scholarly journals Physico-chemical properties of calcium phosphates

2012 ◽  
Vol 59 (1) ◽  
pp. 7-21 ◽  
Author(s):  
Vesna Babic-Ivancic ◽  
Maja Dutour-Sikiric
Keyword(s):  
Calcium Phosphates ◽  
Chemical Properties ◽  
Organic Matrix ◽  
Octacalcium Phosphate ◽  
Carbonate Apatite ◽  
Organic Additives ◽  
Biologically Relevant ◽  
Beta Tricalcium Phosphate ◽  
Physico Chemical

Calcium phosphates have important role in biological and pathological mineralization. While only one of calcium phosphates, carbonate apatite, represents the main mineral component of teeth and bones, octacalcium phosphate, calcium hydrogenphosphate dihydrate and beta-tricalcium phosphate occur in pathological deposits. From the stand-point of chemists, processes of biological and pathological mineralization could be considered as deposition of inorganic phase within organic matrix, i.e. formation of inorganic-organic composites. Although this approach is very simplified at first glance, it allows clarification of important issues related to biomineralization (e.g. what is the role of individual components of organic matrix in the emerging solid tissue), and design and preparation of new materials for hard tissue regeneration (e.g. process of transformation after implantation). The importance of investigation about calcium phosphates will be presented through the overview of basic physico-chemical reactions related to the formation and transformation of biologically relevant calcium phosphates and their interaction with various organic additives in the laboratory.

Properties of Gelatin/Carbonate Apatite Composite Compared to Bovine Bone

2012 ◽  
Vol 529-530 ◽  
pp. 413-416 ◽  
Author(s):  
Prachi Khanna ◽  
Racquel Z. LeGeros
Keyword(s):  
Mechanical Strength ◽  
Dissolution Rate ◽  
Bone Repair ◽  
Calcium Phosphates ◽  
Chemical Properties ◽  
Bovine Bone ◽  
Carbonate Apatite ◽  
Hydrolysis Method ◽  
Physico Chemical ◽  
Bone Substitute Materials

Bone is a composite of approximately 65% inorganic phase (carbonate apatite, CHA) and a 35% organic phase (mostly collagen). To date, several commercial composites consisting of natural or synthetic polymers and calcium phosphates ( hydroxyapatite, tricalcium phosphate, biphasic calcium phosphates) are recommended for use in bone repair. Objective: The aim of this study was to compare the physico-chemical properties of gelatin/carbonate apatite composites with that of bovine bone. Native (Gel) or cross-linked (Gel*) was used. Methods: The CHA was prepared by hydrolysis method. The gelatin (denatured collagen) was cross-linked using Genipin. The gelatin/CHA composite were prepared by mixing of 35% gelatin and 65% CHA and freeze-drying. The composites were characterized using x-ray diffraction (XRD), FT-IR spectroscopy, scanning electron microscopy (SEM) and thermogravimetry (TGA). Dissolution properties were determined in acidic buffer (0.1M KAc, pH 6, 37°C). Mechanical strength was determined using 3-point bend test. Bovine bone was similarly characterized for comparison. Results: The composition and crystallite size of the CHA were similar to that of the bone mineral. The Gel/CHA and Gel*/CHA composites showed several physico-chemical properties (crystallinity, composition, thermal stability, mechanical strength, dissolution rate) similar to that of bone. Gel*/CHA compared to Gel/CHA composites showed lower elastic modulus, flexural strength, dissolution rate, swelling and higher porosity. Conclusion: The Gel*/CHA composites presented several properties similar to those of bovine bone and may have potential as bone substitute materials.

scholarly journals Occurrence of drug target residues within decantation tank sediments: a good clue to assess their historical excretion?

2021 ◽  
Vol 31 (1) ◽  
Author(s):  
Thomas Thiebault ◽  
Laëtitia Fougère ◽  
Anaëlle Simonneau ◽  
Emilie Destandau ◽  
Claude Le Milbeau ◽  
...  
Keyword(s):  
Drug Target ◽  
Chemical Properties ◽  
Deposition Process ◽  
Drug Consumption ◽  
Organic Layers ◽  
Sewer Systems ◽  
Physico Chemical ◽  
Deep Underground ◽  
Deposition Processes

AbstractThis study investigated the potential of sediments accumulated in sewer systems to record human activities through the occurrence of drug target residues (DTR). The installation studied is 17 m deep underground decantation tank that traps the coarse fractions of a unitary sewer system (northern part of Orléans, France), collecting both stormwater and wastewater. The sediments deposited in this tank could constitute a nonesuch opportunity to study the historical evolution of illicit and licit drug consumption in the catchment, however, the deposition processes and the record of DTRs remain largely unknown at present. Five cores were acquired from 2015 to 2017. One hundred fifty-two sediment samples were extracted using a mixture of ultra-pure water:methanol (1:1) prior to analysis of the extracts by high-pressure liquid chromatography coupled to tandem mass spectrometry. Several classical sedimentological analyses such as total organic carbon, facies description and granulometry were also performed on these samples, in order to understand the most important factors (e.g., physico-chemical properties of the DTRs, solid type, assumed load in wastewater) impacting their deposition.The key role of the speciation of DTRs was highlighted by the higher contents in neutral and anionic DTRs in organic layers, whereas only cationic DTRs were found in mineral layers. The considerable modifications in the sediments’ properties, generated by distinct origins (i.e., stormwater or wastewater), are therefore the most important drivers that must be taken into account when back-calculating the historical patterns of drug consumption from their DTR concentrations in decantation tank sediments. Further research remains necessary to fully understand the deposition process, but this study provides new clues explaining these temporal evolutions.

scholarly journals Impact of Quantum Dot Surface on Complex Formation with Chlorin e6 and Photodynamic Therapy

Nanomaterials ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 9 ◽  
Author(s):  
Artiom Skripka ◽  
Dominyka Dapkute ◽  
Jurga Valanciunaite ◽  
Vitalijus Karabanovas ◽  
Ricardas Rotomskis
Keyword(s):  
Photodynamic Therapy ◽  
Cancer Therapy ◽  
Complex Formation ◽  
Chemical Properties ◽  
Disease Diagnosis ◽  
Chlorin E6 ◽  
Deep Tissue ◽  
Physico Chemical

Nanomaterials have permeated various fields of scientific research, including that of biomedicine, as alternatives for disease diagnosis and therapy. Among different structures, quantum dots (QDs) have distinctive physico-chemical properties sought after in cancer research and eradication. Within the context of cancer therapy, QDs serve the role of transporters and energy donors to photodynamic therapy (PDT) drugs, extending the applicability and efficiency of classic PDT. In contrast to conventional PDT agents, QDs’ surface can be designed to promote cellular targeting and internalization, while their spectral properties enable better light harvesting and deep-tissue use. Here, we investigate the possibility of complex formation between different amphiphilic coating bearing QDs and photosensitizer chlorin e6 (Ce6). We show that complex formation dynamics are dependent on the type of coating—phospholipids or amphiphilic polymers—as well as on the surface charge of QDs. Förster’s resonant energy transfer occurred in every complex studied, confirming the possibility of indirect Ce6 excitation. Nonetheless, in vitro PDT activity was restricted only to negative charge bearing QD-Ce6 complexes, correlating with better accumulation in cancer cells. Overall, these findings help to better design such and similar complexes, as gained insights can be straightforwardly translated to other types of nanostructures—expanding the palette of possible therapeutic agents for cancer therapy.

scholarly journals Tryptic phosphopeptides from whole casein. II. Physicochemical properties related to the solubilization of calcium

1989 ◽  
Vol 56 (3) ◽  
pp. 335-341 ◽  
Author(s):  
Rafael Berrocal ◽  
Serge Chanton ◽  
Marcel A. Juillerat ◽  
Blaise Favillare ◽  
Jean-Claude Scherz ◽  
...  
Keyword(s):  
Binding Sites ◽  
Calcium Phosphates ◽  
Chemical Properties ◽  
Sodium Caseinate ◽  
Ph Values ◽  
Physico Chemical ◽  
Casein Phosphopeptides ◽  
Hydrolysis Of ◽  
Phosphate Solutions ◽  
Tryptic Hydrolysis

SummaryCasein phosphopeptides (GPP) were produced by tryptic hydrolysis of sodium caseinate and further purified by precipitation and chromatography on QAE-Sephadex A-25. Their physico-chemical properties were compared with the properties of an enzymically dephosphorylated equivalent preparation (DPP). Binding of Ca2+ to the peptides was measured using a Ca selective electrode and was found to increase with pH and to show 1/1 stoicheiometry Ca/Porg in CPP at pH 6·5 a.nd 7·6. Klotz plots indicated equivalent binding sites at these two pH values, but some heterogeneity was seen at pH 3·5. In contrast, DPP did not bind significant amounts of Ca2+.CPP effectively inhibited the formation of insoluble calcium phosphates at different Ca/P ratios. The effective CPP concentration was 10 mg/1 and complete stability of calcium phosphate solutions was obtained at about 100 mg/1. This stabilizing effect was dependent on the presence of organic P.

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