Synthetic Biodegradable Aliphatic Polyester Nanocomposites Reinforced with Nanohydroxyapatite and/or Graphene Oxide for Bone Tissue Engineering Applications

Abstract

This paper provides review updates on the current development of bionanocomposites with polymeric matrices consisting of synthetic biodegradable aliphatic polyesters reinforced with nanohydroxyaptite (nHA) and/or graphene oxide (GO) nanofillers for bone tissue engineering applications. Biodegradable aliphatic polyesters include poly(lactic acid) (PLA), polycaprolactone (PCL) and copolymers of PLA-PGA (PLGA). Those bionanocomposites have been explored for making 3D porous scaffolds for the repair of bone defects since nHA and GO enhance their bioactivity and biocompatibility by promoting biomineralization, bone cell adhesion, proliferation and differentiation, thus facilitating new bone tissue formation upon implantation. The incorporation of nHA or GO into aliphatic polyester scaffolds also improves their mechanical strength greatly, especially hybrid GO/nHA nanofilllers. Those mechanically strong nanocomposite scaffolds can support and promote cell attachment for tissue growth. Porous scaffolds fabricated from conventional porogen leaching, and thermally induced phase separation have many drawbacks inducing the use of organic solvents, poor control of pore shape and pore interconnectivity, while electrospinning mats exhibit small pores that limit cell infiltration and tissue ingrowth. Recent advancement of 3D additive manufacturing allows the production of aliphatic polyester nanocomposite scaffolds with precisely controlled pore geometries and large pores for the cell attachment, growth, and differentiation in vitro, and the new bone formation in vivo.

Study of the Influence of the Reprocessing Cycles on the Final Properties of Polylactide Pieces Obtained by Injection Molding

“…Many of these polymers have ester groups that can be easily hydrolyzed in the presence of moisture [5]. Some aliphatic and aromatic polyesters such as poly(ε-caprolactone) (PCL), poly(butylene succinate) (PBS), poly(glycolic acid) (PGA), poly(butylene adipate-co-terephthalate) (PBAT), among others, are included in this group [6][7][8][9]. On the other hand, some research studies have been focused on obtaining conventional polymers from natural resources, but these are not biodegradable as their corresponding counterparts.…”

Engineered 3D Polymer and Hydrogel Microenvironments for Cell Culture Applications

“…For example Kothapalli reported the compressive modulus of PLA scaffolds to increase from 4.7 to 9.8 MPa upon the inclusion of 50 wt% nHA while the compressive strength increased from 0.29 to 0.44 MPa [154], albeit using a salt-leaching method for preparation of scaffold. For GO, a tensile modulus of 16.73 MPa and tensile strength of 0.57 MPa for PLA with 15% nHA and 2% GO has been reported [147]. In general, pore size was shown not to affect tensile strength [143].…”

“…Process and Material PLA is a thermoplastic widely used for 3D additive manufacturing. It is adaptable and has been used together with SLS [34,142], FDM [143][144][145][146][147][148][149], and light-assisted techniques [61,150]. For light-assisted fabrication, photopolymerizable PLA can be synthesized by methacrylation and mixed with a photo-initiator to form light active photoresin.…”

“…Concerning SLS of PLA powders, PLA was combined with calcium carbonate powder to lower bending strength to 75 MPa [34]. On the other hand in FDM of PLA, materials such as nano-hydroxyapatite (nHA) [147,148] and graphene oxide (GO) [147,149] can be mixed into the filament to enhance mechanical properties. For example Kothapalli reported the compressive modulus of PLA scaffolds to increase from 4.7 to 9.8 MPa upon the inclusion of 50 wt% nHA while the compressive strength increased from 0.29 to 0.44 MPa [154], albeit using a salt-leaching method for preparation of scaffold.…”

“…To improve bioactivity, PLA has been blended with PEG, hyaluronic acid, and chitosan [153], as well as GO to improve cell growth and attachment [147,149] and nHA for promotion of osteoconductivity [147,148]. Alternatively, nHA has been used together with PLA to decrease the adherence and proliferation of Staphylococcus aureus and Pseudomonas aeruginosa bacterial cell colonies [142].…”