Nanoscale optical and structural characterisation of silk.

Meguya Ryu,Elena P Ivanova,Mark J Tobin,Denver P Linklater,Jitraporn Vongsvivut,Vygantas Mizeikis,Adrian Cernescu,Saulius Juodkazis,Junko Morikawa,Reo Honda,Jing-Liang Li,Arturas Vailionis,Armandas Balčytis

doi:10.3762/bjnano.10.93

Meguya Ryu, Elena P Ivanova + Show 11 more

Open Access

https://doi.org/10.3762/bjnano.10.93

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Abstract

The nanoscale composition of silk defining its unique properties via a hierarchial structural anisotropy needs to be analysed at the highest spatial resolution of tens of nanometers corresponding to the size of fibrils made of β-sheets, which are the crystalline building blocks of silk. Nanoscale optical and structural properties of silk have been measured from 100 nm thick longitudinal slices of silk fibers with ca. 10 nm resolution, the highest so far. Optical sub-wavelength resolution in hyperspectral mapping of absorbance and molecular orientation were carried out for comparison at IR wavelengths of 2–10 μm using synchrotron radiation. A reliable distinction of transmission changes by only 1–2% as the anisotropy of amide bands was obtained from nanometer-thin slices of silk.

Highlights

Recent advances in the nanofabrication of electronic devices require cutting-edge analytical technologies to provide a reliable structural characterisation of materials at the nanoscale.Such technologies are important to probe molecular properties of cross sections smaller than 100 nm in all three dimensions, which is of rapidly growing interest in the field of Beilstein J
We demonstrated that the IR measurements of silk performed using three different methods, i.e., (i) a table-top Fourier-transform infrared (FTIR) transmission spectrometer, (ii) a synchrotron-based attenuated total reflection (ATR) FTIR spectrometer, and (iii) an atomic force microscopy (AFM) tip responding to the absorbed IR light, produced comparable spectral features [10]
The most pronounced peak corresponds to the separation between the equatorial (200) planes d(200) = 4.69 nm and crystal cross section of L ≈ 2.15 nm, while for the meridional (002) planes d(002) = 3.46 nm and crystal size of L ≈ 10.76 nm [18]. These are the dimensions of the β-sheets, which are crystalline segments in the silk fiber

Summary

Introduction

Recent advances in the nanofabrication of electronic devices require cutting-edge analytical technologies to provide a reliable structural characterisation of materials at the nanoscale.Such technologies are important to probe molecular properties of cross sections smaller than 100 nm in all three dimensions, which is of rapidly growing interest in the field of Beilstein J. Nanoscale optical and structural properties of silk have been measured from 100 nm thick longitudinal slices of silk fibers with ca. Optical sub-wavelength resolution in hyperspectral mapping of absorbance and molecular orientation were carried out for comparison at IR wavelengths of 2–10 μm using synchrotron radiation.

Results

Conclusion