Phosphate Layer Research Articles

Porous Zirconia Scaffolds Functionalized with Calcium Phosphate Layers and PLGA Nanoparticles Loaded with Hydrophobic Gentamicin.

Implant-related infections are a worldwide issue that is considered very challenging. Conventional therapies commonly end up failing; thus, new solutions are being investigated to overcome this problem. The in situ delivery of the drug at the implant site appears to be more sufficient compared to systemic antibiotic therapy. In this study, we manufactured porous zirconia scaffolds using the foam replication method. To improve their overall bioactivity, they were coated with a calcium phosphate (CaP) layer containing antibiotic-loaded degradable polymer nanoparticles (NPs) obtained by the double emulsion method to achieve the antibacterial effect additionally. Encapsulation efficiency (EE) and drug loading (DL) were superior and were equal to 99.9 ± 0.1% and 9.1 ± 0.1%, respectively. Scaffolds were analyzed with scanning electron microscopy, and their porosity was evaluated. The porosity of investigated samples was over 90% and resembled the microstructure of spongy bone. Furthermore, we investigated the cytocompatibility with osteoblast-like MG-63 cells and antimicrobial properties with Staphylococcus aureus. Scaffolds coated with a CaP layer were found non-toxic for MG-63 cells. Moreover, the presence of antibiotic-loaded nanoparticles had no significant influence on cell viability, and the obtained scaffolds inhibited bacteria growth. Provided processes of fabrication of highly porous zirconia scaffolds and surface functionalization allow minimizing the risk of implant-related infection.

Influence of pH and temperature in the performance of Zn phosphate conversion coatings

The influence of variations in temperature (from 50 °C to 70 °C) and pH (2.4 and 2.9) in the Zn phosphate conversion treatment of a high-strength steel was assessed in this study. The effect of the temperature changes depends on the pH of the bath. The results evidenced an enhanced corrosion resistance with the increased temperature for baths at pH 2.4, whereas no relevant differences were concluded for baths at pH 2.9. This latter pH condition provided a better surface coverage, even with lower coating masses, than the former value. The microstructural analysis showed the development of films composed of smaller crystals for the treatments at pH 2.9. Impedance spectroscopy was established as a powerful tool with great potential for characterising phosphate layers. The accuracy of this methodology greatly depends on the equivalent circuit used for the simulation. A model based on the transmission line allows the reliable estimation of the percentage of exposed area (coating efficiency), the identification of changes in the film conductivity, and the qualitative analysis of its structure.

Impact of borosilicate bioactive glass scaffold processing and reactivity on in-vitro dissolution properties

In this study, bulk borosilicate glasses and 3D scaffolds (processed by the burn-off technique and by robocasting) were synthesized to investigate the impact of the manufacturing method, glass composition and preincubation time on in vitro dissolution and cell response. The studied compositions are based on commercial bioactive glass S53P4 (BonAlive) where 12.5% SiO2 has been replaced by B2O (labelled B12.5), and part of the CaO is replaced with MgO and SrO (labelled B12.5-Mg-Sr). First, the impact of the processing and glass composition, on the dissolution rate, was assessed. As expected, scaffolds were found to exhibit faster dissolution, due to the increased surface area, when compared to the bulk glass. Furthermore, the 3D printed scaffolds were found to dissolve faster than the burn-off scaffolds. Moreover, scaffolds made from B12.5-Mg-Sr glass composition exhibited slower ion release and precipitation of calcium phosphate (CaP) layer, when compared to B12.5, due to the stabilizing effect of Mg and Sr. Finally, dynamic condition produces lower ion releases that static condition and could be more optimal for in vitro cell growth. Secondly, in culture with murine MC3T3-E1 cells, it was shown that 3 days preincubation would be optimal to decrease the burst of ions that is known to lead to cell death. However, it was found that MC3T3-E1 survived and proliferated only in presence of B12.5-Mg-Sr scaffolds. Finally, it was shown that despite scaffolds having different porosities, they had no significant difference on human adipose-derived stem cells (hADSCs) survival. This manuscript brings new information on 1) the impact of material design (porosity) and composition on dissolution kinetic sand reactivity, 2) the impact of static vs dynamic testing on in-vitro dissolution and 3) the impact of materials’ pre-incubation on cell behavior.

Experimental investigation of galling occurrence in sliding contact under high pressure of a manganese phosphate versus steel interface: Comparison of two greases

In OCTG (Oil Country Tubular Goods) field, surface treatments and greases are used to make connections reliable by avoiding galling in metal-metal contacts. This study compares the anti-galling performances and wear behavior of two tribo-systems: steel versus manganese phosphate coated steel contact tested with two different greases. The damage scenario and the kinetics of the involved tribological phenomena will be investigated thanks to a test based on the ASTM G196 standard and appropriate surface analyses. A rotational oscillatory movement is applied on two cylindrical samples under static normal loads. Friction coefficient is computed using torque-sensor records. Counterparts are made of carbon steel of yield strength 550 MPa. One has been subjected to a manganese phosphate treatment to generate a protective layer of few microns thick. The other counterpart is used as machined. Two different industrial greases with anti-wear and extreme pressure additives are tested. Results showed a significant difference of tribological behavior between both greases. XPS analyses are done to understand the composition of the interfacial materials. The protective mechanisms of both greases are compared. Pb-containing grease allows the instantaneous formation of a protective layer whereas Pb-free grease forms a thin and durable protective layer after quite long running-in phase. Manganese phosphate layer participate in the protective layer formation.

XRD and STA Characterization of Phosphate Layers Deposited on the Carbon Steel Surface

XRD and STA Characterization of Phosphate Layers Deposited on the Carbon Steel Surface

Vibrational Study on the Structure, Bioactivity, and Silver Adsorption of Silk Fibroin Fibers Grafted with Methacrylonitrile

Natural fibers have received increasing attention as starting materials for innovative applications in many research fields, from biomedicine to engineering. Bombyx mori silk fibroin has become a material of choice in the development of many biomedical devices. Grafting represents a good strategy to improve the material properties according to the desired function. In the present study, Bombyx mori silk fibroin fibers were grafted with methacrylonitrile (MAN) with different weight gains. The potential interest in biomedical applications of MAN functionalization relies on the presence of the nitrile group, which is an acceptor of H bonds and can bind metals. IR and Raman spectroscopy were used to characterize the grafted samples and the possible structural changes induced by grafting. Afterward, the same techniques were used to study the bioactivity (i.e., the calcium phosphate nucleation ability) of MAN-grafted silk fibroins after ageing in simulated body fluid (SBF) for possible application in bone tissue engineering, and their interaction with Ag+ ions, for the development of biomaterials with enhanced anti-microbial properties. MAN was found to efficiently polymerize on silk fibroin through polar amino acids (i.e., serine and tryptophan), inducing an enrichment in silk fibroin-ordered domains. IR spectroscopy allowed us to detect the nucleation of a thin calcium phosphate layer and the uptake of Ag+ ions through the nitrile group, which may foster the application of these grafted materials in biomedical applications.

Biomimetic Remineralized Three-Dimensional Collagen Bone Matrices with an Enhanced Osteostimulating Effect.

Bone grafts with a high potential for osseointegration, capable of providing a complete and effective regeneration of bone tissue, remain an urgent and unresolved issue. The presented work proposes an approach to develop composite biomimetic bone material for reconstructive surgery by deposition (remineralization) on the surface of high-purity, demineralized bone collagen matrix calcium phosphate layers. Histological and elemental analysis have shown reproduction of the bone tissue matrix architectonics, and a high-purity degree of the obtained collagen scaffolds; the cell culture and confocal microscopy have demonstrated a high biocompatibility of the materials obtained. Adsorption spectroscopy, scanning electron microscopy, microcomputed tomography (microCT) and infrared spectroscopy, and X-ray diffraction have proven the efficiency of the deposition of calcium phosphates on the surface of bone collagen scaffolds. Cell culture and confocal microscopy methods have shown high biocompatibility of both demineralized and remineralized bone matrices. In the model of heterotopic implantation in rats, at the term of seven weeks, an intensive intratrabecular infiltration of calcium phosphate precipitates, and a pronounced synthetic activity of osteoblast remodeling and rebuilding implanted materials, were revealed in remineralized bone collagen matrices in contrast to demineralized ones. Thus, remineralization of highly purified demineralized bone matrices significantly enhanced their osteostimulating ability. The data obtained are of interest for the creation of new highly effective osteoplastic materials for bone tissue regeneration and augmentation.

Crystal Structure and Properties of Zinc Phosphate Layers on Aluminum and Steel Alloy Surfaces

Many studies have been carried out on the phosphating of steel and aluminum alloys used in automotive engineering, but characterization of the properties of the phosphate layers formed by the co-phosphating of these alloys in the presence of different base metals is still lacking. In this study, the crystal structure and properties of the phosphate conversion layers formed on the surface of the aluminum alloys important in vehicle manufacturing (cast and forged AlSi1MgMn, and AA6014 panel) and the CRS SAE 1008/1010 reference steel plate by co-deposition prior to painting were investigated. On a process line set up for the phosphating of typical iron and steel alloys, the phosphate coating was formed using nitrite and nitroguanidine accelerators under identical technological parameters. The microstructure of the formed phosphate layers was examined using scanning electron microscopy (SEM), its phase composition using X-ray diffraction (XRD), and its elemental composition using energy-dispersive X-ray analysis (EDX). The suggested main crystalline phase (Zn2.3(Ni0.1Mn0.6)(PO4)2·4H2O) in the surface phosphate layer of both aluminum alloys studied was similar to hopeite, whereas in the steel plate, a minor hopeite phase were identified in addition to the main crystalline phosphophyllite phase (~95%). It can be concluded that, during the combined phosphating treatments, the surfaces of different aluminum and steel alloys behaved similarly to the individual treatments and did not impede the coating reactions of the other metal. To obtain an adequate coating of aluminum and steel alloys, fluoride should always be present in the production line. Comparing the effects of accelerators, we found that the use of nitrite accelerator with the same amount of fluoride resulted in a higher coverage and better quality of the surface protective layer of the aluminum alloys. However, for the steel plate, there was no significant difference between the phosphate coatings prepared with the two different accelerators.

Photoelectrochemical Water Splitting with ITO/WO3/BiVO4/CoPi Multishell Nanotubes Enabled by a Vacuum and Plasma Soft-Template Synthesis.

A common approach for the photoelectrochemical (PEC) splitting of water relies on the application of WO3 porous electrodes sensitized with BiVO4 acting as a visible photoanode semiconductor. In this work, we propose a new architecture of photoelectrodes consisting of supported multishell nanotubes (NTs) fabricated by a soft-template approach. These NTs are formed by a concentric layered structure of indium tin oxide (ITO), WO3, and BiVO4, together with a final thin layer of cobalt phosphate (CoPi) co-catalyst. The photoelectrode manufacturing procedure is easily implementable at a large scale and successively combines the thermal evaporation of single crystalline organic nanowires (ONWs), the magnetron sputtering deposition of ITO and WO3, and the solution dripping and electrochemical deposition of, respectively, BiVO4 and CoPi, plus the annealing in air under mild conditions. The obtained NT electrodes depict a large electrochemically active surface and outperform the efficiency of equivalent planar-layered electrodes by more than one order of magnitude. A thorough electrochemical analysis of the electrodes illuminated with blue and solar lights demonstrates that the characteristics of the WO3/BiVO4 Schottky barrier heterojunction control the NT electrode efficiency, which depended on the BiVO4 outer layer thickness and the incorporation of the CoPi electrocatalyst. These results support the high potential of the proposed soft-template methodology for the large-area fabrication of highly efficient multishell ITO/WO3/BiVO4/CoPi NT electrodes for the PEC splitting of water.

Synergetic modulation on structure and interface enables bimetallic phosphide nanoarrays for advanced aqueous zinc batteries

Aqueous zinc batteries characterized by low-cost, high-capacity and high-safety are exciting for the energy storage sector, and the high-performance cathode plays a vital role for the commercialization. Herein, an in situ interfacial modification strategy is presented to construct high-performance cathode (N-NCP@POx) with ultrathin amorphous phosphate interfacial coating for alkaline zinc batteries. The in situ amorphous phosphate layers are beneficial to the adsorption and deprotonation of OH– confirmed by first-principles calculations, and are superior interfacial layers to protect the active species from passivation. This elaborate design enables the interface and structures synergistic effect endowing the electrode of N-NCP@POx with remarkable energy storage capability and electrochemical stability. As results, the full cell of N-NCP@POx//Zn alkaline zinc batteries deliver outstanding specific capacity (358.3 mAh/g at 1 A/g), rate performance (132.2 mAh/g at 20 A/g) and cyclic stability (94% retention after 6000 cycles at 10 A/g). This study will stimulate further development of transition metal phosphides with amorphous interface layers as high performance cathode for energy storage devices.

Phosphate-decorated Ni3Fe-LDHs@CoPx nanoarray for near-neutral seawater splitting

Direct seawater splitting technique can produce clean hydrogen energy without a complicated water desalination process. However, the oxygen evolution reaction (OER) confronts with selectivity challenge in competing with chlorine evolution and severe corrosion issues of the electrode. In this work, phosphate-decorated Ni3Fe-layered double hydroxides grown on cobalt phosphide nanoarray with both high intrinsic activity and 100 % selectivity towards seawater oxidation in a near neutral electrolyte is reported. The as-prepared electrode shows a low overpotential of 370 mV@10 mA cm−2 with high durability in near-neutral seawater oxidation for 350 h. The phosphate layer on the catalyst surface contributes to the enhanced selectivity by weakening the adsorption of Cl–, and thus avoiding the competing chlorine evolution. Meanwhile, the phosphate layer with a strong proton accepting ability can resist the local pH change on the electrode surface in the neutral electrolyte, affording highly stable seawater splitting for prolonged operations in neutral seawater electrolyte.

Formation of environmentally friendly protective Ce2O3-CeO2 conversion coatings on Al, modified by phosphate layers: chemical and electrochemical characterization

Conversion ceria coatings were deposited on substrates of Al-1050 in a solution containing CeCl3×7H2O and CuCl2×2H2O. The post-treatment of as deposited coatings was realized in phosphate-containing solutions: 0.08 M Na3PO4 or 0.22 M NH4H2PO4. The XPS characterization of the surface of samples was carried out on an AXIS Supra electronspectrometer (KratosAnalytical Ltd.). The electrochemical investigations and determination of the basic corrosion parameters (Ecor, icor, Epit, EOCP, Rp, CR, etc.) for the studied systems were carried out on a Gamry Interface 1000 (EISSFR Analyzer EIS300). Based on the XPS investigations, it was ascertained that there is a substantial influence of the “pretreatment” and “post-treatment” operations on the chemical composition and chemical state of the elements on the samples` surface. It is expressed by a strong decrease in the concentration of Аl2O3 and Ce2O3+CeO2 components in the ceria coatings at the expense of formation of AlPO4 and AlOOH, CePO4, as well as PO3-, P2O5 and P4O10 compounds with Al and Се. The comparison of the results of Rp values and concentrations of Ce3+/Се4+, Al and P shows that the changes in Rp and quantity of Се4+ and P on the surface of the studied samples are directly related. The supposed and proved formation of low-soluble corrosion products on the surface of the studied systems and accomplished synergic effect of protective action by the formed cerium and aluminum oxides/phosphates layers determine the increase of the Rp and decrease of icor and CR, respectively. It was also concluded that the mixed conversion layers are a more effective barrier for the chloride ions diffusion to the metal surface and increase the corrosion resistance of Al 1050 to pitting and general corrosion.

Lithostratigraphic and Geochemical Characterization of Tobene Phosphate Deposits: A Case Study of Tobene South 1

Tobene is the third exploitation panel of the Taiba Phosphate deposits. It is divided into five sectors and its exploitation started in 2003 after the closure of the Ndomor and Keur Mor Fall panels. The Taiba phosphate deposit has been the object of several studies based on lithology, biostratigraphy, geochemistry, and petrography; however, few investigations on the variation in thickness of the phosphate layer within the Tobène sector have been conducted. This study seeks to analyze the lithostratigraphic and geochemical characteristics of the phosphate layer in the Tobène South1. Results from the lithostratigraphic study show from top to bottom the following succession: the sandy overburden, the sandstone formation, the Silico-feralitic formation, the variegated roof clays, the Taiba formation (homogeneous ore and heterogeneous ore), and the foliated attapulgite of the wall. Geochemical analysis reveals an unequal distribution of major oxides (P2O5, CaO, Fe2O3, Al2O3, and SiO2). The area is dominated by P2O5 concentrations between 20% and 32%, the K parameter (=CaO/P2O5) has an average of 1.36. The iron associated with aluminum (feral) is present in the southern part and on the contours of the sector; the dominant silica concentration is 20%. Correlations established between the major oxides show a strong relationship with p-values 0.05, nevertheless there is proportionality in the evolutions between the chemical variables CaO and P2O5, on the other hand, an opposite evolution between P2O5 and the two chemical parameters silica (SiO2) and feral.

Mechanistic study of the bioactivity improvement of Al2O3-doped BBG after dynamic flow treatment

A simple and effective method for improving the biological activity of borate bioactive glass (BBG) is to perform dynamic flow treatment with simulated body fluid (SBF). The phosphate layer formed on the BBG surface during flow treatment enhances the biocompatibility of this bioglass. However, the micromechanism of the formation of highly bioactive mineralized products on the surface of BBG under dynamic flow treatment is not clearly understood. In this study, we investigated the effect of dynamic flow treatment on the biological properties of Al 2 O 3 -doped BBG. The results revealed that the SBF-treated Al 2 O 3 -doped BBG exhibits significantly reduced degradation rate and improved bioactivity. The characterization of the treated Al 2 O 3 -doped BBG by Fourier-transform infrared and solid-state NMR spectroscopies revealed that Al mainly exists in the form of four-coordinated aluminum in BBG. During the dynamic flow treatment process, four-coordinated aluminum transforms into six-coordinated aluminum, which chemically interacts with PO 4 3− to improve the biological activity of Al-BBG. In addition, the much more phosphate deposited on BBG sample containing less Al 2 O 3 and promote hydroxyapatite formation on the glass surface. In vitro cell studies suggested that the Al 2 O 3 -doped BBG after treated by dynamic flow treatment boosts the proliferation of MC-3T3E1. This work demonstrates that dynamic flow treatment is a simple and effective method for improving the bioactivity of BBG and also expands our understanding of the micromechanics of the degradation and biomineralization of Al 2 O 3 -doped BBG.

Nanocrystalline fluorapatite mineralization in the calciphile rock-boring bivalve Lithophaga: functional and phylogenetic significance

Abstract Phosphate mineralization as a skeletal material is uncommon in invertebrate animals and rare in Mollusca. Remarkably, apatite minerals were first reported more than 30 years ago in the periostracum of two species of the mytilid bivalve Lithophaga where shells are mostly constructed of calcium carbonate. This discovery extended the range of biominerals secreted by molluscs but has attracted no subsequent research. In this study we review the occurrence of phosphate mineralization in Lithophaga and putatively allied taxa. Lithophagine bivalves, particularly Lithophaga and the more diverse Leiosolenus species, are well known for their endolithic chemical dissolution of calcareous rocks and corals with calcium-binding lipoproteins secreted by mantle glands. Fluorapatite was identified by X-ray diffraction in an outer layer of the periostracum in six species of Lithophaga. Morphological study by scanning electron microscopy of four species showed the fluorapatite crystals embedded in periostracal material in a layer 10–20 µm thick. Dilute bleach treatment revealed the crystals as densely packed euhedral prisms 250–400 nm in size. The succeeding inner layers of the periostracum were unmineralized. Observations of the developing periostracum of Lithophaga teres suggest that the initial mineralization is in the form of amorphous granules that coalesce and transform into euhedral crystals. Periostracal phosphate was not recorded in other members of the Lithophaginae – Leiosolenus, Botula or Zelithophaga species. Leiosolenus species characteristically have extraperiostracal aragonitic encrustations that can be thick and structurally complex. Published molecular phylogenies of Mytilidae bivalves show a division into two major clades with Lithophaga species in one clade and Leiosolenus species in the other, indicating that the subfamily Lithophaginae as presently understood is polyphyletic. This result implies that the two genera have independent evolutionary pathways to endolithic occupation of calcareous substrates although using similar mantle gland secretions to excavate their crypts. Because fluorapatite is considerably less soluble and harder than calcium carbonate, it is suggested that the phosphate layer of Lithophaga is a functional adaptation to protect their shells from self-dissolution from their rock-dissolving glandular secretions and may also act as defence against other shell-eroding organisms.

ON THE ABRASIVE WEAR HIGH STRENGTH COATING LAYERS ON MACHINE PARTS TESTING

<p>Plasma coating technology was applied to machine parts. During application, the jet formed hits the surface of the material and particles are deposited on the surface. In this way, layers of high thickness can be applied and thus revitalize worn machine parts. The paper examines the abrasion resistance of Al2O3 and Al2O3 phosphate layers applied to the base material using plasma technology. The abrasion resistance of the applied layers was tested using the ASTM G 65-85 method. The results of the tests on the loss of the material due to abrasion wear for the two types of coatings in each of the three tested samples are presented. The results of the loss of the material volume at different speeds of the test device wheel are also presented. The phosphate impregnated layer on Al2O3 samples showed significantly higher abrasion wear resistance.</p>

Calcium Phosphates-Chitosan Composite Layers Obtained by Combining Radio-Frequency Magnetron Sputtering and Matrix-Assisted Pulsed Laser Evaporation Techniques.

In this work, we report the synthesis of calcium phosphate-chitosan composite layers. Calcium phosphate layers were deposited on titanium substrates by radio-frequency magnetron sputtering technique by varying the substrate temperature from room temperature (25 °C) up to 100 and 300 °C. Further, chitosan was deposited by matrix-assisted pulsed laser evaporation technique on the calcium phosphate layers. The temperature at the substrate during the deposition process of calcium phosphate layers plays an important role in the embedding of chitosan, as scanning electron microscopy analysis showed. The degree of chitosan incorporation into the calcium phosphate layers significantly influence the physico-chemical properties and the adherence strength of the resulted layers to the substrates. For example, the decreases of Ca/P ratio at the addition of chitosan suggests that a calcium deficient hydroxyapatite structure is formed when the CaP layers are generated on Ti substrates kept at room temperature during the deposition process. The Fourier transform infrared spectroscopy analysis of the samples suggest that the PO43-/CO32- substitution is possible. The X-ray diffraction spectra indicated that the crystalline structure of the calcium phosphate layers obtained at the 300 °C substrate temperature is disturbed by the addition of chitosan. The adherence strength of the composite layers to the titanium substrates is diminished after the chitosan deposition. However, no complete exfoliation of the layers was observed.

ON THE ABRASIVE WEAR HIGH STRENGTH COATING LAYERS ON MACHINE PARTS TESTING

Plasma coating technology was applied to machine parts. During application, the jet formed hits the surface of the material and particles are deposited on the surface. In this way, layers of high thickness can be applied and thus revitalize worn machine parts. The paper examines the abrasion resistance of Al2O3 and Al2O3 phosphate layers applied to the base material using plasma technology. The abrasion resistance of the applied layers was tested using the ASTM G 65-85 method. The results of the tests on the loss of the material due to abrasion wear for the two types of coatings in each of the three tested samples are presented. The results of the loss of the material volume at different speeds of the test device wheel are also presented. The phosphate impregnated layer on Al2O3 samples showed significantly higher abrasion wear resistance.

Chemical-Physical Properties and Bioactivity of New Premixed Calcium Silicate-Bioceramic Root Canal Sealers.

The aim of the study was to analyze the chemical-physical properties and bioactivity (apatite-forming ability) of three recently introduced premixed bioceramic root canal sealers containing varied amounts of different calcium silicates (CaSi): a dicalcium and tricalcium silicate (1-10% and 20-30%)-containing sealer with zirconium dioxide and tricalcium aluminate (CERASEAL); a tricalcium silicate (5-15%)-containing sealer with zirconium dioxide, dimethyl sulfoxide and lithium carbonate (AH PLUS BIOCERAMIC) and a dicalcium and tricalcium silicate (10% and 25%)-containing sealer with calcium aluminate, tricalcium aluminate and tantalite (NEOSEALER FLO). An epoxy resin-based sealer (AH PLUS) was used as control. The initial and final setting times, radiopacity, flowability, film thickness, open pore volume, water absorption, solubility, calcium release and alkalizing activity were tested. The nucleation of calcium phosphates and/or apatite after 28 days aging in Hanks balanced salt solution (HBSS) was evaluated by ESEM-EDX, vibrational IR and micro-Raman spectroscopy. The analyses showed for NeoSealer Flo and AH Plus the longest final setting times (1344 ± 60 and 1300 ± 60 min, respectively), while shorter times for AH Plus Bioceramic and Ceraseal (660 ± 60 and 720 ± 60 min, respectively). Radiopacity, flowability and film thickness complied with ISO 6876/12 for all tested materials. A significantly higher open pore volume was observed for NeoSealer Flo, AH Plus Bioceramic and Ceraseal when compared to AH Plus (p < 0.05), significantly higher values were observed for NeoSealer Flo and AH Plus Bioceramic (p < 0.05). Ceraseal and AH Plus revealed the lowest solubility. All CaSi-containing sealers released calcium and alkalized the soaking water. After 28 days immersion in HBSS, ESEM-EDX analyses revealed the formation of a mineral layer that covered the surface of all bioceramic sealers, with a lower detection of radiopacifiers (Zirconium for Ceraseal and AH Plus Bioceramic, Tantalum for NeoSealer Flo) and an increase in calcium, phosphorous and carbon. The calcium phosphate (CaP) layer was more evident on NeoSealer Flo and AH Plus Bioceramic. IR and micro-Raman revealed the formation of calcium carbonate on the surface of all set materials. A thin layer of a CaP phase was detected only on AH Plus Bioceramic and NeoSealer Flo. Ceraseal did not show CaP deposit despite its highest calcium release among all the tested CaSi-containing sealers. In conclusion, CaSi-containing sealers met the required chemical and physical standards and released biologically relevant ions. Slight/limited apatite nucleation was observed in relation to the high carbonation processes.

Binder-Free Sodium Zinc Phosphate Protection Layer Enabled Dendrite-Free Zn Metal Anode.

Aqueous Zn battery has been a promising alternative battery in large-scale energy storage systems due to its cost-effectiveness, sustainability, and intrinsic safety. However, its cycle life is impeded by the dendrite formation, severe corrosion, and side reactions on the zinc metal anode. Most ex situ coatings on the zinc surface extend the life span of zinc anodes but have drawbacks in Zn2+ ion conductivity. Herein, a robust sodium zinc phosphate layer was in situ built on zinc metal foil anode (Zn@NZP) via facile electrodeposition. The Zn2+ ion conducting protection layer alleviates corrosion, suppresses zinc dendrites, and lowers the energy barrier of Zn2+ plating and stripping. As a result, the Zn@NZP anode renders dendrite-free plating/stripping with a small overpotential of about 44 mV and a 12-fold enhancement long-life span compared to the bare zinc. Furthermore, a full cell using the Zn@NZP anode shows much improved capacity and cycling stability. This work provides a promising anode candidate for dendrite-free aqueous zinc ion batteries.