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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 37: Biopolymers, Biomaterials and Bioinspired Functional Materials (joint session CPP/BP)

CPP 37.2: Talk

Thursday, March 21, 2024, 10:00–10:15, H 0111

Dichroic ATR-FTIR studies on thin bioinspired films of spider silk related peptide blendsMirjam Hofmaier1, •Thomas Scheibel2, Andreas Fery1, and Martin Müller11Leibniz Institute of Polymer Research Dresden (IPF), Institute of Physical Chemistry and Polymer Physics, 01069 Dresden, Germany — 2University of Bayreuth, Chair of Biomaterials, 95447 Bayreuth, Germany

Bioinspired binary blends of a crystalline (C) and amorphous (A) peptide sequence were prepared addressing analogy to C-A multiblockcopolymer-like spider silk proteins. C/A blends were prepared in hexafluoroisopropanol for molar mixing ratios C/(C+A)=0, 25, 50, 77, 100%, deposited as thin films (d=31-44nm) onto silicon substrates and checked for secondary structure and orientation by dichroic transmission (T-) and ATR-FTIR spectroscopy. Amide I band analysis revealed little β-sheet (<15%) and much disordered (>79%) structure and dichroic ratios (R) of Amide I components indicating no β-sheet orientation for all C/(C+A) values. Whereas, after swelling in methanol vapor C/A blend films revealed increasing β-sheet up to 54% and decreasing disordered structure down to 42% with increasing C/(C+A). Furthermore, R values of Amide I components assigned to antiparallel beta-sheet were found by T-FTIR indicating no in-plane orientation, while ATR-FTIR revealed R values indicating significant out-of-plane orientation of β-sheet crystallites for blend films with C/(A+C)>0. SFM microscopy showed larger needle-like fibrillar structures for C/A blend films, while C-A copolymer films revealed smaller fibrillar or spherical structures correlating with the lower orientation obtained by ATR-FTIR.

Keywords: silk protein film; beta-sheet; dichroic ATR-FTIR spectroscopy; circular dichroism; polymer orientation

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