Serena Best - Academia.edu (original) (raw)
Papers by Serena Best
Recent Patents on Engineering, Oct 31, 2007
ABSTRACT
Bioceramics Vol 19 Pts 1 and 2 330 332 503 506, Feb 11, 2007
J Mater Sci Mater Med, 2000
Journal of Materials Science Materials in Medicine 16 1143 1148, Dec 1, 2005
Hydroxyapatite (HA) is important in biomedical applications because of its chemical similarity to... more Hydroxyapatite (HA) is important in biomedical applications because of its chemical similarity to the mineral content of bone and its consequent bioactivity. Silicon substitution into the hydroxyapatite crystal lattice was found to enhance its bioactivity both in vitro and in vivo [1, 2]. However, the mechanism for the enhancement is still not well understood. In this paper, the crystal imperfections introduced by silicon substitution were studied using XRD and Raman spectroscopy. It was found that silicon substitution did not introduce microstrain, but deceased the crystal size in the hk0 direction. Three new vibration modes and peak broadening were observed in Raman spectra following silicon incorporation. The imperfections introduced by silicon substitution may play a role in enhancing bioactivity. A phenomenological relationship between the width of the PO4 v1 peak and crystal size was established.
Journal of Biomedical Materials Research Part a, Jul 1, 2006
J Biomed Mater Res, 1999
Powder mixtures of alpha-Ca(3)(PO(4))(2), Ca(H(2)PO(4))(2), and CaCO(3) were investigated to asse... more Powder mixtures of alpha-Ca(3)(PO(4))(2), Ca(H(2)PO(4))(2), and CaCO(3) were investigated to assess their potential for the precipitation of a carbonated apatite suitable for cement applications from a supersaturated solution. Of particular interest was the requirement of carbon dioxide release during the setting reaction to obtain Ca(9-x)(HPO(4))(1-1.5x) (PO(4))(5-2.5x)(CO(3))(3.5x)(OH)(1 + 1.5x) with a fixed carbonate content. Results indicated that a compromise is necessary with respect to the maximum permissible level of CaCO(3) addition to the powder mixture as against appropriate setting and hardening properties. Cementlike materials with good setting and hardening properties were obtained when alpha-Ca(3)(PO(4))(2) was the main reactant using Ca(H(2)PO(4))(2) and CaCO(3) as additives in relative proportions of <10 wt % corresponding, approximately, to the stability field area (x,lambda) contained within the lines lambda = -1.5x, x = 0.3, and lambda = -1. Desirable workability and setting properties were lost as the parameters x and -lambda increased. Finally, it was also found to be virtually impossible to obtain a predetermined chemical composition for the setting apatite precipitate, since to increase the amount of carbon dioxide released from the initial powder mixture during setting, the solution pH would need to be decreased, and in doing so the nature of the precipitate could be altered to fulfil the thermodynamic conditions of the solubility diagrams of calcium phosphates.
Key Engineering Materials, Dec 31, 2002
ABSTRACT
Bioceramics 16 254 2 111 114, 2004
Bioceramics, 1999
ABSTRACT Four different assays, monitoring different aspects of cellular activity were used to as... more ABSTRACT Four different assays, monitoring different aspects of cellular activity were used to assess the in vitro biocompatibility of three experimental zirconias (ZrO2-A, ZrO2-B and ZrO2-C) with minor chemical modifications. The assays used were Neutral red uptake, MTT, alamarBlue and a live/dead cell stain. No cytotoxic effect was detected in the extracts from the three test zirconia samples using Neutral red uptake and MTT assays. However, a variation in response was observed in cells cultured directly on the surface of three test zirconias using the alamarBlue assay. The three test zirconia substrates showed no toxic effect after 1 and 2 days in culture. After 5 days in direct contact with the experimental zirconias, a significant decrease in cell activity was observed on sample ZrO2-B, which was confirmed by fluorescence microscopy, showing a layer of dead cells (stained by thidium homodimer-1) on the sample surface. The findings from this study indicated that great care is required when selecting assays to assess the biocompatibility of modified materials with regard to the type and sensitivity of the assay and culture conditions.
Bioceramics Vol 19 Pts 1 and 2 330 332 877 880, 2007
Journal of Biomedical Materials Research, Mar 15, 1999
Bioceramic specimens have been prepared by incorporating a small amount of silicon (0.4 wt %) int... more Bioceramic specimens have been prepared by incorporating a small amount of silicon (0.4 wt %) into the structure of hydroxyapatite [Ca10(PO4)6(OH)2, HA] via an aqueous precipitation reaction to produce a silicon-substituted hydroxyapatite (Si-HA). The results of chemical analysis confirmed the proposed substitution of the silicon (or silicate) ion for the phosphorus (or phosphate) ion in hydroxyapatite. The Si-HA was produced by first preparing a silicon-substituted apatite (Si-Ap) by a precipitation process. A single-phase Si-HA was obtained by heating/calcining the as-prepared Si-Ap to temperatures above 700 degrees C; no secondary phases, such as tricalcium phosphate (TCP), tetracalcium phosphate (TeCP), or calcium oxide (CaO), were observed by X-ray diffraction analysis. Although the X-ray diffraction patterns of Si-HA and stoichiometric HA appeared to be identical, refinement of the diffraction data revealed some small structural differences between the two materials. The silicon substitution in the HA lattice resulted in a small decrease in the a axis and an increase in the c axis of the unit cell. This substitution also caused a decrease in the number of hydroxyl (OH) groups in the unit cell, which was expected from the proposed substitution mechanism. The incorporation of silicon in the HA lattice resulted in an increase in the distortion of the PO4 tetrahedra, indicated by an increase in the distortion index. Analysis of the Si-HA by Fourier transform infrared (FTIR) spectroscopy indicated that although the amount of silicon incorporated into the HA lattice was small, silicon substitution appeared to affect the FTIR spectra of HA, in particular the P-O vibrational bands. The results demonstrate that phase-pure silicon-substituted hydroxyapatite may be prepared using a simple precipitation technique.
Bioceramics 18 Pts 1 and 2 309 311 635 638, 2006
ABSTRACT
In Boccaccini Ar and Ma Px Tissue Engineering Using Ceramics and Polymers Woodhead Publishing, Jun 2, 2014
J Biomed Mater Res, 1999
Powder mixtures of alpha-Ca(3)(PO(4))(2), Ca(H(2)PO(4))(2), and CaCO(3) were investigated to asse... more Powder mixtures of alpha-Ca(3)(PO(4))(2), Ca(H(2)PO(4))(2), and CaCO(3) were investigated to assess their potential for the precipitation of a carbonated apatite suitable for cement applications from a supersaturated solution. Of particular interest was the requirement of carbon dioxide release during the setting reaction to obtain Ca(9-x)(HPO(4))(1-1.5x) (PO(4))(5-2.5x)(CO(3))(3.5x)(OH)(1 + 1.5x) with a fixed carbonate content. Results indicated that a compromise is necessary with respect to the maximum permissible level of CaCO(3) addition to the powder mixture as against appropriate setting and hardening properties. Cementlike materials with good setting and hardening properties were obtained when alpha-Ca(3)(PO(4))(2) was the main reactant using Ca(H(2)PO(4))(2) and CaCO(3) as additives in relative proportions of <10 wt % corresponding, approximately, to the stability field area (x,lambda) contained within the lines lambda = -1.5x, x = 0.3, and lambda = -1. Desirable workability and setting properties were lost as the parameters x and -lambda increased. Finally, it was also found to be virtually impossible to obtain a predetermined chemical composition for the setting apatite precipitate, since to increase the amount of carbon dioxide released from the initial powder mixture during setting, the solution pH would need to be decreased, and in doing so the nature of the precipitate could be altered to fulfil the thermodynamic conditions of the solubility diagrams of calcium phosphates.
Journal of the European Ceramic Society, 2008
... film deposition techniques are also being investigated including electrophoresis, solgel rou... more ... film deposition techniques are also being investigated including electrophoresis, solgel routes, electrochemical ... industries for many years, but its potential for bioactive coatings on ... vitro studies have shown that these coatings exhibit enhanced bioactivity and biomineralisation ...
Key Engineering Materials, Nov 30, 2001
Mater Res Ibero Am J Mater, 2000
Cylindrical dental implants made of commercially pure titanium were analysed in four different su... more Cylindrical dental implants made of commercially pure titanium were analysed in four different surface finishes: as-machined, Al2O3 blasted with Al2O3 particles, plasma-sprayed with titanium beads and electrolytically coated with hydroxyapatite. Scanning electron ...
Journal of Biomedical Materials Research, Dec 15, 1999
Powder mixtures of alpha-Ca(3)(PO(4))(2), Ca(H(2)PO(4))(2), and CaCO(3) were investigated to asse... more Powder mixtures of alpha-Ca(3)(PO(4))(2), Ca(H(2)PO(4))(2), and CaCO(3) were investigated to assess their potential for the precipitation of a carbonated apatite suitable for cement applications from a supersaturated solution. Of particular interest was the requirement of carbon dioxide release during the setting reaction to obtain Ca(9-x)(HPO(4))(1-1.5x) (PO(4))(5-2.5x)(CO(3))(3.5x)(OH)(1 + 1.5x) with a fixed carbonate content. Results indicated that a compromise is necessary with respect to the maximum permissible level of CaCO(3) addition to the powder mixture as against appropriate setting and hardening properties. Cementlike materials with good setting and hardening properties were obtained when alpha-Ca(3)(PO(4))(2) was the main reactant using Ca(H(2)PO(4))(2) and CaCO(3) as additives in relative proportions of <10 wt % corresponding, approximately, to the stability field area (x,lambda) contained within the lines lambda = -1.5x, x = 0.3, and lambda = -1. Desirable workability and setting properties were lost as the parameters x and -lambda increased. Finally, it was also found to be virtually impossible to obtain a predetermined chemical composition for the setting apatite precipitate, since to increase the amount of carbon dioxide released from the initial powder mixture during setting, the solution pH would need to be decreased, and in doing so the nature of the precipitate could be altered to fulfil the thermodynamic conditions of the solubility diagrams of calcium phosphates.
Journal of Biomedical Materials Research, 2000
Powder mixtures of alpha-Ca(3)(PO(4))(2), Ca(H(2)PO(4))(2), and CaCO(3) were investigated to asse... more Powder mixtures of alpha-Ca(3)(PO(4))(2), Ca(H(2)PO(4))(2), and CaCO(3) were investigated to assess their potential for the precipitation of a carbonated apatite suitable for cement applications from a supersaturated solution. Of particular interest was the requirement of carbon dioxide release during the setting reaction to obtain Ca(9-x)(HPO(4))(1-1.5x) (PO(4))(5-2.5x)(CO(3))(3.5x)(OH)(1 + 1.5x) with a fixed carbonate content. Results indicated that a compromise is necessary with respect to the maximum permissible level of CaCO(3) addition to the powder mixture as against appropriate setting and hardening properties. Cementlike materials with good setting and hardening properties were obtained when alpha-Ca(3)(PO(4))(2) was the main reactant using Ca(H(2)PO(4))(2) and CaCO(3) as additives in relative proportions of <10 wt % corresponding, approximately, to the stability field area (x,lambda) contained within the lines lambda = -1.5x, x = 0.3, and lambda = -1. Desirable workability and setting properties were lost as the parameters x and -lambda increased. Finally, it was also found to be virtually impossible to obtain a predetermined chemical composition for the setting apatite precipitate, since to increase the amount of carbon dioxide released from the initial powder mixture during setting, the solution pH would need to be decreased, and in doing so the nature of the precipitate could be altered to fulfil the thermodynamic conditions of the solubility diagrams of calcium phosphates.
Recent Patents on Engineering, Oct 31, 2007
ABSTRACT
Bioceramics Vol 19 Pts 1 and 2 330 332 503 506, Feb 11, 2007
J Mater Sci Mater Med, 2000
Journal of Materials Science Materials in Medicine 16 1143 1148, Dec 1, 2005
Hydroxyapatite (HA) is important in biomedical applications because of its chemical similarity to... more Hydroxyapatite (HA) is important in biomedical applications because of its chemical similarity to the mineral content of bone and its consequent bioactivity. Silicon substitution into the hydroxyapatite crystal lattice was found to enhance its bioactivity both in vitro and in vivo [1, 2]. However, the mechanism for the enhancement is still not well understood. In this paper, the crystal imperfections introduced by silicon substitution were studied using XRD and Raman spectroscopy. It was found that silicon substitution did not introduce microstrain, but deceased the crystal size in the hk0 direction. Three new vibration modes and peak broadening were observed in Raman spectra following silicon incorporation. The imperfections introduced by silicon substitution may play a role in enhancing bioactivity. A phenomenological relationship between the width of the PO4 v1 peak and crystal size was established.
Journal of Biomedical Materials Research Part a, Jul 1, 2006
J Biomed Mater Res, 1999
Powder mixtures of alpha-Ca(3)(PO(4))(2), Ca(H(2)PO(4))(2), and CaCO(3) were investigated to asse... more Powder mixtures of alpha-Ca(3)(PO(4))(2), Ca(H(2)PO(4))(2), and CaCO(3) were investigated to assess their potential for the precipitation of a carbonated apatite suitable for cement applications from a supersaturated solution. Of particular interest was the requirement of carbon dioxide release during the setting reaction to obtain Ca(9-x)(HPO(4))(1-1.5x) (PO(4))(5-2.5x)(CO(3))(3.5x)(OH)(1 + 1.5x) with a fixed carbonate content. Results indicated that a compromise is necessary with respect to the maximum permissible level of CaCO(3) addition to the powder mixture as against appropriate setting and hardening properties. Cementlike materials with good setting and hardening properties were obtained when alpha-Ca(3)(PO(4))(2) was the main reactant using Ca(H(2)PO(4))(2) and CaCO(3) as additives in relative proportions of <10 wt % corresponding, approximately, to the stability field area (x,lambda) contained within the lines lambda = -1.5x, x = 0.3, and lambda = -1. Desirable workability and setting properties were lost as the parameters x and -lambda increased. Finally, it was also found to be virtually impossible to obtain a predetermined chemical composition for the setting apatite precipitate, since to increase the amount of carbon dioxide released from the initial powder mixture during setting, the solution pH would need to be decreased, and in doing so the nature of the precipitate could be altered to fulfil the thermodynamic conditions of the solubility diagrams of calcium phosphates.
Key Engineering Materials, Dec 31, 2002
ABSTRACT
Bioceramics 16 254 2 111 114, 2004
Bioceramics, 1999
ABSTRACT Four different assays, monitoring different aspects of cellular activity were used to as... more ABSTRACT Four different assays, monitoring different aspects of cellular activity were used to assess the in vitro biocompatibility of three experimental zirconias (ZrO2-A, ZrO2-B and ZrO2-C) with minor chemical modifications. The assays used were Neutral red uptake, MTT, alamarBlue and a live/dead cell stain. No cytotoxic effect was detected in the extracts from the three test zirconia samples using Neutral red uptake and MTT assays. However, a variation in response was observed in cells cultured directly on the surface of three test zirconias using the alamarBlue assay. The three test zirconia substrates showed no toxic effect after 1 and 2 days in culture. After 5 days in direct contact with the experimental zirconias, a significant decrease in cell activity was observed on sample ZrO2-B, which was confirmed by fluorescence microscopy, showing a layer of dead cells (stained by thidium homodimer-1) on the sample surface. The findings from this study indicated that great care is required when selecting assays to assess the biocompatibility of modified materials with regard to the type and sensitivity of the assay and culture conditions.
Bioceramics Vol 19 Pts 1 and 2 330 332 877 880, 2007
Journal of Biomedical Materials Research, Mar 15, 1999
Bioceramic specimens have been prepared by incorporating a small amount of silicon (0.4 wt %) int... more Bioceramic specimens have been prepared by incorporating a small amount of silicon (0.4 wt %) into the structure of hydroxyapatite [Ca10(PO4)6(OH)2, HA] via an aqueous precipitation reaction to produce a silicon-substituted hydroxyapatite (Si-HA). The results of chemical analysis confirmed the proposed substitution of the silicon (or silicate) ion for the phosphorus (or phosphate) ion in hydroxyapatite. The Si-HA was produced by first preparing a silicon-substituted apatite (Si-Ap) by a precipitation process. A single-phase Si-HA was obtained by heating/calcining the as-prepared Si-Ap to temperatures above 700 degrees C; no secondary phases, such as tricalcium phosphate (TCP), tetracalcium phosphate (TeCP), or calcium oxide (CaO), were observed by X-ray diffraction analysis. Although the X-ray diffraction patterns of Si-HA and stoichiometric HA appeared to be identical, refinement of the diffraction data revealed some small structural differences between the two materials. The silicon substitution in the HA lattice resulted in a small decrease in the a axis and an increase in the c axis of the unit cell. This substitution also caused a decrease in the number of hydroxyl (OH) groups in the unit cell, which was expected from the proposed substitution mechanism. The incorporation of silicon in the HA lattice resulted in an increase in the distortion of the PO4 tetrahedra, indicated by an increase in the distortion index. Analysis of the Si-HA by Fourier transform infrared (FTIR) spectroscopy indicated that although the amount of silicon incorporated into the HA lattice was small, silicon substitution appeared to affect the FTIR spectra of HA, in particular the P-O vibrational bands. The results demonstrate that phase-pure silicon-substituted hydroxyapatite may be prepared using a simple precipitation technique.
Bioceramics 18 Pts 1 and 2 309 311 635 638, 2006
ABSTRACT
In Boccaccini Ar and Ma Px Tissue Engineering Using Ceramics and Polymers Woodhead Publishing, Jun 2, 2014
J Biomed Mater Res, 1999
Powder mixtures of alpha-Ca(3)(PO(4))(2), Ca(H(2)PO(4))(2), and CaCO(3) were investigated to asse... more Powder mixtures of alpha-Ca(3)(PO(4))(2), Ca(H(2)PO(4))(2), and CaCO(3) were investigated to assess their potential for the precipitation of a carbonated apatite suitable for cement applications from a supersaturated solution. Of particular interest was the requirement of carbon dioxide release during the setting reaction to obtain Ca(9-x)(HPO(4))(1-1.5x) (PO(4))(5-2.5x)(CO(3))(3.5x)(OH)(1 + 1.5x) with a fixed carbonate content. Results indicated that a compromise is necessary with respect to the maximum permissible level of CaCO(3) addition to the powder mixture as against appropriate setting and hardening properties. Cementlike materials with good setting and hardening properties were obtained when alpha-Ca(3)(PO(4))(2) was the main reactant using Ca(H(2)PO(4))(2) and CaCO(3) as additives in relative proportions of <10 wt % corresponding, approximately, to the stability field area (x,lambda) contained within the lines lambda = -1.5x, x = 0.3, and lambda = -1. Desirable workability and setting properties were lost as the parameters x and -lambda increased. Finally, it was also found to be virtually impossible to obtain a predetermined chemical composition for the setting apatite precipitate, since to increase the amount of carbon dioxide released from the initial powder mixture during setting, the solution pH would need to be decreased, and in doing so the nature of the precipitate could be altered to fulfil the thermodynamic conditions of the solubility diagrams of calcium phosphates.
Journal of the European Ceramic Society, 2008
... film deposition techniques are also being investigated including electrophoresis, solgel rou... more ... film deposition techniques are also being investigated including electrophoresis, solgel routes, electrochemical ... industries for many years, but its potential for bioactive coatings on ... vitro studies have shown that these coatings exhibit enhanced bioactivity and biomineralisation ...
Key Engineering Materials, Nov 30, 2001
Mater Res Ibero Am J Mater, 2000
Cylindrical dental implants made of commercially pure titanium were analysed in four different su... more Cylindrical dental implants made of commercially pure titanium were analysed in four different surface finishes: as-machined, Al2O3 blasted with Al2O3 particles, plasma-sprayed with titanium beads and electrolytically coated with hydroxyapatite. Scanning electron ...
Journal of Biomedical Materials Research, Dec 15, 1999
Powder mixtures of alpha-Ca(3)(PO(4))(2), Ca(H(2)PO(4))(2), and CaCO(3) were investigated to asse... more Powder mixtures of alpha-Ca(3)(PO(4))(2), Ca(H(2)PO(4))(2), and CaCO(3) were investigated to assess their potential for the precipitation of a carbonated apatite suitable for cement applications from a supersaturated solution. Of particular interest was the requirement of carbon dioxide release during the setting reaction to obtain Ca(9-x)(HPO(4))(1-1.5x) (PO(4))(5-2.5x)(CO(3))(3.5x)(OH)(1 + 1.5x) with a fixed carbonate content. Results indicated that a compromise is necessary with respect to the maximum permissible level of CaCO(3) addition to the powder mixture as against appropriate setting and hardening properties. Cementlike materials with good setting and hardening properties were obtained when alpha-Ca(3)(PO(4))(2) was the main reactant using Ca(H(2)PO(4))(2) and CaCO(3) as additives in relative proportions of <10 wt % corresponding, approximately, to the stability field area (x,lambda) contained within the lines lambda = -1.5x, x = 0.3, and lambda = -1. Desirable workability and setting properties were lost as the parameters x and -lambda increased. Finally, it was also found to be virtually impossible to obtain a predetermined chemical composition for the setting apatite precipitate, since to increase the amount of carbon dioxide released from the initial powder mixture during setting, the solution pH would need to be decreased, and in doing so the nature of the precipitate could be altered to fulfil the thermodynamic conditions of the solubility diagrams of calcium phosphates.
Journal of Biomedical Materials Research, 2000
Powder mixtures of alpha-Ca(3)(PO(4))(2), Ca(H(2)PO(4))(2), and CaCO(3) were investigated to asse... more Powder mixtures of alpha-Ca(3)(PO(4))(2), Ca(H(2)PO(4))(2), and CaCO(3) were investigated to assess their potential for the precipitation of a carbonated apatite suitable for cement applications from a supersaturated solution. Of particular interest was the requirement of carbon dioxide release during the setting reaction to obtain Ca(9-x)(HPO(4))(1-1.5x) (PO(4))(5-2.5x)(CO(3))(3.5x)(OH)(1 + 1.5x) with a fixed carbonate content. Results indicated that a compromise is necessary with respect to the maximum permissible level of CaCO(3) addition to the powder mixture as against appropriate setting and hardening properties. Cementlike materials with good setting and hardening properties were obtained when alpha-Ca(3)(PO(4))(2) was the main reactant using Ca(H(2)PO(4))(2) and CaCO(3) as additives in relative proportions of <10 wt % corresponding, approximately, to the stability field area (x,lambda) contained within the lines lambda = -1.5x, x = 0.3, and lambda = -1. Desirable workability and setting properties were lost as the parameters x and -lambda increased. Finally, it was also found to be virtually impossible to obtain a predetermined chemical composition for the setting apatite precipitate, since to increase the amount of carbon dioxide released from the initial powder mixture during setting, the solution pH would need to be decreased, and in doing so the nature of the precipitate could be altered to fulfil the thermodynamic conditions of the solubility diagrams of calcium phosphates.