Biodegradable PHBV Polymer-Based Scaffolds for Bone Tissue Engineering - Biodegradable Polymer-Based Scaffolds for Bone Tissue Engineering - page 42

Chapter 3
Biodegradable PHBV Polymer-Based
Scaffolds for Bone Tissue Engineering
Abstract This chapter reports the emulsion freezing/freeze-drying technique for
the formation of three-dimensional porous scaffolds for bone tissue engineer-
ing applications. Poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV), which is
a natural, biodegradable polymer, was used as the main polymer for fabricating
various tissue engineering scaffolds. Nano-sized hydroxyapatite (HA), a widely
used bioceramic, was incorporated in the scaffolds in order to obtain bioactive
(i.e., osteoconductive) composite scaffolds. The chapter focused in two areas:
(1) investigations into scaffold fabrication using the emulsion freezing/freeze-
drying technique and the influence of processing parameters on the formation of
PHBV polymer scaffolds, HA/PHBV composite scaffolds and HA-containing
PHBV/PLLA blend-based composite scaffolds; (2) evaluation of different scaf-
folds in terms of their porous structure, porosity, pore size, polymer crystallinity,
compressive mechanical properties, in vitro biodegradation behavior and in vitro
biological performance.
Keywords Emulsion freezing/freeze-drying technique • Porosity • PHBV
polymers • Hydroxyapatite
3.1 Fabrication of Biodegradable Polymer Scaffolds Using
Emulsion Freezing/Freeze-Drying Technique
According to this technique, biodegradable polymer, PHBV was weighed accu-
rately into a centrifuge tube, and then an accurately measured amount of chlo-
roform was added to the tube to make a solution with a desired concentration
of 2.5-10 % (w/v). To obtain a homogeneous polymer solution, the mixture was
then kept at 50 °C in a water bath for a few minutes for several times and mixed
thoroughly. After getting homogeneous solution, water phase was added and
homogenized at a fixed speed in a homogenizer. In order to produce scaffolds,
10 ml of PHBV emulsion was put into a beaker (30 ml, prewarmed to 50 °C).
The beaker containing the mixture was then rapidly transferred into a freezer at a
preset temperature (at − 35 °C) to solidify the emulsion. The solidified emulsion