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Materials Science in Additive Manufacturing Bioactive hydrogels for 3D bioprinting

improved uniformity in the printed filaments and enhanced
shape fidelity in the printed scaffolds. Due to the higher
viscosity, the printing process of hydrogel with more BBG
requires higher extrusion pressure. These insights highlight
the impact of BBG concentration on hydrogel viscosity
and underscore the importance of optimizing temperature
and pressure settings to achieve the desired extrusion
characteristics. The quantitative assessments of printing
outcomes indicated that hydrogel-BBG biomaterial inks
with viscosity in the range of 4.5 – 6.5 Pa·s are desirable
for extrusion-based 3D printing and that 15 – 20 wt% BBG
Figure 11. Shape fidelity versus viscosity plot. The best shape fidelity concentrations in the hydrogels result in improved shape
across all samples was observed within a dynamic viscosity range of 4.5 fidelity in the printing outcomes. This research highlights
– 6.5 Pa·s, at 1< shear rate <10 (s ). This viscosity range exhibited the
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most favorable condition in all gelatin-alginate-BBG compositions for the ability of BBG to refine the capabilities of 3D bioprinting
extrudability and maintaining shape characteristics. of hydrogels and suggests its significant role in advancing
Abbreviation: BBG: Bioactive borate glass. tissue engineering and regenerative medicine.

bioinks exhibit the best printability. According to this study, Acknowledgments
for the hydrogel-BBG hydrogel inks, the best outcome of The authors extend their sincere gratitude to Drs. Douglass
extrusion-based 3D printing occurs at a viscosity of the Bristow, Nathan Leigh, and Gregory Hilmas for their
biomaterial ink in the range of 4.5 – 6.5 Pa·s. consultation advice and infrastructure support. Special
Our data showed that, among H-BBG0, H-BBG10, thanks are extended to Jyothiswaroop Gowdappagari for
H-BBG15, and H-BBG20, 3D-printed H-BBG20 his assistance in mechanical testing and to Abid Hasan Rafi
scaffolds had the highest shape fidelity followed by and Lekhana Gurijala for their contributions to rheology
H-BBG15 scaffolds. The stronger hydrogel network in testing. This work was funded by the Midwest Biomedical
these samples, characterized by reduced free volume Accelerator Consortium (MBArC), an NIH Research
and higher Young’s modulus, contributed to increased Evaluation and Commercialization Hub (REACH) and by
viscosity and improved shear thinning behavior during the Center for Biomedical Research.
the extrusion of the biomaterial ink, enhancing post- Funding
printing filament uniformity and scaffold shape fidelity.
Also, as demonstrated in this research, modulating the This work was funded by the Midwest Biomedical
concentration of BBG allows for control over the physical Accelerator Consortium (MBArC), an NIH Research
and mechanical characteristics of the biomaterial inks. The Evaluation and Commercialization Hub (REACH) and by
enhancement in mechanical integrity and shape fidelity the Center for Biomedical Research.
of the hydrogel-BBG scaffolds along with the inherent
bioactive properties positions BBG as a critical component Conflict of interest
in the development of advanced tissue constructs. The authors declare they have no competing interests.

4. Conclusion Author contributions
This study investigated the effect of BBG on physical Conceptualization: All authors
properties and printability when incorporated into gelatin- Data curation: Fateme Fayyazbakhsh, Mehedi Hasan Tusar
alginate hydrogel biomaterial inks. Inks with higher Formal analysis: Fateme Fayyazbakhsh, Mehedi Hasan
BBG content showed higher density and viscosity. The Tusar
addition of BBG enhanced the mechanical properties Funding acquisition: Fateme Fayyazbakhsh, Ming C. Leu
of 3D-printed hydrogels, evidenced by the increase in Investigation: All authors
Young’s modulus in samples with higher BBG contents. Methodology: Fateme Fayyazbakhsh, Yue-Wern Huang,
The temperature-dependent shear thinning behavior of Ming C. Leu
the hydrogel biomaterial inks is improved by the addition Project administration: Ming C. Leu
of BBG, enabling better control over ink gelation and the Writing – original draft: Fateme Fayyazbakhsh, Mehedi
printing process. The increased viscosity due to higher BBG Hasan Tusar
content improves the hydrogel’s printability as evidenced by Writing – review & editing: Yue-Wern Huang, Ming C. Leu

Volume 3 Issue 1 (2024) 13 https://doi.org/10.36922/msam.2845