Biomineralization Potential Research Articles

Calcium Silicate-Based Sealers: Apatite Deposition on Root Canal Dentin and pH Variation Analysis

Abstract Objective This study analyzes the biomineralization potential of calcium silicate-based sealers Ceraseal (Meta Biomed Co., Cheongju, Korea) and AH Plus Bioceramic (Dentsply Sirona, United States), focusing on evaluating apatite deposition in root canal dentin and pH increases. Materials and Methods Calcium silicate-based sealers Ceraseal (Meta Biomed Co.) and AH Plus Bioceramic (Dentsply Sirona) were applied to the root canal dentin of premolars that had undergone root canal preparation procedures. This was followed by a 14-day immersion in phosphate-buffered saline (PBS). Biomineralization analysis was performed by analyzing the formation of the apatite layer after the 14-day immersion. The thickness of the apatite layer deposits was observed using a scanning electron microscope (SEM). Additionally, the sealers were placed in molds and submerged in PBS solution with pH measurements taken on days 0, 7, and 14 using a digital pH meter. Statistical Analysis The average thickness of apatite deposition in the interfacial layer was analyzed using the Mann–Whitney's test. The pH value differences among the groups were analyzed using a one-way analysis of variance test, followed by a post hoc least significant difference. Results There were differences in the apatite deposition in the interfacial layer between Ceraseal and AH Plus Bioceramic within 14 days of observation. There was a significant difference (p < 0.05) between the pH values of Ceraseal and AH Plus Bioceramic at 7 and 14 days of observation. Ceraseal showed greater alkalizing activity compared with AH Plus Bioceramic. Conclusion Calcium silicate-based sealer Ceraseal showed better biomineralization potential than AH Plus Bioceramic.

Antitumoral-Embedded Biopolymeric Spheres for Implantable Devices.

The bioactive surface modification of implantable devices paves the way towards the personalized healthcare practice by providing a versatile and tunable approach that increase the patient outcome, facilitate the medical procedure, and reduce the indirect or secondary effects. The purpose of our study was to assess the performance of composite coatings based on biopolymeric spheres of poly(lactide-co-glycolide) embedded with hydroxyapatite (HA) and methotrexate (MTX). Bio-simulated tests performed for up to one week evidenced the gradual release of the antitumor drug and the biomineralization potential of PLGA/HA-MTX sphere coatings. The composite materials proved superior biocompatibility and promoted enhanced cell adhesion and proliferation with respect to human preosteoblast and osteosarcoma cell lines when compared to pristine titanium.

Development, Characterisation and Biocompatibility Analysis of a Collagen-Gelatin-Hydroxyapatite Scaffold for Guided Bone Regeneration

Guided Bone Regeneration (GBR) is the choice of treatment for improving the horizontal and vertical bone volume through bone grafting. GBR membranes work on the principle of preventing epithelial migration into the defect space while maintaining the space for cell migration and differentiation at the defect site. Hydroxyapatite has been commonly used as a bone graft for infrabony defects. The study was conducted at the Department of Biomaterials at Saveetha Dental College. GBR membrane was prepared and its material characterization was done using Scanning Electron Microscope (SEM), Energy Dispersive X-ray (EDX) analysis, Fourier Transform Infrared Radiation (FTIR), and Confocal Analysis. The developed GBR membrane revealed SEM properties conducive to cell attachment. EDX and FTIR analysis showed the successful development of the collagen-gelatin-hydroxyapatite membrane. Cell culture and confocal analysis revealed excellent biocompatibility with a homogenous layer of viable cells. The developed composite GBR membrane is a biogenic membrane with relevant biomineralization potential that should be applied for GBR applications.

Carbonate biomineralization potential of endospore-laden polymeric fibers (BioFibers) for bio-self-healing applications

This study explores the capacity and kinetics of microbially-induced calcium carbonate precipitation (MICCP) using BioFibers—endospore-laden polymeric fibers. Innovatively developed as a delivery system, BioFibers incorporate a bio-self-healing feature into quasi-brittle composites like concrete. Constructed with a load-bearing core fiber, a bio-compatible hydrogel sheath, and an outer protective shell layer, BioFibers represent a novel approach to enhancing material healing properties. BioFibers have been engineered to provide the matrix with three functionalities: autonomous self-healing, crack growth control, and damage-induced activation. The primary goal of this study was to focus on the self-healing functionality of BioFibers and evaluate the biomineralization performance through advanced material characterization techniques. In this context, we conducted quantitative and qualitative experiments to study bio-self-healing kinetics and precipitates material characterizations using thermogravimetric analysis (TGA), scanning electron microscopy equipped with energy-dispersive spectroscopy (SEM-EDS) and X-ray powder diffraction (XRD). TGA results revealed that the self-healing kinetics based on calcium carbonate precipitation were mainly exhibited by three stages: (i) endospore germination lag phase, (ii) ureolytic activity, and (iii) saturation degree of carbonate, resulting in precipitations of calcium carbonate per one activated BioFiber (with an average mass of 56.9 ± 1.4 mg) equal to: (i) 3.35–30.30 mg, (ii) 31.08–140.91 mg, and (iii) 381.39–620.08 mg, respectively. SEM imaging revealed growing calcium carbonate crystal formation, primarily vaterite, during the progression of MICCP. EDS data in the initial stage indicated traces of phosphorus, potassium, nitrogen, sodium, and sulfur, signaling the endospore germination phase. In subsequent stages, carbon, calcium, and oxygen elements dominated, confirming calcium carbonate precipitation. XRD phase analysis showed that amorphous content was the primary residue in the first stage, with 85.5% associated with organic matter and 5.6 wt% due to amorphous calcium carbonate. As the MICCP process continued, the amorphous content, mainly organic matter, decreased, reaching 23.5 wt% in the last stage. Conversely, the crystalline phase increased, with calcite accounting for 21.4 wt% and vaterite accounting for 51.7 wt% in the final stage.

Biomineralization ability of an experimental bioceramic endodontic sealer based on nanoparticles of calcium silicates.

The ultimate goal of endodontic therapy is to prevent periradicular disease or to promote the healing of the periradicular lesions. The use of nontoxic, biocompatible, and bioactive materials designed for root canal obturation is preferred due to their increased potential to induce healing and bone regeneration, thereby restoring the functionality of the tooth and the adjacent tissues. The aim of this study was to analyze the biomineralization ability of an experimental endodontic sealer based on synthesized nanoparticles of calcium silicates. Six plastic moulds were filled with the freshly prepared experimental endodontic sealer and kept for 3 days at room temperature in a moist environment. After hardening, four samples were subsequently immersed in simulated body fluid (SBF) and introduced in incubator at 37°C and 100% relative humidity; two of them were kept for 7 days and the other two for 14 days. Two samples were not immersed in SBF and were used for comparison. The biomineralization potential was assessed by XRPD, SEM and EDS analysis. Following immersion in SBF, XRPD analysis identified apatite crystals for experimental material both after 7 and 14 days. SEM images displayed the specific microstructure for bioceramic materials alongside with the presence of apatite crystals on their surface. EDS identified the presence of phosphorus and calcium elements, underlining the biomineralization potential of the experimental material. Interaction between experimental material and SBF succeeded in inducing precipitation of apatite on its surface, evidenced by XRDP, SEM and EDS analysis.

Hydroxyapatite/poly(vinyl alcohol)/chitosan coating with gentamicin for orthopedic implants

Electrophoretic deposition (EPD) was employed to fabricate composite coatings aimed for orthopedic implants. Hydroxyapatite (HAP), poly(vinyl alcohol) (PVA) and chitosan (CS) coatings, with or without antibiotic gentamicin (Gent) were deposited in a single-step process from aqueous suspension, using EPD. Polymer/mineral composite coatings were formed with the aim to mimic the natural composition of bone tissue, along with improved coatings antibacterial properties, at the same time serving as a drug carrier, allowing local administration of antibiotic. Structural and morphological characterization of HAP/PVA/CS and HAP/PVA/CS/Gent coatings was investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TG/DTG), and scanning electron microscopy (SEM) proving carbonate-substituted HAP. The presence of gentamicin contributed to the bactericidal activity of composite HAP/PVA/CS/Gent coating against Staphylococcus aureus and Escherichia coli. Cytotoxicity studies were performed towards human MRC-5 and mice L929 fibroblast cell lines, and both investigated samples (HAP/PVA/CS and HAP/PVA/CS/Gent) expressed good biocompatibility, without causing toxic effect on tested cells. Biomineralization potential was investigated by measuring the alkaline phosphatase activity, demonstrating high potential of HAP/PVA/CS/Gent to induce the growth of new HAP layer. Therefore, the present investigation proposes the production of composite coatings from non-toxic (aqueous) suspensions, consisting of biocompatible and bioactive components, along with antibiotic gentamicin, improving the antibacterial coatings' properties.

Cytotoxicity and Biomineralization Potential of Flavonoids Incorporated into PNVCL Hydrogels.

This study aimed to evaluate the effects of flavonoids incorporated into poly(N-vinylcaprolactam) (PNVCL) hydrogel on cell viability and mineralization markers of odontoblast-like cells. MDPC-23 cells were exposed to ampelopsin (AMP), isoquercitrin (ISO), rutin (RUT) and control calcium hydroxide (CH) for evaluation of cell viability, total protein (TP) production, alkaline phosphatase (ALP) activity and mineralized nodule deposition by colorimetric assays. Based on an initial screening, AMP and CH were loaded into PNVCL hydrogels and had their cytotoxicity and effect on mineralization markers determined. Cell viability was above 70% when MDPC-23 cells were treated with AMP, ISO and RUT. AMP showed the highest ALP activity and mineralized nodule deposition. Extracts of PNVCL+AMP and PNVCL+CH in culture medium (at the dilutions of 1/16 and 1/32) did not affect cell viability and stimulated ALP activity and mineralized nodules' deposition, which were statistically higher than the control in osteogenic medium. In conclusion, AMP and AMP-loaded PNVCL hydrogels were cytocompatible and able to induce bio-mineralization markers in odontoblast-cells.

Regenerative biomineralization potential of commercially available remineralizing agents as a preventive treatment approach for tooth erosion - An in vitro laser-induced breakdown spectroscopy analysis.

In today's era, erosion is the most prevalent type of tooth wear. The prevention of demineralization with biomineralization is the most desired treatment. The aim of this study is to evaluate and compare the surface remineralization potential of two remineralizing agents - self-assembling peptide P11-4 (SAP P11-4) and calcium silicate plus sodium phosphate (CSSP) salts on intact and demineralized enamel using laser-induced breakdown spectroscopy (LIBS). Sixteen maxillary premolars were decoronated and split into buccal and palatal halves embedded in acrylic resin with a total sample size of 32 designated into Group 1 (intact teeth) and Group 2 (demineralized teeth). Further subdivision into Groups 1a and 2a (SAP P11-4 group [n = 8]); Groups 1b and 2b (CSSP group [n = 8]), Group 2 was first exposed to Coca-Cola. Then, all groups were subjected to experimental LIBS. Groups 1a and 2a were treated with SAP P11-4 based product, i.e., CURODONT™ PROTECT gel. Groups 1b and 2b were treated with CSSP-based products regimen, i.e., REGENERATE Enamel Science™ Advanced Toothpaste and Advanced Enamel Serum. The LIBS assessment was redone for all groups to attain a change in Ca and P values. Inferential statistics were done using Wilcoxon signed-rank test (Before-After product application) and Mann-Whitney U-test (between the groups). According to the statistical evaluation there was a statistically significant difference (P < 0.05), in Ca and P values in demineralized teeth when both SAP P11-4 and CSSP groups were evaluated. Although Ca values exhibited a significant difference in intact teeth, P did not exhibit a significant difference on the application of both remineralizing agents. The remineralizing potential between the two agents, SAP P11-4 and CSSP groups. There was no statistically significant difference ( P <0.05) observed between the two agent's remineralization potential for intact and demineralized teeth. SAP P11-4 and CSSP have the potential to remineralize both intact and demineralized enamel. There was increased remineralization in demineralized samples subjected to erosion.

In Vitro Cytotoxicity and Mineralization Potential of an Endodontic Bioceramic Material.

The interest in bioceramic materials has been steadily growing for different applications in endodontics. With the continued introduction of new bioceramic-based materials into the market, it is of great importance to assess the biocompatibility before providing recommendations on their clinical use. This study evaluated the in vitro cytotoxicity and mineralization potential of two consistencies of unset premixed bioceramic material (TotalFill BC RRM putty and TotalFill BC sealer) compared with an epoxy resin-based sealer (AH Plus) on osteoblast cells. Overall, 100% extracts were obtained by weighing 0.1 g of each material in 1 mL of cell culture media. Primary human osteoblast (HOB) cells (n = 4) were treated with different concentrations (100, 50, 25, 12.50, and 6.25%) of each extract. XTT assay and Alizarin Red S staining were used to evaluate the cytotoxic effect and the biomineralization potential, respectively. Data were analyzed by one-way analysis of variance followed by Tukey's post hoc tests. The cytotoxicity assay after 24 h treatment showed that all materials at high concentrations of the extract (100 and 50%) were toxic to HOB (p < 0.001). On the contrary to TotalFill BC RRM Putty, AH Plus and TotalFill BC sealer were toxic at 25% concentration. However, at 12.5% concentration and lower, all materials were nontoxic. The mineralization potential analyzed after 7 and 14 days showed that TotalFill BC material-treated cells could deposit mineralized nodules in the normal and osteogenic medium unlike AH plus-treated cells. At low concentrations, TotalFill BC materials showed higher biocompatibility to HOB cells than AH Plus, enhanced the viability of the cells, maintained their typical morphology, and induced the formation of mineralized nodules. Despite the encouraging data, clinical trials are needed to identify the effect of this material on the long-term outcome of endodontic treatment.

Biomechanical and Chemical Behavior of Various Bioactive Materials in Class II Restorations

The aim of this in vitro study was to evaluate the biomechanical and chemical behavior of various bioactive materials in class II MOD restorations. Forty-eight standardized class II MOD cavities were prepared in sound extracted human molar teeth. The specimens were divided into four groups according to the restorative material: Group 1 (Filtek™ Z350 XT), Group 2 (Biodentine™ as a liner, and then restored with Filtek™ Z350 XT), Group 3 (Cention N™), and Group 4 (Activa™ Bioactive-Restorative). The samples were tested for fracture resistance by subjecting them to a compressive load in a Universal testing Machine. The failure modes of each specimen were evaluated. The alkalinizing potential and calcium ion release of the materials were measured. SEM-EDAX analyses were also performed for all materials. Data were analyzed using ANOVA and post hoc Tukey test (p&lt;0.05). Group 1 showed the higher fracture resistance (p&lt;0.05). Group 3 had greater fracture resistance values but no statistical difference from Group 4. Biodentine™ showed greater biomineralization potential. Class II MOD restorations of Group 1 displayed the higher fracture resistance; however, it was highly associated with catastrophic failure. Conversely, Biodentine™ presented a more significant bioactivity potential, and its use, as in Group 2, promoted the most favorable failure mode.

Cytocompatibility and bioactive potential of AH Plus Bioceramic Sealer: An in vitro study.

AimTo assess the cytocompatibility and bioactive potential of the new calcium silicate cement‐based sealer AH Plus Bioceramic Sealer (AHPbcs) on human periodontal ligament stem cells (hPDLSCs) compared with the epoxy resin‐based sealer AH Plus (AHP) and the calcium silicate cement‐based sealer Endosequence BC Sealer (ESbcs).MethodologyStandardized sample discs and 1:1, 1:2 and 1:4 eluates of the tested materials were prepared. The following assays were performed: surface element distribution via SEM–EDX, cell attachment and morphology via SEM, cell viability via a MTT assay, cell migration/proliferation via a wound‐healing assay, osteo/cemento/odontogenic marker expression via RT‐qPCR and cell mineralized nodule formation via Alizarin Red S staining. HPDLSCs were isolated from extracted third molars. Comparisons were made with hPDLSCs cultured in unconditioned (negative control) or osteogenic (positive control) culture media. Statistical significance was established at p < .05.ResultsA higher peak of Ca2+ was detected from ESbcs compared with AHPbcs and AHP in SEM–EDX. Both AHPbcs and ESbcs showed significantly positive results in the cytocompatibility assays (cell viability, migration/proliferation, attachment and morphology) compared with a negative control group, whilst AHP showed significant negative results. Both AHPbcs and ESbcs exhibited an upregulation of at least one osteo/odonto/cementogenic marker compared with the negative and positive control groups. Both ESbcs and AHPbcs showed a significantly higher calcified nodule formation than the negative and positive control groups, indicative of their biomineralization potential and were also significantly higher than AHP group.ConclusionAH Plus Bioceramic Sealer exhibited a significantly higher cytocompatibility and bioactive potential than AH Plus and a similar cytocompatibility to that of Endosequence BC Sealer. Endosequence BC Sealer exhibited a significantly higher mineralization potential than the other tested sealers. The results from this in vitro study act as supporting evidence for the use of AH Plus Bioceramic Sealer in root canal treatment.

Phosphorus recovery from municipal wastewater through struvite biomineralization using model gram-negative and gram-positive bacterial strains

The present study investigated struvite biomineralization potential of model gram-negative (Enterobacter cloacae) and gram-positive (Bacillus pumilus) bacterial strains in synthetic municipal wastewater. Both micro-organisms were able to precipitate struvite crystals and the growth pattern, change in pH, ammonium and phosphate ion concentration for both the cultures were comparable. The pH of the medium increased from 6.4 to 8.8 after 3 days of incubation when the cultures attained the saturation phase. The ammonium concentration increased from initial concentration of 40 mg/L to nearly 200 mg/L after 3 days of incubation for both the bacterial strains, whereas phosphate concentration decreased from initial 20 mg/L to 3.4 mg/L and 0.8 mg/L for Bacillus pumilus and Enterobacter cloacae respectively. The mechanism involved in struvite biomineralization was also explained in detail for Enterobacter cloacae and Bacillus pumilus. The precipitation of struvite by Enterobacter cloacae is due to biologically controlled mineralization while Bacillus pumilus mineralized struvite crystals through biologically induced mineralization mechanism. Results were further validated in real influent collected from a sequencing batch reactor of an influent treatment plant. Results demonstrated that Bacillus pumilus was able to precipitate crystals in real influent whereas no precipitation was observed by Enterobacter cloacae in real influent. This study gives an insight into bacterial biomineralization in wastewater to enable recovery of nutrients (phosphorus and nitrogen) and circularity in treatment plants. Further utilization of the recovered product as fertilizer can play a key role in contributing towards meeting global food security.

Effect of taxifolin and epigallocatechin-3-gallate on biomineralization potential of stem cells from dental apical papilla

ObjectiveConsidering the variety of pharmacological activities and the potential to mediate biomineralization, the flavonoids taxifolin and epigallocatechin-3-gallate (EGCG) could be explored as biomolecules in scaffolds for regenerative endodontic procedures. The aim of this study was to evaluate the effect of taxifolin and EGCG on the cell viability, differentiation, and expression of biomineralization markers in stem cells from the apical papilla. DesignStem cells from the apical papilla were exposed to single or continuous treatments with taxifolin at 200, 100 and 50 µM and EGCG at 50, 25 and 12.5 µM for 48 h, 8 and 14 days, in regular or mineralizing media. Cell viability, alkaline phosphatase activity and calcium deposition were analyzed using resazurin, p-nitrophenylphosphate and alizarin-based assays. ResultsNone of the flavonoid groups affected cell viability at 48 h, however at 8 and 14 days, Taxifolin 200 µM and EGCG 50 µM were cytotoxic. Cells did not express alkaline phosphatase activity when grown in regular medium, even in the presence of flavonoids. Alkaline phosphatase activity and biomineralization potential were higher in cells treated with Taxifolin 50 µM and EGCG 12.5 µM. ConclusionTaxifolin and EGCG exhibited a concentration, time, and therapeutic mode dependent bioactivity on stem cells from the apical papilla. Both flavonoids at the lower concentrations tested exhibited cytocompatibility and increased expression of mineralization markers in the presence of mineralizing agents.

In vitro biomineralization potential in simulated wound fluid and antibacterial efficacy of biologically-active glass nanoparticles containing B2O3/ZnO

In the present study, SiO2-CaO-B2O3-ZnO (SCBZ), SiO2-CaO-B2O3 (SCB), SiO2-CaO-ZnO (SCZ) and SiO2-CaO (SC) silicate-based glasses were synthesized by the sol-gel method to elucidate the influence of B2O3 and ZnO substitution on glass characteristics aiming to further use in wound healing applications. The amorphous nature, spherical-shaped morphology and nano-sized primary particles of glasses were revealed by XRD and SEM analysis. Moreover, investigating the antibacterial activity of glasses against E.coli and S.aureus bacteria indicated the improved antibacterial properties of SCBZ glass against both bacterial strains compared with SCB and SCZ glasses. Assessment of ion release revealed that the incorporation of zinc induces a more stable glass network with a lower tendency to dissolution contrary to the incorporation of boron, which facilitated the dissolution of glass by the formation of more reactive SiOB and BO bonds. Glasses were immersed in Simulated Wound Fluid (SWF) to predict their mineralization susceptibility. Morphological studies and FTIR analysis showed the formation of cauliflower-like hydroxy-carbonated apatite on the surface of SCB and SC glasses after 14 days. In contrast, the presence of Zn in SCBZ and SCZ glasses inhibited the formation of crystalline apatite and induced the deposition of spherical-shaped amorphous apatite. Our study suggests that the co-incorporation of B and Zn in SCBZ glass make this material a potential multifunctional candidate for accelerating the healing of skin wounds.

Eggshell derived nano-hydroxyapatite incorporated carboxymethyl chitosan scaffold for dentine regeneration: A laboratory investigation.

To assess odontogenic differentiation abilities of porous biomineralizable composite scaffolds comprising eggshell derived nano-hydroxyapatite (HAnp) and carboxymethyl chitosan (CMC) on cultured human dental pulp stem cells (hDPSCs). Nano-hydroxyapatite was derived from eggshells using a simple combustion method and CMC was prepared from chitosan through a chemical route. Several compositions of HAnp-CMC (0:5, 5:0, 1:5, 2:5, 3:5, 4:5 and 1:1 w/w%) scaffolds were prepared by magnetic stirring and freeze-drying methods. HAnp-CMC scaffolds were characterized using high-resolution scanning electron microscopy combined with energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy and X-ray diffraction methods. In vitro bioactivity was determined following the interaction in simulated body fluid for 21days. The optimized composite was then loaded onto hDPSCs to assess cell viability/proliferation, dentine sialophosphoprotein (DSPP) and vascular endothelial growth factor (VEGF) expressions using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay, real-time quantitative polymerase chain reaction and flow cytometry methods, respectively, following 7, 14 and 21days. For intergroup and intragroup comparisons, Kruskal-Wallis and Friedman tests were employed, respectively, followed by appropriate post hoc test (Dunn). Significant levels were set at *p<.05 and *p<.01. Synthesized hydroxyapatite (HAp) comprised crystals ranging from 20 to 50nm (HAnp) with spherulite morphology and calcium/phosphorus (Ca/P) molar ratio of 1.67. The ultrastructure of all the scaffolds revealed a highly interconnected porous microstructure, whilst the chemical characterization displayed specific functional groups of both HAnp and CMC. In vitro bioactivity assessment confirmed the biomineralization potential of all scaffolds with an apatite-like crystal formation on the surface. The 1:5 HAnp-CMC revealed a favourable pore size (60-180µm) that was suitable for cell seeding and was chosen for further experiments. Cell viability/proliferation rates of hDPSCs loaded 1:5 HAnp-CMC at 21st day was significantly greater than that at 7th day (p<.05). The mean relative quantification of DSPP expression by the scaffold was significantly higher (p<.05) on day 21 (3.16) than on day 7 (1.67). Mean fluorescence intensity of the VEGF expression at day 21 (32.5) was also significantly higher (p<.01) than at day 7 (12.54). hDPSCs on 1:5 HAnp-CMC scaffolds displayed increased cell viability/proliferation and enhanced DSPP as well as VEGF expressions. The 1:5 HAnp-CMC composite has the potential to serve as a promising scaffold for dentine regeneration.

Biomineralization potential and biological properties of a new tantalum oxide (Ta2O5)\u2013containing calcium silicate cement

ObjectiveThe present study evaluated the biological effects and biomineralization potential of a new tantalum oxide (Ta2O5)–containing material designed for vital pulp therapy or perforation repair (NeoMTA 2), compared to NeoMTA Plus and Bio-C Repair.Material and methodsHuman dental pulp stem cells (hDPSCs) were exposed to different eluates from NeoMTA Plus, NeoMTA 2, and Bio-C Repair. Ion release from each material was determined using inductively coupled plasma-optical emission spectrometry (ICP-MS). The biological experiments performed were MTT assays, apoptosis/necrosis assays, adhesion assays, migration assays, morphology evaluation, and reactive oxygen species (ROS) production analysis. Biomineralization was assessed by Alizarin red S staining. Finally, osteo/odontogenic gene expression was determined by real-time quantitative reverse-transcriptase polymerase chain reaction (RT-qPCR). Data were analyzed using one-way ANOVA followed by Tukey’s multiple comparison test.ResultsNeoMTA 2 displayed a significantly higher calcium release compared to the other materials (p < 0.05). When hDPSCs were cultured in presence of the different material eluates, all groups exhibited similar hDPSC viability and migration rates when compared to untreated cells. Substantial cell attachment and spreading were observed in all materials’ surfaces, without significant differences. hDPSCs treated with NeoMTA 2 displayed an upregulation of ALP, Col1A1, RUNX2 (p < 0.001), ON, and DSPP genes (p < 0.05), and showed the highest mineralization potential compared to other groups (p < 0.001). Finally, the more concentrated eluates from these materials, specially NeoMTA Plus and NeoMTA 2, promoted higher ROS production in hDPSCs compared to Bio-C Repair and control cells (p < 0.001), although these ROS levels did not result in increased cell death.ConclusionsThe new tantalum oxide (Ta2O5)–containing material shows an adequate cytocompatibility and the ability to promote biomineralization without using chemical osteogenic inducers, showing great potential as a new material for vital pulp therapy.Clinical relevanceNeoMTA 2 seems to be a promising material for vital pulp therapy. Further studies considering its biocompatibility and biomineralization potential are necessary.

Heterotrophic nitrification and biomineralization potential of Pseudomonas sp. HXF1 for the simultaneous removal of ammonia nitrogen and fluoride from groundwater

Pseudomonas sp. HXF1, a strain capable of heterotrophic nitrification, aerobic denitrification (HNAD), and biomineralization was identified and employed for the simultaneous removal of ammonia nitrogen (NH4+-N) and fluoride (F−). It removed 99.2% of NH4+-N without accumulation of nitrous nitrogen (NO2−-N) and nitrate nitrogen (NO3−-N), while removed 87.3% of F−. Response surface methodology (RSM) was used to study the best removal conditions for NH4+-N and F−. The results of nitrogen balance experiments with NH4Cl, NaNO2, and NaNO3 as single nitrogen sources and amplification experiments of denitrification genes proved that the bacterial strains may remove NH4+-N through HNAD. The experimental results of Scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffractometer (XRD) indicated that the way of F− removal may be adsorption and co-precipitation. The results demonstrated that the strain HXF1 has great potential in the biological denitrification and F− removal of groundwater.

High-efficient microbial immobilization of solved U(VI) by the Stenotrophomonas strain Br8

The environmental impact of uranium released during nuclear power production and related mining activity is an issue of great concern. Innovative environmental-friendly water remediation strategies, like those based on U biomineralization through phosphatase activity, are desirable. Here, we report the great U biomineralization potential of Stenotrophomonas sp. Br8 CECT 9810 over a wide range of physicochemical and biological conditions. Br8 cells exhibited high phosphatase activity which mediated the release of orthophosphate in the presence of glycerol-2-phosphate around pH 6.3. Mobile uranyl ions were bioprecipitated as needle-like fibrils at the cell surface and in the extracellular space, as observed by Scanning Transmission Electron Microscopy (STEM). Extended X-Ray Absorption Fine Structure (EXAFS) and X-Ray Diffraction (XRD) analyses showed the local structure of biogenic U precipitates to be similar to that of meta-autunite. In addition to the active U phosphate biomineralization process, the cells interact with this radionuclide through passive biosorption, removing up to 373 mg of U per g of bacterial dry biomass. The high U biomineralization capacity of the studied strain was also observed under different conditions of pH, temperature, etc. Results presented in this work will help to design efficient U bioremediation strategies for real polluted waters.

Efficacy of bioactive nanoparticles on tissue-endotoxin induced suppression of stem cell viability, migration and differentiation.

To characterize a lipopolysaccharide (LPS)-treated dentine tissue model (LPS dentine) to analyse the efficacy of polycationic chitosan nanoparticles (CSnp) and/or dexamethasone conjugate chitosan nanoparticles (Dex-CSnp) on the viability/differentiation potential of stem cells from apical papilla (SCAP) when exposed to LPS dentine. A further aim was to understand the effect of macrophage-dependent inflammation on SCAP migration in the presence of LPS dentine. A total of 88 dentine slabs were used. TOF-SIMS analysis was performed amongst the LPS-treated and untreated dentine groups (n=2/group). The study was conducted using four dentine groups: no treatment (control); LPS treatment only; LPS treatment followed by CSnp conditioning; and LPS treatment followed by Dex-CSnp conditioning groups. SCAP adherence, viability, differentiation and biomineralization potential on dentine from different groups were studied using fluorescent and scanning electron microscopy. Inflammation by macrophages in response to LPS dentine was quantified, and effect on SCAP migration was analysed. Statistical analysis was performed using Student's t-test with a significance level of P<0.05. TOF-SIMS analysis confirmed LPS contamination. LPS dentine affected SCAP viability but not adherence to dentine (P<0.001). Conditioning of LPS dentine with either nanoparticles improved SCAP viability (P<0.01) and rescued other LPS related adverse effects on SCAPs, such as F-actin disruption, decrease in differentiation/biomineralization potential. IL-6 produced by macrophages in response to LPS-treated dentine impeded SCAP migration (P<0.001), diminished on CSnp and Dex-CSnp conditioning groups (P<0.01). This study developed an LPS-dentine model and highlighted the ability of CSnp and Dex-CSnp to promote stem cell viability, migration, differentiation potential and reduce inflammation, providing an environment conducive for tissue regeneration/repair.

Conductive electrospun polyurethane-polyaniline scaffolds coated with poly(vinyl alcohol)-GPTMS under oxygen plasma surface modification

Polyurethane is an important synthetic polymer which considered promising for bone tissue engineering. Besides, presence of conductive polymer such as could play a crucial role in efficient reconstruction of injured tissue. In the present study, the polyurethane-polyaniline scaffolds were fabricated by electrospinning technology. The electrospun fibers were modified by oxygen plasma treatment technique for immobilization of polyvinyl alcohol and 3-Glycidoxypropyl-trimethoxysilane. Eventually, the prepared constructs were characterized using proper analysis including morphology and roughness observation, chemical characterization, water-scaffolds interaction and biomineralization potential, cellular adhesion and proliferation, and finally osteogenic expression. According to microscopy results, bead-free, uniform, and nano-sized fibers were obtained; after coating, the surface was covered homogeneously with polyvinyl alcohol and 3-glycidoxypropyl-trimethoxysilane. The electrospun scaffolds showed highly porous structures, and their large surface-to-volume ratio made them suitable for tissue engineering applications. The degree of roughness and the mean height were increased from 96.59 nm to 144.4 and 267–429 nm, respectively, after the oxygen plasma surface treatment. Additionally, the modified fibers showed improved hydrophilicity and swelling capacity compared with pure polyurethane-polyaniline constructs. The contact angle of the polyurethane-polyaniline, oxygen plasma modified polyurethane-polyaniline, oxygen plasma modified polyurethane-polyaniline coated with polyvinyl alcohol, and oxygen plasma modified polyurethane-polyaniline coated with polyvinyl alcohol-3-glycidoxypropyl-trimethoxysilane scaffolds was 116.33°, 65.64°, 60.17°, and 62.50°, respectively. Although the addition of 3-glycidoxypropyl-trimethoxysilane led to a slight reduction in absorption potential, it could induce mineralization of hydroxyapatite-like layers which was proved by microscopy images and crystalline peaks in X-ray diffraction spectra. Ameliorating the cell attachment and the viability of a higher number of the cells after the surface treatment and coating process confirmed the biocompatible nature of the scaffolds. Also, in the alkaline phosphatase activity, all groups showed significant (p < 0.0001) increases compared with the control group. Expression of alkaline phosphatase proved the initial potential of the constructs for further pre-clinical and clinical analyses in order to reconstruct the injured bones.