Correlative spectroscopy of silicates in mineralised nodules formed from osteoblasts

Physiological silicon incorporation into bone mineral requires orthosilicic acid metabolism to SiO44

Under physiological conditions, the predominant form of bioavailable silicon (Si) is orthosilicic acid (OSA). In this study, given Si's recognized positive effect on bone growth and integrity, we examined the chemical form and position of this natural Si source in the inorganic bone mineral hydroxyapatite (HA). X-ray diffraction (XRD) of rat tibia bone mineral showed that the mineral phase was similar to that of phase-pure HA. However, theoretical XRD patterns revealed that at the levels found in bone, the 'Si effect' would be virtually undetectable. Thus we used first principles density functional theory calculations to explore the energetic and geometric consequences of substituting OSA into a large HA model. Formation energy analysis revealed that OSA is not favourable as a neutral interstitial substitution but can be incorporated as a silicate ion substituting for a phosphate ion, suggesting that incorporation will only occur under specific conditions at the bone-remodelling interface and that dietary forms of Si will be metabolized to simpler chemical forms, specifically [Formula: see text]. Furthermore, we show that this substitution, at the low silicate concentrations found in the biological environment, is likely to be a driver of calcium phosphate crystallization from an amorphous to a fully mineralized state.

Label-Free Time-of-Flight Secondary Ion Mass Spectrometry Imaging of Sulfur-Producing Enzymes inside Microglia Cells following Exposure to Silver Nanowires

There are no methods sensitive enough to detect enzymes within cells, without the use of analyte labeling. Here we show that it is possible to detect protein ion signals of three different H₂S-synthesizing enzymes inside microglia after pretreatment with silver nanowires (AgNW) using time-of-flight secondary ion mass spectrometry (TOF-SIMS). Protein fragment ions, including the fragment of amino acid (C₄H₈N⁺ = 70 amu), fragments of the sulfur-producing cystathionine-containing enzymes, and the Ag⁺ ion signal could be detected without the use of any labels; the cells were mapped using the C₄H₈N⁺ amino acid fragment. Scanning electron microscopy imaging and energy-dispersive X-ray chemical analysis showed that the AgNWs were inside the same cells imaged by TOF-SIMS and transformed chemically into crystalline Ag₂S within cells in which the sulfur-producing proteins were detected. The presence of these sulfur-producing cystathionine-containing enzymes within the cells was confirmed by Western blots and confocal microscopy images of fluorescently labeled antibodies against the sulfur-producing enzymes. Label-free TOF-SIMS is very promising for the label-free identification of H₂S-contributing enzymes and their cellular localization in biological systems. The technique could in the future be used to identify which of these enzymes are most contributory.

Growth performance, meat quality, and bone-breaking strength in broilers fed dietary rice hull silicon

Bone problems have been a key issue that perilously affects broilers' health and welfare, resulting in severe economic loss. The present study was aimed at investigating the influence of dietary rice hull silicon (RHS) on the performance, meat quality, and bone-breaking strength of broilers. One hundred 10-day-old Arbor Acres chicks were used in the study. The birds were divided into 5 groups: one group was kept as the control, and other groups were provided with 2.5, 5.0, 7.5, and 10.0 mg/kg dietary RHS along with their basal diets. Results showed that diets containing various levels of dietary RHS did not adversely affect (P > 0.05) the body weight, feed intake, and feed conversion ratio. Drip loss of thigh meat showed a reduced value in the group supplemented with 7.5 mg/kg dietary RHS compared with other groups (P < 0.05), and the lowest thawing loss was observed in the same group; however, it showed no significant difference among other groups. Similarly, thawing loss of breast meat tended to decrease in the dietary RHS groups and significantly decreased (P < 0.05) in the 7.5 mg/kg RHS group. The shear force of breast meat was higher in all RHS groups, and the highest was in the 7.5 mg/kg RHS group (P < 0.05). Although tibia breaking strength increased significantly (P < 0.05) in the 7.5 mg/kg RHS group (P < 0.05), but a significant difference in femur breaking strength was not found among groups. In conclusion, dietary RHS can be used as a natural mineral supplement for improving bone-breaking strength and reducing drip and thawing loss of breast and thigh muscles, particularly RHS at a level of 7.5 mg/kg in broiler diets.

Nail Damage (Severe Onychodystrophy) Induced by Acrylate Glue: Scanning Electron Microscopy and Energy Dispersive X-Ray Investigations

BACKGROUND

Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) techniques have been used in various fields of medical research, including different pathologies of the nails; however, no studies have focused on obtaining high-resolution microscopic images and elemental analysis of disorders caused by synthetic nails and acrylic adhesives.

METHODS

Damaged/injured fingernails caused by the use of acrylate glue and synthetic nails were investigated using SEM and EDX methods.

RESULTS

SEM and EDX proved that synthetic nails, acrylic glue, and nails damaged by contact with acrylate glue have a different morphology and different composition compared to healthy human nails.

CONCLUSIONS

SEM and EDX analysis can give useful information about the aspects of topography (surface sample), morphology (shape and size), hardness or reflectivity, and the elemental composition of nails.

Static and Dynamic Microscopy of the Chemical Stability and Aggregation State of Silver Nanowires in Components of Murine Pulmonary Surfactant

The increase of production volumes of silver nanowires (AgNWs) and of consumer products incorporating them may lead to increased health risks from occupational and public exposures. There is currently limited information about the putative toxicity of AgNWs upon inhalation and incomplete understanding of the properties that control their bioreactivity. The lung lining fluid (LLF), which contains phospholipids and surfactant proteins, represents a first contact site with the respiratory system. In this work, the impact of dipalmitoylphosphatidylcholine (DPPC), Curosurf, and murine LLF on the stability of AgNWs was examined. Both the phospholipid and protein components of the LLF modified the dissolution kinetics of AgNWs, due to the formation of a lipid corona or aggregation of the AgNWs. Moreover, the hydrophilic proteins, but neither the hydrophobic surfactant proteins nor the phospholipids, induced agglomeration of the AgNWs. Finally, the generation of a secondary population of nanosilver was observed and attributed to the reduction of Ag(+) ions by the surface capping of the AgNWs. Our findings highlight that combinations of spatially resolved dynamic and static techniques are required to develop a holistic understanding of which parameters govern AgNW behavior at the point of exposure and to accurately predict their risks on human health and the environment.

Silicon and boron differ in their localization and loading in bone

Silicon and boron share many similarities, both chemically and biochemically, including having similar effects on bone, although their mechanisms of action are not known. Here we compared the loading of silicon and boron into bone, their localization and how they are influenced by age (growth & development), to obtain further clues as to the biological effects of these elements and, especially, to see if they behave the same or not. Bone samples were obtained from two different studies where female Sprague Dawley rats had been maintained on a normal maintenance diet for up to 43 weeks. Total bone elemental levels were determined by ICP-OES following microwave assisted acid digestion. Silicon and boron levels in the decalcified bones (i.e. the collagen fraction) were also investigated. Silicon and boron showed marked differences in loading and in their localization in bone. Highest silicon and lowest boron concentrations were found in the under-mineralized bone of younger rats and lowest silicon and highest boron concentrations were found in the fully mineralized bone of the adult rat. Overall, however total bone silicon content increased with age, as did boron content, the latter mirroring the increase in calcium (mineral) content of bone. However, whereas silicon showed equal distribution in the collagen and mineral fractions of bone, boron was exclusively localized in the mineral fraction. These findings confirm the reported association between silicon and collagen, especially at the early stages of bone mineralization, and show that boron is associated with the bone mineral but not connective tissues. These data suggest that silicon and boron have different biological roles and that one is unlikely, therefore, to substitute for the other, or at least boron would not substitute for Si in the connective tissues. Finally, we noted that silicon levels in the mineral fraction varied greatly between the two studies, suggesting that one or more nutritional factor(s) may influence the loading of Si into the mineral fraction of bone. This and the nature of the interaction between Si and collagen deserve further attention.

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Boron and silicon show marked differences in bone loading.

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Boron is exclusively found in the mineral fraction of bone.

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Silicon is distributed equally in the mineral and collagen fractions.

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Data suggest boron and silicon have different biological effects on bone.

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Silicon loading into bone mineral may be influenced by nutritional factors.