An oxygenating colloidal bioink for the engineering of biomimetic tissue constructs

Ensuring a sufficient oxygen supply is pivotal for the success of bioprinting applications since it fosters tissue integration and natural regeneration. Variation in oxygen concentration among diverse tissues necessitates the precise recreation of tissue-specific oxygen levels in imprinted constructs to support the survival of targeted cells. Although oxygen-releasing biomaterials, such as oxygen-generating microparticles (OMPs), have shown promise for enhancing the oxygen supply of microenvironments in injured tissues, whether this approach is scalable for large tissues and whether tissue-specific bioinks with varying OMP concentrations remain printable remain unknown. This study addresses this critical gap by introducing an innovative class of engineered oxygenated bioinks that combine colloidal-based microgels with OMPs. We report that incorporating nanosized calcium peroxide (nCaO 2 ) and manganese oxide nanosheets (nMnO 2 ) into hydrophobic polymeric microparticles enables precise modulation of oxygen release while controlling hydrogen peroxide release. Moreover, the fabrication of oxygenating and cytocompatible colloidal gels is achieved using an aqueous two-phase system. This study thoroughly evaluates the fundamental characteristics of the resulting bioink, including its rheological behaviors, printability, shape fidelity, mechanical properties, and oxygen release properties. Moreover, this study demonstrates the macroscopic scalability and cytocompatibility of printed constructs produced via cell-laden oxygenating colloidal bioinks. By showcasing the effectiveness of extrusion-based bioprinting, this study underscores how it can be used to fabricate biomimetic tissues, indicating its potential for new applications. The findings presented here advance the bioprinting field by achieving scalability with both high cell viability and the possibility of mimicking specifically oxygenated tissues. This work thereby offers a promising avenue for the development of functional tissues with enhanced physiological relevance. Graphic abstract