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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 blends — Mirjam Hofmaier1, •Thomas Scheibel2, Andreas Fery1, and Martin Müller1 — 1Leibniz 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