Mineralization Ability Research Articles

EXPERIMENTAL STUDY ON THE EVOLUTION OF MICROPORE STRUCTURE SOFTENED BY NONPRESSURE WATER ABSORPTION STRENGTH OF SANDSTONE

With the increase of mining depth of a coal mine, the strength of the surrounding rock in deep roadways decreases due to the influence of groundwater, which seriously affects the safety of on-site personnel in production. To study the influence of water-rock interaction on the properties of surrounding rock, taking the sandstone in the deep roadway of Wanfu Coal Mine as the research object. The nonpressure water absorption experiment was carried out. According to the compression tests of key water content (0%, 0.8%, 1.6%, 2.4%, 3.3%), the mechanical evolution law of sandstone during water absorption was studied. At the same time, mercury porosimetry (MIP), scanning electron microscopy (SEM), and nuclear magnetic resonance (NMR) experiments are used to study the evolution of experimental microscopic pores. The strength-softening mechanism of sandstone in Wanfu Coal Mine is discussed. The results show the following: (1) The NMR T<sub>2</sub> spectrum curve of sandstone presented a single peak characteristic. With the increase of water content, the total spectrum area increases continuously, and the corresponding relaxation time of peak shifts to the right. According to the ratio of spectral area in the experimental process, the traditional process of water absorption is further divided into four stages: rapid water absorption, uniform water absorption, pore transformation, and stable water absorption, in which the pore transformation mainly occurs in stage III (31-113 h). (2) The strength of sandstone decreases nonlinearly with the increase of water content, and the degree of attenuation is affected by confining pressure. The softening degree of strength decreases with the growth of confining pressure. With the rise in water content, both cohesion and internal friction angle show a negative exponential decreasing trend. (3) Expansion of clay minerals and the restraint of a quartz skeleton during the experiment are reasons for the closure of pores; misalignment of quartz particles, the flow of pore water, and dissolution of soluble minerals will lead to pore enlargement during water absorption. (4) In addition to the lubrication of water film and the decrease of the cementation ability of clay minerals, the expansion and connectivity of the pore are also important aspects of the softening of sandstone and influence the final destructive form of sandstone.

Modification of hydroxyapatite (HA) powder by carboxymethyl chitosan (CMCS) for 3D printing bioceramic bone scaffolds

The poor mechanical properties of 3D printed HA bone scaffold is always a challenge in tissue engineering, to address this issue, carboxymethyl chitosan (CMCS) was proposed to modify HA bone scaffolds by a physical blending method in this research. A series of HA and HA/CMCS composite ceramic scaffolds were printed by using piezoelectric inkjet 3D printing technology, and their properties were investigated in terms of forming quality, structural morphology, mechanical properties, degradability, cytotoxicity, and cell adhesion growth. The results of forming quality and structural morphology show that with the increase of CMCS content, the forming quality of the samples deteriorated, the pore size and porosity increased. However, when the content of CMCS reached 5 wt%, obvious cracks appeared on the surface of the sample, and the forming quality was relatively poor. The mechanical testing results indicated the toughness of composites could be enhanced by incorporating CMCS into HA, which was attributed to the higher strength connections of the CMCS polymer network between HA particles and the stronger interaction between HA and CMCS molecules. FTIR spectra further revealed the strong hydrogen bonding interaction between CMCS and HA. Moreover, the degradation rate and mineralization ability of the sample increased with the content of CMCS, but the compressive strength during degradation increased with the CMCS content, indicating that incorporating CMCS into HA cannot only improve the mechanical property and biological activity of the scaffold but also makes up the defect of slow degradation of pure HA scaffold. Finally, the cytotoxicity, cell adhesion, and cell proliferation tests show that HA and HA/CMCS composite samples had good cytocompatibility, HA/CMCS sample with 3 wt% CMCS possessed the best bioactivity. In summary, HA/CMCS composite powder with 3 wt% CMCS content is the optimal matrix material for 3D printing bone scaffolds.

Improving the osseointegration and soft tissue sealing of zirconia ceramics by the incorporation of akermanite via sol infiltration for dental implants.

Zirconia ceramics are promising dental implant materials due to their high-grade biocompatibility, high mechanical strength, and distinctive aesthetic appearance. Nevertheless, zirconia ceramics are bio-inert with a lack of osseointegration and soft tissue sealing, which limits dental implant applications. As such, the fabrication of zirconia ceramics with high mechanical strength, excellent osseointegration and soft tissue sealing performance remains a great challenge in the dental restoration field. In this article, a novel zirconia ceramic with akermanite (AKT) modification by the negative pressure infiltration method is presented. The effects of AKT sol infiltration at different times on the morphology, phase composition, mechanical properties, bioactivity, osseointegration and soft tissue sealing of the modified zirconia ceramics have been systematically investigated. The modified zirconia ceramics feature excellent mechanical properties and significantly improved surface roughness, hydrophilia, and apatite mineralization ability as compared with unmodified zirconia ceramics. Furthermore, cell-culture experiment results indicated that the surface modification of zirconia ceramics could promote adhesion, spreading, migration, proliferation and osteogenic differentiation of mouse bone marrow stromal stem cells (mBMSCs), as well as the early adhesion, spreading, proliferation and fibroblast differentiation of human gingival fibroblasts (HGFs) in vitro. The prepared bioactive zirconia distinctively enhanced the alkaline phosphate (ALP) activity, osteogenesis-related gene expression of mBMSCs and fibroblast-related-gene expression of HGFs. The in vivo evaluation confirmed that 15-TZP ceramics could promote bone-implant osseointegration to the greatest extent as compared with pure zirconia ceramics. To conclude, our research has shown that AKT-modified zirconia ceramics can achieve bone integration and soft tissue sealing, indicating that they have a lot of potential for application as a novel dental implant material in the clinical setting.

Optimization of the Alizarin Red S Assay by Enhancing Mineralization of Osteoblasts.

The alizarin red S assay is considered the gold standard for quantification of osteoblast mineralization and is thus widely used among scientists. However, there are several restrictions to this method, e.g., moderate sensitivity makes it difficult to uncover slight but significant effects of potentially clinically relevant substances. Therefore, an adaptation of the staining method is appropriate and might be obtained by increasing the mineralization ability of osteoblasts. In this study, cell culture experiments with human (SaOs-2) and murine (MC3T3-E1) osteoblasts were performed under the addition of increasing concentrations of calcium chloride (1, 2.5, 5, and 10 mM) or calcitonin (1, 2.5, 5, and 10 nM). After three or four weeks, the mineralization matrix was stained with alizarin red S and the concentration was quantified photometrically. Only calcium chloride was able to significantly increase mineralization, and therefore enhanced the sensitivity of the alizarin red S staining in a dose-dependent manner in both osteoblastic cell lines as well as independent of the cell culture well surface area. This cost- and time-efficient optimization enables a more sensitive analysis of potentially clinically relevant substances in future bone research.

Effects of L-Chg10-Teixobactin on Viability, Proliferation, and Osteo/Odontogenic Differentiation of Stem Cells from Apical Papilla

IntroductionIntracanal medicament is one of the essential steps for ensuring success in regenerative endodontic procedures. L-Chg10-teixobactin is a novel antimicrobial agent that exhibited potent antibacterial and antibiofilm effects against Enterococcusfaecalis at low concentrations compared with ampicillin. At the same time, its cytotoxicity on dental stem cells has not been studied. This study aimed to investigate the effects of L-Chg10-teixobactin on the viability, proliferation, migration, and osteo/odontogenic differentiation of stem cells from apical papilla (SCAPs). Materials and MethodsSCAPs isolated from immature human third molars were treated with various concentrations of L-Chg10-teixobactin, calcium hydroxide, and dimethyl sulfoxide. The viability and proliferation of SCAPs were assessed using the LIVE/DEAD Viability/Cytotoxicity Kit and Cell Counting Kit-8. A scratch wound healing test was used to evaluate the lateral migration capacity of SCAPs. Alkaline phosphatase (ALP) activity, calcium mineralization ability tests -ie, ALP staining and alizarin red S staining, and quantitative real-time polymerase chain reaction were performed to assess the osteo /odontogenic differentiation of SCAPs. ResultsThe tested concentrations of L-Chg10-teixobactin (0.01, 0.02, and 0.03 mg/mL), 1 mg/mL calcium hydroxide, and 0.03% dimethyl sulfoxide had no significant cytotoxic effect on SCAPs at any time point (P > .05). Besides, there were no significant differences between the control and experimental groups in SCAPs’ viability, proliferation, and migration. L-Chg10-teixobactin upregulated the gene expression of osteo/odontogenic markers in SCAPs, while no significant difference was found in the ALP activity and alizarin red S staining. ConclusionsL-Chg10-teixobactin demonstrated excellent biocompatibility on SCAPs at concentrations from 0.01 to 0.03 mg/mL and potentially enhance the osteo/odontogenic differentiation of SCAPs; suggesting its promising role as root canal medicament for regenerative endodontic procedures.

Dynamic expression of Mage-D1 in rat dental germs and potential role in mineralization of ectomesenchymal stem cells

Mage-D1 (MAGE family member D1) is involved in a variety of cell biological effects. Recent studies have shown that Mage-D1 is closely related to tooth development, but its specific regulatory mechanism is unclear. The purpose of this study was to investigate the expression pattern of Mage-D1 in rat dental germ development and its differential mineralization ability to ectomesenchymal stem cells (EMSCs), and to explore its potential mechanism. Results showed that the expression of Mage-D1 during rat dental germ development was temporally and spatially specific. Mage-D1 promotes the proliferation ability of EMSCs but inhibits their migration ability. Under induction by mineralized culture medium, Mage-D1 promotes osteogenesis and tooth-forming ability. Furthermore, the expression pattern of Mage-D1 at E19.5 d rat dental germ is similar to p75 neurotrophin receptor (p75NTR), distal-less homeobox 1 (Dlx1) and msh homeobox 1 (Msx1). In addition, Mage-D1 is binding to p75NTR, Dlx1, and Msx1 in vitro. These findings indicate that Mage-D1 is play an important regulatory role in normal mineralization of teeth. p75NTR, Dlx1, and Msx1 seem to be closely related to the underlying mechanism of Mage-D1 action.

Elucidating the positive influence of calcined clay on the retention of carbon components during chicken manure composting

Composting is an efficient way of recycling wastes, serious mineralization will lead to loss of organic carbon components in the biodegradation process, which will affect the quality of composting products. Calcination technology was adopted to improve the ability of clay minerals to adsorb and retain organic carbon components, and was applied to chicken manure composting. Five treatments (control group (CK), calcined montmorillonite (M-), montmorillonite (M), calcined illite (I-) and illite (I)) were executed. The results indicated that calcined clay minerals significantly reduced organic carbon loss (CK: 57.22%, M-: 54.56%, M: 56.86%, I-: 52.39% and I: 56.08%) and most of them in the form of humic acids. Therefore, the properties of carbon components were more stable, and ultimately improved quality of final compost products. Meanwhile, the network complexity, interactions and contribution of core bacteria involved in the formation of organic carbon were enhanced in the calcined clay minerals treatments through microbial analysis. Moreover, a series of statistical informatics analysis verified that specific structure of calcined clay minerals could indeed retain organic carbon by enhancing role of core bacteria and physicochemical factors. Therefore, this article revealed mechanism of calcined clay minerals retained organic carbon and proposed rational recommendations for practice of composting.

Baricitinib alleviates lipopolysaccharide‑induced human periodontal ligament stem cell injury and promotes osteogenic differentiation by inhibiting JAK/STAT signaling.

Periodontitis is the chronic inflammation of the periodontal tissue. The present study aimed to investigate the role of baricitinib, a Janus kinase (JAK)1/2 inhibitor, in periodontitis by using a lipopolysaccharide (LPS)-induced human periodontal ligament stem cell (PDLSC) model. The viability of PDLSCs stimulated by LPS was assessed in the presence of baricitinib by Cell Counting Kit-8 assay. The induction of oxidative stress was evaluated by detecting the intracellular reactive oxygen species (ROS) levels, superoxide dismutase (SOD) activity and glutathione (GSH) content. ELISA and reverse transcription-quantitative PCR were used to determine the levels of inflammatory factors TNF-α, IL-1β and IL-6. Alkaline phosphatase (ALP) activity and alizarin red staining were used to assess the osteogenic differentiation of PDLSCs. The expression levels of osteogenic differentiation- and JAK/signal transducer and activator of transcription (STAT) signaling-associated proteins were estimated with western blotting. RO8191, an agonist of the JAK/STAT pathway, was used to treat PDLSCs to investigate the regulatory mechanism of baricitinib. The results indicated that baricitinib elevated the LPS-induced decrease in cell viability. LPS-triggered oxidative stress and inflammation were inhibited by baricitinib, as demonstrated by the decreased levels of ROS, TNF-α, IL-1β, IL-6 and increased levels of SOD and GSH. In addition, baricitinib caused a marked elevation in ALP activity and mineralization ability of PDLSCs, as determined by the upregulated osteocalcin and Runt-related transcription factor 2 expression. Moreover, the expression levels of phosphorylated (p)-JAK1, p-JAK2 and p-STAT3 were downregulated by baricitinib in a dose-dependent manner. Furthermore, addition of RO8191 restored the effect of baricitinib on the induction of oxidative stress, inflammation and osteogenic differentiation of PDLSCs exposed to LPS. Collectively, these findings suggested that baricitinib alleviated oxidative stress and inflammation and promoted osteogenic differentiation of LPS-induced PDLSCs by inhibiting JAK/STAT signaling.

Highly efficient screening and optimal combination of functional isolates for bioremediation of hydrocarbon-polluted soil

The key to enhancing the efficacy of bioremediation of hydrocarbon-contaminated soil is the precise and highly efficient screening of functional isolates. Low screening effectiveness, narrow screening range and an unstable structure of the constructed microflora during bioremediation are the shortcomings of the traditional shaking culture (TSC) method. To improve the secondary screening of isolates and microflora implemented for alkane degradation, this work evaluated the characterization relationship between bacterial function and enzyme activity and devised an enzyme activity assay (EAA) method. The results indicated a substantial positive correlation (r = 0.97) between 24 candidate isolates and their whole enzymes, proving that whole enzyme activity properly reflects the metabolic functions of microorganisms. The functional analysis of the isolates demonstrated that the EAA method in conjunction with microbial abundance and metabolite determination could broaden the screening range of functional isolates, including aliphatic acid-metabolizing isolates (isolates H4 and H7) and aliphatic acid-sensitive isolates (isolate H2) with n-hexadecane degradation ability. The EAA method also guided the construction of functional microflora and optimized the mode of application using combinations of alkane-degrading bacteria and aliphatic acid-degrading bacteria successively (e.g., F1+H7+H7). The combinations maintained a high abundance of functional isolates and stable α diversity and community composition throughout the experiment, which contributed to more advanced alkane degradation and mineralization ability (p < 0.01). Assuming a workload of 100 tests, the screening efficiency of the EAA method is more than 16 times that of the TSC method, and the greater the quantity of isolates, the higher the screening efficiency, enabling high-throughput screening. In conclusion, the EAA method has a broad-spectrum, accurate and highly efficient screening ability for functional isolates and microflora, which can provide intensive technical support for the development of bioremediation materials and the application of bioremediation technology.

Multifunctional titanium surface coating for oral implants with strong resistance to bacteria and mineralization ability

Titanium (Ti) has good mechanical properties, corrosion resistance, and biocompatibility. Biomaterials for the oral cavity have special requirements, such as the ability to resist bacterial adhesion and promote mineralization. Therefore, the modified Ti surface must have good antibacterial adhesion properties and mineralization activity. The material surface with zwitteric ionic polymer modification has a strong hydration and steric resistance effect, providing excellent bacteria resistance. In our previous work, zwitterionic poly[2-(methacryloyloxy)ethyl choline phosphate] (Ti-PMCP) was used to modify Ti surface via surface-initiated atom transfer radical polymerization, which can promote cell adhesion and prevent nonspecific protein adsorption. In this work, we further studied the antibacterial and mineralization properties of Ti-PMCP and its the application potential in oral implant materials.

Cation doped approach for photodegradation of 4-chlorophenol by highly efficient solar active NiS photocatalyst: The case of Cu2+ doping

This study reports an efficient photodegradation of 4-chlorophenol using Cu2+ doped nickel sulfide (NiS) nanoparticles. Our study provides a facile method to synthesize Cu2+ doped NiS nanoparticles by partial polyol method and structurally validates the formation of single phased random-shaped particles. Cu2+ doping in NiS matrix results in a red shift of the absorption band edge, thus lowering the band gap from 3.62 to 2.98 eV and creating electron trapping centers that prevent electron-hole recombination. The presence of such electron trapping centers was attributed to oxygen vacancies which were justified from the appearance of g-signal in electron paramagnetic resonance analysis. Photodegradation study of 4-chlorophenol by Cu2+ doped NiS nanoparticles under ambient solar light showed significant improvement in degradation efficiency up to 90 % as compared to 19 % for undoped NiS nanoparticles. Furthermore, increased degradation efficiency was also backed by total organic carbon (TOC) analysis of the mineralization ability of Cu2+ doped NiS nanoparticles. Moreover, scavenging trapping analysis showed holes, ⋅OH and superoxide radicals as reactive oxidative species (ROS) primarily responsible for increased photodegradation efficiency. Thus, the synthesized Cu doped NiS nanoparticles proved to be an efficient catalyst, which could be used as a potential candidate for industrial photocatalytic applications under ambient solar light.

Ca Minerals and Oral Bioavailability of Pb, Cd, and As from Indoor Dust in Mice: Mechanisms and Health Implications.

Elevating dietary calcium (Ca) intake can reduce metal(loid)oral bioavailability. However, the ability of a range of Ca minerals to reduce oral bioavailability of lead (Pb), cadmium (Cd), and arsenic (As) from indoor dust remains unclear. This study evaluated the ability of Ca minerals to reduce Pb, Cd, and As oral bioavailability from indoor dust and associated mechanisms. A mouse bioassay was conducted to assess Pb, Cd, and As relative bioavailability (RBA) in three indoor dust samples, which were amended into mouse chow without and with addition of , , Ca gluconate, Ca lactate, Ca aspartate, and Ca citrate at . The mRNA expression of Ca and phosphate (P) transporters involved in transcellular Pb, Cd and As transport in the duodenum of mice was quantified using real-time polymerase chain reaction. Serum 1,25-Dihydroxyvitamin D3 [], parathyroid hormone (PTH), and renal CYP27B1 activity controlling synthesis were measured using ELISA kits. Metal(loid) speciation in the feces of mice was characterized using X-ray absorption near-edge structure (XANES) spectroscopy. In general, mice exposed to each of the Ca minerals exhibited lower Pb-, Cd-, and As-RBA for three dusts. However, RBAs with the different Ca minerals varied. Among minerals, mice fed dietary did not exhibit lower duodenal mRNA expression of Ca transporters but did have the lowest Pb and Cd oral bioavailability at the highest Ca concentration (; 51%-95% and 52%-74% lower in comparison with the control). Lead phosphate precipitates (e.g., chloropyromorphite) were observed in feces of mice fed dietary . In comparison, mice fed organic Ca minerals (Ca gluconate, Ca lactate, Ca aspartate, and Ca citrate) had lower duodenal mRNA expression of Ca transporters, but Pb and Cd oral bioavailability was higher than in mice fed . In terms of As, mice fed Ca aspartate exhibited the lowest As oral bioavailability at the highest Ca concentration (; 41%-72% lower) and the lowest duodenal expression of P transporter (88% lower). The presence of aspartate was not associated with higher As solubility in the intestine. Our study used a mouse model of exposure to household dust with various concentrations and species of Ca to determine whether different Ca minerals can reduce bioavailability of Pb, Cd, and As in mice and elucidate the mechanism(s) involved. This study can contribute to the practical application of optimal Ca minerals to protect humans from Pb, Cd, and As coexposure in the environment. https://doi.org/10.1289/EHP11730.

Application of carbon-coated nanomultilayer sintered porous titanium microprosthesis for the repair of osteochondral defects of the knee joint

We constructed a carbon-coated nanomultilayer (CNM) sintered porous titanium (Ti) microprosthesis for the optimal treatment of osteochondral defects of the knee joint. Physicochemical property tests revealed that the porosity of the constructed porous Ti-CNM prosthesis was ∼75%, while the pore size ranged 300–400 μm. The prosthesis had an elastic modulus (9.18 GPa) and compressive strength (98.3 MPa) similar to bone tissue. Furthermore, the CNM effectively reduced the roughness of the prosthesis surface. In animal experiments, the porous Ti-CNM improved the mineralization ability of osteoblasts in bone defects, as indicated by antialkaline phosphatase and osteocalcin, and improved bone mineral density, trabecular thickness, average trabecular number, and cortical bone thickness in the defective regions, thereby shortening the repair time. In addition, porous Ti-CNM effectively improved the production of extracellular matrix components in cartilage defects, such as collagen I, collagen II, and aggrecan, thereby enhancing the repair of cartilage defects and effectively preventing the degeneration of the opposite joint. The porous Ti-CNM prosthesis thus demonstrates great therapeutic potential for middle-aged patients with osteoarthritis.

Promotion effect of apical tooth germ cell-conditioned medium on osteoblastic differentiation of periodontal ligament stem cells through regulating miR-146a-5p

BackgroundMicroRNAs (miRNAs) play an important role in gene regulation that controls stem cells differentiation.Periodontal ligament stem cells (PDLSCs) could differentiate into osteo-/cementoblast-like cells that secretes cementum-like matrix both in vitro and in vivo. Whether miRNAs play key roles in osteoblastic differentiation of PDLSCs triggered by a special microenviroment remains elusive. In this study, we aimed to investigate potential miRNA expression changes in osteoblastic differentiation of PDLSCs by the induction of apical tooth germ cell-conditioned medium (APTG-CM).Methods and resultsFirst, we analyzed the ability of APTG-CM to osteogenically differentiate PDLSCs. The results exhibited an enhanced mineralization ability, higher ALP activity and increased expression of osteogenic genes in APTG-CM-induced PDLSCs. Second, we used miRNA sequencing to analyze the miRNA expression profile of PDLSCs derived from three donors under 21-day induction or non-induction of APTG-CM. MiR-146a-5p was found to be up-regulated miRNA in induced PDLSCs and validated by RT-qPCR. Third, we used lentivirus-up/down system to verify the role of miR-146a-5p in the regulation of osteoblastic differentiation of PDLSCs.ConclusionsIn conclusion, our results demonstrated that miR-146a-5p was involved in the promotion effect of APTG-CM on osteoblastic differentiation of PDLSCs, and suggested that miR-146a-5p might be a novel way in deciding the direction of PDLSCs differentiation.

Gαs-Coupled CGRP Receptor Signaling Axis from the Trigeminal Ganglion Neuron to Odontoblast Negatively Regulates Dentin Mineralization.

An inflammatory response following dental pulp injury and/or infection often leads to neurogenic inflammation via the axon reflex. However, the detailed mechanism underlying the occurrence of the axon reflex in the dental pulp remains unclear. We sought to examine the intracellular cyclic adenosine monophosphate (cAMP) signaling pathway in odontoblasts via the activation of Gs protein-coupled receptors and intercellular trigeminal ganglion (TG) neuron-odontoblast communication following direct mechanical stimulation of TG neurons. Odontoblasts express heterotrimeric G-protein α-subunit Gαs and calcitonin receptor-like receptors. The application of an adenylyl cyclase (AC) activator and a calcitonin gene-related peptide (CGRP) receptor agonist increased the intracellular cAMP levels ([cAMP]i) in odontoblasts, which were significantly inhibited by the selective CGRP receptor antagonist and AC inhibitor. Mechanical stimulation of the small-sized CGRP-positive but neurofilament heavy chain-negative TG neurons increased [cAMP]i in odontoblasts localized near the stimulated neuron. This increase was inhibited by the CGRP receptor antagonist. In the mineralization assay, CGRP impaired the mineralization ability of the odontoblasts, which was reversed by treatment with a CGRP receptor antagonist and AC inhibitor. CGRP establishes an axon reflex in the dental pulp via intercellular communication between TG neurons and odontoblasts. Overall, CGRP and cAMP signaling negatively regulate dentinogenesis as defensive mechanisms.

Properties of Mortar Containing Recycled Fine Aggregate Modified by Microbial Mineralization

Microbial-induced mineralization deposition was used to improve the quality of the recycled fine aggregate (RFA) in this paper. In order to obtain a better improvement effect, the microbial mineralization conditions were first optimized. The effect of the pH value, temperature, bacterial concentration and calcium ion concentration on the mineralization ability of bacteria were investigated. The optimal microbial mineralization conditions were selected for the treatment of RFA and the microbial mineralization modification effect of RFA was evaluated based on the water absorption and crushing index. In addition, the natural fine aggregate (NFA), unmodified RFA and modified RFA were made into ordinary mortar, recycled mortar and modified recycled mortar, respectively. The workability, mechanical properties and chloride ion penetration resistance of mortars was investigated. Meanwhile, the precipitations formed by microbial mineralization were characterized using a scanning electron microscope (SEM) with an energy dispersive spectrometer (EDS) and X-ray diffraction (XRD). The pore structure of mortars was analyzed using the mercury intrusion porosimeter (MIP). The results showed that the bioprecipitations were mainly calcite calcium carbonate and the quality of the RFA was improved by microbial-induced calcium carbonate deposition. The water absorption and crushing index of the modified RFA decreased by 25.7% and 4.2%, respectively. Compared with the crushing index, the water absorption of the RFA was improved more obviously. The workability, mechanical performance, chloride ion penetration resistance and pore structure of the modified recycled mortar was improved. Compared with the recycled mortar, the fluidity of the modified recycled mortar was 7.3% higher, the compressive strength of 28 d was 7.0% higher and the 6 h electric flux was 18.8% lower. The porosity of the ordinary mortar, recycled mortar and modified recycled mortar was 16.49%, 20.83% and 20.27%, respectively. The strengthening of the modified recycled mortar performance may be attributed to the improvement of the mortar microstructure due to the enhancement of the RFA quality after the biotreatment.

Strontium Carbonate and Strontium-Substituted Calcium Carbonate Nanoparticles Form Protective Deposits on Dentin Surface and Enhance Human Dental Pulp Stem Cells Mineralization.

Strontium acetate is applied for dental hypersensitivity treatment; however, the use of strontium carbonates for this purpose has not been described. The use of Sr-carbonate nanoparticles takes advantage of both the benefits of strontium on dentin mineralization and the abrasive properties of carbonates. Here in, we aimed to synthesize strontium carbonate and strontium-substituted calcium carbonate nanoparticles and test them as potential compounds in active dentifrices for treating dental hypersensitivity. For this, SrCO3, Sr0.5Ca0.5CO3, and CaCO3 nanoparticles were precipitated using Na2CO3, SrCl2, and/or CaCl2 as precursors. Their morphology and crystallinity were evaluated by electron microscopy (SEM) and X-ray diffraction, respectively. The nanoparticles were added to a poly (vinyl alcohol) gel and used to brush dentin surfaces isolated from human third molars. Dentin chemical composition before and after brushing was investigated by infrared spectroscopy (FTIR) and X-ray dispersive energy spectroscopy. Dentin tubule morphology, obliteration, and resistance of the coatings to acid attack were investigated by SEM and EDS. The cytotoxicity and ability of the particles to trigger the mineralization of hDPSCs in vitro were studied. Dentin brushed with the nanoparticles was coated by a mineral layer that was also able to penetrate the tubules, while CaCO3 remained as individual particles on the surface. FTIR bands related to carbonate groups were intensified after brushing with either SrCO3 or Sr0.5Ca0.5CO3. The shift of the phosphate-related FTIR band to a lower wavenumber indicated that strontium replaced calcium on the dentin structure after treatment. The coating promoted by SrCO3 or Sr0.5Ca0.5CO3 resisted the acid attack, while calcium and phosphorus were removed from the top of the dentin surface. The nanoparticles were not toxic to hDPSCs and elicited mineralization of the cells, as revealed by increased mineral nodule formation and enhanced expression of COL1, ALP, and RUNX2. Adding Sr0.5Ca0.5CO3 as an active ingredient in dentifrices formulations may be commercially advantageous since this compound combines the well-known abrasive properties of calcium carbonate with the mineralization ability of strontium, while the final cost remains between the cost of CaCO3 and SrCO3. The novel Sr0.5Ca0.5CO3 nanoparticles might emerge as an alternative for the treatment of dental hypersensitivity.

Low frequency pulsed electromagnetic fields exposure alleviate the abnormal subchondral bone remodeling at the early stage of temporomandibular joint osteoarthritis

BackgroundTemporomandibular joint osteoarthritis (TMJOA) is characterized by abnormal subchondral bone remodeling and cartilage degeneration. As a non-invasive biophysical technology, pulsed electromagnetic field (PEMF) treatment has been proven to be efficient in promoting osteogenesis. However, the potential bone protective effect and mechanism of PEMF on abnormal subchondral bone remodeling in TMJOA are unknown.MethodsUnilateral anterior crossbite (UAC) was used to create TMJOA model in rats, and 17β-estradiol (E2) were injected daily to mimic patients with high-physiological levels of estrogen. Mouse osteoblast-like MC3T3-E1 cells treated with recombinant murine IL-1β was used to establish inflammatory environment in vitro. The treatment group were subjected to PEMF (2.0mT, 15 Hz, 2 h/d). Micro-CT scanning, histological staining, real-time PCR and western blotting assays were preformed to observe the changes in the subchondral bone.ResultsAbnormal resorption of subchondral bone induced by UAC, characterized by decreased bone mineral density, increased osteoclast activity and expression of osteoclast-related factors (RANKL) and down-regulated expression of osteogenesis-related factors (OPG, ALP, Runx2 and OCN) at the early stage, could be reversed by PEMF exposure, which was similar to the effect of estrogen. In addition, PEMF exposure and E2 supplement may have a synergistic effect to some extent. Moreover, PEMF exposure could promote the ALP activity and osteogenic mineralization ability of MC3T3-E1 cells. PEMF promoted the expression of factors related to Wnt/β-Catenin signal pathway both in vivo and in vitro.ConclusionsAppropriate PEMF exposure have a protective effect on subchondral bone in TMJOA at early stage, in which canonical Wnt/β-Catenin pathway may be involved. PEMF may be a promising biophysical approach for early intervention of TMJOA in clinic.

Enhanced mineralization of the nanofibers-incorporated aerogels increases mechanical properties of scaffold and promotes bone formation

The poor mechanical performance of the aerogels hampered their potential applications in bone tissue engineering. To reinforce their mechanical properties, an electrospinning nanofibers-incorporated aerogels were fabricated in this study. Here, silk fibroin solution is blended with chitin in various proportions, and then electrospun to produce the hybrid nanofibers. The silk fibroin/chitin hybrid nanofibers were incorporated into the SF-based composite aerogels to enhance their mechanical properties. nHA was deposited onto the surface of the nanofiber-incorporated aerogels via in situ biomineralization, leading to the nanofibers/nHA-reinforced composite aerogels. The as-prepared composite aerogels exhibit favorable mineralization abilities through immersing in simulated body fluid. SEM observation suggested that the mineralization degree of the SF-based aerogels was positively related with the content of electrospinning nanofibers in the composite aerogels. The results obtained from the compress stress-strain curves revealed that the incorporation of nanofibers and in vitro biomineralization of nHA both enhanced the mechanical performance of the composite aerogels. The osteogenic ability of the prepared aerogels was also improved after incorporation of NFSF-0.75%CT and nucleation of nHA in SBF. Therefore, the composite aerogels prepared by the incorporation of NFSF-0.75%CT and immersing into SBF exhibited an enhanced mechanical properties and improved osteogenic ability.

Apigenin Modulates AnxA6- and TNAP-Mediated Osteoblast Mineralization.

Mineralization-competent cells like osteoblasts and chondrocytes release matrix vesicles (MVs) which accumulate Ca2+ and Pi, creating an optimal environment for apatite formation. The mineralization process requires the involvement of proteins, such as annexins (Anx) and tissue-nonspecific alkaline phosphatase (TNAP), as well as low molecular-weight compounds. Apigenin, a flavonoid compound, has been reported to affect bone metabolism, but there are doubts about its mechanism of action under physiological and pathological conditions. In this report, apigenin potency to modulate annexin A6 (AnxA6)- and TNAP-mediated osteoblast mineralization was explored using three cell lines: human fetal osteoblastic hFOB 1.19, human osteosarcoma Saos-2, and human coronary artery smooth muscle cells HCASMC. We compared the mineralization competence, the morphology and composition of minerals, and the protein distribution in control and apigenin-treated cells and vesicles. The mineralization ability was monitored by AR-S/CPC analysis, and TNAP activity was determined by ELISA assay. Apigenin affected the mineral structure and modulated TNAP activity depending on the concentration. We also observed increased mineralization in Saos-2 cells. Based on TEM-EDX, we found that apigenin influenced the mineral composition. This flavonoid also disturbed the intracellular distribution of AnxA6 and TNAP, especially blocking AnxA6 aggregation and TNAP attachment to the membrane, as examined by FM analysis of cells and TEM-gold analysis of vesicles. In summary, apigenin modulates the mineralization process by regulating AnxA6 and TNAP, as well as through various effects on normal and cancer bone tissues or atherosclerotic soft tissue.