Bioprinted nanoparticles for tissue engineering applications.

Tissue engineering may require precise patterning and monitoring of cells and bioactive factors within the scaffold. We investigated a new hybrid nanobioprinting technique that facilitates manipulation and tracking of cells and bioactive factors within a three-dimensional tissue construct. This technique combines the initial patterning capabilities of syringe-based cell deposition with the active patterning capabilities of superparamagnetic nanoparticles. Superparamagnetic iron oxide nanoparticles, either in the alginate biopolymer or loaded inside endothelial cells, were bioprinted using a solid freeform fabrication direct cell writing system. Bioprinting did not impact cell viability when nanoparticles were in the alginate. However, both control and printed samples with 0.1 or 1.0 mg/mL nanoparticles in the alginate showed a 16% or 35% viability loss at 36 h after printing, respectively. Nanoparticle loading in cells decreased cell viability to 11% and bioprinting decreased viability to an additional 29% at 36 h. No changes were observed in any samples after 36 h, suggesting that cell viability stabilized following the initial nanoparticle toxicity effect. Nanoparticles in the alginate and those loaded in cells were moved using an external magnet, depending on biopolymer viscosity, and imaged by microcomputed tomography. The hybrid nanobioprinting method can noninvasively manipulate and track bioactive factors and cells within tissue engineering structures.