Article

The processing and heterostructuring of silk with light

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Abstract

Spider silk is a tough, elastic and lightweight biomaterial, although there is a lack of tools available for non-invasive processing of silk structures. Here we show that nonlinear multiphoton interactions of silk with few-cycle femtosecond pulses allow the processing and heterostructuring of the material in ambient air. Two qualitatively different responses, bulging by multiphoton absorption and plasma-assisted ablation, are observed for low- and high-peak intensities, respectively. Plasma ablation allows us to make localized nanocuts, microrods, nanotips and periodic patterns with minimal damage while preserving molecular structure. The bulging regime facilitates confined bending and microwelding of silk with materials such as metal, glass and Kevlar with strengths comparable to pristine silk. Moreover, analysis of Raman bands of microwelded joints reveals that the polypeptide backbone remains intact while perturbing its weak hydrogen bonds. Using this approach, we fabricate silk-based functional topological microstructures, such as Mobiüs strips, chiral helices and silk-based sensors.

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Acknowledgements

We acknowledge the central facilities of IISER Mohali for Raman spectra, SEM micrographs and optical absorption spectra. We thank R. Yadav for his help with confocal microscopy. K.P.S. acknowledges P. P. Singh and T. Pfeifer for many fruitful discussions. We acknowledge funding from DST, India and IISER Mohali.

Author information

Affiliations

  1. Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, Knowledge City, Manauli 140306, India

    • Mehra S. Sidhu
    • , Bhupesh Kumar
    •  & Kamal P. Singh

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Contributions

K.P.S. conceived the idea. M.S.S. and K.P.S. designed the research. K.P.S. and M.S.S. developed the full processing set-up, performed experiments, and analysed data including Raman analysis, pulling tests, welding silk to other materials, and multiphoton measurements. B.K. participated in an early version of the set-up with K.P.S. K.P.S. and M.S.S. wrote the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Kamal P. Singh.

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