Chemical modification of PLA for the design of 3D printed nanocomposite scaffolds with enhanced degradability for bone tissue engineering

In this study, 3D printing technology is used to develop nanocomposite scaffolds based on polylactic acid (PLA) and hydroxyapatite (HA). PLA was functionalized with itaconic anhydride (PLA_f) via radical grafting to improve affinity with the inorganic nanofiller and accelerate hydrolytic degradation. Fourier‐transform infrared (FTIR) and Nuclear Magnetic Resonance (NMR) spectroscopies confirmed the occurrence of chemical functionalization. Preliminary characterization of films of PLA, PLA_f and relative nanocomposites through water contact angle measurements highlighted an increase of wettability for PLA_f, due to the hydrophilic groups grafted onto polymer chain. Thermal analysis showed an increase of glass transition temperature (T_g) in PLA_f nanocomposites, likely due to enhanced matrix‐nanoparticle interactions. Scanning electron microscopy (SEM) analysis revealed more defined and homogeneous fibers for PLA_f‐HA5 and PLA_f‐HA10, meanwhile results from compression tests indicated improved processability and enhanced mechanical properties of nanocomposite PLA_f‐based scaffolds, as evidenced by increased values of Young modulus. Hydrolytic degradation studies in Phosphate Buffered Saline (PBS) solution showed greater weight loss and molecular weight decrease for PLA_f, PLA_f‐HA5, and PLA_f‐HA10, suggesting faster degradation due to increased hydrophilicity. Biological tests with human Mesenchymal Stem Cells (hMSCs) demonstrated that all scaffolds promoted cell proliferation, with PLA_f‐HA formulations showing higher effect on cellular behavior in terms of cell growth and alkaline phosphatase (ALP) levels, indicating that chemical functionalization improves cell attachment, proliferation and early osteogenic differentiation.

Highlights

Functionalization of PLA enhances hydrophilicity and HA affinity.