Professor: Jonathan Butcher
Project Description: Bioprinting has emerged as an attractive method for creating complex, heterogeneous, patient-specific tissues. However, bioprinting heterogeneous tissue remains difficult because the crosslinking required to maintain shape fidelity in bioactive inks often harms cells, and even after crosslinking, mechanical moduli may not sufficiently mimic physiological properties without pre-conditioning. Our lab has demonstrated heterogeneous bioprinting of heart valves, but the impact of crosslinking on biomechanics and bioink annealing of large constructs has yet to be elucidated. The goal of this project is to determine the effect of UV light crosslinking parameters on print repeatability, cell viability, and mechanical properties of bioprints comprised of heterogeneous materials. Preliminary results have demonstrated the feasibility of bioprinting large constructs using UV crosslinkable bioinks containing mesenchymal stem cells. We will develop UV crosslinking schemes to explore print layer adhesion and annealing properties. Dynamic mechanical analysis (DMA) will be used to measure local moduli of both bulk bioink and homogeneous layer interfaces. Experimental print pathing methods will be developed to measure annealing strength of materials via failure stress measurements in DMA. Rheology measurements during UV crosslinking of the bioinks will determine the changes in material crosslinking necessary to elicit significant changes in annealing strength. Print fidelity and reproducibility will be quantified using microCT and cell viability will be evaluated along the z-axis. Overall, these experiments will determine UV crosslinking conditions and print path planning for anatomical scale bioprints to maintain cell viability and tune mechanical properties.