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Active employment of additive manufacturing for scaffolds preparation requires the development of advanced methods which can accurately characterize the morphologic structure and its changes during an interaction of the scaffolds with substrate and aqueous medium. This paper aims to use the method of nuclear magnetic resonance (NMR) imaging for preclinical characterization of 3D-printed scaffolds based on novel allyl chitosan biocompatible polymer matrices.

Biocompatible polymer scaffolds were fabricated via stereolithography method. Using NMR imaging the output quality control of the scaffolds was performed. Scaffolds stability, polymer matrix homogeneity, kinetic of swelling processes, water migration pathways within the 3D-printed parts, effect of post-print UV curing on overall scaffolds performance were studied in details.

NMR imaging visualization of water uptake and polymer swelling processes during the interaction of scaffolds with aqueous medium revealed the formation of the fronts within the polymer matrices those dynamics is governed by case I transport (Fickian diffusion) of the water into polymer network. No significant difference was observed in front propagation rates along the polymer layers and across the layers stack. After completing the swelling process, the polymer scaffolds retain their integrity and no internal defects were detected.

NMR imaging revealed that post-print UV curing aimed to improve the overall performance of 3D-printed scaffolds might not provide a better quality of the finish product, as this procedure apparently yield strongly inhomogeneous distribution of polymer crosslink density which results in subsequent inhomogeneity of water ingress and swelling processes, accompanied by stress-related cracks formation inside the scaffolds.

This study introduces a method which can successfully complement the standard tests which now are widely used in either additive manufacturing or scaffolds engineering.

This work can help to improve the overall performance of the polymer scaffolds used in tissue engineering.

The results of this study demonstrate feasibility of NMR imaging for preclinical characterization of 3D printed biocompatible polymer scaffolds. The results are believed to contribute to better understanding of the processes vital for improving the design of 3D-printed polymer scaffolds.