Synergistic effect of CaCO₃ addition and in-process cold atmospheric plasma treatment on the surface evolution, mechanical properties, and in-vitro degradation behavior of FDM-printed PLA scaffolds.

Abstract

The ease of processing and biocompatibility of polylactic acid (PLA) have made it a widely used material for fused deposition modeling (FDM)-based 3D printing. In spite of this, PLA suffers from some limitations for its extensive use in tissue engineering applications, including poor wettability, low degradation rate, and insufficient mechanical properties. To address the previously mentioned limitations, this study examined how combining in-process cold atmospheric plasma treatment with the inclusion of CaCO₃ influences the properties of FDM-printed PLA scaffolds. Differential scanning calorimetry results showed that by incorporating CaCO₃ micro-particles into the PLA matrix, heterogeneous nucleation promoted the matrix's crystalline content. Scanning electron microscopy analysis revealed that the surface of the PLA-CaCO₃ scaffold exhibited increased roughness and improved interlayer bonding after undergoing plasma treatment. Atomic force microscopy revealed a significant (up to 80-fold) increase in the roughness value of PLA scaffolds after the incorporation of CaCO₃ and subsequent cold plasma treatment. Furthermore, X-ray photoelectron spectroscopy analysis indicated that atmospheric plasma treatment substantially increased the presence of oxygen-containing bonds, leading to a significant reduction in the water contact angle, which decreased from 89° to 37°. According to the tensile test, the tensile modulus (634.1 MPa) and ultimate tensile strength (25.4 MPa) of PLA were markedly increased and reached 914.3 and 37.2 MPa, respectively, for the plasma-treated PLA-CaCO₃ (PT-PLA-CaCO₃). Additionally, the in-vitro degradation test showed that PT-PLA-CaCO₃ scaffold exhibited higher degradation rate compared to the PLA-CaCO₃ sample. Based on the obtained results, it appears that in-process cold atmospheric plasma treatment could serve as an efficient and straightforward method to enhance the properties of 3D-printed composite parts, particularly for tissue engineering applications.