Ethylenediaminetetraacetic Acid Disodium Salt Dihydrate Research Articles

EDTA-Assisted Self-Assembly of Fluoride-Substituted Hydroxyapatite Coating on Enamel Substrate

Reconstructed layers containing ordered enamel-like structures of fluoride-substituted hydroxyapatite (FHAp) microcrystals were constructed on a human enamel surface using ethylenediaminetetraacetic acid disodium salt dihydrate (EDTA) as the mediating agent under near-physiological conditions (pH 6.00, 37 °C, 1 atm). The effects of initial pH value, fluoride concentration, as well as reaction time on the formation of the FHAp microcrystals, including their microarchitectural structure, crystalline phase, chemical components, and hardness properties, were investigated using transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Vickers microhardness measurements. The results of these in vitro experiments indicated that EDTA induced the assembly of hexagonal prismlike FHAp microcrystals along their c-axis direction, and the microcrystals further amalgamated with the extended reaction time. In addition, fluoride ions were found to play a critical role in the formation of hexagonal FHAp microcrystals. Interestingly, after reaction for 5 days, the Vickers microhardness of the new layer (347–370 VHN) was harder than that of natural tooth. On the basis of the experimental evidence, a mesoscale self-assembly mechanism was proposed to explain the growth of FHAp microcrystals.

Use of bacteriophage endolysin EL188 and outer membrane permeabilizers against Pseudomonas aeruginosa

To select and evaluate an appropriate outer membrane (OM) permeabilizer to use in combination with the highly muralytic bacteriophage endolysin EL188 to inactivate (multi-resistant) Pseudomonas aeruginosa. We tested the combination of endolysin EL188 and several OM permeabilizing compounds on three selected Ps. aeruginosa strains with varying antibiotic resistance. We analysed OM permeabilization using the hydrophobic probe N-phenylnaphtylamine and a recombinant fusion protein of a peptidoglycan binding domain and green fluorescent protein on the one hand and cell lysis assays on the other hand. Antibacterial assays showed that incubation of 10(6) Ps. aeruginosa cells ml(-1) in presence of 10 mmol l(-1) ethylene diamine tetraacetic acid disodium salt dihydrate (EDTA) and 50 μg ml(-1) endolysin EL188 led to a strain-dependent inactivation between 3·01 ± 0·17 and 4·27 ± 0·11 log units in 30 min. Increasing the EL188 concentration to 250 μg ml(-1) further increased the inactivation of the most antibiotic resistant strain Br667 (4·07 ± 0·09 log units). Ethylene diamine tetraacetic acid disodium salt dihydrate was selected as the most suitable component to combine with EL188 in order to reduce Ps. aeruginosa with up to 4 log units in a time interval of 30 min. This in vitro study demonstrates that the application range of bacteriophage encoded endolysins as 'enzybiotics' must not be limited to gram-positive pathogens.

Rapid room-temperature synthesis of silver nanoplates with tunable in-plane surface plasmon resonance from visible to near-IR

We report a rapid (within 15 minutes), simple, green, inexpensive, versatile, and reproducible method for the synthesis of Ag triangular and hexagonal nanoplates in aqueous phase under ambient atmosphere. The method involves reducing silver oxide (Ag2O) with hydrazine (N2H4) in the presence of trisodium citrate (TSC) and ethylenediaminetetraacetic acid disodium salt dihydrate (EDTA) in aqueous phase. In our system, TSC molecules serve as colloidal stabilizers to prevent as-prepared colloids from aggregating, while EDTA molecules serve as a ligand to monomers. The complexation of EDTA to Ag+ not only significantly slows the reduction kinetics of Ag+ by N2H4, but also kinetically controls the formation and growth of nanoplates. By varying the amount of EDTA, the shape (triangular and hexagonal) and edge length of nanoplates have been readily controlled, providing a surface plasmon resonance (SPR) response tunable from visible to near infrared. Most importantly, the SPR response is almost a linear function of the quantity of EDTA. Silver nanocrystals with a required SPR response can be provided, even without considering the actual nature of the Ag colloids. Recent results suggest that this chelation-mediated kinetic control over the sizes and morphologies of nanostructures can also be applied for other metal nanostructures.

Enzymatic digestion—a safe and rapid technique for individual separation of Macrobrachium rosenbergii embryos for cryopreservation studies

A new, safe, and rapid technique for the individual separation of the embryos of giant freshwater prawn Macrobrachium rosenbergii de Man is described. Two protease enzymes, e.g., trypsin and collagenase were used. Embryos in the advanced stage of development (gray embryos with eyespot and heart beat) were selected for the study. Treatment with collagenase and trypsin at respective concentrations of 0.05 and 0.25% for 30 min resulted in 100% separation of 35–40 mg of embryonic mass (∼180 embryos). A chelating agent, EDTA (ethylenediaminetetraacetic acid disodium salt: dihydrate) at 400 mg l −1 enhanced the activity of trypsin. Trypsin and collagenase, when used together, were found to act synergistically. The separated embryos revealed no morphological injury when observed under the microscope. Further, in vitro hatching of the separated embryos was successful indicating that the present technique is safe and effective in achieving individual separation of prawn embryos.