CNT incorporation improves the resolution and stability of porous 3D printed PLGA/HA/CNT scaffolds for bone regeneration.

In this study, 3D printed porous poly(lactide-co-glycolide) (PLGA) and its nanocomposites with 5 wt. % hydroxyapatite (HA) and 0.5, 1 and 2 wt. % multi-walled carbon nanotubes (MWCNT) scaffolds were fabricated by using extrusion-based printing. The printing parameters were optimized by rheological studies. The rheological studies demonstrated shear thinning properties for all compositions and an increase in storage modulus was observed after the addition of MWCNT. Porous PLGA/HA/MWCNT scaffolds were printed by applying a pressure of 4.76 bar at 125 ⁰C. The addition of 0.5 wt. % of MWCNT reduced the strut size and increased the porosity from 42% to 60%. The increase of storage modulus and decrease of strut size was related to hydrogen bonding between MWCNT, HA and PLGA which ultimately improved shape fidelity. The scaffolds were characterized by analysis of their chemical structure, water contact angle measurement, in vitro bioactivity test, biodegradation test, mechanical analysis, and in vitro cell studies. The scaffolds were found to be more hydrophilic by the incorporation of MWCNTs. Also, degradation studies showed that the microstructure of the scaffold became more stable with the addition of HA and MWCNT. The compressive modulus of PLGA/HA/CNT2 scaffold was found to be 548.5 MPa which is found suitable to replace cancellous bone. The scaffolds were found highly biocompatible which is possibly due to alignment of MWCNT and PLGA during 3D printing process. Alizarin red staining indicated improvement of mineralization of MC3T3-E1 cells on the MWCNT incorporated porous 3D scaffolds. The results suggest that the produced porous 3D printed PLGA/HA/MWCNT scaffolds are promising for bone regeneration applications.