High quality and precise patterns can be printed using a patented thermal ink-jet technology (NanoBioJet, R&D Olivetti I-Jet, Italy). This non-contact nano-dispensing CAD/CAM system enables picoliter to nanoliter volumes of liquid to be dispensed in precise locations.
Depending upon the chosen printhead and biological fluid, optimal printing parameters can be set: driving energy, printing frequency, pulse length. Different bio-molecules have been printed with this system (i.e. genipin, albumin-FITC), as well as nano-particles (NP) and cells (i.e. fibroblast, hepatocyte, endothelial).
Figure: Printing phase of the NanoBioJet system and example of printed pattern (i.e. University of Pisa logo)-
Recently we investigated the influence of the deposition surface mechanical properties on viability of printed cells. A Finite-Element Model (FEM) was realised to evaluate the impact force of a droplet ejected with NanoBioJet system varying the substrate properties.
Different substrates were investigated with the FEM model: from a rigid (polystyrene) to a liquid deposition substrate (cell culture medium). As shown in figure the impact force decreases with the stiffness of the deposition surface.
Figure: Droplet shape before the impact (a). Droplet shape and substrate deformation after the impact with different surfaces: a) collagen, b) polystyrene -
Fibroblasts were printed with the NanoBioJet system onto different substrates to confirm the FEM results. Cell viability was evaluated 4, 24, 48 hours after the printing. We showed that a rigid surface causes temporary damage which can be partially recovered only after 48 hours. Visco-elastic or viscous solutions influence cell viability only during the first 4 hours after the printing process and then the proliferation rate is similar to that of controls.
A. Tirella et al., "Substrate stiffness influences high resolution printing of living cells with an ink-jet system", Journal of bioscience and bioengineering, vol. 112, pp. 79–85, 2011