Squid lens and Pi Dan: their material similarities
Department of Physics and Astronomy
University of Pennsylvania, Philadelphia, PA, USA
Underwater vision requires a spherical lens to enable enough photon flux injecting into the camera-like eyes. The refractive index in the lens has a gradient to eliminate spherical aberration. Here, I present the squid lens system, where the whole lens is self-assembled using only one type of proteins. Using small angle X-ray scattering and computational methods, I studied how the proteins interact and the resulted in the homogeneous phase of the lens system. Results showed that the proteins are patchy particles with various patch numbers. The lens is assembled by distributing different patch number proteins at different radial positions to achieve both graded refractive index while maintaining transparency.
The lens system is very similar to Pi Dan（皮蛋） where the egg white proteins experienced a transition to form the gelled structure. We found that during this transition, the beta-sheet structure was preserved, whereas most of the other parts of the protein was unfolded. The unfolded part serves as the patches and the gelled structure was formed by this attractive interaction. At the end, I also compared the Pi Dan to the squid lens, and generalized the requirements of proteins as patchy particle that form transparent gels.
个人简介：蔡静，美国宾夕法尼亚大学物理学博士，现为该校博士后研究员，曾在摩根大通银行从事核心建模。其科研领域主要集中在生物系统的自组织结构。以第一作者的身份在Science上发表题为“eye patches: protein assembly of index-gradient squid lenses”的论文,受到了广泛关注，被Nature Photonics，Physics Today等杂志转载，并被诸多公共媒体报导。攻读博士及博士后期间，数次在American Physical Society March Meeting等国际会议上做相关学术报告；并参与了包括Physical Review Letters等国际知名期刊的评审工作。