Calcium-deficient hydroxyapatite-PLGA composites: Mechanical and microstructural investigation

Abstract

The microstructural and mechanical properties of composites composed of calcium deficient hydroxyapatite (CDHAp) and poly(lactide-co-glycolide) (PLGA) have been investigated. The composites were formed by hydrolysis of alpha-tricalcium phosphate (alpha-TCP) to CDHAp in pressed precomposite compacts of alpha-TCP-PLGA-NaCl. The differences in hydrolysis of alpha-TCP-PLGA-NaCl for two compositions of 80:10:10 wt % and 60:20:20 wt %. were monitored by isothermal calorimetry and X-ray diffraction. The microstructural evolution and variance in final composite microstructure after hydrolysis at 37 degrees C, 45 degrees C, and 56 degrees C were examined by scanning electron microscopy. HAp-PLGA composite formed from the alpha-TCP-PLGA-NaCl (80:10:10) precomposites at 37 degrees C developed a tensile strength of 13.3 +/- 0.9 MPa, a flexural strength of 24.8 +/- 1.7 MPa, and Young's modulus of 2.8 +/- 0.3 GPa. These values were 12.00 +/- 0.2 MPa, 36.1 +/- 2.1 MPa, and 5.5 +/- 0.8 GPa for the precomposite composition 60:20:20. All these mechanical properties showed a variation with hydrolysis temperature and composition. The differences in mechanical properties were related to the final microstructures of the composites, which are governed by the morphological changes in the polymer structure at its glass transition temperature and the extent of cement-type formation of CDHAp by hydrolysis of alpha-TCP.

Biocomposites and hybrid biomaterials based on calcium orthophosphates

“…An interesting list of references assigned to the different ways of preparing HA/ poly(α-hydroxyesters) biodegradable composites might be found in publications by Durucan and Brown. 53,393,394 The authors prepared CDHA/PLA and CDHA/PLGA biocomposites using a solvent casting technique with a subsequent hydrolysis of α-TCP to CDHA in aqueous solutions. The presence of both polymers was found to inhibit α-TCP hydrolysis compared with that of single-phase α-TCP alone; what's more, the inhibiting effect of PLA exceeded that of PLGA.…”

Calcium orthophosphate-based biocomposites and hybrid biomaterials

“…More complex carbonated-FA/PLA porous biocomposite scaffolds are also known [323]. An interesting list of references, assigned to the different ways of preparing HA/poly(a-hydroxyesters) biodegradable composites, might be found in publications by Durucan and Brown [49,324,325]. The authors prepared CDHA/PLA and CDHA/PLGA composites by solvent casting technique with a subsequent hydrolysis of a-TCP to CDHA in aqueous solutions.…”

“…The authors prepared CDHA/PLA and CDHA/PLGA composites by solvent casting technique with a subsequent hydrolysis of a-TCP to CDHA in aqueous solutions. The presence of both polymers was found to inhibit a-TCP hydrolysis, if compared with that of single-phase a-TCP; what is more, the inhibiting effect of PLA exceeded that of PLGA [49,324,325]. The physical interactions between calcium orthophosphates and poly(ahydroxyesters) might be easily seen in Fig.…”

Effects of α-DT cement with hydroxypropyl cellulose on bone augmentation within a titanium cap in the rabbit calvarium

“…Previous studies investigating the use of α-TCP in composites with polymers have indicated that it improved the dissolution properties and enhanced bone formation [6][7][8][9][10] . In an attempt to reduce the dissolution rate of α-TCP by coating it with an organic polymer, Kitamura et al 11) found that a hydroxypropyl cellulose (HPC) coating was effective in controlling bioresorption and improving α-TCP workability.…”