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Effect of silver oxide on hydroxy carbonated apatite formation for simulated body fluid soaked calcium phospho silicate system
Materials Today: Proceedings xxx (xxxx) xxx
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Effect of silver oxide on hydroxy carbonated apatite formation for simulated body fluid soaked calcium phospho silicate system B. Naveen Kumar Reddy a,⇑, P. Kiran b a b
Division of Physics, Department of Sciences & Humanities, Vignan Foundation for Science, Technology & Research, Vadlamudi 522 213, Guntur, Andhra Pradesh, India Geetanjali Institute of Science and Technology, Gangavaram, Nellore 524 137, AP, India
a r t i c l e
i n f o
Article history: Received 18 July 2019 Received in revised form 27 September 2019 Accepted 17 October 2019 Available online xxxx Keywords: Silver oxide HCA SBF XRD SEM
a b s t r a c t In the present work, we have synthesized the 58SiO2-(38-x) CaO-xAg2O-4P2O5 glasses using sol-gel method and these glasses were treated for 7 days in simulated body fluid (SBF) solution. The structural properties of SBF treated samples were studied using characterization techniques such as X-ray diffraction (XRD) technique and scanning electron microscopy (SEM). Dissolution studies also have been studied for SBF treated samples. The XRD pattern indicates that crystalline nature increases with increase in Ag2O for synthesizing samples. The formed Hydroxy Carbonated Apatite (HCA) particles were identified by XRD and EDX analysis. Dissolution studies confirmed that HCA formation decreased with Ag2O content. Finally, it was confirmed that Ag2O content resists the HCA formation. Ó 2019 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the National conference on Functionality of Advanced Materials.
1. Introduction Bioactive glasses are the most essential materials in biomedical applications like tissue engineering [1–4]. It has been reported in the literature that the bonding between the bone and glass material is the precipitation formation (apatite layer) on the glass surface. In body environment, in the case of exact reaction time, the nucleation and growth of hydroxyapatite (HA) layer should be fast on the bioglass surface for growing potential of tissue engineering applications [5–7]. The glass synthesizes methods such as sol-gel and meltquenching, etc. would affect the HA growth rate considerably [8]. To improve bioactive glass properties, among all these methods the sol-gel is the suitable method to synthesize glasses at lower temperature condition to achieve the glassy material in powder form with uniform microstructure [9–30]. Mahmad Mami et al. [8], stated that melt quenched 47S SiO2CaO-P2O5-Na2O bio-active glass forms HCA after 30 soaking days in SBF. The sol-gel based calcium phosphosilicate glasses mainly depends upon CaO quantity and with the lower P2O5 and higher SiO2 quantities, these glasses have shown good bioactivity. The amorphous nature of HA is due to the presence of greater CaO ⇑ Corresponding author. E-mail address: [email protected] (B. Naveen Kumar Reddy).
quantity with SBF treatment [30]. It has been reported in the recent studies that the lower concentration of barium composition acts as a muscle stimulant and is noticed in human teeth [31,32]. The chemical composition absorbs the bone stimulator ions to advance the bone stimulating property in the human body. However, very few researchers have been reported on the silver doped phosphosilicate glasses with the calcium oxide substitution for HCA development. In addition to this, the studies also revealed the effect of Ag2O composition on the HCA forming ability in phosphosilicate bioactive glass system. SiO2, and P2O5 present in glass act as glass network formers. P2O5 acts as network modifier which is more favorable for dissolution of SBF in lower P2O5 compositions. Glass exhibits crystalline nature if SiO2 composition is greater than 58 mol%. Due to this reason, composition with 58 mol% has been selected for the present study. CaO is required for silica gel layer formation in SBF soaked glasses for the dissolution process. Higher CaO in the presence of very low P2O5 content is favored for HCA formation in SBF treatment. Hence, 38 mol% of CaO was selected. The HCA formation on the glass surface in the dissolution process is dependent on the process of glass synthesis such as melt quenching and sol-gel technique, etc. The melt quenching technique induces more density and sol-gel technique produces highly porous structures. The porous structure is more favorable for dissolution of SBF treated samples and also requires very less time (less
https://doi.org/10.1016/j.matpr.2019.10.097 2214-7853/Ó 2019 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the National conference on Functionality of Advanced Materials.
Please cite this article as: B. Naveen Kumar Reddy and P. Kiran, Effect of silver oxide on hydroxy carbonated apatite formation for simulated body fluid soaked calcium phospho silicate system, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.10.097
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B. Naveen Kumar Reddy, P. Kiran / Materials Today: Proceedings xxx (xxxx) xxx
than a week) to achieve HCA form on the glass surface when compared to melt quenching. Therefore, in the present study 7 days, time was taken for dissolution studies. In this work, we have mainly concentrated on the preparation of [58SiO2-(38-x)CaO-xAg2O-4P2O5 (x = 5, 10, 15 and 20 mol%) bioactive glass system using a sol-gel method. These synthesized samples are treated with SBF for 7 days. Structural properties studied using XRD technique, SEM for synthesized and SBF treated glass samples. Dissolution properties were studied for 7 days of SBF soaked samples.
2. Materials and methods 2.1. Synthesis and characterization The bioactive glass system 58SiO2-(38-x)CaO-xAg2O-4P2O5 (x = 5, 10, 15 and 20 mol%) synthesized using sol-gel method and the samples are labeled as A1, A2, A3, and A4 respectively. The precursors used for synthesis purpose were Si(OC2H5)4, (C2H5O)3PO, calcium nitrate tetrahydrate Ca(NO3)24H2O, AgNO3, HNO3, and water (H2O) is selected on the basis of ratio of [(mol of H2O)/(mol of Si(OC2H5)4 + mol of (C2H5O)3PO)) = 10] and [(mol of HNO3)/(mol of Si(OC2H5)4 + mol of (C2H5O)3PO)] = 0.05], respectively. The precursors Si(OC2H5)4, was mixed with H2O and HNO3 and the solution is stirred for 1 h. After one hour, the precursors such as (C2H5O)3PO, calcium nitrate [Ca(NO3)2], and AgNO3 were added subsequently in continuous stirring process. To acquire the sols, Teflon beakers were used. After that, the beakers were sealed and kept inside hot air oven by maintaining a constant temperature of 60 °C for 72 h duration and achieved aged gel. The aged gels were dried at a temperature of 130 °C for 4 h and made into powders. The powder samples were subjected to heat up to 700 °C at the rate of 5 °C/min. Finally, the samples were stabilized at that temperature for 4 h and achieved samples in the powder form. Using these powders, the sample pellets were prepared [27]. The X-ray diffractometer (JOEL, JDX-8P X-Japan) with CuKa radiation was used to analyze the amorphous and crystalline glass samples within the diffraction angle range 20°–80°. To study the HCA properties SBF solution has been considered as a physiological environment for the glass samples analogous to human blood plasma. By dissolving reagents such as KH2PO4, CaCl2, MgCl26H2O, NaHCO3, KCl and NaCl in the presence of de-ionized water while maintaining pH value as 7.4 using tris-buffer by maintaining a temperature at 37 °C. The pH values of the SBF treated and untreated glass samples were measured with a pH meter (Eutech, pH 510, India). Scanning electron microscope (JOEL-JSM-6380LA, Japan) was used to observe the surface morphology of the glass samples and the elements were identified by EDX analyzer using auto fine sputter coater (JFC 1600 JOEL, Japan) with gold sputtering. The SEM/EDX (JOEL, JEM 2100, Japan) was used to confirm the presence of HCA layer on to the glass samples.
3. Results and discussion 3.1. XRD analysis The XRD patterns of synthesized silver doped calcium phospho silicate samples are as shown in Fig. 1(a). All synthesized glass samples have a broad hump between 20 and 30° with some sharp intense peaks. It provides evidence to prove the ceramic nature of all synthesized samples. From XRD analysis it has been noticed that as the Ag2O composition is increasing from 5 to 20 mol % the peak intensities of glass samples are decreases.
The major diffraction peak identified at an angle of 2h = 32° was (hkl) = (2 1 1) confirmed using standard JCPDS file (01-074-0565). During the chemical reaction process, Ca2+ ions dissolve in SBF solution and it leads to the formation of silanol (Si-OH) group. The silica gel layer formation on the glass surface occurs due to the poly-condensation process. Phosphate and calcium ions would migrate in the silica gel layer and it forms the apatite layer on the surface of the glass sample. This apatite layer mainly reacts with calcium, phosphate and hydroxyl ions in SBF solution and forms an amorphous layer on the surface of the sample. HA crystalline intensities are observed increasing order with a decrease in Ag2O from 20 to 5 mol% [for (2 1 1) plane] [Fig. 1(b)]. The Ca2+ ions dissolution in SBF solution possesses a major role in the formation of HA layer. The CaO compositional quantity is increased from sample A4 to A1. Due to this, Ca2+ ions dissolution in SBF solution increases from sample A4 to A1, in same manner HA crystalline intensity also increases from sample A4 to A1. From all these studies, it has been noticed that both the conditions, explicitly such as less Ag2O content and increase in CaO content favors the apatite layer formation. 3.2. Surface morphology SEM images of synthesized, SBF treated samples are as shown in Fig. 2. It has been observed from the SEM images that all synthesized samples [Fig. 2 (a, c, e, and g)] have not shown spherical shaped particles and corresponding EDX analysis exhibited the presence of Si, Ca, P and O elements. The SEM images [Fig. 2 (b, d, f, and h)] of the SBF treated samples have shown spherical shaped particles on the sample surface. By identifying the elements such as Ca, P, C and O the EDX analysis confirmed the HCA layer formation on the surface of the glass surface. The local field strength of glass sample mainly depends on the network modifier Ag2O. The local field strength decreases due to a decrease in Ag2O and also increases the dissolution of glass sample in SBF. Ag2O content is increasing from sample A4 to A2. Because of this reason, the surface morphology is changed from plane to flake structure. The sample A1 is having a lesser amount of Ag2O when compared to A2, and it causes more dissolution and leads to more HCA formation. 3.3. pH assessment, dissolution, and weight loss studies The calcium ions dissolve into SBF during the dissolution process and it leads to the formation of silanol groups (Si-OH) on to the sample surface. The silica gel layer formed on the surface of the sample due to the polycondensation process. The Ca2+ and PO34 ion is a leach on to the silica gel layer and forms the calcium phosphate layer formation on the sample surface. To form the crystalline HCA the OH , PO34 , Ca2+ and carbonate ions are incorporated into apatite layer. The pH values of the SBF solution have been measured for synthesized samples before and after soaking in SBF solution for 7 days. The pH values are increased to 10 h duration as shown in Fig. 3 is due to the fast release of Ca2+ ions into SBF solution forms silanol groups [32]. From these studies, we have observed that after 10 h of duration the pH values of SBF solution were closely stabilized. Weight loss for SBF treated A1, A2, A3 and A4 samples observed as 58%, 48%, 32%, and 24% respectively. All synthesized samples have very less (4 mol %) P2O5 quantity. The HA formation mainly depends on CaO composition. The Ca2+ ions dissolution in SBF solution for the samples are in the order of A1 > A2 > A3 > A4 and HA layer formation were in the reducing order as shown in Fig. 3. HCA formation also mainly depends on CaO. Due to this, the weight loss noticed is in the order of A4 > A3 > A2 > A1 [21]. Ag2+ has more ionic radius compared to Ca2+. The field strength decreases for a
Please cite this article as: B. Naveen Kumar Reddy and P. Kiran, Effect of silver oxide on hydroxy carbonated apatite formation for simulated body fluid soaked calcium phospho silicate system, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.10.097
B. Naveen Kumar Reddy, P. Kiran / Materials Today: Proceedings xxx (xxxx) xxx
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Fig. 1. XRD pattern of SN samples (a) before and (b) after soaking in SBF.
Fig. 2. (a), (c), (e) and (g) represents SEM surface morphology images (b), (d), (f) and (h) represents EDX images of synthesised and SBF treated samples A1, A2, A3 and A4 respectively.
Please cite this article as: B. Naveen Kumar Reddy and P. Kiran, Effect of silver oxide on hydroxy carbonated apatite formation for simulated body fluid soaked calcium phospho silicate system, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.10.097
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Geetanjali Institute of Science and Technology, Gangavaram, Nellore, Andhra Pradesh, India. References
Fig. 3. pH variation of SBF solution concerning glass soaking time.
decrease in Ag2O content and increases the dissolution of SBF treated sample. Sample A4 has less Ag+ ions when compared to A1 and it increases the Ca2+, PO34 ion dissolution in SBF. The sample A1 consists of lower number Ag+ ions and more Ca2+ ions compared to sample A4 and it decreases the local field strength. Because of this reason the PO34 ions dissolution is increasing from sample A4 to A1. From all these observations, it can be resolved that HCA formation ability is less for lower Ag2O composition. 4. Summary SiO2-Ag2O-CaO-P2O5 glasses have been prepared by a conventional technique such as sol-gel method. From XRD analysis it is cleared that the crystalline nature of the synthesized glasses increases with increase in Ag2O content. Based on Ag2O mol %, different glasses exhibit different properties before and after SBF treatment. High CaO concentrated glasses can release more Ca2+ ions into SBF solution in the dissolution process and it increases the calcium phosphate (Apatite) layer formation on the glass surface. It is also observed from these studies that HCA formation was greatly influenced by the CaO and Ag2O mol%. Acknowledgments The authors are thankful for Division of Physics, Department of Sciences & Humanities, Vignan Foundation for Science, Technology & Research, Vadlamudi, Guntur, Andhra Pradesh, India and also
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Please cite this article as: B. Naveen Kumar Reddy and P. Kiran, Effect of silver oxide on hydroxy carbonated apatite formation for simulated body fluid soaked calcium phospho silicate system, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.10.097
Contents lists available at ScienceDirect
Materials Today: Proceedings journal homepage: www.elsevier.com/locate/matpr
Effect of silver oxide on hydroxy carbonated apatite formation for simulated body fluid soaked calcium phospho silicate system B. Naveen Kumar Reddy a,⇑, P. Kiran b a b
Division of Physics, Department of Sciences & Humanities, Vignan Foundation for Science, Technology & Research, Vadlamudi 522 213, Guntur, Andhra Pradesh, India Geetanjali Institute of Science and Technology, Gangavaram, Nellore 524 137, AP, India
a r t i c l e
i n f o
Article history: Received 18 July 2019 Received in revised form 27 September 2019 Accepted 17 October 2019 Available online xxxx Keywords: Silver oxide HCA SBF XRD SEM
a b s t r a c t In the present work, we have synthesized the 58SiO2-(38-x) CaO-xAg2O-4P2O5 glasses using sol-gel method and these glasses were treated for 7 days in simulated body fluid (SBF) solution. The structural properties of SBF treated samples were studied using characterization techniques such as X-ray diffraction (XRD) technique and scanning electron microscopy (SEM). Dissolution studies also have been studied for SBF treated samples. The XRD pattern indicates that crystalline nature increases with increase in Ag2O for synthesizing samples. The formed Hydroxy Carbonated Apatite (HCA) particles were identified by XRD and EDX analysis. Dissolution studies confirmed that HCA formation decreased with Ag2O content. Finally, it was confirmed that Ag2O content resists the HCA formation. Ó 2019 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the National conference on Functionality of Advanced Materials.
1. Introduction Bioactive glasses are the most essential materials in biomedical applications like tissue engineering [1–4]. It has been reported in the literature that the bonding between the bone and glass material is the precipitation formation (apatite layer) on the glass surface. In body environment, in the case of exact reaction time, the nucleation and growth of hydroxyapatite (HA) layer should be fast on the bioglass surface for growing potential of tissue engineering applications [5–7]. The glass synthesizes methods such as sol-gel and meltquenching, etc. would affect the HA growth rate considerably [8]. To improve bioactive glass properties, among all these methods the sol-gel is the suitable method to synthesize glasses at lower temperature condition to achieve the glassy material in powder form with uniform microstructure [9–30]. Mahmad Mami et al. [8], stated that melt quenched 47S SiO2CaO-P2O5-Na2O bio-active glass forms HCA after 30 soaking days in SBF. The sol-gel based calcium phosphosilicate glasses mainly depends upon CaO quantity and with the lower P2O5 and higher SiO2 quantities, these glasses have shown good bioactivity. The amorphous nature of HA is due to the presence of greater CaO ⇑ Corresponding author. E-mail address: [email protected] (B. Naveen Kumar Reddy).
quantity with SBF treatment [30]. It has been reported in the recent studies that the lower concentration of barium composition acts as a muscle stimulant and is noticed in human teeth [31,32]. The chemical composition absorbs the bone stimulator ions to advance the bone stimulating property in the human body. However, very few researchers have been reported on the silver doped phosphosilicate glasses with the calcium oxide substitution for HCA development. In addition to this, the studies also revealed the effect of Ag2O composition on the HCA forming ability in phosphosilicate bioactive glass system. SiO2, and P2O5 present in glass act as glass network formers. P2O5 acts as network modifier which is more favorable for dissolution of SBF in lower P2O5 compositions. Glass exhibits crystalline nature if SiO2 composition is greater than 58 mol%. Due to this reason, composition with 58 mol% has been selected for the present study. CaO is required for silica gel layer formation in SBF soaked glasses for the dissolution process. Higher CaO in the presence of very low P2O5 content is favored for HCA formation in SBF treatment. Hence, 38 mol% of CaO was selected. The HCA formation on the glass surface in the dissolution process is dependent on the process of glass synthesis such as melt quenching and sol-gel technique, etc. The melt quenching technique induces more density and sol-gel technique produces highly porous structures. The porous structure is more favorable for dissolution of SBF treated samples and also requires very less time (less
https://doi.org/10.1016/j.matpr.2019.10.097 2214-7853/Ó 2019 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the National conference on Functionality of Advanced Materials.
Please cite this article as: B. Naveen Kumar Reddy and P. Kiran, Effect of silver oxide on hydroxy carbonated apatite formation for simulated body fluid soaked calcium phospho silicate system, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.10.097
2
B. Naveen Kumar Reddy, P. Kiran / Materials Today: Proceedings xxx (xxxx) xxx
than a week) to achieve HCA form on the glass surface when compared to melt quenching. Therefore, in the present study 7 days, time was taken for dissolution studies. In this work, we have mainly concentrated on the preparation of [58SiO2-(38-x)CaO-xAg2O-4P2O5 (x = 5, 10, 15 and 20 mol%) bioactive glass system using a sol-gel method. These synthesized samples are treated with SBF for 7 days. Structural properties studied using XRD technique, SEM for synthesized and SBF treated glass samples. Dissolution properties were studied for 7 days of SBF soaked samples.
2. Materials and methods 2.1. Synthesis and characterization The bioactive glass system 58SiO2-(38-x)CaO-xAg2O-4P2O5 (x = 5, 10, 15 and 20 mol%) synthesized using sol-gel method and the samples are labeled as A1, A2, A3, and A4 respectively. The precursors used for synthesis purpose were Si(OC2H5)4, (C2H5O)3PO, calcium nitrate tetrahydrate Ca(NO3)24H2O, AgNO3, HNO3, and water (H2O) is selected on the basis of ratio of [(mol of H2O)/(mol of Si(OC2H5)4 + mol of (C2H5O)3PO)) = 10] and [(mol of HNO3)/(mol of Si(OC2H5)4 + mol of (C2H5O)3PO)] = 0.05], respectively. The precursors Si(OC2H5)4, was mixed with H2O and HNO3 and the solution is stirred for 1 h. After one hour, the precursors such as (C2H5O)3PO, calcium nitrate [Ca(NO3)2], and AgNO3 were added subsequently in continuous stirring process. To acquire the sols, Teflon beakers were used. After that, the beakers were sealed and kept inside hot air oven by maintaining a constant temperature of 60 °C for 72 h duration and achieved aged gel. The aged gels were dried at a temperature of 130 °C for 4 h and made into powders. The powder samples were subjected to heat up to 700 °C at the rate of 5 °C/min. Finally, the samples were stabilized at that temperature for 4 h and achieved samples in the powder form. Using these powders, the sample pellets were prepared [27]. The X-ray diffractometer (JOEL, JDX-8P X-Japan) with CuKa radiation was used to analyze the amorphous and crystalline glass samples within the diffraction angle range 20°–80°. To study the HCA properties SBF solution has been considered as a physiological environment for the glass samples analogous to human blood plasma. By dissolving reagents such as KH2PO4, CaCl2, MgCl26H2O, NaHCO3, KCl and NaCl in the presence of de-ionized water while maintaining pH value as 7.4 using tris-buffer by maintaining a temperature at 37 °C. The pH values of the SBF treated and untreated glass samples were measured with a pH meter (Eutech, pH 510, India). Scanning electron microscope (JOEL-JSM-6380LA, Japan) was used to observe the surface morphology of the glass samples and the elements were identified by EDX analyzer using auto fine sputter coater (JFC 1600 JOEL, Japan) with gold sputtering. The SEM/EDX (JOEL, JEM 2100, Japan) was used to confirm the presence of HCA layer on to the glass samples.
3. Results and discussion 3.1. XRD analysis The XRD patterns of synthesized silver doped calcium phospho silicate samples are as shown in Fig. 1(a). All synthesized glass samples have a broad hump between 20 and 30° with some sharp intense peaks. It provides evidence to prove the ceramic nature of all synthesized samples. From XRD analysis it has been noticed that as the Ag2O composition is increasing from 5 to 20 mol % the peak intensities of glass samples are decreases.
The major diffraction peak identified at an angle of 2h = 32° was (hkl) = (2 1 1) confirmed using standard JCPDS file (01-074-0565). During the chemical reaction process, Ca2+ ions dissolve in SBF solution and it leads to the formation of silanol (Si-OH) group. The silica gel layer formation on the glass surface occurs due to the poly-condensation process. Phosphate and calcium ions would migrate in the silica gel layer and it forms the apatite layer on the surface of the glass sample. This apatite layer mainly reacts with calcium, phosphate and hydroxyl ions in SBF solution and forms an amorphous layer on the surface of the sample. HA crystalline intensities are observed increasing order with a decrease in Ag2O from 20 to 5 mol% [for (2 1 1) plane] [Fig. 1(b)]. The Ca2+ ions dissolution in SBF solution possesses a major role in the formation of HA layer. The CaO compositional quantity is increased from sample A4 to A1. Due to this, Ca2+ ions dissolution in SBF solution increases from sample A4 to A1, in same manner HA crystalline intensity also increases from sample A4 to A1. From all these studies, it has been noticed that both the conditions, explicitly such as less Ag2O content and increase in CaO content favors the apatite layer formation. 3.2. Surface morphology SEM images of synthesized, SBF treated samples are as shown in Fig. 2. It has been observed from the SEM images that all synthesized samples [Fig. 2 (a, c, e, and g)] have not shown spherical shaped particles and corresponding EDX analysis exhibited the presence of Si, Ca, P and O elements. The SEM images [Fig. 2 (b, d, f, and h)] of the SBF treated samples have shown spherical shaped particles on the sample surface. By identifying the elements such as Ca, P, C and O the EDX analysis confirmed the HCA layer formation on the surface of the glass surface. The local field strength of glass sample mainly depends on the network modifier Ag2O. The local field strength decreases due to a decrease in Ag2O and also increases the dissolution of glass sample in SBF. Ag2O content is increasing from sample A4 to A2. Because of this reason, the surface morphology is changed from plane to flake structure. The sample A1 is having a lesser amount of Ag2O when compared to A2, and it causes more dissolution and leads to more HCA formation. 3.3. pH assessment, dissolution, and weight loss studies The calcium ions dissolve into SBF during the dissolution process and it leads to the formation of silanol groups (Si-OH) on to the sample surface. The silica gel layer formed on the surface of the sample due to the polycondensation process. The Ca2+ and PO34 ion is a leach on to the silica gel layer and forms the calcium phosphate layer formation on the sample surface. To form the crystalline HCA the OH , PO34 , Ca2+ and carbonate ions are incorporated into apatite layer. The pH values of the SBF solution have been measured for synthesized samples before and after soaking in SBF solution for 7 days. The pH values are increased to 10 h duration as shown in Fig. 3 is due to the fast release of Ca2+ ions into SBF solution forms silanol groups [32]. From these studies, we have observed that after 10 h of duration the pH values of SBF solution were closely stabilized. Weight loss for SBF treated A1, A2, A3 and A4 samples observed as 58%, 48%, 32%, and 24% respectively. All synthesized samples have very less (4 mol %) P2O5 quantity. The HA formation mainly depends on CaO composition. The Ca2+ ions dissolution in SBF solution for the samples are in the order of A1 > A2 > A3 > A4 and HA layer formation were in the reducing order as shown in Fig. 3. HCA formation also mainly depends on CaO. Due to this, the weight loss noticed is in the order of A4 > A3 > A2 > A1 [21]. Ag2+ has more ionic radius compared to Ca2+. The field strength decreases for a
Please cite this article as: B. Naveen Kumar Reddy and P. Kiran, Effect of silver oxide on hydroxy carbonated apatite formation for simulated body fluid soaked calcium phospho silicate system, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.10.097
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Fig. 1. XRD pattern of SN samples (a) before and (b) after soaking in SBF.
Fig. 2. (a), (c), (e) and (g) represents SEM surface morphology images (b), (d), (f) and (h) represents EDX images of synthesised and SBF treated samples A1, A2, A3 and A4 respectively.
Please cite this article as: B. Naveen Kumar Reddy and P. Kiran, Effect of silver oxide on hydroxy carbonated apatite formation for simulated body fluid soaked calcium phospho silicate system, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.10.097
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B. Naveen Kumar Reddy, P. Kiran / Materials Today: Proceedings xxx (xxxx) xxx
Geetanjali Institute of Science and Technology, Gangavaram, Nellore, Andhra Pradesh, India. References
Fig. 3. pH variation of SBF solution concerning glass soaking time.
decrease in Ag2O content and increases the dissolution of SBF treated sample. Sample A4 has less Ag+ ions when compared to A1 and it increases the Ca2+, PO34 ion dissolution in SBF. The sample A1 consists of lower number Ag+ ions and more Ca2+ ions compared to sample A4 and it decreases the local field strength. Because of this reason the PO34 ions dissolution is increasing from sample A4 to A1. From all these observations, it can be resolved that HCA formation ability is less for lower Ag2O composition. 4. Summary SiO2-Ag2O-CaO-P2O5 glasses have been prepared by a conventional technique such as sol-gel method. From XRD analysis it is cleared that the crystalline nature of the synthesized glasses increases with increase in Ag2O content. Based on Ag2O mol %, different glasses exhibit different properties before and after SBF treatment. High CaO concentrated glasses can release more Ca2+ ions into SBF solution in the dissolution process and it increases the calcium phosphate (Apatite) layer formation on the glass surface. It is also observed from these studies that HCA formation was greatly influenced by the CaO and Ag2O mol%. Acknowledgments The authors are thankful for Division of Physics, Department of Sciences & Humanities, Vignan Foundation for Science, Technology & Research, Vadlamudi, Guntur, Andhra Pradesh, India and also
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Please cite this article as: B. Naveen Kumar Reddy and P. Kiran, Effect of silver oxide on hydroxy carbonated apatite formation for simulated body fluid soaked calcium phospho silicate system, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.10.097