Abstract
Spider silk is an extraordinary natural material that combines strength, extensibility, and toughness in a lightweight, protein-based fiber. While the recombinant production of spidroins has advanced, the creation of silk fibers with additional intrinsic functionalities, such as color, remains a major challenge. Here, we report the rational design, expression, and spinning of intrinsically red-colored artificial silk fibers. A mini-spidroin variant was engineered as a fusion with the red fluorescent protein mCherry, expressed at high yields (20 g/L) in E. coli fed-batch fermentations, and purified under native conditions. Although the presence of the mCherry globular domain reduced spinnability when used alone, blending with wild-type mini-spidroins enabled continuous wet spinning into robust, fluorescent fibers. Our biomimetic spinning approach preserved the correct folding of the mCherry domain within the fiber, resulting in stable red coloration and fluorescence, while maintaining mechanical properties comparable to those of other recombinant silks. This work establishes a scalable, sustainable strategy for fabricating colored bio-based fibers, opening avenues for environmentally friendly textiles and functional biomaterials that may reduce reliance on synthetic and chemically dyed fibers.
Similar content being viewed by others
Data availability
The data that support the findings of this study are available from the corresponding author upon reasonable request.
References
Gosline, J. M., Guerette, P. A., Ortlepp, C. S. & Savage, K. N. The mechanical design of spider silks: from fibroin sequence to mechanical function. J. Exp. Biol. 202, 3295–3303 (1999).
Braxton, T., Holland, C. & Greco, G. The circular argument behind spider and silkworm silk mechanical properties. Mater. Des. 260, 115224 (2025).
Breslauer, D. N. Current Progress on Scale-Up and Commercialization of Microbially-Produced Silk. Adv. Funct. Mater. https://doi.org/10.1002/adfm.202408386 (2024).
Guessous, G., Blake, L., Bui, A., Woo, Y. & Manzanarez, G. Disentangling the web: an interdisciplinary review on the potential and feasibility of spider silk bioproduction. Acs Biomater. Sci. Eng. 10, 5412–5438 (2024).
Schmuck, B. et al. Strategies for making high-performance artificial spider silk fibers. Adv. Funct. Mater. 34, 2305040 (2024).
Schiller, T. & Scheibel, T. Bioinspired and biomimetic protein-based fibers and their applications. Commun. Mater. 5, 56 (2024).
Andersson, M. et al. Biomimetic spinning of artificial spider silk from a chimeric minispidroin. Nat. Chem. Biol. 13, 262–264 (2017).
Schmuck, B. et al. High-yield production of a super-soluble miniature spidroin for biomimetic high-performance materials. Mater. Today 50, 16–23 (2021).
Pasupuleti, R. et al. Site-specific functionalization of recombinant spider silk using enzymatic sortase coupling. Acs Omega 10, 5943–5952 (2025).
Fan, R. X. et al. Sustainable spinning of artificial spider silk fibers with excellent toughness and inherent potential for functionalization. Adv. Funct. Mater. 35, https://doi.org/10.1002/adfm.202410415 (2025).
Bowen, C. H. et al. Recombinant spidroins fully replicate primary mechanical properties of natural spider silk. Biomacromolecules 19, 3853–3860 (2018).
Li, J. Y. et al. Microbially synthesized polymeric amyloid fiber promotes β-nanocrystal formation and displays gigapascal tensile strength. Acs Nano 15, 11843–11853 (2021).
Xia, X. X. et al. Native-sized recombinant spider silk protein produced in metabolically engineered results in a strong fiber. Proc. Natl. Acad. Sci. USA 107, 14059–14063 (2010).
Nakamura, H. et al. Correlating mechanical properties and sequence motifs in artificial spider silk by targeted motif substitution. Acs Biomater. Sci. Eng. https://doi.org/10.1021/acsbiomaterials.4c01389 (2024).
Orlandi, V. T., Martegani, E., Giaroni, C., Baj, A. & Bolognese, F. Bacterial pigments: a colorful palette reservoir for biotechnological applications. Biotechnol. Appl. Bioc 69, 981–1001 (2022).
Ziarani, G. M., Moradi, R., Lashgari, N. & Kruger, H. G. in Metal-Free Synthetic Organic Dyes (eds Ghodsi Mohammadi Ziarani, Razieh Moradi, Negar Lashgari, & Hendrik G. Kruger) 1–7 (Elsevier, 2018).
Islam, T., Repon, M. R., Islam, T., Sarwar, Z. & Rahman, M. M. Impact of textile dyes on health and ecosystem: a review of structure, causes, and potential solutions. Environ. Sci. Pollut. R. 30, 9207–9242 (2023).
Raja, A. S. M., Arputharaj, A., Saxena, S. & Patil, P. G. in Water in Textiles and Fashion (ed Subramanian Senthilkannan Muthu) 155–173 (Woodhead Publishing, 2019).
Ammayappan, L., Jose, S. & Arputha Raj, A. in Green Fashion: Volume 1 (eds Subramanian Senthilkannan Muthu & Miguel Angel Gardetti) 185–216 (Springer Singapore, 2016).
Lara, L., Cabral, I. & Cunha, J. Ecological approaches to textile dyeing: a review. Sustainability-Basel 14, https://doi.org/10.3390/su14148353 (2022).
Fried, R., Oprea, I., Fleck, K. & Rudroff, F. Biogenic colourants in the textile industry - a promising and sustainable alternative to synthetic dyes. Green. Chem. 24, 13–35 (2022).
Yang, D., Park, S. Y. & Lee, S. Y. Production of rainbow colorants by metabolically engineered. Adv. Sci. 8, https://doi.org/10.1002/advs.202100743 (2021).
Liljeruhm, J. et al. Engineering a palette of eukaryotic chromoproteins for bacterial synthetic biology. J. Biol. Eng. 12, https://doi.org/10.1186/s13036-018-0100-0 (2018).
Watkins, T., Moffitt, K., Speight, R. E. & Navone, L. Chromogenic fusion proteins as alternative textiles dyes. Biotechnol. Bioeng. 121, 2820–2832 (2024).
Arndt, T. et al. Engineered spider silk proteins for biomimetic spinning of fibers with toughness equal to dragline silks. Adv. Funct. Mater. 32, 2200986 (2022).
Schmuck, B. et al. Impact of physio-chemical spinning conditions on the mechanical properties of biomimetic spider silk fibers. Commun. Mater. 3, 83 (2022).
Shaner, N. C. et al. Improved monomeric red, orange and yellow fluorescent proteins derived from Discosoma sp red fluorescent protein. Nat. Biotechnol. 22, 1567–1572 (2004).
Edlund, A. M., Jones, J., Lewis, R. & Quinn, J. C. Economic feasibility and environmental impact of synthetic spider silk production from Escherichia coli. N. Biotechnol. 42, 12–18 (2018).
Gao, Z. W. et al. Structural characterization of minor ampullate spidroin domains and their distinct roles in fibroin solubility and fiber formation. Plos One 8, https://doi.org/10.1371/journal.pone.0056142 (2013).
Hagn, F. et al. A conserved spider silk domain acts as a molecular switch that controls fibre assembly. Nature 465, 239–U131 (2010).
Greco, G., Schmuck, B., Jalali, S. K., Pugno, N. M. & Rising, A. Influence of experimental methods on the mechanical properties of silk fibers: a systematic literature review and future road map. Biophys. Rev. (Melville) 4, 031301 (2023).
Greco, G., Mirbaha, H., Schmuck, B., Rising, A. & Pugno, N. M. Artificial and natural silk materials have high mechanical property variability regardless of sample size. Sci Rep-Uk 12, https://doi.org/10.1038/s41598-022-07212-5 (2022).
Schmuck, B., Greco, G., Shilkova, O. & Rising, A. Effects of mini-spidroin repeat region on the mechanical properties of artificial spider silk fibers. ACS Omega 9, 42423–42432 (2024).
Jansson, R., Courtin, C. M., Sandgren, M. & Hedhammar, M. Rational design of spider silk materials genetically fused with an enzyme. Adv. Funct. Mater. 25, 5343–5352 (2015).
Humenik, M., Mohrand, M. & Scheibel, T. Self-assembly of spider silk-fusion proteins comprising enzymatic and fluorescence activity. Bioconjug. Chem. 29, 898–904 (2018).
da Silva, A. J. et al. Non-conventional induction strategies for production of subunit swine erysipelas vaccine antigen in fed-batch cultures. Springerplus 2, https://doi.org/10.1186/2193-1801-2-322 (2013).
Gasteiger, E. et al. in The Proteomics Protocols Handbook (Walker, J. M. ed) 571–607 (Humana Press, 2005).
Schneider, C. A., Rasband, W. S. & Eliceiri, K. W. NIH Image to ImageJ: 25 years of image analysis. Nat. Methods 9, 671–675 (2012).
Greco, G. et al. Properties of biomimetic artificial spider silk fibers tuned by PostSpin Bath incubation. Molecules 25, https://doi.org/10.3390/molecules25143248 (2020).
Jafari, M. J. et al. Force-induced structural changes in spider silk fibers introduced by ATR-FTIR spectroscopy. Acs Appl. Polym. Mater. 5, 9433–9444 (2023).
Rana, M. S., Wang, X. Y. & Banerjee, A. An improved strategy for fluorescent tagging of membrane proteins for overexpression and purification in mammalian cells. Biochemistry 57, 6741–6751 (2018).
Acknowledgements
This work was supported by grants from Olle Engkvist stiftelse (233-0334), Knut and Alice Wallenberg Foundation (2023.0331, WASP-DDLS2 2:035 and Wallenberg Launch Pad), FORMAS (2023-01313), and the Swedish Research Council (2024-02919) to A.R. B.S. was supported by FORMAS (2023-00871). G.G. was supported by the project “EPASS” under the HORIZON TMA MSCA Postdoctoral Fellowships - European Fellowships (project number 101103616). A special thank you to Anil Putri for assisting in protein purification.
Funding
Open access funding provided by Swedish University of Agricultural Sciences.
Author information
Authors and Affiliations
Contributions
A.R. was the principal investigator of this study and conceived the idea. T.B.P. and B.S. expressed and purified the proteins. B.S. conducted the spinning experiments. G.G. performed the tensile tests, calculated the mechanical properties, and analyzed the data. S.S. and B.G. performed microscopy and evaluated the data. E.K. conducted FTIR measurements. A.L. and M.L. performed MS and MP experiments. All authors discussed the results. The first draft of the manuscript was written by T.B.P., B.S., and A.R., and edited by all authors.
Corresponding author
Ethics declarations
Competing interests
The authors declare no competing interests.
Peer review
Peer review information
Communications Materials thanks Mattheos Koffas and the other, anonymous, reviewer for their contribution to the peer review of this work. A peer review file is available.
Additional information
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
About this article
Cite this article
Bohn Pessatti, T., Schmuck, B., Greco, G. et al. Intrinsically colored artificial silk fibers made from mini-spidroin fusion proteins. Commun Mater (2026). https://doi.org/10.1038/s43246-026-01079-z
Received:
Accepted:
Published:
DOI: https://doi.org/10.1038/s43246-026-01079-z
