nano-FTIR resolves protein secondary structure with unprecedented resolution
The ultimate nanoscale resolution of nano-FTIR goes beyond spatial & ensemble averaged measurements known from conventional FT-IR spectroscopy and reveals the composition and orientation of single protein structures with an unmatched level of detail .
AFM height Reflectance image Fibril nano-FTIR absorption
α-helix β-sheet
1 µ m |
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ATR-FTIR absorption |
nano-FTIR absorption |
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1000 1200 1400 1600 1800 2000 |
Insulin / TMV mixture Pure insulin |
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Insulin |
TMV |
Wavenumber [ cm -1 ] |
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ß-amyloid fibrils |
1,600 1,650 1,700 Frequency ω ( cm -1 )
nano-FTIR quantifies a-helix and β-sheet content of single protein fibrils at the 10 -nm -scale .
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1,600 1,650 1,700 Frequency ω ( cm -1 ) nano-FTIR spectra of β-amyloid fibrils show variance in the Amide I band clearly differentiating α-helical and β-sheet secondary structures . The nanoscale observation of β-sheet formation in such aggregated proteins is crucial for the investigation of amyloid diseases such as Alzheimer ’ s or mad cow disease , and for the respective drug-development . An additional application involves the chemical identification of morphologically similar biological structures , such as distinguishing between Insulin fibers and the TMV virus . This type of identification would otherwise be impossible using standard ATR spectroscopy .
P . Schaefer et al ., NanoBio & Med 2017 , 11 , 22
I . Amenabar et al ., Nature Communications 2013 , 4 , 2890