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International Journal of Bioprinting Drop-on-demand laser bioprinting

3.6. Limitations and future perspectives bioink shear rate through flow rate adjustments, catering
The new LIST approach significantly enhances the printing to various bioprinting applications. Stable printing
workflow compared to the initial implementation, all while conditions were successfully established with a model
maintaining the viability of primary cells. Interestingly, ink, and our results affirm that bioprinted HUVECs
the stable printing observed at high flow rates (300 μL/ exhibit no viability loss, maintaining the ability to recruit
min) in both withdrawal and perfusion pressure modes perivascular cells. Overall, these findings underscore
suggests the potential for achieving higher printing speeds. the method’s potential for applications requiring DOD
However, our exploration of printing speeds above 30 bioprinting of HUVECs.
Hz was limited by the maximum repetition rate of our
available laser system. High repetition rate (kHz) and small Acknowledgments
footprint lasers are available at the required power levels The authors would like to thank Dr. Malcolm Latorre for
in the market and can be used to explore the maximum
printing speed. technical support on the bioprinting setup, Dr. Mikhail
Sergeev for technical support on microscopy, as well as
A limitation in LIST using 532 nm is the necessity of Dr. Erika Hooker and Mr. Kevin Lanthier for assisting in
adding a biocompatible light-absorbing dye to bioinks. establishing the cell culture and staining protocols.
This constraint restricts the applicability of LIST in
bioprinting applications involving transparent constructs. Funding
An alternative approach to achieve dye-free printing can
be the use of near-infrared irradiation at 1064 nm, as Christos Boutopoulos acknowledges financial support
water-based inks are expected to absorb 30 times more from the Natural Sciences and Engineering Research
light at 1064 nm than at 532 nm. Utilizing ns laser pulses at Council of Canada (RGPIN-2018-06767) and the Fonds
mid-infrared wavelengths can further reduce the required de la Recherche en Santé du Quebec (#312263). Hamid
energy for dye-free printing, as water exhibits even higher Ebrahimi Orimi acknowledges the financial support
absorption at these wavelengths. In fact, ns laser irradiation from the Fonds de Recherche du Quebec Nature et
at 2.9 μm has already been considered as an attempt to Technologies (#263066).
avoid the use of sacrificial layers in nozzle-less LIFT. 29
Conflict of interest
Another limitation in our approach is the requirement
for micromachining commercially available capillaries, as The authors declare no conflicts of interest.
fs-machining equipment can be expensive and not widely
available. However, several companies commercially offer Author contributions
fs-machining services, providing a potential solution Conceptualization: Mahyar Erfanian, Bruno Larrivée,
for those lacking access to the necessary infrastructure. Christos Boutopoulos
We used the inner capillary size in the initial LIST Formal analysis: Mahyar Erfanian, Christos Boutopoulos
demonstration as a guide for our selection of the hole Funding acquisition: Christos Boutopoulos
size (200 μm) in the redesigned LIST. Yet, the effects Investigation: Mahyar Erfanian, Ahad Mohammadi, Hamid
of the hole size on printability and cell viability remain Ebrahimi Orimi, Jennyfer Zapata-Farfan, Joe Saade,
unknown. Our future work will focus on developing Bruno Larrivée, Christos Boutopoulos
a computational model of the entire setup to optimize Methodology: Mahyar Erfanian, Ahad Mohammadi,
the architecture and study these effects. A potential Hamid Ebrahimi Orimi, Jennyfer Zapata-Farfan, Joe
opportunity in the new LIST implementation is to exploit Saade, Michel Meunier, Bruno Larrivée, Christos
continuous perfusion as a means to control the bioink Boutopoulos
temperature or to introduce bioink multiplexing using an Resources: Michel Meunier, Bruno Larrivée,
external fluidic control system. Christos Boutopoulos
Supervision: Michel Meunier, Bruno Larrivée,
4. Conclusion Christos Boutopoulos
In conclusion, we have introduced and validated a new Visualization: Mahyar Erfanian, Christos Boutopoulos
approach for performing DOD bioprinting using LIST. Writing – original draft: Mahyar Erfanian
The primary advancement in this new implementation Writing – review & editing: Mahyar Erfanian, Ahad
involves continuous capillary perfusion, eliminating the Mohammadi, Hamid Ebrahimi Orimi, Jennyfer
need for active compensation for liquid loss during drop Zapata-Farfan, Joe Saade, Michel Meunier, Bruno
ejection. The redesigned approach enables the control of Larrivée, Christos Boutopoulos

Volume 10 Issue 3 (2024) 516 doi: 10.36922/ijb.2832