Strontium leaching from municipal waste subjected to incineration.

The aim of the study was to determine the content and leachability of Sr in ashes obtained through combusting municipal waste in household furnaces. The waste had been collected as a mixed stream and as separate fractions (i.e. furniture, sponges, waste paper, PCV packaging, plastic-coated paper cartons, imitation leather, rubber, textiles and polystyrene). Using single-step chemical extractions, (HCl + HNO3, H2O, 0.01 M CaCl2, 0.1 M CH3COOH), we determined the total content of Sr (TC) and proportions of the following fractions: water-leachable, phytoavailable and easily soluble and bound to carbonates. We also analyzed the effect of reducing pH in the extraction solutions on St leachability from the study material. The study showed that Sr concentration in ash generated from the combustion of conventional fuels, alternative fuels and municipal waste ranged from 114 to 1006 mg/kg. The largest amounts of Sr were found in ash generated from the combustion of alternative fuels (coal pellets 488-1006 mg/kg), conventional fuels (hard coal 430-670 mg/kg) and mixed waste (237-825 mg/kg). The most mobile fraction of Sr (water-leachable) comprised from 1.3% to nearly 91% TC; the phytoavailable fraction and the ion-exchange and carbonate-bound fraction comprised 3-92% TC and 9-72% TC, respectively. We also found that the greatest pH reductions do not always entail the greatest amounts of extracted Sr. A much more significant factor in this respect is the mineral and chemical composition of primary materials, which can buffer changes in pH. The Risk Assessment Code (RAC) values pointed to a varied environmental risk and the highest RAC values (> 70) were found for coal pellets, wood pellets, straw, rubber and plastic containers for mixed oils.

Effect of grain size variation on strontium sorption to heterogeneous aquifer sediments.

Strontium-90 (90Sr) is a major contaminant at nuclear legacy sites. The mobility of 90Sr is primarily governed by sorption reactions with sediments controlled by high surface area phases such as clay and iron oxides. Sr2+ adsorption was investigated in heterogeneous unconsolidated aquifer sediments, analogous to those underlying the UK Sellafield nuclear site, with grainsizes ranging from gravels to clays. Batch sorption tests showed that a linear Kd adsorption model was applicable to all grainsize fractions up to equilibrium [Sr] of 0.28 mmol L-1. Sr2+ sorption values (Kd; Langmuir qmax) correlated well with bulk sediment properties such as cation exchange capacity and surface area. Electron microscopy showed that heterogeneous sediments contained porous sandstone clasts with clay minerals (i.e. chlorite) providing an additional adsorption capacity. Therefore, gravel corrections that assumed that the > 2 mm fractions are inert were not appropriate and underestimated Kd(bulk) adsorption coefficients. However, Kd (<2 mm) values measured from sieved sediment fractions, were effectively adjusted to within error of Kd (bulk) using a surface area dependant gravel correction based on particle size distribution data. Amphoteric pH dependent Sr2+ sorption behaviour observed in batch experiments was consistent with cation exchange modelling between pH 2-7 derived from the measured cation exchange capacities. Above pH 7 model fits were improved by invoking a coupled cation exchange/surface complexation which allowed for addition sorption to iron oxide phases. The overall trends in Sr2+ sorption (at pH 6.5-7) produced by increasing solution ionic strength was also reproduced in cation exchange models. Overall, the results showed that Sr2+ sorption to heterogeneous sediment units could be estimated from Kd (<2 mm) data using appropriate gravel corrections, and effectively modelled using coupled cation exchange and surface complexation processes.

Removal of pollutants through photocatalysis, adsorption, and electrochemical sensing by a unique plasmonic structure of palladium and strontium oxide nanoparticles sandwiched between 2D nanolayers.

The redesigned engineering building of nanocomposite (NCP) depends on metal oxides of palladium oxide (PdO) nanoparticles (NPs) conjugate with the n-type semiconductor of strontium oxide (SrO) NPs on the electron carrier surface of graphene oxide (GO) and reduce graphene oxide (rGO) nanosheet is the main target of the current work. The low efficiency of PdO (n-type) and SrO (p-type) gave an overview of the increasing generation electron efficiency via building the ohmic area on the GO and rGO surface using the Z-scheme mechanism. The efficiency of the NCP surface for destroying organic pollutants such as mixed dyes of Rhodamine B and methylene blue (RhB/MB), as against insecticides like imidacloprid, and the removal of heavy metals such as chromium ions was studied. The production of clean water against pollutants materials was investigated through adsorption and photocatalytic processes, electrochemical, and spectroscopy methods to detect the activity of NCP. The rate constant of the adsorption pollutants is 0.1776 min-1 (MB), 0.3489 min-1 (RhB), 0.3627 min-1 (imidacloprid), and 0.5729 min-1 (Cr3+). The photocatalytic rate recorded at 0.01218 min-1 (MB), 0.0096 min-1 (RhB), appeared degradation rate at 0.0086 min-1 (imidacloprid), 0.0019 min-1 (Cr6+), and 0.0471 min-1 (Cr3+). The adsorption and photocatalytic efficiency of nanocatalyst (NCP) was calculated at 91% (RhB), 93% (MB), 73% (imidacloprid), 63% (Cr3+), while the photocatalytic efficiency is 63% (RhB), 94% (MB), 86% (imidacloprid), 33% (Cr3+). The recyclability of NCP was tested for five cycles, and the efficiency was discovered at 55% after the fifth cycle. The cytotoxicity of NCP was studied to detect the safety of the fabricated materials. The study validates that the fabricated nanocomposite exhibits great potential as an innovative material for producing clean water.

Fe3+-activated magnetoplumbite persistent luminescence phosphor by modulating the oxygen vacancy.

Broadband near-infrared (NIR) spectroscopy has gained significant attention due to its versatile application in various fields. In the realm of NIR phosphors, Fe3+ ion is an excellent activator known for its nontoxic and harmless nature. In this study, we prepared an Fe3+-activated SrGa12O19 (SGO) NIR phosphor and analyzed its phase and luminescence properties. Upon excitation at 326 nm, the SGO:Fe3+ phosphor exhibited a broadband emission in the range 700-1000 nm, peaking at 816 nm. The optical band gap of SGO:Fe3+ was evaluated. To enhance the long-lasting phosphorescence, an oxygen vacancy-rich SGO:Fe3+ (VO-SGO:Fe3+) sample was prepared for activation. Interestingly, the increase in the oxygen-vacancy concentration indeed contributed to the activation of persistent luminescence of Fe3+ ions. The VO-SGO:Fe3+ sample has a long duration and high charge storage capacity, allowing it to perform efficiently in various applications. This work provides the foundation for further design of Cr3+-free PersL phosphors with efficient NIR PersL.

On the Ion Implantation Synthesis of Ag-Embedded Over Sr-Substituted Hydroxyapatite on a Nano-Topography Patterned Ti for Application in Acetabular Fracture Sites.

Introduction: There is an ongoing need for improved healing response and expedited osseointegration on the Ti implants in acetabular fracture sites. To achieve adequate bonding and mechanical stability between the implant surface and the acetabular fracture, a new coating technology must be developed to promote bone integration and prevent bacterial growth. Methods: A cylindrical Ti substrate mounted on a rotating specimen holder was used to implant Ca2+, P2+, and Sr2+ ions at energies of 100 KeV, 75 KeV and 180 KeV, respectively, using a low-energy accelerator to synthesize strontium-substituted hydroxyapatite at varying conditions. Ag2+ ions of energy 100 KeV were subsequently implanted on the as-formed surface at the near-surface region to provide anti-bacterial properties to the as-formed specimen. Results: The properties of the as-formed ion-implanted specimen were compared with the SrHA-Ag synthesized specimens by cathodic deposition and low-temperature high-speed collision technique. The adhesion strength of the ion-implanted specimen was 43 ± 2.3 MPa, which is well above the ASTM standard for Ca-P coating on Ti. Live/dead cell analysis showed higher osteoblast activity on the ion-implanted specimen than the other two. Ag in the SrHA implanted Ti by ion implantation process showed superior antibacterial activity. Discussion: In the ion implantation technique, nano-topography patterned surfaces are not concealed after implantation, and their efficacy in interacting with the osteoblasts is retained. Although all three studies examined the antibacterial effects of Ag2+ ions and the ability to promote bone tissue formation by MC3T3-E1 cells on SrHA-Ag/Ti surfaces, ion implantation techniques demonstrated superior ability. The synthesized specimen can be used as an effective implant in acetabular fracture sites based on their mechanical and biological properties.

Abatement of microbes and organic pollutants using heterostructural nanocomposites of rice straw CQDs with substituted strontium ferrite.

Sustainable use of agricultural waste still remains a challenging task. Herein, we used rice straw as a carbon precursor to prepare carbon quantum dots (CQDs) for photocatalytic applications. Nanocomposites of CQDs with Ti4+ and Mg2+ substituted strontium ferrite (Sr0·4Ti0·4Mg0·2Fe2O4.4) nanoparticles (NPs) in varying w:w ratio was synthesized by ultrasonication method. The successful formation of nanocomposites was confirmed by various microscopic and spectroscopic techniques. The photocatalytic and antibacterial activity of NPs, CQDs and nanocomposites was comparatively evaluated using tetracycline hydrochloride, azure B, Staphylococcus aureus and Escherichia coli as model pollutants. The CQDs-Sr0.4Ti0·4Mg0·2Fe2O4.4 nanocomposite with a w:w ratio of 2:1 showed excellent photocatalytic and antibacterial activity, with the degradation and inactivation efficiency ranging from 97.1% to 99.0% in presence of visible light. The increased specific surface area (117.2 m2/g), and reduction in band gap (2.48 eV-2.09 eV) and decreased photoluminescence intensity of nanocomposites all corroborated these results. The impacting experimental parameters such as catalyst dose, pH and contact time were also examined. Quenching experiments confirmed that hydroxyl radicals (HO∙) radicals and holes (h+) played a vital role in the degradation of pollutants. The kinetics of photodegradation was explained by using the Langmuir-Hinshelwood model. Box-Behnken statistical modelling was used to optimize photocatalytic parameters. Results indicated that the nanocomposite of CQDs with Sr0·4Ti0·4Mg0·2Fe2O4.4 can serve as a promising photocatalyst for the removal of pollutants and microbes.

Investigation of Osteomyelitis Inducing Methicillin-Resistant Staphylococcus aureus Inhibition Effect by Strontium-Substituted Borate Bioactive Glasses.

Borate glass transforms into hydroxycarbonate apatite more rapidly than silicate glass. This research aims to evaluate strontium's structural and biological effects on borate bioactive glass (BBG) and the influence of strontium concentrations (0%, 5%, 10%, and 15% Sr) prepared via the sol-gel method. The study reveals significant findings related to the physicochemical properties of the glass. Immersion of the glass powders in a simulated body fluid (SBF) led to the development of a hydroxyapatite (HAP) layer on the glass surfaces. This transformation was verified through X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) analyses. In particular, 5% strontium exhibited gradual degradation, resulting in particle sizes below 100 nm. The BBG-15%Sr demonstrates heightened pathogenic activity as it shows a significant inhibition zone of 14 mm at 250 µg/mL, surpassing other substituted BBGs. It effectively combats Gram-positive bacteria, completely inhibiting MRSA growth at 50 µg/mL. This underscores its robust biofilm disruption capabilities, eradicating biofilms, even at minimal concentrations after prolonged exposure. C. elegans when subjected to BBG-15%Sr shows less ROS production when compared with the others. Moreover, the results suggest that the modified glass could be a potential material for the treatment of osteomyelitis-affected bone repair.

Vanadium and strontium co-doped hydroxyapatite enriched polycaprolactone matrices for effective bone tissue engineering: A synergistic approach.

Scientific research targeted at enhancing scaffold qualities has increased significantly during the last few decades. This emphasis frequently centres on adding different functions to scaffolds in order to increase their usefulness as instruments in the field of regenerative medicine. This study aims to investigate the efficacy of a multifunctional sustainable polymer scaffold, specifically Polycaprolactone (PCL) embedded with hydroxyapatite co-doped with vanadium and strontium (HVS), for bone tissue engineering applications. Polycaprolactone was used to fabricate the scaffold, while hydroxyapatite co-doped with vanadium and strontium (HVS) served as the nanofiller. A thorough investigation of the physicochemical and biological characteristics of the HVS nanofiller was carried out using cutting-edge techniques including Dynamic Light Scattering (DLS), and X-ray Photoelectron Spectroscopy (XPS) and in vitro cell studies. A cell viability rate of more than 70 % demonstrated that the synthesised nanofiller was cytotoxic, but in an acceptable range. The mechanical, biological, and physicochemical properties of the scaffold were extensively evaluated after the nanofiller was integrated. The water absorption characteristics of scaffold were enhanced by the addition of HVS nanofillers, leading to increased swelling, porosity, and hydrophilicity. These improvements speed up the flow of nutrients and the infiltration of cells into the scaffold. The scaffold has been shown to have important properties that stimulate bone cell activity, including better biodegradability and improved mechanical strength, which increased from 5.30 ± 0.37 to 10.58 ± 0.42 MPa. Further, its considerable antimicrobial qualities, blood-compatible nature, and capacity to promote biomineralization strengthen its appropriateness for usage in biomedical applications. Mainly, enhanced Alkaline phosphatase (ALP) activity, Alizarin Red Staining (ARS) activity, and excellent cell adhesive properties, indicating the outstanding osteogenic potential observed in rat bone marrow-derived stromal cells (rBMSC). These combined attributes highlight the pivotal role of these nanocomposite scaffolds in the field of bone tissue engineering.

Sr-Incorporated Bioactive Glass Remodels the Immunological Microenvironment by Enhancing the Mitochondrial Function of Macrophage via the PI3K/AKT/mTOR Signaling Pathway.

The repair of critical-sized bone defects continues to pose a challenge in clinics. Strontium (Sr), recognized for its function in bone metabolism regulation, has shown potential in bone repair. However, the underlying mechanism through which Sr2+ guided favorable osteogenesis by modulating macrophages remains unclear, limiting their application in the design of bone biomaterials. Herein, Sr-incorporated bioactive glass (SrBG) was synthesized for further investigation. The release of Sr ions enhanced the immunomodulatory properties and osteogenic potential by modulating the polarization of macrophages toward the M2 phenotype. In vivo, a 3D-printed SrBG scaffold was fabricated and showed consistently improved bone regeneration by creating a prohealing immunological microenvironment. RNA sequencing was performed to explore the underlying mechanisms. It was found that Sr ions might enhance the mitochondrial function of macrophage by activating PI3K/AKT/mTOR signaling, thereby favoring osteogenesis. Our findings demonstrate the relationship between the immunomodulatory role of Sr ions and the mitochondrial function of macrophages. By focusing on the mitochondrial function of macrophages, Sr2+-mediated immunomodulation sheds light on the future design of biomaterials for tissue regenerative engineering.

Near-infrared mechanoluminescence sensor: A new method for on-site infrastructure detection.

Near-infrared mechanoluminescence is a phenomenon that produces high penetrating near-infrared light under external stimulation. Near-infrared light coincides with the biological window, lower optical loss, and the fact that the mechanoluminescence material is a medium that converts mechanical energy into light energy. The near-infrared mechanoluminescence material has potential application prospects in the fields of biological imaging, medical diagnosis, and monitoring of building materials. In this article, we report on a perovskite-type Sr3Sn2O7:Nd3+ near-infrared mechanoluminescence material, and its peaks locate in the first near-infrared window (800-1000 nm) and the second near-infrared window (1080, 1350 nm), respectively. Under the condition of pre-sintering with Li2CO3 as flux, the best sintering conditions are obtained, and the luminescence of material is in perfect agreement with the applied mechanical stress. In addition, a near-infrared mechanoluminescence sensor is proposed to solve the problem of building damage and timely maintenance.

Study on the performance and mechanism of cobaltous ion removal from water by a high-efficiency strontium-doped hydroxyapatite adsorbent.

In this study, a high-efficiency strontium-doped hydroxyapatite (Sr-HAP) adsorbent was synthesized by a sol-gel method for removing cobaltous ions (Co(II)) from water. The effects of adsorbent dose, initial solution pH, initial Co(II) concentration and temperature on the removal performance of Co(II) were investigated. Experimental results indicated that the optimum Sr-HAP dose was 0.30 g/50 mL solution, the Sr-HAP adsorbent could effectively remove Co(II) in a wide pH range of 3-8. Increasing temperature was conducive to the adsorption, and the maximum Co(II) adsorption capacity by Sr-HAP reached 48.467 mg/g at 45 °C. The adsorption of Co(II) followed the pseudo-second-order kinetic model, indicating that the Co(II) adsorption by Sr-HAP was attributed mainly to chemisorption. The isothermal adsorption results showed that at lower Co(II) equilibrium concentration, the Langmuir model fitted the data better than the Freundlich model but opposite at higher Co(II) equilibrium concentration. Therefore, the adsorption of Co(II) was a process from monolayer adsorption to multilayer adsorption with the increase of the Co(II) equilibrium concentration. The diffusion analysis of Co(II) to Sr-HAP indicated that the internal diffusion and surface adsorption were the rate-controlled steps of Co(II) adsorption. Thermodynamic study demonstrated that the Co(II) adsorption process was spontaneous and endothermic. The mechanism study revealed that in addition to chemisorption, Sr-HAP also removed Co(II) ions from water via ion exchange and surface complexation.

Osteosarcoma cell death induced by innovative scaffolds doped with chemotherapeutics.

Osteosarcoma (OS) cancer treatments include systemic chemotherapy and surgical resection. In the last years, novel treatment approaches have been proposed, which employ a drug-delivery system to prevent offside effects and improves treatment efficacy. Locally delivering anticancer compounds improves on high local concentrations with more efficient tumour-killing effect, reduced drugs resistance and confined systemic effects. Here, the synthesis of injectable strontium-doped calcium phosphate (SrCPC) scaffold was proposed as drug delivery system to combine bone tissue regeneration and anticancer treatment by controlled release of methotrexate (MTX) and doxorubicin (DOX), coded as SrCPC-MTX and SrCPC-DOX, respectively. The drug-loaded cements were tested in an in vitro model of human OS cell line SAOS-2, engineered OS cell line (SAOS-2-eGFP) and U2-OS. The ability of doped scaffolds to induce OS cell death and apoptosis was assessed analysing cell proliferation and Caspase-3/7 activities, respectively. To determine if OS cells grown on doped-scaffolds change their migratory ability and invasiveness, a wound-healing assay was performed. In addition, the osteogenic potential of SrCPC material was evaluated using human adipose derived-mesenchymal stem cells. Osteogenic markers such as (i) the mineral matrix deposition was analysed by alizarin red staining; (ii) the osteocalcin (OCN) protein expression was investigated by enzyme-linked immunosorbent assay test, and (iii) the osteogenic process was studied by real-time polymerase chain reaction array. The delivery system induced cell-killing cytotoxic effects and apoptosis in OS cell lines up to Day 7. SrCPC demonstrates a good cytocompatibility and it induced upregulation of osteogenic genes involved in the skeletal development pathway, together with OCN protein expression and mineral matrix deposition. The proposed approach, based on the local, sustained release of anticancer drugs from nanostructured biomimetic drug-loaded cements is promising for future therapies aiming to combine bone regeneration and anticancer local therapy.

Enhanced osteogenesis and physicochemical properties of PMMA bone cement with SrBG/HA porous core-shell microspheres.

Artificial bone graft with osteoconductivity, angiogenesis, and immunomodulation is promising clinical therapeutics for the reluctant healing process of bone defects. Among various osteogenic substitutes, polymethyl methacrylate (PMMA) bone cement is a quit competitive platform due to its easy deployment to the bone defects with irregular shape and biomimetic mechanical properties. However, the biologically inert essence of PMMA is reliant on the passive osseointegration and cannot provide sufficient biologic cues to induce fast bone repair. Bioactive glass could serve as an efficient platform for the active osteogenesis of PMMA via ionic therapy and construction of alkaline microenvironment. However, the direct of deployment of bioactive glass into PMMA may trigger additional cytotoxicity and hinder cell growth on its surface. Hence we incorporated ionic therapy as osteogenic cue into the PMMA to enhance the biomedical properties. Specifically, we synthesized core-shell microspheres with a strontium-doped bioactive glass (SrBG) core and hydroxyapatite (HA) shell, and then composited them with PMMA to introduce multifunctional effects of HA incorporation, alkaline microenvironment construction, and functional ion release by adding microsphere. We preparedxSrBG@HA/PMMA cements (x= 30, 40, 50) with varied microsphere content and evaluated impacts on mechanical/handling properties, ion release, and investigated the impacts of different composite cements on proliferation, osteogenic differentiation, angiogenic potential, and macrophage polarization. These findings provide new perspectives and methodologies for developing advanced bone biomaterials to promote tissue regeneration.

Synergistic Improvement of Antibacterial and Osteogenic Differentiation of Thermomechanically Processed Mg-Zr-Sr-Ce Alloy: Insights into the Role of Precipitate Evolution Supported by AIMD Simulation Study.

In the present study, we have discussed the influence of forging temperature (623 K (FT623), 723 K (FT723) and 823 K (FT823)) on microstructure and texture evolution and its implication on mechanical behavior, in vitro-in vivo biocorrosion, antibacterial response, and cytocompatibility of microalloyed Mg-Zr-Sr-Ce alloy. Phase analysis, SEM, and TEM characterization confirm the presence of Mg12Ce precipitate, and its stability was further validated by performing ab initio molecular dynamic simulation study. FT723 exhibits strengthened basal texture, higher fraction of second phases, and particle-stimulated nucleation-assisted DRX grains compared to other two specimens, resulting in superior strength with comparable ductility. FT723 also exhibits superior corrosion resistance mainly due to the strengthened basal texture and lower dislocation density. All the specimens exhibit excellent antibacterial behavior with Gram-negative E. coli, Gram-positive Staphylococcus aureus, and Pseudomonas aeruginosa bacteria. 100% reduction of bacterial growth is observed within 24 h of culture of the specimens. Cytocompatibility was determined by challenging specimen extracts with the MC3T3-E1 cell lines. FT723 specimen exhibits the highest cell proliferation and alkaline phosphatase activity (ALP) because of its superior corrosion resistance. The ability of the specimens to be used in orthopedic implant application was evaluated by in vivo study in rabbit femur. Neither tissue-related infection nor the detrimental effect surrounding the implant was confirmed from histological analysis. Significant higher bone regeneration surrounding the FT723 specimen was observed in SEM analysis and fluorochrome labeling. After 60 days, the FT723 specimen exhibits the highest bone formation, suggesting it is a suitable candidate for orthopedic implant application.

Strontium-Doped Hydroxyapatite Coating Improves Osteo/Angiogenesis for Ameliorative Graft-Bone Integration via the Macrophage-Derived Cytokines-Mediated Integrin Signal Pathway.

Polyethylene terephthalate (PET) artificial ligaments, renowned for their superior mechanical properties, have been extensively adopted in anterior cruciate ligament (ACL) reconstruction surgeries. However, the inherent bio-inertness of PET introduces formidable barriers to graft-bone integration, a critical aspect of rehabilitation. Previous interventions, ranging from surface roughening to chemical modifications, have aimed to address this challenge; however, consistently effective techniques for inducing graft-bone integration remain scarce. Our study employed advanced surface-coating methodologies to introduce strontium-doped hydroxyapatite (SrHA) onto PET ligaments. Detailed scanning electron microscopy (SEM) examinations revealed a uniform and integrative coating of SrHA on PET fibers. Furthermore, spectroscopic analysis confirmed the steady release of strontium ions from the coated surface under physiological conditions. In-depth cellular studies proved that extracellular strontium emanating from SrHA-coated PET (PET@SrHA) ligaments actively steers the M2 macrophage polarization. Additionally, macrophages (Mφs) manifested a heightened secretion of prohealing cytokines when exposed to PET@SrHA. Subsequent investigations showed that these cytokines acted as mediators, activating integrin signaling pathways among macrophages, vascular endothelial cells, and osteoblasts. As a direct consequence, an increased rate of angiogenesis and osteogenic differentiation was observed, vital for graft-bone integration following ACL reconstruction with PET@SrHA ligaments. From a biochemical standpoint, our results pinpoint strontium ions as influential immunomodulators, sculpting the graft-bone interface's immune environment. This insight presents the SrHA-coating technique as a viable therapeutic strategy, holding sound promise for improving angiogenesis and osseointegration outcomes during ACL reconstruction using PET-based grafts.

Controlled solvothermal synthesis of self-assembled SrTiO3 microstructures for expeditious solar-driven photocatalysis dye effluents degradation.

In this work, the self-assembled SrTiO3 (STO) microstructures were synthesized via a facile one-step solvothermal method. As the solvothermal temperature increased from 140 °C to 200 °C, the STO changed from a flower-like architecture to finally an irregularly aggregated flake-like morphology. The photocatalytic performance of as-synthesized samples was assessed through the degradation of rhodamine B (RhB) and malachite green (MG) under simulated solar irradiation. The results indicated that the photocatalytic performance of STO samples depended on their morphology, in which the hierarchical flower-like STO synthesized at 160 °C demonstrated the highest photoactivities. The photocatalytic enhancement of STO-160 was benefited from its large surface area and mesoporous configuration, hence facilitating the presence of more reactive species and accelerating the charge separation. Moreover, the real-world practicality of STO-160 photocatalysis was examined via the real printed ink wastewater-containing RhB and MG treatment. The phytotoxicity analyses demonstrated that the photocatalytically treated wastewater increased the germination of mung bean seeds, and the good reusability of synthesized STO-160 in photodegradation reaction also promoted its application in practical scenarios. This work highlights the promising potential of tailored STO microstructures for effective environmental remediation applications.

A Multifunctional Metal-Phenolic Nanocoating on Bone Implants for Enhanced Osseointegration via Early Immunomodulation.

Surface modification is an important approach to improve osseointegration of the endosseous implants, however it is still desirable to develop a facile yet efficient coating strategy. Herein, a metal-phenolic network (MPN) is proposed as a multifunctional nanocoating on titanium (Ti) implants for enhanced osseointegration through early immunomodulation. With tannic acid (TA) and Sr2+ self-assembled on Ti substrates, the MPN coatings provided a bioactive interface, which can facilitate the initial adhesion and recruitment of bone marrow mesenchymal stem cells (BMSCs) and polarize macrophage toward M2 phenotype. Furthermore, the TA-Sr coatings accelerated the osteogenic differentiation of BMSCs. In vivo evaluations further confirmed the enhanced osseointegration of TA-Sr modified implants via generating a favorable osteoimmune microenvironment. In general, these results suggest that TA-Sr MPN nanocoating is a promising strategy for achieving better and faster osseointegration of bone implants, which can be easily utilized in future clinical applications.

Effect of strontium fluoride on mechanical and remineralization properties of enamel: An in-vitro study on a modified orthodontic adhesive.

OBJECTIVES: Evaluate the ability of strontium fluoride on bond strength and enamel integrity after incorporation within orthodontic adhesive system as a delivery vehicle. METHODS: Experimental orthodontic adhesive system Transbond™ XT were modified with 1% Sr2+, 0.5% SrF2, 1% strontium, 0.5% Sr2+, 1% F-, 0.5% F-, and no additions were control. Mixing of formulation was monitored using Fourier transform infrared spectroscopy. Small-molecule drug-discovery suite was used to gain insights into Sr2+, F-, and SrF2 binding. Shear bond testing was performed after 6-months of ageing. Enamel blocks were cut, and STEM pictures were recorded. Specimens were indented to evaluate elastic modulus. Raman microscope was used to collect Raman spectra and inspected using a scanning electron microscope. Crystal structural analysis was performed using X-ray diffraction. Effect of material on cellular proliferation was determined. Confocal was performed to evaluate the effect of formulation on biofilms. RESULTS: FTIR of modified adhesives depicted peak changes within range due to various functional groups existing within samples. TEM represented structurally optimized hexagonal unit-cell of hydroxyapatite. Mean shear bond strength is recorded highest for Transbond XT with 1% SrF2. Dead bacterial percentage appeared higher in 0.5% SrF2 and 1% F- specimens. Crystal lengths showed an increase in 0.5% and 1% SrF2 specimens. Phase contrast within TEM images showed a union of 0.5% SrF2 crystal with enamel crystal with higher elastic modulus and highly mineralized crystalline hydroxyapatite. Intensity of ν1 PO43- and ν1 CO32- along with carbonate - / ν1PO43- ratio displayed good association with strontium fluoride. The formulation showed acceptable cell biocompatibility (p < 0.353). All specimens displayed characteristic diffraction maxima of different apatite angles within XRD. SIGNIFICANCE: Experimental results suggested good biocompatibility, adequate mechanical strength, and far-ranging crystallization ability. This would provide a new strategy to overcome the two major challenges of fixed orthodontics, biofilm growth, and demineralization of enamel.

Structural insight and in silico prediction of the pharmacokinetic parameters and toxicity of alkaline earth metal compounds strontium and barium with the non-steroidal anti-inflammatory drug nimesulide.

In the crystals of alkaline earth metal compounds strontium and barium with the non-steroidal anti-inflammatory drug nimesulide, the strontium cation is nine-coordinated with a distorted tricapped trigonal prismatic geometry TCTPR-9, whereas the ten-coordinated barium ion exhibits a distorted tetracapped trigonal prismatic geometry TCTPR-10.

Enhanced remineralisation ability and antibacterial properties of sol-gel glass ionomer cement modified by fluoride containing strontium-based bioactive glass or strontium-containing fluorapatite.

OBJECTIVES: This study aimed to compare two types of bioactive additives which were strontium-containing fluorinated bioactive glass (SrBGF) or strontium-containing fluorapatite (SrFA) added to sol-gel derived glass ionomer cement (SGIC). The objective was to develop antibacterial and mineralisation properties, using bioactive additives, to minimize the occurrence of caries lesions in caries disease. METHODS: Synthesized SrBGF and SrFA nanoparticles were added to SGIC at 1 wt% concentration to improve antibacterial properties against S. mutans, promote remineralisation, and hASCs and hDPSCs viability. Surface roughness and ion-releasing behavior were also evaluated to clarify the effect on the materials. Antibacterial activity was measured via agar disc diffusion and bacterial adhesion. Remineralisation ability was assessed by applying the material to demineralised teeth and subjecting them to a 14-day pH cycle, followed by microCT and SEM-EDS analysis. RESULTS: The addition of SrFA into SGIC significantly improved its antibacterial property. SGIC modified with either SrBGF or SrFA additives could similarly induce apatite crystal precipitation onto demineralised dentin and increase dentin density, indicating its ability to remineralise dentin. Moreover, this study also showed that SGIC modified with SrBGF or SrFA additives had promising results on the in vitro cytotoxicity of hASC and hDPSC. SIGNIFICANT: SrFA has superior antibacterial property as compared to SrBGF while demonstrating equal remineralisation ability. Furthermore, the modified SGIC showed promising results in reducing the cytotoxicity of hASCs and hDPSCs, indicating its potential for managing caries.