# Observation of Spider Silk by Femtosecond Pulse Laser Second Harmonic Generation Microscopy

## TL;DR

This study uses femtosecond pulse laser second harmonic generation microscopy to analyze the structure of spider silk's ta-sheets and their role in its mechanical strength.

## Contribution

It introduces a non-scanning femtosecond laser microscopy method to observe ta-sheet behavior in spider silk under force, revealing structural insights.

## Key findings

- ta-sheets become more unidirectional when extended
- The physical arrangement of ta-sheets may contribute to silk's high strength
- The microscopy technique effectively characterizes silk's molecular structure

## Abstract

An asymmetric \b{eta}-sheet structure of spider silk is said to induce optical second harmonic generation. In this paper, using an in-house non-scanning type femtosecond pulse laser second harmonic generation microscope, we characterized the behavior of the \b{eta}-sheet of spider silk under an applied external force. The orientation of the \b{eta}-sheets was more unidirectional when the silk was extended. One of the origins of the high mechanical strength of the dragline is suggested to be the physical arrangement of its \b{eta}-sheets.