Characterization of Novel Cement-Based Carboxymethyl Chitosan/Amorphous Calcium Phosphate

Objective This study aimed to analyze, evaluate, and characterize novel cement-based carboxymethyl chitosan/amorphous calcium phosphate (CMC/ACP). Materials and Methods The three cement groups studied were gypsum (Gyp), and CMC/ACP—gypsum cement-based 5% (5% CAG) and 10% (10% CAG). The groups were characterized using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), setting time, and scanning electron microscopy (SEM) data. The characterization results were analyzed qualitatively, but the data for setting time were analyzed using SPSS (p < 0.05). Statistical Analysis Data were statistically analyzed. One-way analysis of variance was used to compare numerical (parametric) data between more than two separate groups followed by post hoc Tukey. Results FTIR showed phosphate groups indicate the presence of calcium phosphate in the form of amorphous (ACP) in the CMC/ACP, CMC/ACP post-milled powder, and CMC/ACP cement-based (5% CAG and 10% CAG). XRD showed no difference in the diffraction spectra among the Gyp, 5% CAG, and 10% CAG groups. SEM images revealed that the CMC/ACP cement-based groups (5% CAG and 10% CAG) showed CMC/ACP cluster filled with hollow spaces between the gypsum crystals and aggregations surrounding the gypsum crystals. The CMC/ACP showed envelopes and attached to the crystalline structures of the gypsum. Setting times of 5% CAG and 10% CAG showed significant differences compared with Gyp (p < 0.05). Conclusion The result of our study showed that CMC/ACP cement-based (5% CAG and 10% CAG) demonstrated amorphous characteristic, which can stabilize calcium ions and phosphate group (ACP). In addition, the modification of gypsum using CMC/ACP as cement-based extended the time of setting.

Efficacy of Nano Crystallised Calcium Phosphate (NCCP) and Casein Phosphopeptide – Amorphous Calcium Phosphate (CPP-ACP) for Controlling Postoperative Sensitivity After Power Bleaching-A Comparative In-Vivo Study

Tooth bleaching is one of the most popular cosmetic dental procedures opted by the patients who desire pleasing smile. It is the simplest, least invasive means available to lighten discolored vital teeth. A number of desensitizing agents have been tried in an attempt to counteract bleaching-related sensitivity. This study was done to compare the effect of two different desensitizing agents for controlling post operative sensitivity after power bleach procedure. Sixty volunteers with mild to moderate dental fluorosis in maxillary anterior teeth, who fulfilled the inclusion and exclusion criteria, were randomly selected for this study. After the bleaching procedurea demo was given to the patient while application of desensitising gel and was instructed to use the gel for 14 days.All the patients were recalled at an interval of 1st day, 3rdday, 5th day, 7th day, and on 14th day to record the post operative sensitivity after power bleach procedure. The observations were analyzed using one way analysis of variance (ANOVA), Tukeys post hoc test. On the basis of VAS results, all the groups showed post operative sensitivity of varied intensity at different intervals. NCCP showed less sensitivity followed by CPP-ACP and Control group. Keywords: Power Bleaching, Post operative sensitivity, Nano Crystallized Calcium Phosphate, Casein Phosphopeptide-Amorphous Calcium Phosphate

PRECIPITATION OF HYBRID HYDROXYAPATITE / AUTOFIBRIN NANOCOMPOSITES

Синтезированы гибридные нанокомпозиты на основе гидроксиапатита и аутофибрина в форме фибринового сгустка либо цитратной плазмы путем осаждения при pH 9. «Мягкие» условия осаждения и быстрое выделение нанокомпозитов способствовали сохранению биополимерной матрицы аутофибрина. Дестабилизация дополнительной фазы аморфного фосфата кальция с образованием стехиометрического гидроксиапатита обусловлена влиянием макромолекул фибрина. Формирование кальцийдефицитного гидроксиапатита с x« 0,1 и Ca / P 1,65 происходило в среде цитратной плазмы, который после 800 °С превращался в смесь гидроксиапатит / 3 -трикальцийфосфат. Синтез композитов на основе биомиметического апатита осуществляли при добавлении 30 об.% модельного раствора Simulated Body Fluid (SBF). Влияние ионов Mg, CO~, входящих в состав SBF, способствовало стабилизации аморфного фосфата кальция и образованию карбонатзамещенного гидроксиапатита, устойчивого к термическим превращениям до 800°С. Совокупное влияние аутофибрина и ионов введенного SBF позволило управлять составом минеральной составляющей гибридных нанокомпозитов без разрушения биополимерной матрицы. Hybrid composites based on hydroxyapatite and autofibrin were synthesized by precipitation in a medium with pH = 9. Soft precipitation conditions and rapid isolation of the composite precipitates favored preservation of a biopolymer matrix of autofibrin. An effect of fibrin macromolecules contributed to destabilization of the amorphous calcium phosphate phase and formation of stoichiometric hydroxyapatite. The medium of the citrated plasma stimulated precipitation of calcium-deficient hydroxyapatite with x « 0,1 and the Ca / P ration of 1,65 which transformed into the mixture of hydroxyapatite / 3 -tricalcium phosphate at 800 °С. Biomimetic apatite composites were synthesized with an addition of 30 vol. % of a Simulated Body Fluid (SBF) model solution. The effect of Mg, CO~ ions of SBF promoted the stabilization of amorphous calcium phosphate and formation of carbonated hydroxyapatite that exhibited thermal stability up to 800 °С. The cummulative effect of autofibrin and ions of induced SBF provided controlling composition of the mineral part of hybrid nanocomposites without disruption of an autofibrin matrix.

Physiological and Molecular Investigation of Urea Uptake Dynamics in Cucumis sativus L. Plants Fertilized With Urea-Doped Amorphous Calcium Phosphate Nanoparticles

At present, the quest for innovative and sustainable fertilization approaches aiming to improve agricultural productivity represents one of the major challenges for research. In this context, nanoparticle-based fertilizers can indeed offer an interesting alternative with respect to traditional bulk fertilizers. Several pieces of evidence have already addressed the effectiveness of amorphous calcium phosphate-based nanoparticles as carriers for macronutrients, such as nitrogen (N), demonstrating increase in crop productivity and improvement in quality. Nevertheless, despite N being a fundamental nutrient for crop growth and productivity, very little research has been carried out to understand the physiological and molecular mechanisms underpinning N-based fertilizers supplied to plants via nanocarriers. For these reasons, this study aimed to investigate the responses of Cucumis sativus L. to amorphous calcium phosphate nanoparticles doped with urea (U-ACP). Urea uptake dynamics at root level have been investigated by monitoring both the urea acquisition rates and the modulation of urea transporter CsDUR3, whereas growth parameters, the accumulation of N in both root and shoots, and the general ionomic profile of both tissues have been determined to assess the potentiality of U-ACP as innovative fertilizers. The slow release of urea from nanoparticles and/or their chemical composition contributed to the upregulation of the urea uptake system for a longer period (up to 24 h after treatment) as compared to plants treated with bulk urea. This prolonged activation was mirrored by a higher accumulation of N in nanoparticle-treated plants (approximately threefold increase in the shoot of NP-treated plants compared to controls), even when the concentration of urea conveyed through nanoparticles was halved. In addition, besides impacting N nutrition, U-ACP also enhanced Ca and P concentration in cucumber tissues, thus having possible effects on plant growth and yield, and on the nutritional value of agricultural products.

The Mechanical Consequences of the Interplay of Mineral Distribution and Organic Matrix Orientation in the Claws of the Sea Slater Ligia pallasii

Exposed regions of the arthropod exoskeleton have specialized structure and mineral composition. Their study can provide insights into the evolutionary optimization of the cuticle as a material. We determined the structural and compositional features of claws in the crustacean Ligia pallasii using X-ray micro-computed tomography, scanning electron microscopy (SEM), and analytical scanning transmission electron microscopy (STEM). In addition, we used nanoindentation to determine how these features fine-tune the mechanical properties of the claw cuticle. We found that the inner layer of the claw cuticle—the endocuticle—contains amorphous calcium phosphate, while the outer layer—the exocuticle—is not mineralized and contains elevated amounts of bromine. While the chitin–protein fibers in crustacean exoskeletons generally shift their orientation, they are aligned axially in the claws of L. pallasii. As a consequence, the claw cuticle has larger elastic modulus and hardness in the axial direction. We show that amorphous calcium phosphate mineralization and the brominated cuticle are widespread in isopod crustaceans inhabiting terrestrial habitats. We discuss how the features of the claw cuticle may aid in minimizing the likelihood of fracture. Ultimately, our study points out the features that increase the durability of thin skeletal elements.

Nanocomposites based on apatitic tricalcium phosphate and autofibrin

Nanocomposites based on apatitic tricalcium phosphate in an autofibrin matrix were obtained by precipitation at a Ca/P ratio of 1.50, pH 9 and a maturation time from 30 min to 7–14 days. The resorbability of nanocomposites was determined by the composition of calcium phosphates, which, during long-term maturation, formed as the calcium-deficient hydroxyapatite with a Ca/P ratio of 1.66, whereas biopolymer matrix favored the formation of more soluble calcium phosphates with a Ca/P ratio of 1.53–1.59. It was found that the fibrin clot stabilized, along with apatitic tricalcium phosphate, the phase of amorphous calcium phosphate, which after 800 °C was transformed into resorbable α-tricalcium phosphate. Citrated plasma inhibited the conversion of apatitic tricalcium phosphate into stoichiometric hydroxyapatite, which also facilitated the formation of resorbable β-tricalcium phosphate after 800 °C. The combined effect of the maturation time and the biopolymer matrix determined the composition, physicochemical and morphological properties of nanocomposites and the possibililty to control its extent of resorption

Enamel Remineralization and Dentine Tubules Occlusion by Bioactive Formulations Based on Ion-Doped Nanohydroxyapatite and Precursor Nanoparticles.

Recent health care products are based on formulations claimed to provide enamel remineralization and dentinal tubules occlusion through calcium-phosphate bioactive nanocompounds ( ion-doped hydroxyapatite and precursor nanoparticles). This study aimed to test and characterize for the first time the structure and composition of a representative sample of remineralizing toothpastes and topical mousses available on the market. The enamel remineralization and dentinal tubules occlusion efficacy of tested formulations were investigated in vitro. Formulations were characterized in terms of water- and acid-insoluble fractions, and PXRD, FTIR, and EDS analyses were performed to determine their composition and investigate the presence of bioactive compounds and doping elements. All formulations containing Ca-P bioactive nanocompounds showed remineralizing ability, notably when hydroxyapatite and amorphous calcium phosphate compounds were doped with small amounts of CO3-, F, Mg, and Sr. Topical mousse formulations showed a higher tubules occlusion capability than toothpastes, independently from their composition. In conclusion, all tested formulations could express remineralizing potential both on enamel and dentin thanks to the presence of biomimetic Ca-P compounds. The presence of doping elements or CPP-ACP seems essential to allow such performances.