Search results for "calcium phosphates"
showing 10 items of 44 documents
Influence of different biomaterials on the viability of Aggregatibacter actinomycetemcomitans
2011
Abstract Objectives The aim of the present in vitro study was to evaluate the effects of different biomaterials used for regenerative periodontal surgery on the growth of the periodontopathogen Aggregatibacter actinomycetemcomitans . Methods Three commercially available biomaterials of synthetic origin (hydroxyapatite/beta-tricalcium phosphate, nanostructured hydroxyapatite paste, oily calcium hydroxide suspension), a bovine-derived xenograft as well as an enamel matrix derivative (EMD) were added in different concentrations to calibrated suspensions of A. actinomycetemcomitans ATCC 43718/33384 (serotype b/c). Equal aliquots (0.1 ml) for the viability assay were taken after 5 min, 1 h, 3 h,…
Amplified morphogenetic and bone forming activity of amorphous versus crystalline calcium phosphate/polyphosphate.
2020
Amorphous Ca-phosphate (ACP) particles stabilized by inorganic polyphosphate (polyP) were prepared by co-precipitation of calcium and phosphate in the presence of polyP (15% [w/w]). These hybrid nanoparticles showed no signs of crystallinity according to X-ray diffraction analysis, in contrast to the particles obtained at a lower (5% [w/w]) polyP concentration or to hydroxyapatite. The ACP/15% polyP particles proved to be a suitable matrix for cell growth and attachment and showed pronounced osteoblastic and vasculogenic activity in vitro. They strongly stimulated mineralization of the human osteosarcoma cell line SaOS-2, as well as cell migration/microvascularization, as demonstrated in th…
An injectable bone substitute composed of beta-tricalcium phosphate granules, methylcellulose and hyaluronic acid inhibits connective tissue influx i…
2011
In this study, the in vivo tissue reaction to a new triphasic and injectable paste-like bone-substitute material composed of beta-tricalcium phosphate (β-TCP), methylcellulose and hyaluronic acid was analyzed. Using a subcutaneous implantation model, the interaction of these materials and the peri-implant tissue reaction were tested in Wistar rats for up to 60 days by means of established histological methods, including histomorphometrical analysis. The study focused on tissue integration, classification of the cellular inflammatory response and the degradation of the material. Groups composed of animals injected only with β-TCP granules, sham-operated animals and animals injected with sali…
A biphasic calcium phosphate coating for potential drug delivery affects early osseointegration of titanium implants.
2016
Background Calcium phosphate (CaP) surface coatings may accelerate osseointegration and serve as a drug delivery system for mineral-binding biomolecules. In a pilot study, the impact of a commercially available, thin CaP coating on early osseous bone remodeling was compared with a modern, subtractive-treated rough surface (SLA-like) in an animal trial. Methods In 16 rabbits, 32 endosseous implants (CaP; n = 16, SLA-like; n = 16) were bilaterally inserted in the proximal tibia after randomization. After 2 and 4 weeks, bone-implant contact (BIC;%) in the cortical (cBIC) and the trabecular bone (sBIC) as well as volume of bone within the screw thread with the highest amount of new-formed bone …
Amorphous Calcium Phosphates: Solvent-Controlled Growth and Stabilization through the Epoxide Route.
2020
Calcium phosphates stand among the most promising nanobiomaterials in key biomedical applications, such as bone repairment, signalling or drug/gene delivery. Their intrinsic properties as crystalline structure, composition, particle shape and size define their successful use. Among these compounds, metastable amorphous calcium phosphate (ACP) is currently gaining particular attention due to its inherently high reactivity in solution, which is crucial in bone development mechanisms. However, the preparation of this highly desired (bio)material with control over its shape, size and phase purity remains as a synthetic challenge. In this work, the epoxide route was adapted for the synthesis of …
Biosynthesis and characterization of titanium dioxide nanoparticles and its effects along with calcium phosphate on physicochemical attributes of whe…
2021
Abstract Drought stress is reducing the production of crops globally. This research was designed to evaluate the role of titanium dioxide (TiO2 NPs) nanoparticles and calcium phosphate on wheat facing drought stress. TiO2 NPs were prepared by green synthesis and their characterization (by UV–visible spectroscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX)) was also done. The results showed that TiO2 NPs worked efficiently and improved plant growth under drought. However, the best results were obtained from combined applications of 40 ppm TiO2 NPs and 40 ppm calcium phosphate on plants. They increased root length (33%), shoot length (53%), fresh weight (48%), and d…
Calcium phosphate precipitation in a SBR operated for EBPR: interactions with the biological process.
2008
The aim of this paper is to study the precipitation process in a sequencing batch reactor (SBR) operated for EBPR (enhanced biological phosphorus removal) and the possible effects of this phosphorus precipitation in the biological process. Four experiments were carried out under different influent calcium concentration. The experimental results and the equilibrium study, based on the Saturation Index calculation, confirm that the process controlling the calcium behaviour in a SBR operated for EBPR is the calcium phosphate precipitation. This precipitation takes place at two stages initially precipitation of the ACP and later crystallization of HAP. Also the accumulation of phosphorus precip…
Phosphorus recovery by struvite crystallization in WWTPs: Influence of the sludge treatment line operation
2010
Phosphorus recovery by struvite (MgNH(4)PO(4).6H(2)O) crystallization is one of the most widely recommended technologies for treating sludge digester liquors especially in wastewater treatments plants (WWTP) with enhanced biological phosphorus removal (EBPR). In this paper, phosphorus recovery by struvite crystallization is assessed using the rejected liquors resulting from four different operational strategies of the sludge treatment line. Phosphorus precipitation and recovery efficiencies of between 80-90% and 70-85%, respectively, were achieved in the four experiments. The precipitates formed were mainly struvite, followed by amorphous calcium phosphate and, in some experiments, by calci…
Isotopic composition of cattle pancreatic stones: biological and geochemical implications.
1977
Latitudinal variations of the O18/O16-ratios of carbonate and phosphate of cattle pancreatic stones parallel a similar pattern of oxygen isotope values in rain water. C13/C12-ratios were virtually identical for the 7 cases studied. Isotopic measurements of mammalian hard tissues may be used for studying short-term climatic variations through Quaternary.
Crystallized nano-sized alpha-tricalcium phosphate from amorphous calcium phosphate: microstructure, cementation and cell response
2015
New insight on the conversion of amorphous calcium phosphate (ACP) to nano-sized alpha tricalcium phosphate (α-TCP) provides a faster pathway to calcium phosphate bone cements. In this work, synthesized ACP powders were treated with either water or ethanol, dried, crystallized between 700 and 800 °C, and then cooled at different cooling rates. Particle size was measured in a scanning electron microscope, but crystallite size calculated by Rietveld analysis. Phase composition and bonding in the crystallized powder was assessed by x-ray diffraction and Fourier-transform infrared spectroscopy. Results showed that 50 nm sized α-TCP formed after crystallization of lyophilized powders. Water trea…