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Bioactive alginate/carrageenan/calcium silicate porous scaffolds for bone tissue engineering
(2021-03-01)
Sathain, Ammara
;
Monvisade, Pathavuth
;
Siriphannon, Punnama
Porous bioactive alginate/carrageenan/calcium silicate scaffolds for bone tissue engineering were fabricated. The scaffolds were prepared by dispersing the synthesized calcium silicate in an aqueous solution of alginate and carrageenan at 90 °C. The scaffolds were shaped by freeze-drying and further crosslinked by 0.5, 1.0 and 1.5 M CaCl<inf>2</inf> for 60 and 120 min. The scaffolds crosslinked by 1.5 M CaCl<inf>2</inf> for 120 min achieved the highest in vitro dimension stability. The formation of hydroxyapatite crystals was observed on the scaffolds surface after soaking in simulated body fluid (SBF) at 37 °C for 7–28 days, indicating in vitro bioactivity of the scaffolds. The presence of calcium silicate could enhance not only the bioactivity, but also the mechanical properties of the scaffolds comparable to the cancellous bone. Moreover, the dimension and mechanical properties of the wet scaffolds could recover to the original after four cycles of mechanical testing at 50 % strain. The scaffolds were nontoxic to human living cells, in which the in vitro drug release behavior of the scaffold using diclofenac as a model drug was suitable for the treatment of acute inflammation after surgery. Therefore, these scaffolds were considered to be the candidate materials for bone replacement.
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In situ ring-opening polymerization of hydroxyapatite/poly(ethylene adipate)-co-(ethylene terephthalate) biomimetic composites
(2013-02-01)
Siriphannon, Punnama
;
Monvisade, Pathavuth
Hydroxyapatite/poly(ethylene adipate)-co-poly(ethylene terephthalate) biomaterials (HAp/PEA-co-PET) have been prepared by ring opening polymerization (ROP) of cyclic oligo(ethylene adipate)-co-oligo(ethylene terephthalate) (C-OEA-co-C-OET) in the porous hydroxyapatite (HAp) scaffolds at 250 °C for 24 h under vacuum. The content of ROP-PEA-co-PET in the HAp/PEA-co-PET composite was about 20 wt% with the values of number average molecular weight (Mn) and weight average molecular weight (MW) of 3380 and 7160 g/mol, respectively. Compressive strength and modulus of the HAp/PEA-co-PET composites were about 29 and 246 MPa, respectively. These mechanical properties were higher than those of the porous HAp templates and natural cancellous bone. In vitro bioactivity of the HAp/PEA-co-PET composites was studied by soaking in simulated body fluid (SBF) under the flowing system at the rate of 130 mL/day for 7, 14, 21 and 28 days. The formation of hydroxyapatite nanocrystals was observed on the composite surfaces through the consumption of calcium and phosphorus from the SBF solution, indicating the bioactivity of these HAp/PEA-co-PET composites. These results indicated the competency of HAp/PEA-co-PET composites for biomedical applications. © Indian Academy of Sciences.
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Poly(ethylene terephthalate)/hydroxyapatite biomaterials: Preparation, characterization, and in vitro bioactivity
(2009-02-01)
Siriphannon, Punnama
;
Monvisade, Pathavuth
Poly(ethylene terephthalate)/hydroxyapatite (PET/HAp) composites were prepared by mixing HAp powder with a mixture solution of cyclic oligo(ethylene terephthalate) (C-OET) and dibutyl tinoxide catalyst in dichrolomethane, and then shaping the precomposites in cylindrical pellets. The C-OET in the precomposites was ring-opening polymerized (ROP) to PET under vacuum at 250°C for 24 h. The PET/HAp composites were formulated with HAp to PET ratios of 60:40 (H6P4) and 50:50 (H5P5). The ROP-PET in the composites was present as a thin-layer coating on the HAp grains and evenly distributed throughout the samples. Compressive strength of the PET/HAp composites was significantly increased from 8 MPa of the H10P0 to 17 and 29 MPa for H6P4 and H5P5, respectively. In vitro bioactivity of the PET/HAp composites was studied by soaking in simulated body fluid (SBF) at 36.5°C for 7-28 days. After prolonged soaking, the HAp nanocrystals precipitated from the SBF solution and formed as a layer of globular aggregates, coated on the composite surfaces. The H6P4 composite showed faster formation rate of nano-HAp than the H5P5 composite, indicating that the bioactivity of PET/HAp composites depended on the amount of HAp. © 2008 Wiley Periodicals, Inc.
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Preparation and characterization of hydroxyapatite/poly(ethylene adipate) hybrid composites
(2008-06-01)
Siriphannon, Punnama
;
Monvisade, Pathavuth
Hydroxyapatite/poly(ethylene adipate) (HAp/PEA) composites were prepared by in situ ring-opening polymerization of cyclic oligo(ethylene adipate) (C-OEA) within the porous HAp templates. HAp was firstly prepared by a co-precipitation method using calcium hydroxide and phosphoric acid and then shaped as a rectangular porous template. PEA precursor was synthesized by bulk polymerization of dimethyl adipate and ethylene glycol in the presence of tetraisopropyl orthotitanate. C-OEA was obtained by cyclo-depolymerization of the PEA precursor under high dilution condition using dibutyl tinoxide as a catalyst. The HAp/PEA composites were prepared by immersing the porous HAp templates in the mixture solution of C-OEA and dibutyl tinoxide catalyst overnight and ring-opening polymerizing at 180, 200 and 220°C for 24 h. The ring-opening polymerized PEA formed as a thin film coating on the surface of porous HAp template. The HAp/PEA composites contained PEA in the range of 20-26 wt%. The weight-average molecular weights of ring-opening polymerized PEA were in the range of 3800-4450 g/mol. Compressive strength of the HAp/PEA composite was significantly increased from 25 MPa in the porous HAp template to 140 MPa in the composite. © 2008 VSP.
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Preparation and characterization of hydroxyapatite/poly(ethylene glutarate) biomaterials
(2007-05-01)
Siriphannon, Punnama
;
Monvisade, Pathavuth
;
Jinawath, Supatra
;
Hemachandra, Khemchai
Hydroxyapatite/poly(ethylene glutarate) (HAp/PEG) biomaterial composites were prepared by ring-opening polymerization (ROP) of cyclic oligo(ethylene glutarate) (C-PEG) in porous HAp scaffolds. The HAp/C-PEG pre-composites were prepared by immersing the porous HAp scaffolds in the mixture solution of C-PEG and dibutyl tin-oxide catalyst overnight and polymerizing at 200°C for 24, 48, and 72 h under vacuum. The successful ROP of C-PEG in the porous HAp scaffolds was corroborated by the signals of hydroxyl end-group of PEG shown in the <sup>1</sup>H NMR spectrum of the ROP-products extracted from the composites. PEG in the composites was present as a thin layer coating on the HAp grains and was evenly distributed throughout the samples. The PEG content was about 13-16 wt % and decreased with increasing polymerization time. Its molecular weight (M̄<inf>w</inf>, weight average) measured by gel permeation chromatography was in the range of 4300-6800 g/mol. Compressive strength of the HAp/PEG composites was significantly increased from 3 MPa of the porous HAp scaffold to 11-15 MPa, depending on the PEG content in the composites. In vitro bioactivity of the HAp/ PEG composites was studied by soaking in simulated body fluid (SBF) at 36.5°C for 7-28 days. After prolonged soaking, the HAp nanocrystals precipitated from the SBF solution and formed as a layer of globular aggregates, coated on the composite surfaces. This result suggested that the HAp/PEG composite was a bioactive material. © 2006 Wiley Periodicals, Inc.

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