Impact of exposure time and power intensity on cell viability in 3D bioprinting

In 3D bioprinting, the photopolymerization of bioinks is a critical step in building desired structures with high precision. The chosen parameters, such as exposure time and light intensity during photopolymerization of the bioinks, significantly influence the resolution, cell viability, and proliferation of the bioprinted constructs. This study investigates how varying exposure times (10-30 s) and light intensities (0.04-0.11 mW/mm^2) in a laser-based bioprinter affect the performance of 3T3 fibroblasts embedded in GelMA bioinks. The metabolic activity and cell morphology of the bioprinted constructs were assessed over a week-long culture period. The findings reveal a clear relationship between longer exposure times and reduced cell viability. On day seven, samples exposed for extended periods exhibited the lowest metabolic activity, with differences of around 40% between treatments. In contrast, samples exposed to different light intensities resulted in variations below 15% in metabolic activity. GelMA bioinks exhibited less favorable outcomes under prolonged exposure, with cells displaying more rounded and less proliferative morphologies. In contrast, lower exposure times promoted more elongated cell shapes and network formation. These results highlight the importance of optimizing exposure time and light intensity to preserve cell wellness in 3D bioprinted constructs.