Photoclickable inks: 3D printing intelligent gelling systems with biomedical applications

• Main Author: Malafaia, Andreia Isabel Pinho
• Publication Date: 2023
• Format: Master thesis
• Language: eng
• Source: Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
• Download full: http://hdl.handle.net/10773/44617
• topic: Biofabrication; 3D printing; Inks; Hydrogels; Photocrosslinking; Thiol-ene click chemistry

Over the past decade, 3D printing has gained increasing popularity, being a technique capable of producing well-defined tissue-like structures. One of its most appealing features is the ability to create personalized therapies to meet the specific demands of individual patients. However, challenges including the selection of materials, as well as crosslinking strategies still need to be addressed, in order to enhance the inks characteristics and simultaneously create printable, robust, and cytocompatible biomaterials. Hence, this study reports the development of natural-based photoclickable inks, composed of hyaluronic acid (HA) and proteins [bovine serum albumin (BSA) and human platelet lysates (hPL)] for 3D extrusion printing, taking advantage of the versatility, efficiency, and fast kinetics of thiol-ene click chemistry. To this end, HA was modified with norbornene (HA-Nor) moieties, while proteins were thiolated (BSA-SH and hPL-SH). 1H-NMR and ATR-FTIR analysis of the resulting polymers, HA-Nor, BSA-SH and hPL-SH, confirmed the success of their modification. These polymers were mixed, varying the protein concentration and, subsequently, bio-orthogonally photo-crosslinked, using visible light and LAP as photoiniator, creating hydrogel cell-friendly networks. Rheological characterization affirmed the chemistry’s potential in rapidly gelling networks (t < 20 s) achieving an elastic modulus, G’, of approximately 104 Pa, highlighting its suitability for 3D printing applications. Moreover, the mechanical characterization of the hydrogels revealed that those containing higher BSA-SH concentration were more robust, indicating the presence of more crosslinking points, as expected. The mechanical and rheological properties of the inks enabled 3D extrusion printing. Additionally, direct and indirect contact of hASCs with the materials through seeding, confirmed their cytocompatibility and non-toxicity, maintaining cell viability up to 14 days, which was assessed through fluorescence microscopy images and metabolic activity. Therefore, HA-Nor/BSA-SH and HA-Nor/hPL-SH inks are expected to be promising future bioinks for regenerative medicine and tissue engineering of soft tissues, opening avenues for personalized medicine.