Experimental investigations on polydopamine coated poly lactic acid based biomaterial fabricated using 3D printing for orthopedic applications

Abstract

Polymer based implants provide excellent biocompatibility due to porous structure and minimum chances of stress shielding. However, 3D Printed PLA structures possess insufficient mechanical strength, restricting their utility in biomedical domain. This challenge can be addressed by enhancing their mechanical properties through surface modification. The one-step oxidative polymerization process transforms dopamine hydrochloride into biocompatible polydopamine coating, that facilitates adhesion to both hydrophilic and hydrophobic surfaces. The mechanical performance of these structures is influenced significantly by the printing and coating parameters. Thus, this study undertakes the fabrication of bone plates at varying printing parameters followed by investigating the effects of polydopamine coating on their tensile and flexural behavior across varying coating conditions. In the study, SEM/EDS analysis has been performed for examining the morphological characteristics, interaction of coating with PLA and assessing the elemental distribution on the coated surface. The study further explores the impact of coating on substrate roughness and hydrophilicity through AFM and water contact angle measurement techniques. The deposition of polydopamine coating on PLA bone plates was confirmed using XRD and Raman spectroscopy. Upon application of coating, the findings suggested enhancement in tensile strength and flexural strength in the ranges of 47.18%–94.47% and 8.5%–33.78% respectively, across varying printing parameters. Similarly, varying coating parameters resulted in improvement ranging from 38.68% to 93.03% for tensile strength and 2.8%–30.57% for flexural strength. Furthermore, the deposition of coating substantially enhanced the hydrophilicity of the bone plates, making them suitable for tissue engineering applications. Thus, the successful deposition of polydopamine coating not only enhanced the mechanical behavior but also improved the hydrophilicity of bone plates, thereby advancing their suitability for biomedical applications.