scholarly journals The mechanism of biomineralization of bone-like apatite on synthetic hydroxyapatite: an in vitro assessment

2004 ◽  
Vol 1 (1) ◽  
pp. 17-22 ◽  
Author(s):  
Hyun-Min Kim ◽  
Teruyuki Himeno ◽  
Masakazu Kawashita ◽  
Tadashi Kokubo ◽  
Takashi Nakamura
Keyword(s):  
Calcium Phosphate ◽  
Amorphous Phase ◽  
Surface Potential ◽  
Atomic Ratio ◽  
The Third ◽  
Phosphate Ions ◽  
Transmission Electron ◽  
Negative Surface ◽  
Synthetic Hydroxyapatite

The mechanism of biomineralization of bone-like apatite on synthetic hydroxyapatite (HA) has been investigated in vitro , in which the HA surface was surveyed as a function of soaking time in simulated body fluid (SBF). In terms of surface structure by transmission electron microscopy with energy-dispersive X-ray spectrometry, the HA whose Ca/P atomic ratio was 1.67 revealed three different characteristic soaking periods in SBF, i.e. the first soaking period, in which the HA surface increased the Ca/P ratio up to 1.83 to form an amorphous phase of Ca-rich calcium phosphate; the second soaking period, in which the HA surface decreased the Ca/P ratio up to 1.47 to form an amorphous phase of Ca-poor calcium phosphate; and the third soaking period, in which the HA surface gradually increased the Ca/P ratio up to 1.65 to eventually produce the bone-like nano-cerystallites of apatite, which grew forming complex crystal assemblies with a further increase in immersion time. Analysis using electrophoresis spectroscopy indicated that, immediately after immersion in SBF, the HA revealed a highly negative surface potential, which increased to reach a maximum positive value in the first soaking period. The surface potential then decreased to again reach a negative value in the second soaking period and thereafter converge to a constant negative value in the third soaking period. This implies that the HA induces biomineralization of apatite by smartly varying its surface potential to trigger an electrostatic interaction, first with positive calcium ions and second with negative phosphate ions in the SBF.

Study of Bio-Mineralization of BCP with Compensation of Calcium and Phosphate Ions

2009 ◽  
Vol 610-613 ◽  
pp. 1391-1394
Author(s):  
Hua De Zheng ◽  
Ying Jun Wang ◽  
Qiang Ma ◽  
Cheng Yun Ning ◽  
Xiao Feng Chen
Keyword(s):  
Free Energy ◽  
Calcium Phosphate ◽  
Calcium Ions ◽  
Biphasic Calcium Phosphate ◽  
Porous Ceramic ◽  
Apatite Layer ◽  
Apatite Formation ◽  
Phosphate Ions

In the present study, an Intelligent Multi-parameter Simulated Evaluation in vitro （IMSE system） was used to study the deposition properties of apatite formation on the surface of biphasic calcium phosphate porous ceramic (BCP) from static and dynamic r-SBF. Results showed that apatite formed on the surface of BCP from static and dynamic r-SBF differed between each other. In static r-SBF, ions were transferred by diffusion, which could not compensate the consuming of calcium ions, and mist apatite layer was formed on the surface of samples. But in the dynamic r-SBF, simulated fluid was adjusted precisely and flowed forcedly, the concentrations of ions were homogeneous; with the compensation of ions, calcium and phosphate were supersaturated, and the free energy of apatite formation was negative, bone-like apatite sheets were formed on the surface of samples.

scholarly journals MMP20 Proteolysis of Native Amelogenin Regulates Mineralization In Vitro

2016 ◽  
Vol 95 (13) ◽  
pp. 1511-1517 ◽  
Author(s):  
S.Y. Kwak ◽  
Y. Yamakoshi ◽  
J.P. Simmer ◽  
H.C. Margolis
Keyword(s):  
Calcium Phosphate ◽  
Full Length ◽  
Protein Solutions ◽  
Mineral Formation ◽  
C Protein ◽  
Ordered Arrays ◽  
Transmission Electron ◽  
Precursor Phase ◽  
Lower Capacity

Recent studies have shown that native phosphorylated full-length porcine amelogenin (P173) and its predominant cleavage product (P148) can inhibit spontaneous calcium phosphate formation in vitro by stabilizing an amorphous calcium phosphate (ACP) precursor phase. Since full-length amelogenin undergoes proteolysis by matrix metalloproteinase 20 (MMP20, enamelysin) soon after secretion, the present study was conducted to assess the effect of amelogenin proteolysis on calcium phosphate formation. Calcium and phosphate were sequentially added to protein solutions without and with added MMP20 (ratio = 200:1) under physiological-like conditions of ionic strength (163 mM) in 50 mM Tris-HCl (pH 7.4) at 37 °C. Protein degradation with time was assessed by gel-electrophoresis, and mineral products formed were characterized by transmission electron microscopy (TEM). MMP20 was found to cleave P173 to primarily generate P148, along with P162, P46-148, and P63/64-148. In sharp contrast, MMP20 did not cleave P148. In addition, the formation of well-aligned bundles of enamel-like hydroxyapatite (HA) crystals was promoted in the presence of P173 with added MMP20, while only ACP particles were seen in the absence of MMP20. Although P148 was found to have a somewhat lower capacity to stabilize ACP and prevent HA formation compared with P173 in the absence of MMP20, essentially no HA formation was observed in the presence of somewhat higher concentrations of P148 regardless of MMP20 addition, due to the lack of observed protein proteolysis. Present findings suggest that ACP transformation to ordered arrays of enamel crystals may be regulated in part by the proteolysis of full-length native amelogenin, while the predominant amelogenin degradation product in developing enamel (e.g., P148) primarily serves to prevent uncontrolled mineral formation during the secretory stage of amelogenesis.

Fabrication and Characterisation of Calcium Phosphate - Liposome Composites as an Implant Coating

2000 ◽  
Vol 662 ◽  
Author(s):  
Tarinee Pongsaanutin ◽  
Jan T. Czernuszka
Keyword(s):  
Electron Microscopy ◽  
Calcium Phosphate ◽  
Dark Field ◽  
Electrophoretic Method ◽  
Phosphate Ions ◽  
Transmission Electron ◽  
Stainless Steel Cathode ◽  
Cathode Substrate ◽  
Implant Coating ◽  
Drug Delivery Devices

AbstractCalcium phosphate in the form of apatite has been successfully precipitated on the surface of liposomes. Liposome vesicles were prepared by sonication of phosphatidylcholine and this was introduced into an aqueous solution of calcium and phosphate ions supersaturated with respect to hydroxyapatite. Calcium phosphate was shown to precipitate solely on the outer layer surface of the liposome vesicles. These composite assemblies were then deposited onto a stainless steel cathode substrate using an electrophoretic method at physiological temperatures.Scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder xray diffraction (PXRD) and Fourier transform infrared spectroscopy (FTIR) were used to analyse the morphology, structure and chemical composition of the composite coating. The results from PXRD and FTIR show a mixture of amorphous and poor crystalline hydroxyapatite (HAp). This was verified by electron diffraction. Dark field images confirmed that the precipitated HAp deposited solely at the outer surface of the liposomes. SEM micrographs demonstrated a thin uniform coating at the microstructure level. These results suggest that these calcium phosphateliposome composites can be formed. They have tremendous potential for use as drug delivery devices in aiding the treatments of bone disorders.

scholarly journals Synthesis of Poly(Malic Acid) Derivatives End-Functionalized with Peptides and Preparation of Biocompatible Nanoparticles to Target Hepatoma Cells

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 958
Author(s):  
Clarisse Brossard ◽  
Manuel Vlach ◽  
Elise Vène ◽  
Catherine Ribault ◽  
Vincent Dorcet ◽  
...  
Keyword(s):  
Light Scattering ◽  
Spherical Shape ◽  
Hepatoma Cells ◽  
Poly Ethylene Glycol ◽  
Site Specific ◽  
Transmission Electron ◽  
Negative Surface ◽  
Negative Surface Charge ◽  
Poly Ethylene

Recently, short synthetic peptides have gained interest as targeting agents in the design of site-specific nanomedicines. In this context, our work aimed at developing new tools for the diagnosis and/or therapy of hepatocellular carcinoma (HCC) by grafting the hepatotropic George Baker (GB) virus A (GBVA10-9) and Plasmodium circumsporozoite protein (CPB)-derived peptides to the biocompatible poly(benzyl malate), PMLABe. We successfully synthesized PMLABe derivatives end-functionalized with peptides GBVA10-9, CPB, and their corresponding scrambled peptides through a thiol/maleimide reaction. The corresponding nanoparticles (NPs), varying by the nature of the peptide (GBVA10-9, CPB, and their scrambled peptides) and the absence or presence of poly(ethylene glycol) were also successfully formulated using nanoprecipitation technique. NPs were further characterized by dynamic light scattering (DLS), electrophoretic light scattering (ELS) and transmission electron microscopy (TEM), highlighting a diameter lower than 150 nm, a negative surface charge, and a more or less spherical shape. Moreover, a fluorescent probe (DiD Oil) has been encapsulated during the nanoprecipitation process. Finally, preliminary in vitro internalisation assays using HepaRG hepatoma cells demonstrated that CPB peptide-functionalized PMLABe NPs were efficiently internalized by endocytosis, and that such nanoobjects may be promising drug delivery systems for the theranostics of HCC.

scholarly journals Preparation of Protein–Peptide–Calcium Phosphate Composites for Controlled Protein Release

Molecules ◽  
2020 ◽  
Vol 25 (10) ◽  
pp. 2312
Author(s):  
Katsuya Kato ◽  
Sungho Lee ◽  
Fukue Nagata
Keyword(s):  
Calcium Phosphate ◽  
Protein Delivery ◽  
In Vitro Release ◽  
Protein Release ◽  
Homogeneous Distribution ◽  
Transmission Electron ◽  
Release Studies ◽  
Scanning Transmission ◽  
Basic Polypeptides

Protein–peptide–calcium phosphate composites were developed for achieving sustainable and controlled protein release. Bovine serum albumin (BSA) as a model acidic protein was efficiently encapsulated with basic polypeptides such as polylysine and polyarginine during the precipitation of calcium phosphate (CaP). The prepared composites were fully characterized in terms of their morphologies, crystallinities, and the porosity of their structures, and from these analyses, it was observed that there are no significant differences between the composites. Scanning transmission electron microscopy and energy dispersive X-ray spectroscopy analysis indicated a homogeneous distribution of nitrogen and sulfur, confirming the uniform distribution of BSA and polypeptide in the CaP composite. In vitro release studies demonstrated that the composite prepared with the peptides α-polylysine and polyarginine were suitable for the gradual release of the protein BSA, while those containing ε-polylysine and no peptide were unsuitable for protein release. Additionally, these composites showed high hemocompatibility for mouse red blood cells, and the osteoblast-like cell proliferation and spread in media with the composites prepared using BSA and α-polylysine showed similar tendencies to medium with no composite. From these results, protein–peptide–CaP composites are expected to be useful as highly biocompatible protein delivery agents.

scholarly journals Formation and Evolution of Nanoscale Calcium Phosphate Precursors Under Biomimetic Conditions

2021 ◽  
Author(s):  
ludovica epasto ◽  
tristan georges ◽  
albina selimovic ◽  
Jean-Michel Guigner ◽  
Thierry Azaïs ◽  
...  
Keyword(s):  
Calcium Phosphate ◽  
Building Blocks ◽  
Human Blood Plasma ◽  
Spherical Building ◽  
Ionic Clusters ◽  
Research Fields ◽  
Phosphate Ions ◽  
Formation And Evolution ◽  
Conformational Rearrangements

Simulated body fluids that mimic human blood plasma are widespread media for in-vitro studies in an extensive array of research fields, from biomineralization to surface and corrosion sciences. We show that these solutions undergo dynamic nanoscopic conformational rearrangements on the timescale of minutes to hours, even though they are commonly considered stable or metastable. In particular, we find and characterize nanoscale inhomogeneities made of calcium phosphate (CaP) aggregates that emerge from homogeneous SBF within a few hours and evolve into prenucleation species (PNS) that act as precursors in CaP crystallization processes. These ionic clusters consist of about 2 nm large spherical building units that can aggregate into supra-structures with sizes of over 200 nm. We show that the residence times of phosphate ions in the PNS depend critically on the total PNS surface. These findings are particularly relevant for understanding non-classical crystallization phenomena, in which PNS are assumed to act as building blocks for the final crystal structure.<br>

Injectable TEMPO-oxidized nanofibrillated cellulose/biphasic calcium phosphate hydrogel for bone regeneration

2018 ◽  
Vol 32 (10) ◽  
pp. 1371-1381 ◽  
Author(s):  
Engie Safwat ◽  
Mohammad L Hassan ◽  
Sayed Saniour ◽  
Dalia Yehia Zaki ◽  
Mervat Eldeftar ◽  
...  
Keyword(s):  
Calcium Phosphate ◽  
Bone Regeneration ◽  
Rice Straw ◽  
Biphasic Calcium Phosphate ◽  
Cellulose Nanofibers ◽  
Testing Machine ◽  
Fixed Ratio ◽  
Nanofibrillated Cellulose ◽  
Transmission Electron

Nanofibrillated cellulose, obtained from rice straw agricultural wastes was used as a substrate for the preparation of a new injectable and mineralized hydrogel for bone regeneration. Tetramethyl pyridine oxyl (TEMPO) oxidized nanofibrillated cellulose, was mineralized through the incorporation of a prepared and characterized biphasic calcium phosphate at a fixed ratio of 50 wt%. The TEMPO-oxidized rice straw nanofibrillated cellulose was characterized using transmission electron microscopy, Fourier transform infrared, and carboxylic content determination. The injectability and viscosity of the prepared hydrogel were evaluated using universal testing machine and rheometer testing, respectively. Cytotoxicity and alkaline phosphatase level tests on osteoblast like-cells for in vitro assessment of the biocompatibility were investigated. Results revealed that the isolated rice straw nanofibrillated cellulose is a nanocomposite of the cellulose nanofibers and silica nanoparticles. Rheological properties of the tested materials are suitable for use as injectable material and of nontoxic effect on osteoblast-like cells, as revealed by the positive alkaline phosphate assay. However, nanofibrillated cellulose/ biphasic calcium phosphate hydrogel showed higher cytotoxicity and lower bioactivity test results when compared to that of nanofibrillated cellulose.

scholarly journals THE EFFECT OF CASEIN PHOSPHOPEPTIDE-AMORPHOUS CALCIUM PHOSPHATE-PROPOLIS CHEWING GUM ON CALCIUM AND PHOSPHATE ION LEVELS IN CARIES-FREE SUBJECT’S SALIVA AND STREPTOCOCCUS MUTANS BIOFILM FORMATION

2017 ◽  
Vol 10 (17) ◽  
pp. 174
Author(s):  
Sri Angky Soekanto ◽  
Gadiacanaparimita Ghrena Duhita ◽  
Endang Winiati Bachtiar ◽  
Muhamad Sahlan
Keyword(s):  
Calcium Phosphate ◽  
Streptococcus Mutans ◽  
Calcium Ions ◽  
Amorphous Calcium Phosphate ◽  
Chewing Gum ◽  
Phosphate Ion ◽  
Phosphate Ions ◽  
Casein Phosphopeptide ◽  
Mass Formation

 Objective: The aim of this study is to analyze the amount of calcium and phosphate ion released by casein phosphopeptide-amorphous calcium phosphate (CPP-ACP), which supports the remineralization and the effectiveness of propolis wax in suppressing the mass formation of Streptococcus mutans biofilm on caries-free subjects and to observe if these two active components are effective when combined into one substance and placed inside sugar-free chewing gum.Methods: Twenty-five samples of caries-free saliva before and after the mastication simulation (five concentrations of chewing gum) in vitro were observed to check for release of calcium and phosphate ions along with a biofilm assay. The release of calcium ions was detected using AAS, the release of phosphate ions was detected using spectrophotometry ultraviolet-visible, and the biofilm assay was detected using a crystal violet 96-well plate ELISA and was evaluated with an ELISA reader.Result: Chewing gum with a concentration of 0% prop + 5% CPP-ACP showed the highest release level of calcium ions (p<0.05) and phosphate ions (p>0.05) and is significant in suppressing the mass formation of the S. mutans biofilm (p<0.05).Conclusions: Mastication simulation of CPP-ACP-Propolis chewing gum can increase calcium and phosphate ion levels in caries-free saliva and decrease S. mutans biofilm mass formation; this can support remineralization and becomes a dental caries prevention alternative.

scholarly journals Formation and Evolution of Nanoscale Calcium Phosphate Precursors Under Biomimetic Conditions

2021 ◽  
Author(s):  
ludovica epasto ◽  
tristan georges ◽  
albina selimovic ◽  
Jean-Michel Guigner ◽  
Thierry Azaïs ◽  
...  
Keyword(s):  
Calcium Phosphate ◽  
Building Blocks ◽  
Human Blood Plasma ◽  
Spherical Building ◽  
Ionic Clusters ◽  
Research Fields ◽  
Phosphate Ions ◽  
Formation And Evolution ◽  
Conformational Rearrangements

Simulated body fluids that mimic human blood plasma are widespread media for in-vitro studies in an extensive array of research fields, from biomineralization to surface and corrosion sciences. We show that these solutions undergo dynamic nanoscopic conformational rearrangements on the timescale of minutes to hours, even though they are commonly considered stable or metastable. In particular, we find and characterize nanoscale inhomogeneities made of calcium phosphate (CaP) aggregates that emerge from homogeneous SBF within a few hours and evolve into prenucleation species (PNS) that act as precursors in CaP crystallization processes. These ionic clusters consist of about 2 nm large spherical building units that can aggregate into supra-structures with sizes of over 200 nm. We show that the residence times of phosphate ions in the PNS depend critically on the total PNS surface. These findings are particularly relevant for understanding non-classical crystallization phenomena, in which PNS are assumed to act as building blocks for the final crystal structure.<br>

Maytansine-Induced Mitotic Arrest in Human Lymphoblasts

1977 ◽  
Vol 35 ◽  
pp. 460-461
Author(s):  
Tai-Te Chao ◽  
John Sullivan ◽  
Awtar Krishan
Keyword(s):  
Electron Microscopy ◽  
Cell Cycle ◽  
Transmission Electron Microscopy ◽  
Tubulin Polymerization ◽  
Vinca Alkaloids ◽  
Antimitotic Activity ◽  
Transmission Electron ◽  
Flow Microfluorometry ◽  
Brain Tubulin

Maytansine, a novel ansa macrolide (1), has potent anti-tumor and antimitotic activity (2, 3). It blocks cell cycle traverse in mitosis with resultant accumulation of metaphase cells (4). Inhibition of brain tubulin polymerization in vitro by maytansine has also been reported (3). The C-mitotic effect of this drug is similar to that of the well known Vinca- alkaloids, vinblastine and vincristine. This study was carried out to examine the effects of maytansine on the cell cycle traverse and the fine struc- I ture of human lymphoblasts.Log-phase cultures of CCRF-CEM human lymphoblasts were exposed to maytansine concentrations from 10-6 M to 10-10 M for 18 hrs. Aliquots of cells were removed for cell cycle analysis by flow microfluorometry (FMF) (5) and also processed for transmission electron microscopy (TEM). FMF analysis of cells treated with 10-8 M maytansine showed a reduction in the number of G1 cells and a corresponding build-up of cells with G2/M DNA content.

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