Nanoscale chemical mapping of laser-solubilized silk

ArticleinMaterials Research Express 4(11) · August 2017with 181 Reads
Abstract
A water soluble amorphous form of silk was made by ultra-short laser pulse irradiation and detected by nanoscale IR mapping. An optical absorption-induced nanoscale surface expansion was probed to yield the spectral response of silk at IR molecular fingerprinting wavelengths with a high ~20 nm spatial resolution defined by the tip of the probe. Silk microtomed sections of 1-5 micrometers in thickness were prepared for nanoscale spectroscopy and a laser was used to induce amorphisation. Comparison of silk absorbance measurements carried out by table-top and synchrotron Fourier transform IR spectroscopy proved that chemical imaging obtained at high spatial resolution and specificity (able to discriminate between amorphous and crystalline silk) is reliably achieved by nanoscale IR. A nanoscale material characterization using synchrotron IR radiation is discussed.

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  • ... Such information is currently not experimentally accessible and could help a limited understanding of phase transitions. This method can be used for analysis of bio-materials, e.g., laser structured dominantly crystalline silk fibers and its amorphisation into water soluble form [20], molecular orientation in micro-thin silk fibers [21] at different spectral ranges [22], and bactericidal bio-materials [23] where structure influence to the biocidal function has to be better understood. Internal laser structuring of transparent glasses and dielectrics [24] can also benefit from the presented analysis of optical anisotropy in real and imaginary parts of the refractive index. ...
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