Ethylenediaminetetraacetic Acid Solution Research Articles

Noncultured epidermal suspension procedure of vitiligo surgery using freeze-dried trypsin coated on silicon pellets.

Non-cultured epidermal suspension technique is currently the surgical treatment of choice for vitiligo. Storage of trypsin ethylenediaminetetraacetic acid solution has a stringent requirement. We propose usage of freeze-dried trypsin for the procedure which can be kept in usual refrigerator at 2-8°C. This can help us to perform the procedure at resource poor settings.

How Does Ethylenediaminetetraacetic Acid Irrigation Affect Biodentine? A Multimethod Ex Vivo Study.

The activity of biomaterials used during endodontic treatment can be affected by various factors. One of them is the chemical action of the irrigant that they are exposed to. The aim of this multimethod ex vivo study was to evaluate the influence of ethylenediaminetetraacetic acid (EDTA) on the surface appearance and chemical composition of Biodentine used in perforation repair. Twenty material specimens were prepared according to manufacturers' recommendations and divided into two setting-time-based groups, tested after 45 min (group A) and 24 h (group B) of setting. Material was irrigated with 17% EDTA solution with or without simultaneous ultrasonic activation. The surface characteristics and the chemical composition analysis of the Biodentine specimens were performed with the aid of a scanning electron microscope (SEM) and an energy dispersive spectroscopy (EDS) method, respectively. The volumetric loss of material was measured by dedicated digital software in an optical microscope. Statistical analysis was performed. The EDS study confirmed that after the rinsing protocol, the percentage content of elements differed between the groups. The EDTA rinse, whether ultrasonically activated or not, visibly affected the surface appearance and chemical composition of Biodentine. The specimens' surface subjected to irrigation was more irregular under SEM than in a control group. The US activation of the liquid amplified its impact on the tested material. The average volume loss in group A after 5 min irrigation was 3.98 µm3 for each µm2 of the chosen area and it increased up to 7.74 µm3/μm2 after the ultrasonic activation. In group B, indicated volume loss values were 6.30 and 11.70 µm3/μm2 for 5 min irrigation without and with US activation, respectively. Using a 20 min irrigation time and ultrasonic activation increased it up to 32.71 µm3/µm2. Each rinsing protocol involving irrigation with ethylenediaminetetraacetic acid modified the surface features and the chemical composition of the evaluated hydraulic tricalcium silicate cement. Further research is needed to indicate the possible impact of the observed changes on its long-term clinical performance.

Enhancing the Antibacterial Effect of Erythrosine-Mediated Photodynamic Therapy with Ethylenediamine Tetraacetic Acid

This study evaluated the additive impact of ethylenediamine tetraacetic acid (EDTA) on erythrosine-mediated photodynamic therapy (PDT) against <i>Streptococcus mutans</i> (<i>S. mutans</i>) biofilm by measuring colony-forming units and applying confocal laser scanning microscopy. Fifty-six bovine incisors, free from dental caries or structural defects, were utilized in this study. Dentin specimens were created by cutting with a low-speed diamond disk under a continuous flow of water, resulting in dimensions of 6.0 mm × 3.0 mm × 2.0 mm. The specimens were categorized into 4 groups: Control, EDTA, PDT, and EDTA + PDT. <i>S. mutans</i> ATCC 25175 was employed to establish biofilm on the dentin specimens. A 17% EDTA solution was applied for 1 min. For PDT, erythrosine served as the photosensitizer. Finally, a light-emitting diode source (385 - 515 nm) was employed in this study. The PDT group exhibited a significantly lower bacterial count than both the control and EDTA groups (<i>p</i> < 0.001). The EDTA + PDT group demonstrated a significantly reduced bacterial count compared to the other 3 groups (<i>p</i> < 0.001). This study demonstrated that EDTA enhances the antimicrobial efficacy of PDT on S. mutans biofilm. Even at a low concentration of photosensitizer, the combination of EDTA and PDT yields a significant antibacterial effect.

Molecular engineering of a new method for effective removal of cadmium from water

Cadmium (Cd) is a widespread and highly toxic environmental pollutant, seriously threatening animal and plant growth. Therefore, monitoring and employing robust tools to enrich and remove Cd from the environment is a major challenge. In this work, by conjugating a fluorescent indicator (CCP) with a functionalized glass slide, a special composite material (CCPB) was constructed to enrich, remove, and monitor Cd2+ in water rapidly. Then Cd2+ could be effectively eluted by immersing the Cd-enriched CCPB in an ethylenediaminetetraacetic acid (EDTA) solution. With this, the CCPB was continuously reused. Its recovery of Cd2+was above and below 100 % after multiple uses by flame atomic absorption spectrometry (FAAS), which was excellent for practical use in enriching and removing Cd2+ in real aqueous samples. Therefore, CCPB is an ideal material for monitoring, enriching, and removing Cd2+ in wastewater, providing a robust tool for future practical applications of Cd enrichment and removal in the environment.

Effect of Sterilization and Irrigating Solutions on Nanostructure Alteration of Ni-Ti Rotary Instruments in Endodontics: An Atomic Force Microscopic Study.

This study aimed to evaluate the effect of 5.25% sodium hypochlorite (NaOCl) and 17% ethylenediaminetetraacetic acid (EDTA) and sterilization on the nanostructural alteration of nickel titanium (Ni-Ti) rotary file systems in endodontics using the atomic force microscopy (AFM). The study was performed on four commercially available rotary Ni-Ti files: group I-Vortex Blue (Dentsply), group II-ProTaper Next (Dentsply), group III-Mtwo (VDW), and group IV-iRaCe (FKG). Each group was divided into four subgroups (n = 4), that is, subgroup A-control (new rotary file), subgroup B-subjected for five cycles of autoclave, subgroup C-immersed in 5.25% NaOCl for 5 minutes, and subgroup D-immersed in 17% EDTA solutions for 5 minutes. All the specimens were evaluated with AFM using roughness average (RA) and root-mean-square (RMS) values for surface roughness. Among control groups, Vortex Blue showed the least RA and RMS values; the highest surface roughness was seen with Mtwo files. All the Ni-Ti rotary files showed a statistically significant (P <0.05) increase in surface hardness when subjected to autoclave and treatment with different irrigating solutions. In particular, 17% EDTA caused the highest surface deterioration in all the groups. AFM analysis revealed increased surface roughness values recorded for all the rotary files when treated with irrigating solutions and autoclave cycles.

Extraction of copper (II) ions from oxidized ore in the presence of an ethylenediaminetetraacetic acid solution in a basic environment

An experiment was conducted to obtain copper (II) ions in a basic environment using ethylenediaminetetraacetic acid (EDTA) and oxidized copper minerals from Cerro Azoguini in Puno, Peru. Specific objectives included investigating the solubility of Cu2+ ions in a mineral with high silica, limestone, and iron content, as well as studying the influence of pH, EDTA concentration, and extraction time. 1.5 grams of ground mineral at -100 mesh (150 µm), with 80% pass and 6% solids, were leached with a 0.5 M NaHCO3 solution at different pH levels and EDTA concentrations. The results indicated the extraction of 3.5 g/L of Cu2+ ions at pH 10 with 0.12 M EDTA, without agitation, at room temperature (19°C), over a period of 83 hours. It was observed that the NaHCO3 solution extracted copper from the mineral, and EDTA quickly chelated it, forming ionic complexes such as CuHEDTA ∧ (1−), CuHEDTA ∧ (2−), and CuHEDTA ∧ (3−). Other metals present in the gangue were not chelated by EDTA, demonstrating its high selectivity based on solubility constants and precipitation formation at different pH levels. Additionally, high copper extraction rates were obtained at a pH of 13.15, possibly due to decreased protons and increased ions from both the reagent and leached mineral. In conclusion, the physicochemical analyses revealed the feasibility of obtaining Cu2+ ions by solubilizing oxidized minerals, followed by rapid chelation with EDTA to form diverse metal complexes depending on the pH of the medium.

Reactive flow of microemulsion-based EDTA fluid for carbonate stimulation

Traditional methods for stimulating carbonate formations primarily rely on the use of highly reactive acids, such as hydrochloric acid (HCl), to create wormholes. However, the limitations of this approach in certain scenarios have prompted the exploration of alternative strategies. In this study, we investigate the synergistic potential between microemulsion and ethylenediaminetetraacetic acid (EDTA) for stimulating carbonate formations. Microemulsion systems were formulated using a nonionic surfactant, sec-butanol as a cosurfactant, xylene as the oily phase, and an aqueous solution of EDTA as the water phase. The microemulsions were characterized by phase equilibrium and rheological behavior. Coreflooding and static dissolution experiments were performed. We employ microCT imaging to evaluate the change in porosity in static dissolution experiments. The results reveal that microemulsions containing EDTA presented remarkable stability and were able to significantly enhance carbonate rock permeability up to 85%, indicating that dissolution occurred and the rock was stimulated. Analyses of microCT images on static dissolution experiments of Indiana limestones in reactive microemulsions indicate an increase in porosity, confirming the dissolution process. These findings highlight the synergistic effect of EDTA in microemulsion media for enhancing the rock permeability of carbonate formation as an alternative as low reactive system.

Development of high-volume steel slag as cementitious material by ethylenediamine tetraacetic acid induced accelerated carbonation

Steel slag, a by-product of primary steel production, is produced in large quantities and is primarily used as landfill or aggregate. Due to its high reactivity with CO2, steel slag can form calcium carbonate at room temperature and pressure, making it an ideal material for CO2 capture in the development of sustainable construction materials. Due to the transport properties of CO2 and carbonation kinetics, carbonation of steel slag is frequently carried out using pure gas under high pressure. In this study, ethylenediamine tetraacetic acid (EDTA)-induced accelerated carbonation was used to produce cement paste mixes consisting of up to 100% steel slag powder. Combination of cement and EDTA with steel slag proved to be effective in accelerating the carbonation reaction. EDTA increased the leaching of Ca from the steel slag, thereby enhancing the carbonation reaction, which was more obvious in longer durations (up to 28 days). The optimum cement paste mix (80% steel slag and 20% cement, with 0.1 mol/L EDTA solution) achieved maximum compressive strength of 14 MPa and CO2 uptake of 8.7% after 28 days of accelerated carbonation. Results demonstrated that the use of high-volume steel slag as a cementitious material has great potential in non-structural building applications.

A comparative study of ethylenediamine tetraacetic acid induced gas-solid and liquid-solid accelerated carbonation for enhancement of steel slag aggregates

Accelerated carbonation is an effective technique to enhance the hydration reactivity and volume stability of steel slag aggregates (SSA). However, due to limitations in CO2 transport and carbonation kinetics, carbonation of SSA is frequently carried out using pure CO2 under high pressures. In this study, carbonation under 10% CO2 concentration and ambient temperature and pressure was employed to treat SSA. To accelerate the carbonation of SSA, ethylenediamine tetraacetic acid (EDTA)-induced gas–solid (dry) and liquid–solid (wet) carbonation processes were proposed. Effect of EDTA on the physical and mechanical properties and microstructure of carbonated SSA; and the performance of resulting concrete with a selected mix design were examined. Dry carbonation of SSA, prior to which EDTA was sprayed on the surface of SSA, resulted in a denser carbonated layer and consequently higher specific gravity compared to uncarbonated SSA. Concrete samples involving carbonated SSA, on which 0.1 mol/L EDTA was sprayed at 50% of water absorption mass of SSA, followed by carbonation curing for 24 hrs, revealed 24% increase in strength and 75% reduction in expansion when compared to those containing uncarbonated SSA. Wet carbonation of SSA, during which CO2 was injected into SSA-EDTA solution, promoted both carbonation and hydration of SSA, especially in 0.2 mol/L EDTA solution, resulting in the consumption of periclase and enabling the formation of brucite. While strength improvement was not obvious in the presence of brucite that weakened the interfacial transition zone (ITZ) of concrete, expansion was further reduced by the reduced periclase in SSA. Comparatively, EDTA-induced dry carbonation was more effective and required only 0.4 kg EDTA per tonne of SSA.

Morphological Analyses of Effects of Endodontic Irrigant Solutions Using a Root Canal Model and an Immersion Model.

This study aimed to compare an experimental model simulating clinical root canal irrigation (root canal model) with a conventional experimental model immersing dentin sample to irrigants (immersion model) to evaluate removal of the smear layer and decalcification of the root canal dentin using sodium hypochlorite (NaOCl) and two different concentrations of ethylenediaminetetraacetic acid (EDTA) solution. Forty-five single-rooted extracted human teeth were prepared using a Ni-Ti rotary file. EDTA, NaOCl, and citric acid were used in the root canal models and the immersion models. After the irrigation protocol, root canal surfaces were observed under scanning electron microscopy. Residual smear and decalcification of the root canal dentin were evaluated objectively by measuring the percentage of the area occupied by visible dentin tubules, the number of visible dentin tubules, and the mean area of a visible single dentin tubule. Root canal and immersion models with the same irrigation protocol showed significantly different results for smear residues and decalcification of root canal dentin. In the root canal model, neither different EDTA concentrations nor the order of EDTA and NaOCl applications significantly impacted smear residues or decalcification of root canal dentin. Furthermore, no erosion of the root canal dentin surface was observed in any experimental groups in the root canal model using EDTA and NaOCl compared to intact dentin. Experimental design affected results for residual smear layer and decalcification of root canal dentin. The order of EDTA and NaOCl use and the concentration of EDTA did not affect results. EDTA and NaOCl irrigation did not cause erosion in the root canal model in this study.

The effect of the gel with tricolor violet extract on the activity of the antioxidant defense system in rats with a model of parodontitis

The authors investigated the antioxidant properties of the gel with tricolor violet extract when used in rats with an experimental pаrodontitis model. To simulate periodontal pa-thology, white laboratory rats were given a solution of ethylenediaminetetraacetic acid (2%) daily with drinking water and three times a week; the drug "Warfarin Orion" was administered per os for 30 days. Animals were randomly divided into four equal groups of 10 each. Group 1 - intact rats; group 2 - rats with a model of pаrodontitis; group 3 - rats with a model and applications on the mucous membrane of the alveolar process gel "Pla-cebo". Group 4 - rats with a pаrodontitis model and applications on the mucous mem-brane of the alveolar process of the gel with the violet extract. In periodontal tissues and blood serum, we studied the level of inflammation markers - malondialdehyde (MDA) and diene conjugation. The state of the antioxidant defense system (AODS) was also assessed by the activity of glutathione peroxidase (GP), glutathione reductase (GR), glucose-6-phosphate dehydrogenase (G-6-PD), superoxide dismutase (SOD), and catalase. The pаro-dontitis model in rats of the 2nd group was characterized by the development of inflam-matory processes in periodontal tissues and blood, which is confirmed by changes in the pro- and antioxidant protection system. In rats of the 4th group, the content of MDA was restored in periodontal tissues. The state of the AOP system was normalized (decrease in the activity of SOD and catalase to the values of group 1), the tension in the glutathione-antioxidant defense system disappeared (the activity of GP decreased, and the activity of GR and G-6-PDH increased to the level control). In the blood serum, the content of MDA significantly reduced, and the level of DC remained higher than in group 1.In contrast, sta-bilization of the activity of marker enzymes of glutathione-antioxidant protection in blood serum (GP, GR, G-6-PDH) was noted with significant activation of the activity of SOD and catalase, with stabilization of SOD and catalase. Conclusion. The periodontal protective effectiveness of the gel with tricolor violet was es-tablished, as evidenced by the restoration of the state of protective antioxidant systems and the inhibition of lipid peroxidation processes both directly in the periodontal tissues and at the system level.

The effect of EDTA solution on corneal endothelial cells in rabbits

Corneal disease threatens vision globally. Among corneal diseases, calcific band keratopathy has severe effects on vision owing to its unique location. Currently, ethylene diamine tetraacetic acid (EDTA) chelation remains the most important treatment. However, only the safety of low-dose topical EDTA eye drops is well established in humans. Therefore, the purpose of this study was to determine the safe dose range of EDTA for calcific band keratopathy surgery and its toxic effects on rabbit eyes. Rabbits were administered different doses of EDTA solutions (0.50, 0.20, 0.10, 0.05, and 0.01 M) for twenty minutes. In day seven, the rabbits were euthanized and pathological examination was performed for cornea. We found severe corneal edema in 0.50 M group, while milder edema in lower-concentration treated groups. Followed by corneal thickness measurement, the measured values increase to the peak in post-operative three day (0.20 M group) or one day (lower-concentration groups), then decreased. Groups comparison shown significant difference between BSS control group and higher concentration groups (0.20 M and 0.10 M) (P < 0.001) in observation period, but no significance was observed between low concentration and control group in the day seven after surgery (P > 0.05). Confocal microscopy examination suggested, the number of corneal endothelial cells significantly decreased from 3428.6 ± 180.3 cells/mm2 to 2808 ± 80.6 cells/mm2 in the 0.50 M group, while the lower-concentration groups showed lesser toxic effects on corneal endothelial cells. Finally, our histological examination demonstrated inflammation in each experimental group and dose-dependent, compared with control group. Our study found 0.05 M and 0.01 M EDTA solutions had no obvious toxic effect on the corneal endothelium compared with higher concentration. However, further study of EDTA side effect by clinical trials, and therapeutic effect observation with different concentration are necessary.

Size Tunable Fabrication of Magnetic Alginate Microparticles Using Flow Focusing Microfluidics

AbstractThe size tunable formulation of magnetic alginate microparticles (MAMs) using a 3D flow‐focusing microfluidic device is reported. The droplet phase consists of iron oxide nanoparticles (IONPs) in an alginate solution and the continuous phase consists of fluorocarbon oils. The stability of IONP colloids in alginate and calcium ethylenediamine tetraacetic acid solutions using optical microscopy, dynamic light scattering, and zeta potential measurements is studied. These studies suggest that IONPs coated with polyethylene glycol (PEG) are most stable. MAMs using the PEG‐coated IONP colloid are then formulated and it is studied how MAM the average size and coefficient of variance vary as a function of droplet and continuous phase flow rates and viscosities. Droplet and MAM size decrease when the carrier flow rate or viscosity increases, and droplet and MAM size increase when droplet flow rate or viscosity increases. Crosslinking and drying of droplets result in MAMs whose diameter is ≈44% less than the original droplets while maintaining a population coefficient of variance below 8%. Conditions are identified that enable fabrication of MAMs with diameters between 30 and 60 µm with coefficients of variance of ≈6–7%. These results may guide future work exploring the role of MAM size on various applications.

Evaluation of osteogenic potential of demineralized dentin matrix hydrogel for bone formation

ObjectivesDentin, the bulk material of the tooth, resemble the bone’s chemical composition and is considered a valuable bone substitute. In the current study, we assessed the cytotoxicity and osteogenic potential of demineralized dentin matrix (DDM) in comparison to HA nanoparticles (n-HA) on bone marrow mesenchymal stem cells (BMMSCs) using a hydrogel formulation.Materials and methodsHuman extracted teeth were minced into particles and treated via chemical demineralization using ethylene diamine tetra-acetic acid solution (EDTA) to produce DDM particles. DDM and n-HA particles were added to the sodium alginate then, the combination was dripped into a 5% (w/v) calcium chloride solution to obtain DDM hydrogel (DDMH) or nano-hydroxyapatite hydrogel (NHH). The particles were evaluated by dynamic light scattering (DLS) and the hydrogels were evaluated via scanning electron microscope (SEM). BMMSCs were treated with different hydrogel concentrations (25%, 50%, 75% and neat/100%) and cell viability was evaluated using MTT assay after 72 h of culture. Collagen-I (COL-I) gene expression was studied with real-time quantitative polymerase chain reaction (RT-qPCR) after 3 weeks of culture and alkaline phosphatase (ALP) activity was assessed using enzyme-linked immune sorbent assay (ELISA) over 7th, 10th, 14th and 21st days of culture. BMMSCs seeded in a complete culture medium were used as controls. One-way ANOVA was utilized to measure the significant differences in the tested groups.ResultsDLS measurements revealed that DDM and n-HA particles had negative values of zeta potential. SEM micrographs showed a porous microstructure of the tested hydrogels. The viability results revealed that 100% concentrations of either DDMH or NHH were cytotoxic to BMMSCs after 72 h of culture. However, the cytotoxicity of 25% and 50% concentrations of DDMH were not statistically significant compared to the control group. RT-qPCR showed that COL-I gene expression was significantly upregulated in BMMSCs cultured with 50% DDMH compared to all other treated or control groups (P < 0.01). ELISA analysis revealed that ALP level was significantly increased in the groups treated with 50% DDMH compared to 50% NHH after 21 days in culture (P < 0.001).ConclusionThe injectable hydrogel containing demineralized dentin matrix was successfully formulated. DDMH has a porous structure and has been shown to provide a supporting matrix for the viability and differentiation of BMMSCs. A 50% concentration of DDMH was revealed to be not cytotoxic to BMMSCs and may have a great potential to promote bone formation ability.

In vivo Study to Evaluate the Effect of Instrument Size on the Accuracy of Three Different Apex Locators when Various Irrigation Solutions are used in Vital and Non-Vital Teeth.

Root canal success requires working length (WL) optimization. The current study examined how different apex locators on vital and non-vital teeth responded to instrument size. Three hundred patients (180 men and 120 women) receiving root canal therapy at the department of Conservative Dentistry and Endodontics were evaluated. Therefore, we determined that 200 of the patients' teeth (100 vital and 100 non-vital teeth from the upper and lower jaws' first molars) qualified for inclusion in our study. The pulp chamber was accessed using a sterile round bur. The coronal region of the root canal was preflared with successive Gates Glidden drills (Mani Inc. Japan) and irrigated with any one of the solutions 3% sodium hypochlorite (NaOCl), 2% chlorhexidine (CHX), or 17% ethylenediaminetetraacetic acid (EDTA) solution after checking canal patency with a size #10 K file, where (#-number). Later, the working length was established using Ingle's technique and a radiovisiograph (RVG) 0.5 mm short of the radiographic apex. Two endodontists approved this RVG. Overall, the #15 K file and apex locators did not differ from Ingle's method. While the #8 K file differs significantly from all apex locators, the #10 K file showed a significant difference with all apex locators except Root ZX with 2% CHX (P = 0.06). Irrigation didn't influence apex locators' accuracy. Even in the presence of irrigating solutions, electronic apex locator (EAL) can be utilized to calculate the working length with accuracy. The apex locators #15 k files, #10 k files, and #8 k files showed the most promising results.

Construction of a competitive electrochemical immunosensor based on sacrifice of Prussian blue and its ultrasensitive detection of alpha-fetoprotein

Effective signal amplification is a prerequisite for ultrasensitive detection by electrochemical immunosensors. For quantitative and ultrasensitive detection of alpha-fetoprotein (AFP), we designed a competitive electrochemical immunosensor and transferred the immunoreactivity from the electrode surface to the cuvette. AFP antigen was captured using AFP primary antibody (Ab1) immobilized on magnetic nanobeads (MBs), and ZIF-8 nanomaterials attached to secondary antibody (Ab2) were used as probes. MBs helped retain the sandwich structure in the test tube through incubation and washing steps. Then, an appropriately fixed excess of sodium ethylenediaminetetraacetic acid (EDTA) solution was added to the cuvettes, resulting in etching of Zn ions from ZIF-8 and formation of Zn-EDTA complexes. After magnetic separation, a certain amount of supernatant is added dropwise to the Prussian blue (PB)-modified electrode (GCE), and Fe ions (from PB) complex with the remaining EDTA in the supernatant, thus reducing the signal response value of PB. The higher the AFP concentration, the lower the amount of free EDTA in the supernatant, the less the destruction of PB, and therefore the higher the current. Under optimal conditions, the immunosensor achieved ultra-sensitive detection of AFP in the range of 10−4 ng/mL-100 ng/mL with a limit of detection (LOD) as low as 0.032 pg/mL (S/N = 3). The excellent performance provides an important tool for the early screening and detection of AFP.

Modification of UHPC Matrix and Fiber Surface for Improving the Mechanical Performance of Ultra-High-Performance Fiber-Reinforced Concrete

In this study, filler and silica fume were substituted by Liquid crystal display glass powder (LCDGP) and nanosilica, respectively, to improve the performance of ultra-high- performance fiber-reinforced concrete. In addition, the surface of steel fiber was modified with ethylenediaminetetraacetic acid (EDTA) solution to improve the interfacial friction between the fiber and Ultra-high-performanceconcrete (UHPC) matrix. Both LCDGP and nanosilica reacted with calcium hydroxide to form hydrates, and the fiber surface roughness increased owing to the EDTA treatment. When LCDGP was used, the compressive strength decreased owing to a decrease in packing density; however, the compressive and tensile strengths of Ultra-high-performance fiber-reinforced-concrete (UHPFRC) were improved on using nanosilica. It was observed that the surface modification of the fiber increased the friction force between the UHPC and fiber interface; therefore, it was more effective in improving the tensile strength than the compressive strength.

Reversible adsorption of iridium in lyophilized cells of the unicellular red alga Galdieria sulphuraria.

Iridium (Ir) is one of the rarest elements in the Earth's crust and is valuable in industry due to its high corrosion resistance. In this study, we used lyophilized cells of a unicellular red alga, Galdieria sulphuraria for the selective recovery of small amounts of Ir from hydrochloric acid (HCl) solutions. The Ir recovery efficiency of the lyophilized cells was higher than that of activated carbon and comparable to that of an ion-exchange resin in up to 0.2 M acid. Lyophilized G. sulphuraria cells showed different selectivity from the ion-exchange resin, adsorbing Ir and Fe in 0.2 M HCl solution while the ion-exchange resin adsorbed Ir and Cd. The adsorbed Ir could be eluted with more than 90% efficiency using HCl, ethylenediaminetetraacetic acid, and potassium hydroxide solutions, but could not be eluted using a thiourea-HCl solution. After the elution of Ir with a 6 M HCl solution, lyophilized cells could be reused up to five times for Ir recovery with over 60% efficiency. Scanning electron-assisted dielectric microscopy and scanning electron microscopy revealed that Ir accumulated in the cytosol of the lyophilized cells. X-ray absorption fine structure analysis demonstrated the formation of an outer-sphere complex between Ir and the cellular residues, suggesting the adsorption via ion exchange, and explaining the ability to elute the Ir and reuse the cells. Our results provide a scientific basis for inexpensive and environmentally friendly biosorbents as an alternative to ion-exchange resins for the recovery of Ir.

Synthesis of Biomass-Derived Activated Carbons and Their Immobilization on Alginate Gels for the Simultaneous Removal of Cr(VI), Cd(II), Pb(II), As(III), and Hg(II) from Water.

Low-cost alginate gels of activated carbons were prepared, which were derived from the peels of banana and sweet lime. The synthesized carbon was activated and immobilized on alginate, producing its gel. These gels were categorized according to their methods of drying, in which air drying, freeze drying, and supercritical drying led to the formation of xerogels, cryogels, and aerogels, respectively. The gels were used for adsorption of heavy metals from their aqueous solution. The heavy metals that were targeted for removal were Pb(II), Cd(II), Cr(VI), As(III), and Hg(II). Among all the adsorbents, the alginate cryogel of sweet lime-derived activated carbon (SLACC) showed the highest removal percentage of heavy metals, and thus, it was used for batch study. The adsorption of heavy metals by SLACC was checked at different times, pH values, adsorbent doses, temperatures, and adsorbate concentrations. The study revealed that the pseudo-second-order model best described the kinetic study, while the adsorption followed the Freundlich isotherm. SLACC showed maximum adsorption capacities (q cal) of 3.71, 4.22, 20.04, 7.31, and 4.37 mg/g for Cr, Cd, Pb, As, and Hg, respectively, when 20 mg of SLACC was used for the removal of 4 ppm concentration of the targeted heavy metals from their 20 mL solution. Based on the thermodynamic study, it was found that the adsorption was spontaneous and exothermic. Furthermore, the adsorbent was also used on real water samples and showed up to 90% removal efficiency for these targeted heavy metals. SLACC was regenerated with 0.1 M ethylenediaminetetraacetic acid (EDTA) solution and reused for five cycles, in which the percentage removal of heavy metals was more than 50% till the fourth cycle. Furthermore, the leaching study showed that no toxic elements had leached from SLACC into water, making it a safe adsorbent.

Characterization of pulp calcifications and changes in their composition after treatments with citric acid and ethylenediaminetetraacetic acid solutions.

The ectopic calcifications of non-mineralized tissues can occur in several forms throughout life, such as pulpal calcification. The presence of pulp stones is a challenge in endodontic treatment because they partially or fully obliterate the pulp chamber hindering access to root canals and their subsequent shaping. This study aimed to determine their crystallographic properties and evaluate the capacity of citric acid (CA) and ethylenediaminetetraacetic acid (EDTA) to promote the demineralization of pulp calcifications. The samples were obtained from patients with indications of endodontic treatment, and the radiographic examination was suggestive of pulp stone in at least one permanent tooth. The samples were isolated and analyzed by scanning electron microscopy/energy-dispersive x-ray spectroscopy (SEM/EDX). The Fourier Transform by high resolution-transmission electron microscopy, Raman microscopy, and X-ray diffraction (XRD) were used to identify the mineral phase and crystallographic characteristics. To evaluate the effect of CA and EDTA on the crystallinity of calcifications, they were submerged into these two individual solutions and the changes were assessed in situ by Raman spectroscopy. The SEM images obtained from calcifications demonstrated irregular morphologies. EDX of sample surfaces shows a high presence of oxygen, carbon, calcium, and phosphorous, however, other elements such as sodium, magnesium, nitrogen, chlorine, potassium, sulfur, and zinc were identified in less quantity. According to Raman, XRD, and high-resolution transmission electron microscopy, the predominant mineral phase identified in the pulpal calcification was a poor crystallinity apatite. According to in situ analyses, the effect of CA and EDTA was observed on the signals of PO4 3- and CH2 groups corresponding to inorganic and organic components. The changes with CA were evident at 7min while the effect of EDTA was observed until 15 min of treatment. All results indicate that pulp stones have a heterogeneous composition principally composed of apatite with low crystallinity. The solubility of these pathological minerals is adequate using solutions such as EDTA or CA; however, the effectivity depends on the mineralization grade of calcifications, time, and concentration of exposition to this chemical.