scholarly journals Role of Aspartic and Polyaspartic Acid on the Synthesis and Hydrolysis of Brushite.

2019 ◽  
Vol 10 (1) ◽  
pp. 11 ◽  
Author(s):  
Katia Rubini ◽  
Elisa Boanini ◽  
Adriana Bigi
Keyword(s):  
Aspartic Acid ◽  
Octacalcium Phosphate ◽  
Physiological Solution ◽  
Cooperative Action ◽  
Phosphate Dihydrate ◽  
Mineral Phases ◽  
Carboxylate Groups ◽  
Hydrolysis Of ◽  
Thermal Stability Of

Dicalcium phosphate dihydrate (DCPD) is one of the mineral phases indicated as possible precursors of biological apatites and it is widely employed in the preparation of calcium phosphate bone cements. Herein, we investigated the possibility to functionalize DCPD with aspartic acid (ASP) and poly-aspartic acid (PASP), as models of the acidic macromolecules of biomineralized tissues, and studied their influence on DCPD hydrolysis. To this aim, the synthesis of DCPD was performed in aqueous solution in the presence of increasing concentrations of PASP and ASP, whereas the hydrolysis reaction was carried out in physiological solution up to three days. The results indicate that it is possible to prepare DCPD functionalized with PASP up to a polyelectrolyte content of about 2.3 wt%. The increase of PASP content induces crystal aggregation, reduction of the yield of the reaction and of the thermal stability of the synthesized DCPD. Moreover, DCPD samples functionalized with PASP display a slower hydrolysis than pure DCPD. On the other hand, in the explored range of concentrations (up to 10 mM) ASP is not incorporated into DCPD and does not influence its crystallization nor its hydrolysis. At variance, when present in the hydrolysis solution, ASP, and even more PASP, delays the conversion into the more stable phases, octacalcium phosphate and/or hydroxyapatite. The greater influence of PASP on the synthesis and hydrolysis of DCPD can be ascribed to the cooperative action of the carboxylate groups and to its good fit with DCPD structure.

Structural changes during the hydrolysis of dicalcium phosphate dihydrate to octacalcium phosphate and hydroxyapatite

2015 ◽  
Vol 51 (4) ◽  
pp. 355-361 ◽  
Author(s):  
V. F. Shamrai ◽  
A. E. Karpikhin ◽  
A. Yu. Fedotov ◽  
V. P. Sirotinkin ◽  
S. M. Barinov ◽  
...  
Keyword(s):  
Structural Changes ◽  
Octacalcium Phosphate ◽  
Dicalcium Phosphate ◽  
Dicalcium Phosphate Dihydrate ◽  
Phosphate Dihydrate ◽  
Hydrolysis Of

Surface Induced Calcium Phosphate Nucleation and Growth

1995 ◽  
Vol 414 ◽  
Author(s):  
L. Song ◽  
A. A. Campbell ◽  
X. S. Li ◽  
B. C. Bunker
Keyword(s):  
Calcium Phosphate ◽  
Phase Formation ◽  
Octacalcium Phosphate ◽  
Crystal Nucleation ◽  
X Ray Diffraction ◽  
Nucleation Kinetics ◽  
Constant Composition ◽  
Phosphate Dihydrate ◽  
Induction Times

AbstractCalcium phosphate nucleation on colloidal oxide surfaces, such as TiO2, SiO2 and Al2MO3, has been studied as a model system to understand the role of surface chemistry on crystal nucleation kinetics and phase formation. The nucleation induction times have been measured using Constant Composition (CC) technique and calcium phosphate phases formation have been determined mainly by X-ray diffraction. The results indicated TiO2 not only significantly reduces the nucleation induction time and interfacial energy but also stimulates octacalcium phosphate formation over dicalcium phosphate dihydrate. SiO2 and Al2O3 have little effect on both nucleation kinetics and phase formation.

scholarly journals The Influence of Different Classes of Amino Acids on Calcium Phosphates Seeded Growth

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4798
Author(s):  
Tea Mihelj Josipović ◽  
Monika Kovačević ◽  
Sarah Mateša ◽  
Marina Kostešić ◽  
Nives Matijaković ◽  
...  
Keyword(s):  
Amino Acids ◽  
Calcium Phosphate ◽  
Control Systems ◽  
Aspartic Acid ◽  
Significant Influence ◽  
Calcium Phosphates ◽  
Octacalcium Phosphate ◽  
Seeded Growth ◽  
Material Synthesis

Amino acids (AAs) attract attention for elucidating the role of proteins in biomineralization and the preparation of functionalized biomaterials. The influence that AAs exert on calcium phosphate (CaP) mineralization is still not completely understood, as contradictory results have been reported. In this paper, the influence of the addition of different classes of AAs, charged (L-aspartic acid, Asp; L-lysine, Lys), polar (L-asparagine, Asn; L-serine, Ser; L-tyrosine, Tyr), and non-polar (L-phenylalanine, Phe), on CaP growth in the presence of octacalcium phosphate (OCP) and calcium hydrogenphosphate dihydrate (DCPD) seeds was investigated. In control systems (without AAs), a calcium-deficient apatite (CaDHA) layer was formed on the surface of OCP, while a mixture of CaDHA and OCP in the form of spherical aggregates was formed on the surface of DCPD crystals. Charged and non-polar promoted, while polar AAs inhibited CaDHA formation on the OCP seeds. In the case of DCPD, Lys, Asp, and Phe promoted CaP formation, while the influence of other AAs was negligible. The most efficient promotor of precipitation in both cases was non-polar Phe. No significant influence of AAs on the composition and morphology of precipitates was observed. The obtained results are of interest for understanding biomineralization processes and additive controlled material synthesis.

scholarly journals The role of the substrate on the mechanical and thermal stability of Pd thin films during hydrogen (de)sorption

2021 ◽  
Vol 46 (5) ◽  
pp. 4137-4153
Author(s):  
Neha Verma ◽  
Rob Delhez ◽  
Niek M. van der Pers ◽  
Frans D. Tichelaar ◽  
Amarante J. Böttger
Keyword(s):  
Thin Films ◽  
Thermal Stability ◽  
Thermal Stability Of

Mossbauer Study of the Role of Aluminum and Chromium in Nitrogen Implanted Iron

1991 ◽  
Vol 235 ◽  
Author(s):  
M. Kopcewicz ◽  
J. Jagielski ◽  
A. Turos ◽  
D. L. Williamson
Keyword(s):  
Thermal Stability ◽  
Ion Implantation ◽  
Metallic Iron ◽  
Conversion Electron ◽  
Alloying Elements ◽  
Mössbauer Study ◽  
Conversion Electron Mössbauer Spectroscopy ◽  
Conversion Electron Mossbauer Spectroscopy ◽  
Thermal Stability Of

ABSTRACTThe role of alloying elements such as Cr and Al in the formation and stability of the nitride phases formed due to N ion implantation into metallic iron was studied by conversion electron Mössbauer spectroscopy (CEMS). The thermal stability of nitride phases upon 1 h annealing was greatly increased as a result of co-implanting either Cr or Al with N as compared to pure α-Fe implanted only with N.

scholarly journals Studies on the role of actin's aspartic acid 3 and aspartic acid 11 using oligodeoxynucleotide-directed site-specific mutagenesis.

1988 ◽  
Vol 263 (36) ◽  
pp. 19662-19669
Author(s):  
T L Solomon ◽  
L R Solomon ◽  
L S Gay ◽  
P A Rubenstein
Keyword(s):  
Aspartic Acid ◽  
Site Specific

scholarly journals Steroid Sulphatase and Its Inhibitors: Past, Present and Future

Molecules ◽  
2021 ◽  
Vol 26 (10) ◽  
pp. 2852
Author(s):  
Paul A. Foster
Keyword(s):  
Good Evidence ◽  
The Past ◽  
Steroid Sulphatase ◽  
University Of Oxford ◽  
Therapeutic Value ◽  
Breast And Prostate Cancer ◽  
The University ◽  
Further Development ◽  
Hydrolysis Of

Steroid sulphatase (STS), involved in the hydrolysis of steroid sulphates, plays an important role in the formation of both active oestrogens and androgens. Since these steroids significantly impact the proliferation of both oestrogen- and androgen-dependent cancers, many research groups over the past 30 years have designed and developed STS inhibitors. One of the main contributors to this field has been Prof. Barry Potter, previously at the University of Bath and now at the University of Oxford. Upon Prof. Potter’s imminent retirement, this review takes a look back at the work on STS inhibitors and their contribution to our understanding of sulphate biology and as potential therapeutic agents in hormone-dependent disease. A number of potent STS inhibitors have now been developed, one of which, Irosustat (STX64, 667Coumate, BN83495), remains the only one to have completed phase I/II clinical trials against numerous indications (breast, prostate, endometrial). These studies have provided new insights into the origins of androgens and oestrogens in women and men. In addition to the therapeutic role of STS inhibition in breast and prostate cancer, there is now good evidence to suggest they may also provide benefits in patients with colorectal and ovarian cancer, and in treating endometriosis. To explore the potential of STS inhibitors further, a number of second- and third-generation inhibitors have been developed, together with single molecules that possess aromatase–STS inhibitory properties. The further development of potent STS inhibitors will allow their potential therapeutic value to be explored in a variety of hormone-dependent cancers and possibly other non-oncological conditions.

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