Injectable Biodegradable Thermosensitive Hydrogel Composite for Orthopedic Tissue Engineering. 1. Preparation and Characterization of Nanohydroxyapatite/Poly(ethylene glycol)−Poly(ε-caprolactone)−Poly(ethylene glycol) Hydrogel Nanocomposites

Abstract

In this study, we synthesized a biodegradable triblock copolymer poly(ethylene glycol)-poly(epsilon-caprolactone)-poly(ethylene glycol) (PEG-PCL-PEG, PECE) by ring-opening copolymerization, and nanohydroxyapatite (n-HA) powder was prepared by a hydrothermal precipitation method. The obtained n-HA was incorporated into the PECE matrix to prepare injectable thermosensitive hydrogel nanocomposites. (1)H NMR, FT-IR, XRD, DSC, and TEM were used to investigate the properties of PECE copolymer and n-HA/PECE nanocomposites. The rheological measurements for n-HA/PECE nanocomposites revealed that the gelation temperature was approximately 36 degrees C. The sol-gel-sol transition behavior and phase transition diagrams were recorded through a test tube inverting method. The results showed that n-HA/PECE nanocomposites still had thermoresponsivity like that of PECE thermosensitive hydrogel. The morphology of the nanocomposites was observed by SEM; the results showed that the nanocomposites had a 3D network structure. In addition, the effects of n-HA contents on the properties of n-HA/PECE nanocomposites are also discussed in the paper. From the results, n-HA/PECE hydrogel is believed to be promising for injectable orthopedic tissue engineering due to its good thermosensitivity and injectability.

Preparation and properties of nano‐hydroxyapatite/PCL‐PEG‐PCL composite membranes for tissue engineering applications

“…n-HA powder was prepared through a hydrothermal method as described elsewhere. 35,36 To enhance the dispersion of n-HA particles into PCEC matrix, n-HA was coated with poly (ethylene glycol) (PEG, M n ¼ 4000): the obtained n-HA powder was firstly dispersed in DMF to form a suspension, and then PEG was added into the suspension, the mixture was stirred for 24 h at room temperature; after filtered and centrifuged, the n-HA slurry was fully washed with ethanol to remove unabsorbed PEG, the obtained PEG-coated HA slurry was dried to constant weight in a vacuum oven and stored in a desiccator before use. According to the thermogravimetric analysis (TGA) result, the amount of PEG coated on HA was about 4%.…”

“…Bioactive calcium phosphate is commonly used as a filler to fabricate various implant materials, such as nanohydroxyapatite (n-HA), b-tricalcium phosphate, or bioceramics. [35][36][37] Among the inorganic fillers, n-HA has been widely introduced into biodegradable polymers for fabricating HA/ polymer composites. [38][39][40][41] Because n-HA has excellent bioactivity and biocompatibility, it can provide a favorable environment for osteoconduction, protein adhesion, and osteoblast proliferation.…”

“…The pattern of pure PCEC membrane revealed that PCEC belonged to a poor crystalline pattern; moreover, in the pattern of n-HA/PCEC composite membrane, the intensity of n-HA and PCEC peaks both decreased slightly, suggesting that the interactions of HA particles and PCEC matrix weakened the crystallization ability each other. 35 The results of water contact angle measurements were shown in Figure 3. The contact angle values of all samples were less than 90 which indicated that these membranes were of certain hydrophilic.…”

Sol–gel transition of novel temperature responsive ABA triblock copolymer P(MEO2MA-co-HMAM)-b-PEG-b-P(MEO2MA-co- HMAM)

“…For the temperature-responsive block copolymer micellar gel, the central blocks, or B blocks of an ABA triblock copolymer, form bridge among micelles. The higher the degree of polymerization of the A block there is, the lower the LCST of this ABA triblock copolymer, the lower its micellization temperature, and the lower the T sol-gel of its aqueous solution [36][37][38][39]. In addition, the higher the concentration of an ABA triblock copolymer aqueous solution is, the greater the number of micelles forming above its LCST, and the lower the T sol-gel of the ABA triblock copolymer aqueous solution.…”

Synthesis of novel temperature responsive PEG-b-[PCL-g-P(MEO2MA-co-OEGMA)]-b-PEG (tBG) triblock-graft copolymers and preparation of tBG/graphene oxide composite hydrogels via click chemistry

“…Among all the reported polyesters, Poly(ε-caprolactone) (PCL) and its block copolymers, such as PEG-b-PCL, PEG-b-PCL-b-PEG and PCL-b-PEG-b-PCL, have been intensively studied for possible applications in biomedical field [2][3][4][5][6][7][8][9][10][11][12]. However, because of the hydrophobicity of PCL blocks, the copolymers can only exist in micelle form in aqueous solutions, which is the major limitation to carry on studies on copolymers composed of PEG and PCL [3,5,6,[9][10][11].…”