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 (PLAf) 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, PLAf and relative nanocomposites through water contact angle measurements highlighted an increase of wettability for PLAf, due to the hydrophilic groups grafted onto polymer chain. Thermal analysis showed an increase of glass transition temperature (Tg) in PLAf nanocomposites, likely due to enhanced matrix-nanoparticle interactions. Scanning electron microscopy (SEM) analysis revealed more defined and homogeneous fibers for PLAf-HA5 and PLAf-HA10, meanwhile results from compression tests indicated improved processability and enhanced mechanical properties of nanocomposite PLAf-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 PLAf, PLAf-HA5, and PLAf-HA10, suggesting faster degradation due to increased hydrophilicity. Biological tests with human Mesenchymal Stem Cells (hMSCs) demonstrated that all scaffolds promoted cell proliferation, with PLAf-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. Nanocomposite scaffolds based on PLAf are successfully developed by 3D printing. PLA functionalization enhances ink printability, making more uniform structures. PLAf-based scaffolds exhibit an accelerated hydrolytic degradation PLAf-HA scaffolds support cell adhesion and early osteogenic differentiation.