43 mg L-1 F-, 45.0 mg L-1 SO42-, 0.61 mg L-1 PO43-, pH 8.62, and 577 µS cm-1 conductivity. The effect of current densities (4≤j≤8 mA cm-2) and mean linear flow velocities (1.1≤u≤4.6 cm s-1) on the pollutant's removal was systematically addressed. The best EC trial that showed the lowest overall cost and complied with the WHO guideline (<10 µg L-1 As) was obtained at j = 6 mA cm-2 and u = 2.3 cm s-1, reaching residual concentrations of As and HS of 4.6 µg L-1 and 150.0 mg L-1, respectively. A large amount of HS was found after electrolysis; therefore, a second EC was applied to reduce the HS concentration further. This time, residual concentrations of HS and As of 37.0 mg L-1 and 1.2 µg L-1 were obtained, with electrolytic energy consumption and overall cost of EC of 0.872 kWh m-3 and 0.178 USD m-3, respectively. XRF, EDS, XRD, and FTIR analyzes on flocs indicate that hydrated silica reacts with iron, forming iron silicates with divalent cations as flocs. Arsenic and PO43- are abated by adsorption on flocs. The modest removal of F- and SO42- (44% and 12%, respectively) is due to its weak adsorption on flocs.

Inhibitory effects of orthosilicic acid on osteoclastogenesis in RANKL-stimulated RAW264.7 cells.

Numerous studies have reported on the positive effects of silicon (Si) on bone metabolism, particularly on the stimulatory effects of Si on osteoblast cells and on bone formation. Inhibitory effects of Si on osteoclast formation and bone resorption have also been demonstrated in vitro and are suggested to be mediated indirectly via stromal and osteoblast cells. Direct effects of Si on osteoclasts have been less studied and mostly using soluble Si, but no characterisation of the Si treatment solutions are provided. The aims of the present study were to (a) further investigate the direct inhibitory effects of Si on osteoclastogenesis in RANKL-stimulated RAW264.7 cells, (b) determine at what stage during osteoclastogenesis Si acts upon, and (c) determine if these effects can be attributed to the biologically relevant soluble orthosilicic acid specie. Our results demonstrate that silicon, at 50 µg/ml (or 1.8 mM), does not affect cell viability but directly inhibits the formation of TRAP+ multinucleated cells and the expression of osteoclast phenotypic genes in RAW264.7 cells. The inhibitory effect of Si was clearly associated with the early stages (first 24 hr) of osteoclastogenesis. Moreover, these effects can be attributed to the soluble orthosilicic acid specie.

Fluorosilicic acid induces DNA damage and oxidative stress in bone marrow mesenchymal stem cells.

Excess fluoride in water can produce changes in tooth enamel mineralization and lead to diseases such as dental or skeletal fluorosis. The present study aimed to assess the genotoxic effects, oxidative stress, and osteoblastic mineralization induced by fluorosilicic acid (FA) in murine bone marrow-derived mesenchymal stem cells (BM-MSCs). BM-MSCs were isolated from the femurs and tibias of rats and cultured under standard conditions. Cells exposure occurred for 3, 7, 14, and 21 days to different concentrations of FA (0.6-9.6 mg/L). Cytotoxicity was observed in 14 and 21 days of exposure for all concentrations of FA (cell proliferation below 60%), and for 3 and 7 days, in which the proliferation was above 80%. Alkaline comet assay results demonstrated significant increased damage at concentrations of 0.3-2.4 mg/L, and the micronucleus test showed increased rates for micronucleus (1.2-2.4 mg/L) and nuclear buds (NBUDs) (0.3-2.4 mg/L) (P < 0.05/Dunnett's test). An alkaline comet assay modified by repair endonuclease (FPG) was used to detect oxidized nucleobases, which occurred at 0.6 mg/L. The oxidative stress was evaluated by lipid peroxidation (TBARS) and antioxidant activity (TAC). Only lipid peroxidation was increased at concentrations of 0.6 mg/L and 1.2 mg/L (P < 0.001/Tukey's test). The osteogenesis process determined the level of extracellular matrix mineralization. The mean concentration of Alizarin red increased significantly in 14 days at the 0.6 mg/L concentration group (P < 0.05/Tukey's test) compared to the control group, and a significant difference between the groups regarding the activity of alkaline phosphatase (ALP) was observed. Unlike other studies, our results indicated that FA in BM-MSCs at concentrations used in drinking water induced genotoxicity, oxidative stress, and acceleration of bone mineralization.

Iron reduction and diopside-based glass ceramic preparation based on mineral carbonation of steel slag.

In this article, a new process for treating steel slag and CO2 simultaneously and preparing calcium carbonate, metallic iron, and glass ceramics without wastewater or gas production is proposed. The reduction of iron and preparation of diopside glass ceramics are studied in this paper, and the results show that the carbon thermal reduction product of the original slag does not reach its melting point, and the slag and iron are well separated in the samples containing the leached steel slag and added silica. Part of the parent glass is converted into a glass ceramic after heat treatment, and the crystalline phases of samples are melilite, diopside, and partial melilite, and diopside and anorthite, respectively. The crystallization activation energy of the best sample in this article is E = 660.664 kJ/mol. The Avrami indices calculated at different heating rates are all less than 3, which indicates that the crystallization mode of the glass involves surface crystallization. This finding is consistent with the results for the prepared glass ceramics.

Ortho-silicic Acid Inhibits RANKL-Induced Osteoclastogenesis and Reverses Ovariectomy-Induced Bone Loss In Vivo.

Numerous experiments in vitro and in vivo have shown that an appropriate increase intake of silicon can facilitate the synthesis of collagen and its stabilization and promote the differentiation and mineralization of osteoblasts. In this study, we examined whether ortho-silicic acid restrains the differentiation of osteoclast through the receptor activator of nuclear factor κB ligand (RANKL)/receptor activator of nuclear factor κB (RANK)/osteoprotegerin (OPG) signaling pathway by investigating its effect in vitro and in vivo. Bone marrow macrophage (BMM) cells were isolated and cultured with or without ortho-silicic acid, and then TRAP staining and immunofluorescence were performed to detect the differentiation of osteoclast. The RANKL-induced osteoclast marker gene and protein expression including c-Fos, nuclear factor of activated T cells cl (NFATcl), tumor necrosis factor receptor-associated factor 6 (TRAF6), nuclear factor kappa B P50 (NF-κB P50), NF-κB P52, RANK, integrin ß3, cathepsin K (CTSK), DC-STAMP, and TRAP were quantitatively detected by western blot and RT-PCR. Ovariectomized (OVX) rats were injected with ortho-silicic acid (OVX+Si group) and normal saline (OVX group), and sham-operated rats were injected with normal saline (Sham group). And micro-CT, H&E, and TRAP staining, ELISA, and western blot were performed. Ortho-silicic acid could inhibit the differentiation of osteoclast, and the marker genes and proteins were decreased. The OVX-induced bone loss could be reversed by ortho-silicic acid. Our finding demonstrated that ortho-silicic acid suppresses RANKL-induced osteoclastogenesis and has potential value as a therapeutic agent for OVX-induced bone loss.

Ortho-silicic acid enhances osteogenesis of osteoblasts through the upregulation of miR-130b which directly targets PTEN.

AIMS: Osteoporosis is considered a common skeletal disease. Ortho-silicic acid has been found to enhance the osteogenic differentiation of osteoblasts. However, the molecular mechanism of osteogenesis induced by ortho-silicic acid is still undefined totally. MicroRNAs (miRs) play a key role in osteogenesis of osteoblasts. This study investigated the role of miR-130b in promoting osteogenesis induced by ortho-silicic acid. MAIN METHODS AND KEY FINDINGS: In this study, we found ortho-silicic acid enhanced osteogenesis of osteoblasts in vitro and promoted preventing and treating osteoporosis in vivo. Furthermore, the expression of miR-130b increased under application of ortho-silicic acid. In vitro, experiments demonstrated miR-130b overexpression or inhibition significantly promoted or suppressed osteogenic differentiation of osteoblasts under application of ortho-silicic acid, respectively. Consistently, downregulation of miR-130b in ovariectomy (OVX) rats dropped off the beneficial effect of ortho-silicic acid against bone loss. Mechanistically, we identified phosphatase and tensin homologue deleted on human chromosome 10 (PTEN) as the direct target of miR-130b during osteogenesis induced by ortho-silicic acid. SIGNIFICANCE: In conclusion, our findings reveal that ortho-silicic acid promotes the osteogenesis of osteoblasts mediated by the miR-130b/PTEN signaling axis, which identifies a new target to prevent and treat osteoporosis.

Silicon reduces the iron uptake in rice and induces iron homeostasis related genes.

Gramineous plants take up silicon (Si) that enhances the formation of exodermal Casparian bands (CBs) in the roots of rice (Oryza sativa L.). Furthermore, it is known that Si supply reduces the concentration of Fe in rice shoots. We hypothesized that the Si-enhanced CB formation in the exodermis reduces in the flux of Fe in the apoplast and the uptake of Fe loaded deoxymugineic acid. Thus, the effect of silicic acid supply at varied Fe concentrations and Fe forms was investigated in nutrient solution. The Fe concentrations in the shoot and apoplastic Fe concentrations in the root were determined and an Affymetrix GeneChip experiment was carried out together with qRT-PCR measurements for observation of transcriptomic reactions. Additionally, the Fe uptake of an overexpression mutant of OsABCG25 with an enhanced exodermal CB formation was investigated. The application of silicic acid reduced the Fe concentrations in shoot DM independently of the supplied Fe concentration and Fe form. As a reaction to the Fe shortage, the full cascade of Fe-homeostasis-related genes in the roots was upregulated. Silicic acid supply also decreased the apoplastic Fe concentrations in roots. In addition, an overexpression mutant of OsABCG25 with an enhanced CB formation showed a reduced uptake of Fe in excess Fe conditions. The results suggest that the Si-induced CB formation in the exodermis hampers the flux of Fe into the apoplast of the cortex and, thus, Fe uptake of rice grown in nutrient solution which is reflected in the upregulation of Fe homeostasis-related genes.

Biocompatibility and bioactivity of hardystonite-based nanocomposite scaffold for tissue engineering applications.

Bone injury, especially bone damages due to the removal of bone tumors, is one of the most important issues in the field of therapeutic research in tissue engineering applications. In this context, ceramic-based composites have attracted widespread attention since they have mechanical properties close to the natural bone, hence providing similar conditions for the extracellular matrix (ECM). Thus, in this study, hardystonite and diopside (HT-Di) scaffolds containing various diopside amounts from 5 to 25 wt% were prepared by the space holder method. The results revealed that the fabricated scaffolds contain 70%-75% porosity with a pore size of 300-500 µm and a compressive strength of about 0.54 to 1.71 MPa which is perfectly in the range of the compressive strength of the sponge bone. Noticeably, great apatite formation ability was observed in the scaffold with diopside, although the scaffold without diopside showed poor bioactivity. The MTT assay depicted that the inclusion of diopside into hardystonite scaffold resulted in dramatic enhancement in the MG-63 cell viability. Moreover, the scaffold with diopside offered greater cell attachment and spreading than the scaffold without diopside. Therefore, the synergistic effects of the scaffold with 12.5 wt% of diopside, including great mechanical characteristic, excellent bioactivity, and appealing biocompatibility enable it to be an appealing choice for bone tissue engineering applications.

A simplified protocol to determine total fluoride concentration in NaF/silica-based toothpastes

Aim: To determine total fluoride (TF) concentration in Na2FPO3/Ca-based toothpastes, using fluoride ion selective electrode (F-ISE) by the direct technique, it is necessary to use acid (Ac+) to hydrolyze the FPO32- ion and to dissolve insoluble fluoride salts bound to the abrasive. For NaF/silica-based toothpastes, the use of acid is not necessary (Ac-) and a simplified protocol could be followed. Methods: Thus, we evaluated TF concentration in seven brands of NaF/silica-based toothpastes, following the validated conventional Cury's protocol (Ac+) or a simplification of this protocol (Ac-).Fluoride was analyzed with ISE calibrated with fluoride standard solutions prepared in the same conditions as the samples (Ac+ or Ac-). Results: The mean (±SD; n=21) of TF concentrations (µg F/g) found by Ac+ (971.3±191.2) and Ac- (982.4±201.3) protocols were not statistically different (t test, p=0.22). The TF concentrations found agree with those declared by the manufacturers, except for one toothpaste imported from China. Conclusion: The findings suggest that the determination of fluoride in NaF/silica-based toothpastes can be accurately made using a simplified protocol of analysis

Biological aspects and feeding behavior of cotton aphid in watermelon cultivars submitted to silicon application / Aspectos biológicos e comportamento alimentar do pulgão-do-algodoeiro em cultivares de melancia submetidas à aplicação de silício

This research aimed to evaluate the biological aspects and the feeding behavior of Aphis gossypii in watermelon cultivars submitted to silicon application. The experiment was conducted at the Institute of Education, Agriculture and Environment of the Federal University of Amazonas, Humaitá, Brazil. The experimental design was completely randomized in a 2×3 factorial (with and without silicon; cultivars Crimson Sweet, Fairfax and Charleston), with ten replications. The application of silicic acid (1%) was carried out directly on the substrate using dose equivalent to 1 ton SiO2·ha-1, 25 days after sowing. The rearing of aphids was kept in cucumber plants, cultivar Caipira. Insect biology tests were conducted to evaluate the duration of the prereproductive, reproductive and postreproductive periods, longevity, number of nymphs, and feeding behavior using the honeydew secretion technique. Analysis of variance was performed using the statistical program SISVAR and the means were compared by the F and Scott­Knott test (p ≤ 0.05). The silicon application to watermelon plants affects the reproduction and feeding of A. gossypii. The watermelon plants cultivar Crimson Sweet treated with silicon has high resistance to feeding by A. gossypii.(AU)

Nesta pesquisa objetivou-se avaliar os aspectos biológicos e o comportamento alimentar de Aphis gossypii em cultivares de melancia submetidas à aplicação de silício. O experimento foi conduzido no Instituto de Educação, Agricultura e Ambiente da Universidade Federal do Amazonas, Humaitá, Brasil. Utilizaram-se o delineamento experimental inteiramente ao acaso e o esquema fatorial 2×3 (sem silício e com silício; cultivares Crimson Sweet, Fairfax e Charleston), com dez repetições. A aplicação do ácido silícico (1%) foi realizada diretamente no substrato, com dose equivalente a 1 ton SiO2·ha-1, 25 dias após a semeadura. Os pulgões da criação foram mantidos em plantas de pepino, cultivar Caipira. Foram conduzidos ensaios de biologia do inseto para avaliação da duração dos períodos pré-reprodutivo, reprodutivo e pós-reprodutivo, longevidade, número de ninfas e comportamento alimentar por meio da técnica de secreção de honeydew. Realizou-se a análise de variância dos dados utilizando-se o programa estatístico SISVAR e as médias foram comparadas pelo teste de F e Scott­Knott (p ≤ 0,05). A aplicação de silício em plantas de melancia afeta a reprodução e a alimentação de A. gossypii. Plantas de melancia do cultivar Crimson Sweet tratadas com silício apresentam alta resistência à alimentação por A. gossypii.(AU)

Co-incorporation of strontium and fluorine into diopside scaffolds: Bioactivity, biodegradation and cytocompatibility evaluations.

This study focuses on the effect of Sr-, F-, and their co-doping on the structure, biodegradation, bioactivity and cytocompatibility of diopside-based scaffolds, using X-ray diffraction, Raman spectroscopy, field-emission scanning electron microscopy, Archimedes densitometry, inductively coupled plasma spectroscopy, pH-metry, and cell MTT assay. The structural characterization of the scaffolds confirmed the successful incorporation of the dopants into the ceramic. In addition, all the doped scaffolds presented higher apatite-forming ability levels in comparison to the undoped one, where the highest and the least impact of doping on bioactivity belonged to F- and co-doping, respectively. It was found that the biodegradation difference of the scaffolds in terms of principal ions and the chance of F-incorporation into precipitated apatite determine the bioactivity difference of the samples. Osteoblast-like MG-63 cells exhibited the highest and lowest compatibility to the Sr-doped and co-doped scaffolds, respectively. In summary, F- and Sr-doping offered the highest bioactivity and cytocompatibility, respectively, whereas co-doping presented the weakest behaviors comparatively.

Colloidal Dynamics of Freshly Formed Iron Oxides under the Influence of Silicic Acid.

Silicic acid and soluble Fe are among the most abundant components in acid mine drainage. During the oxidation of Fe(II), the interaction between silicic acid and freshly formed Fe oxides might change the colloidal dynamics, altering surface charge properties. However, the effects of silicic acid on colloidal Fe oxides formed from acid mine drainage are not fully understood. In this work, we examined the colloidal dynamics of freshly formed Fe oxides in synthetic acid mine drainage (prepared from FeSO solution) under the effect of silicic acid as a function of changes in pH and ionic strength. The results demonstrate that through adsorption, silicic acid progressively slows oxidation and enhances the dispersion of freshly formed Fe oxides by shifting the surface charge toward more negative values. This effect was most prominent between pH 5 and 9. The current results demonstrate that silicic acid enhances the dispersion and transport of freshly formed Fe oxides and suggest that aggregation-based techniques for the treatment of Fe-rich drainage may require further consideration of this effect.

A Histologic Perspective on Electrical and Thermal Burn-Injured Human Skin.

OBJECTIVE: To analyze specific spectroscopic (FT-Raman) and thermal (limiting oxygen index) aspects of skin samples exposed to electrical injury compared with thermal injury. METHODS: An observational case-control study was conducted at the Dr Stanislaw Sakiel Center for Burns Treatment in Siemianowice, Silesia, Poland. A scanning electron microscope was used to diagnose and illustrate the topography of skin samples from electrical and thermal burns and the morphologic effects on damaged versus undamaged skin surfaces. In particular, researchers attempted to detect spectroscopic and thermal changes at the molecular level, namely, specific biomarkers of tissue degeneration and their regeneration under the influence of the applied modifiers (antioxidants and orthosilicic acid solutions). RESULTS: Modification with L-ascorbic acid and hydrogel of orthosilicic acid caused an increase in the intensity of the amide I Raman peaks, whereas modification with sodium ascorbate and orthosilicic acid resulted in the separation of the band protein side chains (1,440-1,448 cm), which is a part of tissue regeneration. The best result was obtained when the skin was treated with 7% orthosilicic acid (limiting oxygen index, 26%). CONCLUSIONS: Antioxidant treatment may be advantageous in minimizing injury in patients with thermal burns but not always in electrical burns.

A comparative study on biological properties of novel nanostructured monticellite-based composites with hydroxyapatite bioceramic.

In this research, novel monticellite/hydroxyapatite (HA) ceramic composites were successfully prepared by mechanical method. The ability of nanostructured monticellite-based ceramic composites to form a suitable bond to living hard tissues, and stimulate osteoblast-like cells proliferation may be different for various ratios of the reinforcement to monticellite matrix. The differences in physico-chemical characteristics, bone-like apatite formation, cytocompatibility, cell viability and in vitro osteogenic activity of nanostructured monticellite/HA ceramic composites were explored. The surface reactivity and bioactivity of the composite samples were evaluated in vitro in simulated body fluid (SBF). A comparative time- and dose-dependent MTT test showed that the ions release from nanostructured monticellite/HA composites dissolution significantly stimulated cell proliferation and growth than control at a certain concentration range. The cells viability exposed to the composite extract was higher than control and mineral material of bone (HA), illustrating that cytocompatibility was improved due to the presence of magnesium (Mg) and silicon (Si) elements in the composite structure. The comparative results of alkaline phosphatase (ALP) bioactivity assay showed that the osteogenic proliferation of osteoblast-like G292 cell was increased more by the ceramic composites extract than control. These comparative results demonstrated that nanostructured monticellite-based ceramic composites possessed good in vitro bioactivity, cytocompatibility and osteogenic properties, and may be utilized as the promising bioactive materials for bone tissue regeneration and replacement.