SrCl2 Solutions Research Articles

Electrochemical sensing of strontium ions cyclic voltammetry and investigation of rosemary extract's effects on their behavior: Antibacterial properties of rosemary extract and molecular docking analysis for potential COVID-19 therapeutic benefits

This work presents an electrochemical sensing for the estimation of strontium ions by cyclic voltammetry and studies its electrochemical behavior in the presence and absence of rosemary using 18 an Karat Gold working electrode in 0.1 M KBr at 295.15 K. The potential therapeutic effects of carnosol and carnosic acid against COVID-19 were explored through molecular docking analysis, suggesting their antiviral effects. The results showed that the obtained cyclic voltammograms showed well-defined redox peaks, and the peak current was found to increase linearly with increasing strontium chloride concentration. Rosemary has been shown to have antioxidant properties, which affect the redox behavior of strontium ions, leading to changes in the peak current and potential observed. SrCl2 solution has higher oxygen solubility and is useful in various industries. Additionally, plant extract showed inhibition of the growth of Gram-positive and Gram-negative bacteria due to its antibacterial activity. Overall, this research offers a promising electrochemical approach for measuring strontium ions and, the antibacterial activity of the Rosemary extract and reveals the potential therapeutic benefits of it against COVID-19.

Reexpansion of charged nanoparticle assemblies in concentrated electrolytes

Electrostatic forces in solutions are highly relevant to a variety of fields, ranging from electrochemical energy storage to biology. However, their manifestation in concentrated electrolytes is not fully understood, as exemplified by counterintuitive observations of colloidal stability and long-ranged repulsions in molten salts. Highly charged biomolecules, such as DNA, respond sensitively to ions in dilute solutions. Here, we use non-base-pairing DNA-coated nanoparticles (DNA-NP) to analyze electrostatic interactions in concentrated salt solutions. Despite their negative charge, these conjugates form colloidal crystals in solutions of sufficient divalent cation concentration. We utilize small-angle X-ray scattering (SAXS) to study such DNA-NP assemblies across the full accessible concentration ranges of aqueous CaCl2, MgCl2, and SrCl2 solutions. SAXS shows that the crystallinity and phases of the assembled structures vary with cation type. For all tested salts, the aggregates contract with added ions at low salinities and then begin expanding above a cation-dependent threshold salt concentration. Wide-angle X-ray scattering (WAXS) reveals enhanced positional correlations between ions in the solution at high salt concentrations. Complementary molecular dynamics simulations show that these ion-ion interactions reduce the favorability of dense ion configurations within the DNA brushes below that of the bulk solution. Measurements in solutions with lowered permittivity demonstrate a simultaneous increase in ion coupling and decrease in the concentration at which aggregate expansion begins, thus confirming the connection between these phenomena. Our work demonstrates that interactions between charged objects continue to evolve considerably into the high-concentration regime, where classical theories project electrostatics to be of negligible consequence.

Facilitation of Hydrate Dissociation and Structural Evolution by Major Marine Anions under Static Electric Fields.

Electric fields have been proven to be capable of significantly affecting the equilibrium state of hydrates. In this study, the thermodynamic properties and structural changes of methane hydrate (MH) in various anion solutions in an electric field at 0.7 V/nm were investigated by molecular dynamics simulations. The presence of anions significantly enhances the instability of methane hydrates under electric fields, leading to a staged dissociation process. First, the anions coexist with MH to form a temporary metastable structure under the action of an electric field. Then, the migration of anions causes the dissociation of nearby hydrates and the formation of flow channels in the hydrate layer, which leads to the complete dissociation of MH after a period. The promotive effects of F-, Br-, I-, and Cl- ions were close, while SO42- was relatively weak. The anions are still in hydration shells in the MH phase, but the structure of the hydration shells differs slightly from that in solution (the coordination numbers of I- and SO42- ions increased). The migration resistances of multiple anions to cross the surface of the hydrate layer are similar. However, inside the hydrate phase, the anions with a larger radius have a higher migration resistance. It is difficult for SO42- ions to migrate inside the hydrate phase, and they tend to form a metastable structure on the hydrate surface. Combining our previous studies, SrCl2 solution has the best hydrate promotion under an electric field environment.

Strontium chloride improves bone mass by affecting the gut microbiota in young male rats.

Bone mass accumulated in early adulthood is an important determinant of bone mass throughout the lifespan, and inadequate bone deposition may lead to associated skeletal diseases. Recent studies suggest that gut bacteria may be potential factors in boosting bone mass. Strontium (Sr) as a key bioactive element has been shown to improve bone quality, but the precise way that maintains the equilibrium of the gut microbiome and bone health is still not well understood. We explored the capacity of SrCl2 solutions of varying concentrations (0, 100, 200 and 400 mg/kg BW) on bone quality in 7-week-old male Wistar rats and attempted to elucidate the mechanism through gut microbes. The results showed that in a Wistar rat model under normal growth conditions, serum Ca levels increased after Sr-treatment and showed a dose-dependent increase with Sr concentration. Three-point mechanics and Micro-CT results showed that Sr exposure enhanced bone biomechanical properties and improved bone microarchitecture. In addition, the osteoblast gene markers BMP, BGP, RUNX2, OPG and ALP mRNA levels were significantly increased to varying degrees after Sr treatment, and the osteoclast markers RANKL and TRAP were accompanied by varying degrees of reduction. These experimental results show that Sr improves bones from multiple angles. Further investigation of the microbial population revealed that the composition of the gut microbiome was changed due to Sr, with the abundance of 6 of the bacteria showing a different dose dependence with Sr concentration than the control group. To investigate whether alterations in bacterial flora were responsible for the effects of Sr on bone remodeling, a further pearson correlation analysis was done, 4 types of bacteria (Ruminococcaceae_UCG-014, Lachnospiraceae_NK4A136_group, Alistipes and Weissella) were deduced to be the primary contributors to Sr-relieved bone loss. Of these, we focused our analysis on the most firmly associated Ruminococcaceae_UCG-014. To summarize, our current research explores changes in bone mass following Sr intervention in young individuals, and the connection between Sr-altered intestinal flora and potentially beneficial bacteria in the attenuation of bone loss. These discoveries underscore the importance of the "gut-bone" axis, contributing to an understanding of how Sr affects bone quality, and providing a fresh idea for bone mass accumulation in young individuals and thereby preventing disease due to acquired bone mass deficiency.

Strontium Chloride Improves Reproductive Function and Alters Gut Microbiota in Male Rats.

Strontium (Sr) is an essential trace element in the human body and plays an important role in regulating male reproductive health. Recent studies have shown that gut flora plays a key role in maintaining spermatogenesis, as well as testicular health, through the gut-testis axis. At present, it is unclear whether gut microbiota can mediate the effects of Sr on sperm quality, and what the underlying mechanisms may be. We investigated the effects of different concentrations of strontium chloride (SrCl2) solutions (0, 50, 100, and 200 mg/kg BW) on reproductive function and gut microbiota in male Wistar rats (6-8 weeks, 250 ± 20 g). All the animals were euthanized after 37 days of treatment. The Sr-50 group significantly increased sperm concentration, sperm motility, and sperm viability in rats. After Sr treatment, serum and testicular testosterone (T) and Sr levels increased in a dose-dependent manner with increasing Sr concentration. At the same time, we also found that testicular marker enzymes (ACP, LDH) and testosterone marker genes (StAR, 3β-HSD, and Cyp11a1) increased significantly in varying degrees after Sr treatment, while serum NO levels decreased significantly in a dose-dependent manner. Further investigation of intestinal flora showed that SrCl2 affected the composition of gut microbiome, but did not affect the richness and diversity of gut microbiota. Sr treatment reduced the number of bacteria with negative effects on reproductive health, such as Bacteroidetes, Tenericutes, Romboutsia, Ruminococcaceae_UCG_014, Weissella, and Eubacterium_coprostanoligenes_group, and added bacteria with negative effects on reproductive health, such as Jeotgalicoccus. To further explore the Sr and the relationship between the gut microbiota, we conducted a Spearman correlation analysis, and the results showed that the gut microbiota was closely correlated with Sr content in serum and testicular tissue, sex hormone levels, and testicular marker enzymes. Additionally, gut microbiota can also regulate each other and jointly maintain the homeostasis of the body's internal environment. However, we found no significant correlation between intestinal flora and sperm quality in this study, which may be related to the small sample size of our 16S rDNA sequencing. In conclusion, the Sr-50 group significantly increased T levels and sperm quality, and improved the levels of testicular marker enzymes and testosterone marker genes in the rats. Sr treatment altered the gut flora of the rats. However, further analysis of the effects of gut microbiota in mediating the effects of SrCl2 on male reproductive function is needed. This study may improve the current understanding of the interaction between Sr, reproductive health, and gut microbiota, providing evidence for the development of Sr-rich foods and the prevention of male fertility decline.

Dielectric and piezoelectric properties of cement-containing piezoelectric composites: Experiments and modeling

In this work, porous honeycomb lead zirconate titanate (PZT) ceramics with one dimensional ordered pore channels were fabricated by the ionotropic gelation of sodium alginate/PZT suspension with SrCl2 solution, then the piezoelectric cement/PZT paste with different mass fraction of PZT component were cast into the porous ceramics to produce cement-containing piezoelectric composites. The influences of PZT mass fraction of piezoelectric cement/PZT paste on the microscopic morphology were studied. The relative permittivity (εr) and longitudinal piezoelectric strain coefficient (d33) of piezoelectric composites were measured and predicted by experiments and modified “unit cell” model respectively, while both results displayed consistency. The composites presented typical electromechanical coupling behavior for the direct and inverse piezoelectric effect of PZT component, when the PZT mass fraction increased to 50 wt%, the cement-containing piezoelectric composites acquired the greatest thickness electromechanical coupling coefficient (Kt) value of 55.69% and acoustic impedance (Z) value of 10.00 MRayls, making it an appropriate candidate material in the structure health monitoring system.

Sr2+ vs. Ca2+ as post-processing ionic crosslinkers: implications for 3D bioprinting of polysaccharide hydrogels in tissue engineering

Among the possible ionic crosslinkers Ca2+ is the most widely used. However, due to its numerous physiological functions, other cations such as Sr2+ may be more suitable depending on the application. Because a systematic comparison is currently lacking, this work aims to compare solutions of CaCl2 and SrCl2 as ionic crosslinkers of alginate- and cellulose-based materials and to investigate their effects on the structural and biological properties of 3D bioprinted scaffolds. In particular, swelling and degradation under cell culture conditions, mechanical properties (with quasi-static compression tests), surface topology (with scanning electron microscopy and atomic force microscopy) and elemental composition were investigated. In addition, cytotoxicity on pancreatic islet cells was assessed by measuring viability, metabolic activity and morphology. The obtained results show that Sr2+-crosslinked scaffolds have higher compressive strength, swell faster and degrade more slowly under cell culture conditions and have a rougher surface. Both crosslinking agents were gentle on the cells, either when directly embedded into scaffolds or in contact with scaffold extracts, and allowed stable culture for 30 days. However, Sr2+-crosslinked scaffolds elicited higher metabolic activity. Overall, Sr2+ are a viable crosslinking alternative to Ca2+ and allow expanding the range of scaffold properties by adjusting the concentration or ratio in a mixed solution.

Efficient separation of CO2 from methane at high pressures by modified microporous titanosilicates; design and breakthrough studies

In this work, type-4 titanosilicate (TS-4) having a micro-pore size of 3–4 Å, was synthesized from inexpensive source materials, such as commercial silicon dioxide, with the template-free hydrothermal method. The XRD analysis confirmed formation of the TS-4 crystalline phase. Then, strontium cation modification was performed using SrCl2 solution to adjust the pore structure and increase the basicity of the surface to improve CO2 selectivity versus methane. In this study, the adsorption isotherms of methane and CO2 were measured in the range of 0 to 50 bars, at two different temperatures of 298 K and 308 K, then the ideal selectivities of CO2/CH4 were calculated at different pressures. The ideal CO2/CH4 selectivity was determined at 19.04 and 38.49 for TS-4 and Sr-TS-4, respectively, at the pressure of 50 bar and the temperature of 298 K. The isosteric heat of adsorption of CO2 was calculated by Van’t Hoff equation as −29.63 kJ/mol and −26.22 kJ/mol, respectively. Low CO2 heat of adsorption of Sr-TS-4 and high selectivity of CO2/CH4 at high pressures, against zeolites, offer Sr-TS-4 as an economic and efficient adsorbent for cyclic adsorption processes. To study the dynamic selectivity of CO2/CH4, dynamic adsorption experiments were conducted at the temperature of 298 K, pressures of 7 and 15 bars, flow rates of 10 and 20 Nml/min in a bed of 2.7 gr adsorbent, with the inlet molar fraction of 5–95 % CO2-CH4 mixture. Comparison of the breakthrough curves indicated that Sr-TS-4 had a longer breakpoint and a larger used ratio of the length at any feed flow rate. The maximum relative dynamic selectivity of CO2/CH4 at 15 bar, by the Sr-TS-4, was obtained 95.29 at CO2 breakpoint of 40 min, whereas maximum relative dynamic selectivity, by the TS-4, was obtained 63.54 at CO2 breakpoint of 30 min. It is concluded that Sr-TS-4 would be an efficient adsorbent for separation of CO2 from natural gas in commercial scales at high pressures with high methane recovery.

Electro-adsorption of Sr(II) from aqueous solution by activated carbon cloth/nickel hexacyanoferrate composite electrode through capacitive deionization

The activated carbon cloth/nickel hexacyanoferrate (ACC/NiHCF) electrode was successfully synthesized by a co-precipitation method, and the performance was comprehensively evaluated as CDI electrode materials for Sr2+ removal. The as-prepared ACC/NiHCF electrode had the mesoporous and the coordination framework structure, which provided convenient transport channels for ions or electrons. As a result, the ACC/NiHCF electrode exhibited the high Sr2+ removal efficiency. The maximum removal efficiency was 77.20% at 0.6 V in 5 mg L−1 SrCl2 solution, much higher that of pristine ACC. The isotherm models and mass transfer models suggested that the adsorption process of Sr2+ onto ACC/NiHCF was mainly through the multi-layer adsorption, and adsorption onto the active sites was the main rate-limiting step. In addition, the comprehensive characterizations elaborated the mechanism involved physic-chemical adsorption and electrostatic adsorption. Above all, ACC/NiHCF is an efficient electrode for Sr2+ removal. This study provided new insight into the fabrication of high-efficiency composite electrode materials for Sr2+ removal by CDI.

In Situ EXAFS Study of Sr Adsorption on TiO2(110) under High Ionic Strength Wastewater Conditions

In order to provide important details concerning the adsorption reactions of Sr, batch reactions and a set of both ex situ and in situ Grazing Incidence X-ray Absorption Fine Structure (GIXAFS) adsorption experiments were completed on powdered TiO2 and on rutile(110), both reacted with either SrCl2 or SrCO3 solutions. TiO2 sorption capacity for strontium (Sr) ranges from 550 ppm (SrCl2 solutions, second order kinetics) to 1400 ppm (SrCO3 solutions, first order kinetics), respectively, and is rapid. Sr adsorption decreased as a function of chloride concentration but significantly increased as carbonate concentrations increased. In the presence of carbonate, the ability of TiO2 to remove Sr from the solution increases by a factor of ~4 due to rapid epitaxial surface precipitation of an SrCO3 thin film, which registers itself on the rutile(110) surface as a strontianite-like phase (d-spacing 2.8 Å). Extended X-ray Absorption Fine Structure (EXAFS) results suggest the initial attachment is via tetradental inner-sphere Sr adsorption. Moreover, adsorbates from concentrated SrCl2 solutions contain carbonate and hydroxyl species, which results in both inner- and outer-sphere adsorbates and explains the reduced Sr adsorption in these systems. These results not only provide new insights into Sr kinetics and adsorption on TiO2 but also provide valuable information concerning potential improvements in effluent water treatment models and are pertinent in developing treatment methods for rutile-coated structural materials within nuclear power plants.

Characterization of particle size distribution in slurries using ultrasonic attenuation spectroscopy: Addressing challenges of unknown physical properties

Ultrasonic attenuation spectroscopy (UAS) has many advantages in online in-process characterization of particle size distribution (PSD) in slurries. It can be applied to systems with relatively high solid concentration and wide particle size range from nanometres to millimetres sized particles. The model used by a UAS instrument to estimate the PSD from an attenuation spectrum requires some physical properties of both the liquid and solid phases to be known. For instance, the most popular UAS model, the Epstein–Carhart and Allegra–Hawley (ECAH) model, requires fourteen physical properties. Therefore, applications where all or some of the required physical properties are unknown or difficult to measure, such as crystallization, pose a major challenge to its use. In this work, a procedure for estimating the unknown physical properties is proposed. This is done by iteratively learning the unknown physical properties to minimise the difference between the measured attenuation spectra and that predicted by the ECAH model. One of the main challenges of this procedure is the presence of multiple local minima but these can be eliminated by a combination of a global optimisation algorithm, the use of multiple particle size distributions and solid concentrations. The procedure was validated using Silica and Titania standard reference materials, and applied to the estimation of the relevant physical properties of saturated aqueous solution of SrCl2.6H2O and Sr(OH)2.8H2O. The properties thus obtained was used for acoustic monitoring of the real-time evolution of PSD during the batch cooling crystallization of SrCl2.6H2O in water.

The Effect of Topical Application of Strontium on Bond Strength in Orthodontics. (In Vitro Study)

Objective: to evaluate the effects of topical application of strontium on bond strength in orthodontics in vitro by using Instron universal testing machine . Materials and Methods: forty eight bovine enamel specimens were randomly allocated to four groups (n =12). Specimens of group I were not demineralized and were not pretreated, but served as controls. The other specimens were demineralized by using Featherstone pH cycling technique to form artificial carious lesions. Samples from group II were only demineralized. The other samples were pretreated with strontium chloride solution(Srcl2) for 5 minutes. Teeth in groups III were treated with Srcl2 solution before acid-etching. Teeth in groups IV were treated with Srcl2 after acid-etching. The brackets were then bonded .The brackets' SBS was measured and the adhesive remnant was assessed using adhesive remnant index (ARI). Analyses were done for SBS values between the four groups using One-Way ANOVA test followed by Post Hoc Tukey’s analysis between each two groups .Fisher’s exact test was used to evaluate differences in ARI scores between the groups. Results: srcl2treated group before acid etching )showed the highest mean SBS value when compared to other groups (Mean ± SD =24.7±7.4 MPa). There was insignificant difference between the four groups as regarding ARI scores (p=0.406). Conclusion: The topical application of srcl2 did not compromise the bond strength of orthodontic brackets to demineralized bovine enamel.

Ion-exchange properties of Zn4(OH)6(SO4) 2.5H2O

The aim of the present study is to check the possibilities for ion exchange of a new zinc-hydroxy-sulfate-hydrate phase, Zn4(OH)6SO4·2–2.25H2O. The new zinc hydroxy sulfate hydrate phase was obtained by mixing of 0.5 g of Zn5(OH)8(NO3)2.2H2O and 50 ml of 1M Na2SO4 for 48h at room temperature and pH of the solution between 5–7. Ion-exchange properties were investigated by mixing of 0.2 g Zn4(OH)6(SO4) 2.5H2O with 20 ml water solution of NaCl, CaCl2 or SrCl2 with different concentrations (0.5М, 1М, or 2M) for different time (24h, 48h and 72h) at room temperature. The pH of the solutions varied in the range 6–8. The new phase has exchange properties potentials, like other zinc hydroxy sulfate hydrates composed of octahedral-tetrahedral layers. The results obtained for the kinetics of ion-exchange reactions are additional useful data for the solving of the structure of the new zinc-hydroxy-sulfate-hydrate phase in the future.

Physicochemical and Sorption Properties of Anionites Based on Aromatic Amines, Epichlorohydrin and Polyethylenimine with Regard to Strontium (II) Ions

Multifunctional anion exchangers based on aromatic amines, epichlorohydrin and polyethylenimine have been synthesized. Their composition, structure, and thermal stability have been studied using IR spectroscopy, elemental and thermogravimetric analyses. Extraction of strontium ions has been studied using classical polarography, and sorption of strontium (II) ions in static regime has been determined as a function of solution acidity, metal ion concentration, and contact duration of ionites with SrCl2 solution. It has been established that the obtained ion exchangers are characterized by high sorption properties with regard to strontium ions. The novelty of these studies is that the sorption dependence of synthesized ionites with regard to Sr2+ ions has been studied for the first time. The practical importance of this work is the development of anion exchangers with higher extractability, which could successfully solve the issues of elimination of strontium (II) ions from process wastes of nonferrous metallurgy.

Piezoelectric properties of 3-1 type porous PMN-PZT ceramics doped with strodium

In this work, 3-1 type porous lead magnesium niobate-lead zirconate titanate (PMN-PZT) ceramics with one-dimensional ordered pore channels and strontium oxides (SrO) doping on a molecular level have been fabricated by the ionotropic gelation of sodium alginate/PMN-PZT suspensions with SrCl2 solution. By adjusting the concentration of SrCl2 (0.5–2.5 mol/L), the doping amount of SrO in 3-1 type PMN-PZT ceramics increased from 1.954 wt% to 4.052 wt%, making the morphotropic phase boundary (MPB) deviate from rhombohedral (R3m) to tetragonal (P4mm) phase with the decrease in the ratio of the lattice parameters c/a. Increase in the concentration of SrCl2 led to a reduction in the tanδ, an increase in the d33 and ε33. As a result, the prepared samples possessed a maximal hydrostatic figure of merit (HFOM) value of 5045 × 10−15 Pa−1, and a low acoustic impedance (Z) value of 5.88 MRayls, making them promising candidates for application in ultrasonic transformers.

The Formation of Barite and Celestite through the Replacement of Gypsum

Barite (BaSO4) and celestite (SrSO4) are the end-members of a nearly ideal solid solution. Most of the exploitable deposits of celestite occur associated with evaporitic sediments which consist of gypsum (CaSO4·2H2O) or anhydrite (CaSO4). Barite, despite having a broader geological distribution is rarely present in these deposits. In this work, we present an experimental study of the interaction between gypsum crystals and aqueous solutions that bear Sr or Ba. This interaction leads to the development of dissolution-crystallization reactions that result in the pseudomorphic replacement of the gypsum crystals by aggregates of celestite or barite, respectively. The monitoring of both replacement reactions shows that they take place at very different rates. Millimeter-sized gypsum crystals in contact with a 0.5 M SrCl2 solution are completely replaced by celestite aggregates in less than 1 day. In contrast, only a thin barite rim replaces gypsum after seven days of interaction of the latter with a 0.5 M BaCl2 solution. We interpret that this marked difference in the kinetics of the two replacement reactions relates the different orientational relationship that exists between the crystals of the two replacing phases and the gypsum substrate. This influence is further modulated by the specific crystal habit of each secondary phase. Thus, the formation of a thin oriented layer of platy barite crystals effectively armors the gypsum surface and prevents its interaction with the Ba-bearing solution, thereby strongly hindering the progress of the replacement reaction. In contrast, the random orientation of celestite crystals with respect to gypsum guarantees that a significant volume of porosity contained in the celestite layer is interconnected, facilitating the continuous communication between the gypsum surface and the fluid phase and guaranteeing the progress of the gypsum-by-celestite replacement.

Zeta Potential Determination from Molecular Simulations

Zeta potential (ZP) is among key physical properties characterizing the behavior of nanoparticles in colloidal solutions. Despite many attempts to calculate and neatly interpret the ZP, full understanding of various factors influencing its values has not been reached yet even for standard metal-oxides, particularly when considering high ionic concentrations and the effect of temperature. This contribution extends our recent work [Langmuir 2016, 32, 10189−10198], where we suggested a direct approach to calculate the ZP from nonequilibrium molecular dynamics (NEMD) simulations. Here we investigate NaCl, RbCl, CaCl2, SrCl2, and Na2C2O4 aqueous solutions interacting with TiO2 and SiO2 surfaces, and show contrasting ZP behavior for these metal-oxides, elucidated by theoretical insights gained by molecular simulations. We show that both surface-specific and ion-specific properties play a key role in the observed electrokinetics. Additionally, we explore concentration and temperature influence on the ZP of selec...

Use of Polyphenol Tannic Acid to Functionalize Titanium with Strontium for Enhancement of Osteoblast Differentiation and Reduction of Osteoclast Activity.

Implant anchorage remains a challenge, especially in porous osteoporotic bone with high osteoclast activity. The implant surface is modified with osteogenic molecules to stimulate osseointegration. Strontium (Sr) is known for its osteogenic and anti-osteoclastogenic effects. In this study, Sr was immobilized on a titanium (Ti) surface using bioinspired polyphenol tannic acid (pTAN) coating as an ad-layer (Ti-pTAN). Two separate coating techniques were employed for comparative analysis. In the first technique, Ti was coated with a tannic acid solution containing Sr (Ti-pTAN-1Stp). In the second method, Ti was first coated with pTAN, before being immersed in a SrCl2 solution to immobilize Sr on Ti-pTAN (Ti-pTAN-2Stp). Ti-pTAN-1Stp and Ti-pTAN-2Stp augmented the alkaline phosphatase activity, collagen secretion, osteocalcin production and calcium deposition of MC3T3-E1 cells as compared to those of Ti and Ti-pTAN. However, osteoclast differentiation of RAW 264.7, as studied by TRAP activity, total DNA, and multinucleated cell formation, were decreased on Ti-pTAN, Ti-pTAN-1Stp and Ti-pTAN-2Stp as compared to Ti. Of all the substrates, osteoclast activity on Ti-pTAN-2Stp was the lowest. Hence, an economical and simple coating technique using pTAN as an adlayer preserved the dual biological effects of Sr. These results indicate a promising new approach to tailoring the cellular responses of implant surfaces.

Positive modulation of osteogenesis on a titanium oxide surface incorporating strontium oxide: An in vitro and in vivo study

Surface chemistry and topography can determinatively affect the osseointegration of dental implants. Strontium (Sr) has a significant effect on the promotion of bone formation and inhibitation of bone resorption. The emphasis of this study lies on the evaluation of a new surface treatment that aims to improve the early osseointegration of dental implantation both in vitro and in vivo. A hydrothermal method was used to prepare an SrTiO3 incorporation on sandblasted large-grit double acid-etched (SLA) titanium surfaces in SrCl2 solution. The composition and morphology of the SrTiO3 doped surface were analyzed by X-ray diffraction, X-ray photoelectron spectroscopy，and scanning electron microscopy. In addition, the external release figure of Sr was examined by inductively coupled plasma mass spectrometry. The proliferation, adhesion and differentiation of MC3T3-E1 cells on this surface were evaluated in vitro and presented a significant increase in SLA-Sr group compared with that in SLA group. An in vivo study in 24 New Zealand rabbits indicated a remarkable growth in the volume of direct bone-to-implant contact and peri-implant bone in SLA-Sr group, which were compared with SLA group after 3 and 6 weeks, and removal torque tests exhibited a higher torque removal value of SLA-Sr implants. The study gave the result that the biological effect of SLA-Sr implants was significantly superior to that of the SLA implants at the early stage of osseointegration.

Effect of sodium carboxymethylcellulose biopolymer on sedimentation properties of trimagnesium, tricalcium and tristrontium phosphates precipitates

Sedimentation data of bioactive materials are essential in formulation of suspension with desirable requirements. Batch-wise precipitation and sedimentation tests were conducted to evaluate the effect of sodium carboxymethylcellulose (Na-CMC) biopolymer solution on the sedimentation properties (rate and compaction) of trimagnesium phosphate (TMP), tricalcium phosphate (TCP) and tristrontium phosphate (TSP) precipitates. Fixed volume (1ml) of different concentrations (200ppm - 2000ppm) of Na-CMC solution was mixed with fixed volume (50ml) of 0.5M, 0.05M Na3PO4 solutions. Accordingly, the resulting solutions were separately mixed with fixed volumes (50ml) of 0.5M Mg (NO3)2, 0.05M CaCL2 and 0.05M SrCL2 solutions and settling of the precipitates formed monitored. The results showed that whereas for TCP, Na-CMC exhibited a curvilinear relationship with precipitate sedimentation, non-linear relationships were observed for TMP and TSP precipitates. Between 200ppm and 2000ppm of Na-CMC addition, sedimentation rate and compaction of TCP precipitate increased by 187% and 18.5%, whereas for TMP and TSP precipitates, they increased by only (19.89% and 1%) and (30% and 0%), respectively. The results suggest that Na-CMC biopolymer is not the preferred suspending medium for suspension formulations containing TCP. For TMP and TSP precipitates, further study is needed in the light of the fact that magnesium and strontium resemble calcium.Keywords: sedimentation rate, compaction, precipitates, sodium carboxymethylcellulose