Development of agarose–gelatin bioinks for extrusion-based bioprinting and cell encapsulation

Three-dimensional bioprinting continues to advance as an attractive biofabrication technique to employ cell-laden hydrogel scaffolds in the creation of precise, user-defined constructs that can recapitulate the native tissue environment. Development and characterisation of new bioinks to expand the existing library helps to open avenues that can support a diversity of tissue engineering purposes and fulfil requirements in terms of both printability and supporting cell attachment. In this paper, we report the development and characterisation of agarose–gelatin (AG–Gel) hydrogel blends as a bioink for extrusion-based bioprinting. Four different AG–Gel hydrogel blend formulations with varying gelatin concentration were systematically characterised to evaluate suitability as a potential bioink for extrusion-based bioprinting. Additionally, autoclave and filter sterilisation methods were compared to evaluate their effect on bioink properties. Finally, the ability of the AG–Gel bioink to support cell viability and culture after printing was evaluated using SH-SY5Y cells encapsulated in bioprinted droplets of the AG–Gel. All bioink formulations demonstrate rheological, mechanical and swelling properties suitable for bioprinting and cell encapsulation. Autoclave sterilisation significantly affected the rheological properties of the AG–Gel bioinks compared to filter sterilisation. SH-SY5Y cells printed and differentiated into neuronal-like cells using the developed AG–Gel bioinks demonstrated high viability (>90%) after 23 d in culture. This study demonstrates the properties of AG–Gel as a printable and biocompatible material applicable for use as a bioink.