Towards understanding the mechanism of 3D printing using protein: Femtosecond laser direct writing of microstructures made from homopeptides

Femtosecond laser direct write (fs-LDW) is a promising technology for three-dimensional (3D) printing due to its high resolution, flexibility, and versatility. A protein solution can be used as a precursor to fabricate 3D proteinaceous microstructures that retain the protein's native function. The large diversity of protein molecules with different native functions allows diverse applications of this technology. However, our limited understanding of the mechanism of the printing process restricts the design and generation of 3D microstructures for biomedical applications. Therefore, we used eight commercially available homopeptides as precursors for fs-LDW of 3D structures. Our experimental results show that tyrosine, histidine, glutamic acid, and lysine contribute more to the fabrication process than do proline, threonine, phenylalanine, and alanine. In particular, we show that tyrosine is highly beneficial in the fabrication process. The beneficial effect of the charged amino acids glutamic acid and lysine suggests that the printing mechanism involves ions in addition to the previously proposed radical mechanism. Our results further suggest that the uneven electron density over larger amino acid molecules is key in aiding fs-LDW. The findings presented here will help generate more desired 3D proteinaceous microstructures by modifying protein precursors with beneficial amino acids.

Automated summary

Femtosecond laser direct write (fs-LDW) is a promising technology for high-resolution, flexible, and versatile three-dimensional printing using protein solution as a precursor. The diverse proteins with different native functions enable various applications of this technology. However, the lack of understanding of the printing mechanism hampers the design and generation of 3D microstructures for biomedical applications. In this study, we used eight commercially available homopeptides as precursors and found that tyrosine, histidine, glutamic acid, and lysine contribute more to the fabrication process, indicating the involvement of ions in addition to the previously proposed radical mechanism. The findings suggest that the uneven electron density over larger amino acid molecules plays a significant role in aiding fs-LDW.