Nozzle Jamming Granularized Blood-Derived Proteins for Bioprinting Cell-Instructive Architectures

Exploring the natural availability and intrinsic bioactivity of blood-derived proteins opens new avenues for fabricating bioactive and patient-specific solutions for biomedical applications. Despite their several advantages, their use as inks for 3D printing is limited due to suboptimal rheological properties. To address this, we propose a dual-step strategy based on the initial generation of blood protein-based bulk hydrogels encompassing pristine and photo-responsive protein mixtures to allow their mechanical granularization followed by jamming, establishing injectable and printable granular inks. In this study, two globular-based protein matrices—human platelet lysates (PL) and bovine serum albumin (BSA)—were used as granular inks for 3D printing. We hypothesize that nozzle jamming—in contrast to the typically employed centrifugal jamming—would render optimized results for the granular protein inks’ processability. Printability was evaluated in filaments, scaffold grids, and convoluted structures. Taking advantage of the previously introduced photocurable moieties, post-printing photocrosslinking was used for the annealing of the microgels, leading to increased scaffold mechanical stability and robustness. The nozzle jamming methodology imparted the best print performance and reproducibility, where PLMA-based inks outperformed the BSAMA-based. In addition, the microgel granular constructs allowed primary human-derived adipose stem cells to adhere and proliferate, whereas the PLMA-based ink demonstrated higher cell affinity and enhanced biological performance. We further demonstrated that bioinks could be developed from PLMA-based inks, showcasing high viability without compromising 3D printing performance. Overall, this study gives clear insights into the importance of the jamming process as well as the granularization outcome requirements for the obtention of highly reproducible granular inks for 3D printing.