3D printing is an established technique used in many areas in industry to create advanced structures from polymers, metals, and ceramics.  In tissue engineering 3D printing can be used to create patient specific cell-laden scaffolds from hydrogels for the application in soft tissue regeneration [1]. Hydrogels are highly hydrophilic crosslinked polymer networks that can be tuned in degradation behaviour, mechanical properties, and chemistry [2]. Hyaluronic acid (HA) is a biodegradable, biocompatible and non-immunogenic polysaccharide native to the human body extracellular matrix (ECM) [3]. Through an oxidation process aldehyde groups are formed in the polysaccharide chain which can be used to covalently crosslink the oxidized hyaluronic acid (OHA) to amino groups in proteins, such as gelatine (GEL) by Schiff base formation [3]. In this work, we optimize the properties of an OHA-based bioink with regards to printability, mechanical properties, degradation, and cell viability by varying different parameters such as chemistry, concentration and crosslinking in order to achieve the optimal conditions for the 3D printing of soft tissue matrices. From initial 16 different constellations which were characterized step by step, two were found as superior for the application as bioinks in soft tissue engineering.

ACKNOWLEDGEMENT:
The authors thank the FAU Emerging Fields Initiative (EFI) on “Novel Biopolymer Hydrogels for Understanding Complex Tissue Biomechanics” and the Staedtler Foundation for financial support during this project.

REFERENCES:
 
 
[1]        J. Malda et al., Adv. Mater. 25 (2013) 5011–5028.
[2]        J. Thiele et al., Adv. Mater. 26 (2014) 125–148.
[3]        A.H. Pandit et al., Int. J. Biol. Macromol. 137 (2019) 853–869.