Synthesis, structural and mechanical properties of porous polymeric scaffolds for bone tissue regeneration based on neat poly(ε‐caprolactone) and its composites with calcium carbonate

Abstract

The aim of the present study was to develop new materials which could be applicable as bone substitutes or be used in bone tissue engineering. Two types of porous scaffolds based on poly(ecaprolactone) (PCL) were investigated. Type 1 scaffolds were prepared by solvent casting/particulate leaching technique, using NaCl with the grain size 250-500 mm as a porogen. In the case of Type 2 scaffolds, the biodegradable polymer was blended with calcium carbonate, which, in contrast to NaCl, is not leached out from the product during manufacture, either in the form of calcite powder or aragonite (needle-like crystals). Influence of manufacturing technique and initial substrate composition on product properties was investigated. The tests involved porosity measurements, structure analysis by optical and scanning electron microscopy and mechanical studies (determination of compression strength and modulus). The results indicate the important role of the phase exchange process in the formation of micropores. In this process PCL precipitated from its acetone solution in the presence of water creating microporous three-dimensional polymer structures. The Type 1 scaffolds possessed both micropores and macropores. Good interconnectivity between the pores was observed for samples of the initial porogen content higher than 33%. Microporous samples containing inorganic filler have lower porosity and higher compression strength. For Type 2 scaffolds the shape of filler particles has an important influence on mechanical properties-replacing powder with needle-like crystals (in the same weight amount) results in a three-to five-fold increase in compression modulus. #

Preparation of porous apatite granules from calcium phosphate cement

“…The use of NaCl as the porogen to achieve such significant pore sizes in biomaterials was rather seen in the production of porous scaffolds of polymeric origin, such as polycaprolactone [40], gelatin [41], polyurethane [42,43], silk fibroin [44], polylactic-co-glycolic acid (PLGA) [45,46], poly-L-lactic acid (PLLA) [47,48], polypropylene fumarate [49], copoly-L-lactide-epsilon-caprolactone [50], and polymethylmetacrylate [51].…”

Formation of porous PLGA scaffolds by a combining method of thermally induced phase separation and porogen leaching

“…31 The porosity of the scaffolds was generally determined by volume fraction of the porogen, and the maximum amount of porogen was controlled by the processing feasibility and the required mechanical properties of the scaffold. 2 In our study, the maximum volume fraction of the porogen was 95% in the case of a lower polymer concentration, that is, 0.12 g/mL, whereas it had to be decreased to 90% when the polymer concentration was higher to 0.15 g/mL or 0.20 g/mL. Once the porogen amounts were more than the maximum fraction, the polymer/sucrose/ solvent dope would be difficultly stirred, and the porogen particles could not be dispersed homogeneously.…”

“…In addition, when the porogen volume fraction and the freezing temperature kept unchanged, the compressive modulus and strength of the PLGA scaffold also exhibited a decrease tendency with decreasing the solution concentration (Nos. 2,7,8).…”

“…The scaffold porosity increased slightly with increasing the polymer concentration (Nos. 2,7,8) and lowering the freezing temperature (Nos. 8-10).…”

“…There are many bone graft options including autografts, allografts, or xenografts, but the bone grafts are still deficient to the requirement. 1,2 Tissue engineering, as a technique to create new tissues from cultured cells in a scaffold directed by signals, has now been considered as a potential alternative for organ or tissue reconstruction. Meanwhile, biodegradable porous scaffolds, serving as transplant vehicles for cultured cells or templates to guide tissue regeneration, play an important role.…”