A bio-inspired 3D printed device for burn wounds

Abstract

This study focused on the design, development and evaluation of 3D printed polypeptide-based hydrogel scaffolds as potential healing devices for burn wounds. The versatility of the hydrogels in terms of their physicochemical and biofunctional properties was explored to contribute to the development of biomaterial inks, suitable for 3D printing. 3D printed acellular scaffolds with customised physicochemical properties were further investigated to contribute to the limited knowledge on structure-function relationships of 3D printed scaffolds in terms of their in vitro and in vivo wound healing performance. Controlled ring-opening polymerisation (ROP) and optimised hydrogel compositions were used to tailor the inherent physicochemical and biofunctional properties of a new library of hydrogels composed of poly(ʟ-lysine-ran-ʟ-alanine) and 4-arm poly(ethylene glycol) (P(KA)/4-PEG). This allowed the identification of P(KA)/4-PEG hydrogel compositions that displayed suitable combinations of properties for potential wound healing applications. One of the most promising hydrogels was the 4 wt% 1:1 functional molar ratio hydrogel with P(KA) concentrations as low as 0.65 wt%, which demonstrated low cytotoxicity and desirable cell adhesion towards fibroblasts. P(KA)/4-PEG hydrogels were further processed into composite microgel pastes as new 3D biomaterial inks. The inks displayed good 3D printability, while the biofunctionality of the P(KA)/4-PEG hydrogels was retained. The physical properties of chitosan-P(KA)/4-PEG was further controlled using different 3D printing patterns. The mechanical properties of these scaffolds were relatively low with compressive and tensile moduli between ~45 and 147 Pa. Nonetheless, the scaffolds demonstrated adequate adhesion and spreading of fibroblasts seeded onto the scaffold surfaces for 4 days. The in vivo performance of two chitosan-P(KA)/4-PEG scaffolds with porous and non-porous 3D printed architectures were then investigated using a full-thickness burn wound model of Sprague Dawley rats. These 3D printed scaffolds led to faster wound contraction in the first 5 days of the treatment, compared to the control groups. Interestingly, the porous 3D printed scaffold facilitated much reduced scar formation after 20 days. This was ascribed to the tailored physical properties of the porous 3D printed scaffold. However, histological evaluations could not provide definitive evidence to account for the improved scar appearance caused by the porous 3D printed scaffold